Nyob rau hauv lub teeb ntawm ib puag ncig kev txhawj xeeb thiab kev hloov hluav taws xob, electrochemical CO2 txo (ECR) rau tus nqi-ntxiv multicarbon (C2+) fuels thiab tshuaj, siv hluav taws xob tauj dua tshiab, nthuav tawm cov kev daws teeb meem ntev ntev los kaw cov pa roj carbon monoxide nrog cov txiaj ntsig kev lag luam ntxiv.Txawm li cas los xij, electrocatalytic C─C coupling hauv aqueous electrolytes tseem yog ib qho kev sib tw qhib vim kev xaiv qis, kev ua haujlwm, thiab kev ruaj ntseg.Kev tsim cov catalysts thiab reactors tuav tus yuam sij los daws cov teeb meem no.Peb sau cov kev kawm tsis ntev los no yuav ua li cas kom ua tau zoo C─C coupling ntawm ECR, nrog rau cov tswv yim hauv electrocatalysts thiab electrocatalytic electrode / reactor tsim, thiab lawv cov txheej txheem sib thooj.Tsis tas li ntawd, tam sim no lub fwj thiab lub sijhawm yav tom ntej rau C2 + cov khoom tsim tau tham.Peb lub hom phiaj los muab cov ncauj lus kom ntxaws txog cov tswv yim sib koom ua ke ntawm lub xeev-ntawm-the-art C─C rau lub zej zog rau kev txhim kho ntxiv thiab kev tshoov siab hauv ob qho tib si kev nkag siab thiab kev siv thev naus laus zis.

Kev tso tawm ntau dhau ntawm cov pa roj carbon dioxide (CO2) mus rau hauv huab cua tau ua rau muaj kev cuam tshuam loj rau ib puag ncig thiab tseem ua rau muaj kev kub ntxhov thiab muaj peev xwm hloov tsis tau rau tib neeg lub neej (1, 2).Raws li atmospheric CO2 concentration nce sharply los ntawm 270 ppm (ib feem ntawm ib lab) nyob rau hauv thaum ntxov 1800s mus rau 401.3 ppm nyob rau hauv Lub Xya hli ntuj 2015, ib tug thoob ntiaj teb kev pom zoo ntawm kev rov ua dua cov pa roj carbon hneev taw tawm los ntawm tib neeg kev ua ub no tau mus txog (3, 4).Txhawm rau kom paub qhov ze ze rau cov pa roj carbon hneev taw, ib txoj hauv kev muaj peev xwm yog hloov qhov kev vam khom ntawm lub zog tam sim no thiab tshuaj lom neeg kev lag luam kom deb ntawm cov fossil fuels mus rau qhov chaw txuas ntxiv xws li hnub ci thiab cua (5-8).Txawm li cas los xij, feem ntau ntawm lub zog los ntawm cov peev txheej txuas ntxiv tsuas yog txwv rau 30% vim lawv qhov xwm txheej tsis sib xws, tshwj tsis yog tias txoj hauv kev rau cov khoom siv hluav taws xob loj yuav muaj (9).Yog li, raws li lwm txoj hauv kev, kev ntes CO2 los ntawm cov ntsiab lus xws li cov chaw tsim hluav taws xob, ua raws li kev hloov pauv mus rau hauv cov khoom siv tshuaj thiab cov roj, yog qhov ua tau zoo dua (9-12).Electrocatalytic CO2 txo (ECR) siv hluav taws xob tauj dua tshiab sawv cev rau qhov kev daws teeb meem ntev ntev vim yog qhov kev ua haujlwm me me uas yuav tsum tau ua rau kev hloov pauv, uas cov khoom muaj nqis ntxiv tuaj yeem xaiv tau (13).Raws li schematically illustrated nyob rau hauv daim duab 1, nyob rau hauv cov txheej txheem no, lub electrochemical electrolyzer converts CO2 thiab dej rau hauv chemicals thiab fuels powered los ntawm hluav taws xob tauj dua tshiab.Cov roj tshwm sim muaj peev xwm khaws cia ntev ntev thiab tseem tuaj yeem muab faib lossis siv tau, muab CO2 los ua cov khib nyiab loj, uas yuav raug ntes thiab muab rov qab rau lub reactor kom kaw lub voj voog.Ntxiv mus, qhov tshwm sim me me-molecule chemical feedstocks [piv txwv li, carbon monoxide (CO) thiab formate] los ntawm ECR tuaj yeem siv los ua cov khoom siv raw rau kev siv tshuaj lom neeg nyuaj.

Roj thiab tshuaj tuaj yeem ua tiav los ntawm ECR nrog kaw lub voj voog uas siv los ntawm cov khoom siv hluav taws xob txuas ntxiv xws li hnub ci, cua, thiab hydro.Cell engineering thiab catalyst engineering ua lub luag haujlwm tseem ceeb los txhawb kev xaiv, kev ua, thiab kev ua haujlwm rau CO2 hloov mus rau cov khoom muaj nqis ntxiv C2 + nrog lub zog ntom ntom.

Txawm li cas los xij, CO2 yog ib qho ruaj khov linear molecule nrog lub zog C═O daim ntawv cog lus (750 kJ mol−1) (14), ua rau nws nyuaj rau kev hloov pauv hluav taws xob.Yog li, nws yuav tsum muaj kev ua kom muaj zog siab, uas, dhau los, ua rau muaj peev xwm loj heev (15).Tsis tas li ntawd, ECR hauv aqueous electrolyte suav nrog ntau cov khoom siv hluav taws xob / proton hloov pauv ua ke nrog ntau qhov sib txawv ntawm cov tshuaj tiv thaiv nruab nrab thiab cov khoom lag luam (16-18), ua rau nws nyuaj heev.Table 1 piav qhia txog ib nrab ntawm electrochemical thermodynamic cov tshuaj tiv thaiv ntawm ECR cov khoom tseem ceeb, suav nrog CO, methane (CH4), methanol (CH3OH), formic acid (HCOOH), ethylene (C2H4), ethanol (CH3CH2OH), thiab lwm yam, ua ke nrog lawv. coj tus qauv redox peev xwm (19).Feem ntau, thaum lub sij hawm ECR txheej txheem, CO2 molecules thawj zaug adsorption thiab cuam tshuam nrog atoms ntawm catalyst nto rau daim * CO2-, ua raws li los ntawm ntau yam stepwise hloov ntawm protons thiab / los yog electrons mus rau txawv cov khoom kawg.Piv txwv li, CH4 ntseeg tau tsim los ntawm txoj hauv kev hauv qab no: CO2 → * COOH → * CO → * CHO → * CH2O → * CH3O → CH4 + * O → CH4 + * OH → CH4 + H2O (20).

Daim duab 2A qhia txog qhov ua tau zoo ntawm Faradaic (FE) nyob rau hauv cov nqi sib txawv (tam sim no ntom) rau cov ntawv tshaj tawm ECR electrocatalysts, uas sawv cev rau cov khoom xaiv ntawm cov tshuaj tiv thaiv (21–43).Qhov tseem ceeb, thaum lub xeev-of-the-art electrocatalysts tuaj yeem hloov CO2 rau hauv C1 cov khoom (CO lossis formate) nrog ntau dua 95% FE nyob rau hauv siab ntau lawm (> 20 mA cm−2 rau H-hom cell thiab> 100 mA cm- 2 rau ndlwg ntawm tes) (9, 21, 22, 25, 28, 44, 45), qhov kev xaiv zoo heev (> 90%) thiab cov khoom siv tau zoo ntawm cov tshuaj muaj ntau ntau (C2+) tsis tau paub txog tam sim no.Qhov no yog vim lub fact tias coupling rau C2 + cov khoom yuav tsum tau tuaj txog thiab adsorption ntawm ob peb CO2 molecules rau saum npoo, stepwise transformation, thiab spatial positioning (13).Yuav kom paub meej, raws li qhia hauv daim duab 2B, cov kev tshwm sim tom qab ntawm * CO intermediates txiav txim siab kawg C2 + cov khoom ntawm ECR.Feem ntau, C2H6 thiab CH3COO- qhia tib yam * CH2 nruab nrab, uas yog tsim los ntawm proton-coupled electron hloov cov kauj ruam ntawm * CO.Ntxiv protonation ntawm * CH2 muab * CH3 nruab nrab, uas ua rau tsim C2H6 ntawm * CH3 dimerization.Tsis zoo li C2H6 tiam, CH3COO- yog tsim los ntawm CO tso rau hauv * CH2.Lub * CO dimerization yog tus nqi-txhais kauj ruam rau C2H4, CH3CH2OH, thiab n-propanol (n-C3H7OH) tsim.Tom qab ib tug series ntawm electron hloov mus thiab protonation cov kauj ruam, lub * CO─CO dimer daim ntawv lub * CH2CHO intermediate, uas ua hauj lwm raws li ib tug selectivity-kev txiav txim kauj ruam rau C2H4 thiab C2H5OH.Tsis tas li ntawd, nws tau pom tias txo * CH2CHO rau C2H4 muaj qis zog thaiv dua li hloov * CH3CHO rau C2H5OH (46), uas yuav piav qhia qhov siab dua FE rau C2H4 tshaj C2H5OH ntawm feem ntau cov tooj liab catalysts.Tsis tas li ntawd, stabilized C2 intermediates tuaj yeem hloov mus rau n-C3H7OH ntawm CO insertion.Txoj kev nyuaj thiab tswj tsis tau cov tshuaj tiv thaiv thaum lub sij hawm C2 + tshuaj tsim yog vim muaj ntau ntau permutations mus rau qhov chaw protonation, nrog rau kev koom tes ntawm nonelectrochemical kauj ruam (19, 47).Yog li ntawd, kev tsim cov khoom siv electrocatalysts yog qhov yuav tsum tau ua ua ntej rau cov khoom tsim C2 + ntawm high yield.Hauv kev tshuaj xyuas no, peb tsom mus hais txog qhov kev nce qib tsis ntev los no ntawm cov tswv yim hauv electrocatalyst tsim rau xaiv C2 + khoom tsim los ntawm ECR.Peb kuj muab cov ntsiab lus ntawm kev nkag siab ntawm cov txheej txheem muaj feem xyuam.Electrode thiab reactor tsim kuj tseem yuav tau hais qhia tias yuav ua li cas kom ua tau zoo, ruaj khov, thiab ua haujlwm loj ntawm ECR.Tsis tas li ntawd, peb yuav tham txog cov kev sib tw uas tseem tshuav thiab yav tom ntej rau electrochemical hloov pauv ntawm CO2 rau hauv cov tshuaj muaj nqis ntxiv C2 +.

(A) FE nyob rau hauv cov nqi sib txawv (tam sim no ceev) rau cov qhia ECR electrocatalysts (21–43, 130).(B) Feem ntau ua tau C2+ txoj hauv kev thaum ECR.Rov ua dua nrog kev tso cai los ntawm American Chemical Society (47).

Electrocatalytic transformation ntawm CO2 rau hauv cov tshuaj fuels thiab feedstocks yog lub peev xwm thev naus laus zis kom ua tiav lub voj voog hluav taws xob tsis nruab nrab (11).Txawm li cas los xij, FE ntawm C2 + cov khoom lag luam tseem nyob deb ntawm kev siv tswv yim, qhov twg lub xeev-of-the-art catalysts tso cai rau kev tsim cov khoom C2 nrog ib ncig ntawm 60% FE (13, 33), thaum C3 ntau lawm tsuas yog tsawg dua 10%. FE (48, 49).Txo kev sib txuas ntawm CO2 rau C2 + cov khoom lag luam yuav tsum muaj cov catalysts heterogeneous nrog kev sib koom ua ke morphological thiab hluav taws xob ntau (50, 51).Lub catalytic nto yuav tsum tau rhuav tshem cov kev sib raug zoo ntawm cov intermediates (47, 52, 53).Ntxiv mus, kom ua tiav C─C daim ntawv cog lus, cov tshuaj tiv thaiv absorbed intermediates ntawm catalyst nto yuav tsum nyob ze rau ib leeg.Tsis tas li ntawd, txoj hauv kev los ntawm qhov pib adsorbed nruab nrab mus rau qhov tshwj xeeb C2 + cov khoom yuav tsum tau tswj kom zoo vim tias muaj ntau yam proton-pab electron hloov cov kauj ruam.Xav txog qhov nyuaj ntawm CO2 txo qis rau C2 + cov khoom, electrocatalysts yuav tsum tau ua tib zoo tailored kom cov selectivity.Raws li cov tsiaj nruab nrab thiab cov tshuaj muaj pes tsawg leeg, peb categorize C2 + cov khoom rau hauv multicarbon hydrocarbons thiab oxygenates (4, 54).Txhawm rau ua kom muaj txiaj ntsig zoo electrocatalysts rau kev tsim C2 + molecule, ntau lub tswv yim tsim catalyst, xws li heteroatom doping, crystal facet regulation, alloy / dealloying, oxidation state tuning, thiab deg ligand control, tau ua kom pom (35, 41, 55-61) .Kev tsim kho kom zoo yuav tsum xav txog cov txiaj ntsig tau hais los saum no thiab ua kom cov txiaj ntsig zoo tshaj plaws.Tsis tas li ntawd, kev nkag siab txog dab tsi active-site motifs ua rau xws li ib tug tshwj xeeb catalytic cwj pwm tej zaum yuav ntxiv ci ntsa iab ib tug meej catalyst tsim rau C─C coupling.Li no, yuav ua li cas tsim ECR catalyst rau cov khoom tshwj xeeb (multicarbon hydrocarbons thiab oxygenates) thiab cov txheej txheem cuam tshuam yuav tau tham hauv ntu no.

C2 + hydrocarbons, xws li C2H4, yog cov tshuaj nexus rau ntau yam kev lag luam tshuaj, xws li polyethylene ntau lawm (62, 63).Tsis tas li ntawd, nws tuaj yeem siv ncaj qha los ua cov roj rau vuam lossis cov khoom sib xyaw hauv cov pa roj (12).Hydrogenation ntawm CO (Fischer-Tropsch synthesis) thiab CO2 tau siv los tsim C2 + hydrocarbons rau lub sijhawm ntev hauv kev lag luam nplai tab sis sib tw los ntawm kev siv hluav taws xob siab thiab kev cuam tshuam ib puag ncig (64).Hauv qhov tsis sib xws, electrochemical CO2 txo qis siv lub zog tauj dua tshiab muab txoj hauv kev huv dua thiab ruaj khov dua.Kev siv zog loj tau tsim los txhim kho cov electrocatalysts mus rau C2 + hydrocarbons (32, 33, 65-70).

Bimetallic electrocatalysts tau raug tshawb xyuas los ua txhaum qhov kev sib raug zoo thaum lub sij hawm electrochemical CO2 hloov dua siab tshiab, uas tuaj yeem txhim kho qhov tseem ceeb nruab nrab thiab qis dua qhov muaj peev xwm thiab, yog li, tig, nce qhov kev xaiv (71-74).Thaum muaj cov ntaub ntawv alloy xws li Au-Cu, Ag-Cu, Au-Pd, thiab Cu-Pt tau ua kom pom kev ua haujlwm siab C1 ntau lawm los ntawm kev ruaj khov ntawm qhov tseem ceeb nruab nrab (73, 75), cov nyhuv alloy rau C2 + hydrocarbon tsim zoo li yuav tsum complex (76).Piv txwv li, hauv Cu-Ag bimetallic system, cov khoom faib tuaj yeem tswj tau yooj yim los ntawm kev kho qhov atomic piv ntawm Ag thiab Cu (77).Cov qauv Cu-nplua nuj yog nyiam rau cov khoom siv hydrocarbon, thaum cov khoom ntawm qhov chaw Ag-nplua nuj yog tus thawj coj los ntawm CO, qhia txog qhov tseem ceeb ntawm atomic piv rau alloyed ECR electrocatalysts.Cov txiaj ntsig geometric tshwm sim los ntawm kev teeb tsa atomic hauv zos tuaj yeem cuam tshuam rau kev khi lub zog ntawm cov nruab nrab.Gewirth thiab cov neeg ua haujlwm ua haujlwm (36) tau pom tias Cu-Ag alloys los ntawm cov khoom siv hluav taws xob ntxiv-tswj electrodeposition tau nthuav tawm ~ 60% FE rau C2H4 hauv alkaline flow electrolyzer (Fig. 3, A thiab B).Nyob rau hauv cov ntaub ntawv no, optimized C2H4 selectivity yuav ua tau tiav los ntawm morphology thiab Ag-loading tuning.Cov chaw Ag tau ntseeg tias ua lub luag haujlwm ntawm kev txhawb nqa rau CO tsim thaum ECR.Tom qab ntawd, qhov muaj txiaj ntsig zoo ntawm CO intermediate tuaj yeem pab C─C coupling hauv Cu nyob sib ze.Tsis tas li ntawd, Ag kuj tseem tuaj yeem txhawb kev tsim ntawm Cu2O thaum lub sij hawm Cu-Ag catalyst synthesis (Fig. 3C), uas ua rau kev txhim kho C2H4 ntau lawm efficiency.Qhov kev sib koom ua ke no qhib qhov muaj peev xwm tshiab rau kev tsim C─C coupling catalysts.Tsis tas li ntawd, cov qauv sib xyaw ntawm cov hlau sib txawv hauv cov txheej txheem hlau kuj tseem tuaj yeem txiav txim siab txog kev faib khoom ntawm ECR.Siv Pd-Cu alloy ua piv txwv (Fig. 3D), Kenis thiab cov neeg ua haujlwm ua haujlwm (71) tau pom tias cov txheej txheem sib cais Pd-Cu catalyst tuaj yeem muab qhov kev xaiv siab tshaj plaws (~ 50%) rau C2H4 piv nrog nws qhov kev txiav txim thiab tsis zoo. cov neeg sib tw.Raws li txoj kev xav d-band, feem ntau, kev hloov pauv hlau nrog qhov chaw qis dua d-band qhia pom tias tsis muaj zog ntawm kev sib txuas ntawm qhov chaw tsim khoom nruab nrab ntawm cov hlau nto (78).Thaum lub sij hawm sib cais Pd-Cu alloy pom zoo ib yam catalytic selectivity thiab kev ua si rau CO nrog Cu nanoparticles (NPs), nws muaj tag nrho sib txawv binding zog rau intermediates los ntawm Pd tuning.Raws li pom nyob rau hauv daim duab 3E, theem-sib cais Cu-Pd alloy pom qhov qis tshaj-d-band chaw, whereas ntawm Cu NP yog siab tshaj.Nws qhia tias cov theem sib cais Cu-Pd alloy muaj qhov qis tshaj qhov sib khi lub zog rau CO intermediate.Qhov kev soj ntsuam no txhais tau hais tias cov txiaj ntsig geometric thiab cov qauv tuaj yeem ua lub luag haujlwm ntau dua li cov txiaj ntsig hluav taws xob rau kev txhim kho cov hydrocarbon selectivity nyob rau hauv theem sib cais Cu-Pd alloy rooj plaub.Txog rau tam sim no, tsuas yog tooj liab ntshiab lossis tooj liab-raws li alloy qhia tau hais tias muaj kev xaiv zoo dua thiab ua haujlwm rau electrochemical txo CO2 rau C2 + hydrocarbons.Yog li, nws yog qhov tsim nyog los tsim ib qho tshiab electrocatalyst rau C2 + hydrocarbon ntau lawm los ntawm ECR.Kev tshoov siab los ntawm CO2 hydrogenation, kev tshawb fawb ua ntej pom tau tias Ni-Ga alloy nrog cov theem sib txawv tuaj yeem siv rau C2H4 tiam (79).Nws pom tias Ni5Ga3 zaj duab xis tuaj yeem txo CO2 rau C2H4 thiab ethane (C2H6).Txawm hais tias FE rau C2 + hydrocarbons tsawg dua 5%, nws tuaj yeem qhib cov kab tshiab rau kev tshuaj ntsuam electrocatalyst mus rau C─C coupling raws li cov nyhuv alloy.

(A rau C) Cu-Ag bimetallic catalysts fabricated los ntawm additive-tswj electrodeposition: (A) scanning electron microscopy (SEM) ntawm Cu hlau, Cu-Ag poly, thiab Cu-Ag hlau thiab (B) sib xws C2H4 FE.(C) EXAFS tau qhia tias Cu-Ag hlau yog homogeneously tov thiab Cu (I) oxide tau nthuav tawm.(A) mus rau (C) raug tsim tawm nrog kev tso cai los ntawm American Chemical Society (36).(D thiab E) Cu-Pd catalysts nrog cov qauv sib txawv: (D) Daim duab qhia, kis tau tus mob electron microscopy (TEM) cov duab, thiab lub zog-dispersive spectroscopy element maps ntawm kev txiav txim, kev tsis sib haum xeeb, thiab theem sib cais Cu-Pd alloys thiab (E ) nto valence band photoemission spectra thiab d-band center (txoj kab ntsug) ntawm Cu-Pd alloys txheeb ze rau qib Fermi.(D) thiab (E) raug tsim dua tshiab nrog kev tso cai los ntawm American Chemical Society (71).aw, arbitrary units.

Dhau li ntawm cov nyhuv alloy, kev tswj cov oxidation xeev yog lwm lub hauv paus ntsiab lus tseem ceeb los kho qhov kev ua tau zoo ntawm electrocatalysts, uas tuaj yeem cuam tshuam rau cov qauv hluav taws xob hauv zos ntawm cov khoom.Thawj qhov piv txwv rau oxidation lub xeev tuning ntawm catalyst yog siv oxide-derived cov ntaub ntawv.Cov pa oxygen residual nyob rau saum npoo los yog subsurface ntawm catalyst tom qab nyob rau hauv qhov txo qis tuaj yeem tswj cov oxidation lub xeev ntawm cov hlau chaw.Piv txwv li, plasma-oxidized Cu tau pom ntau dua 60% kev xaiv rau C2H4, uas tau sau tseg rau qhov txo qis-resistant Cu + (37).Txhawm rau paub meej tias Cu + yog qhov tseem ceeb rau kev xaiv ethylene siab, peb tau ua cov kev sim tswj kev siv cov ntshav sib txawv (Fig. 4A).Nyob rau hauv situ nyuaj x-ray absorption spectroscopy ntxiv qhia tau hais tias cov residual oxides nyob rau hauv lub (sub) deg txheej yog ruaj khov tiv thaiv txo tus mob, nrog ib tug tseem ceeb npaum li cas ntawm Cu + hom tshuav tom qab 1 teev ntawm kev txo nyob rau hauv kuj muaj peev xwm ntawm −1.2 V piv rau reversible. hydrogen electrode (RHE).Tsis tas li ntawd, electroredeposition ntawm tooj liab los ntawm sol-gel tooj liab oxychloride tau txheeb xyuas dua tias stabilized nto Cu + hom tuaj yeem txhim kho kev xaiv ntawm C2H4 (61).Lub xeev oxidation ntawm cov tooj liab catalyst nyob rau hauv ntau qhov kev siv peev xwm tau taug qab siv lub sijhawm daws teeb meem hauv situ soft x-ray absorption spectroscopy.Thawj kauj ruam hloov ntawm Cu2 + mus rau Cu + yog ceev heev;Txawm li cas los xij, ntxiv electrochemical txo ntawm Cu + hom rau Cu0 yog qeeb dua.Nyob ib ncig ntawm 23% ntawm Cu+ hom tseem nyob txawm tias tom qab 1-teev txo qis hauv qab −1.2 V piv rau RHE (Fig. 4B).Cov kev tshawb fawb Mechanistic tau qhia tias qhov sib cuam tshuam ntawm Cu + thiab Cu0 ua rau electrostatic attraction ntawm intermediates txij thaum C atom ntawm * CO@Cu + raug nqi zoo, hos * CO@Cu0 yog tsis zoo them (80), uas, nyob rau hauv lem, txhawb lub C─C daim ntawv cog lus tsim thiab yog li tsim C2 + hydrocarbons.Ntxiv rau cov khoom siv oxide-derived, tooj liab nitride (Cu3N) kuj tau siv los ua kom tiav (sub) deg Cu + hom kom txo tau lub zog dimerization ntawm * CO (81).Tsis tas li ntawd, piv nrog oxide-derived Cu, Cu3N-derived Cu + hom muaj ntau ruaj khov (Fig. 4C).Raws li qhov tshwm sim, nitride-derived tooj liab catalyst muaj FE ntawm 39 ± 2% rau C2H4, outperforming cov ntshiab Cu (~ 23%) thiab oxide-derived Cu (~ 28%).Analogous rau cov lus hais saum toj no Cu + / Cu catalytic system, boron tau siv los ua heteroatom dopant los qhia thiab stabilize Cuδ + (41).Qhov nruab nrab oxidation xeev ntawm tooj liab tuaj yeem tswj tau ntawm +0.25 txog +0.78 los ntawm kev hloov cov concentration ntawm boron dopant.Kev ntsuas qhov ceev ntawm lub xeev tau pom tias cov hluav taws xob hloov pauv ntawm tooj liab mus rau boron, ua rau cov dopant-induced zoo them tooj liab qhov chaw.Cov boron-doped tooj liab tau pom tias muaj zog ntau ntxiv ntawm * CHO intermediate thiab, yog li, suppressed cov tshuaj tiv thaiv txoj kev mus rau C1 cov khoom.Tsis tas li ntawd, nws tuaj yeem ua rau kom muaj kev xaiv rau ntau cov pa roj carbon hydrocarbons los ntawm kev txo qis * CO dimerization cov tshuaj tiv thaiv lub zog (Fig. 4D).Los ntawm optimizing qhov nruab nrab oxidation lub xeev ntawm tooj liab, siab C2 FE ntawm ~ 80% nrog ~ 53% C2H4 yuav ua tiav nyob rau hauv ib tug nruab nrab tooj liab oxidation xeev ntawm +0.35 (Fig. 4E).Txog niaj hnub no, cov chaw nquag ntawm tooj liab tau raug txheeb xyuas tias Cu0, Cuδ+, thiab / lossis lawv qhov cuam tshuam rau ECR hauv kev tshawb fawb sib txawv (39, 41, 42, 81, 82).Txawm li cas los xij, dab tsi yog lub vev xaib nquag tseem tab tom sib cav.Thaum lub heteroatom doping-induced Cuδ + catalysts tau pom tias muaj zog heev rau ECR rau C2 + cov khoom, cov nyhuv synergistic los ntawm ib txhij generated tsis xws luag thiab interfaces yuav tsum tau xav txog.Yog li ntawd, cov txheej txheem hauv operando characterizations yuav tsum tau tsim los txheeb xyuas qhov chaw nquag ntawm tooj liab thiab saib xyuas lub peev xwm hauv qhov hloov pauv ntawm cov chaw nquag hauv cov xwm txheej tshwm sim.Tsis tas li ntawd, kev ruaj ntseg ntawm qhov zoo ntawm cov tooj liab yog lwm qhov kev txhawj xeeb hauv electrochemical txo cov xwm txheej.Yuav ua li cas los tsim cov catalysts nrog cov chaw ruaj khov Cuδ + tseem yog qhov nyuaj.

(A) Cov ntsiab lus ntawm C2H4 selectivity ntawm cov plasma-activated tooj liab catalysts sib txawv.Luam tawm nrog kev tso cai los ntawm Nature Publishing Group (37).Scale bar, 500nm.(B) Ratio ntawm Cu oxidation xeev txheeb ze rau lub sij hawm cov tshuaj tiv thaiv ntawm −1.2 V piv rau RHE nyob rau hauv electroredeposited tooj liab.Luam tawm nrog kev tso cai los ntawm Nature Publishing Group (61).(C) Qhov piv ntawm Cu + hom nrog lub sijhawm ua haujlwm ntawm −0.95 V piv rau RHE hauv Cu-on-Cu3N lossis Cu-on-Cu2O.Luam tawm nrog kev tso cai los ntawm Nature Publishing Group (81).(D) Boron doping muaj peev xwm hloov qhov nruab nrab adsorption zog ntawm CO nyob rau hauv tooj liab nto thiab txo cov CO─CO dimerization zog.1 [B], 2 [B], 3 [B], 4 [B], thiab 8 [B] hais txog qhov concentration ntawm subsurface boron doping nyob rau hauv cov tooj liab catalysts, uas yog 1/16, 1/8, 3/ 16, 1/4, thiab 1/2, feem.(E) Kev sib raug zoo ntawm lub xeev oxidation thiab FE ntawm C2 lossis C1 cov khoom hauv boron-doped tooj liab catalysts.(D) thiab (E) raug luam tawm nrog kev tso cai los ntawm Nature Publishing Group (41).(F) SEM dluab ntawm tooj liab foils nrog txawv thicknesses ntawm Cu2O films ua ntej (sab saum toj) thiab tom qab (hauv qab) ECR.Luam tawm nrog kev tso cai los ntawm American Chemical Society (83).

Sib nrug los ntawm cov qauv hluav taws xob, cov khoom siv oxide-derived tuaj yeem ua rau morphology lossis cov qauv hloov pauv thaum lub sijhawm txo cov txheej txheem.Los ntawm qhov kev xav ntawm morphology los yog cov qauv, kev txhim kho electrochemical kev ua tau zoo ntawm oxide-derived electrocatalysts tau raug ntaus nqi los ntawm kev tsim cov active grain ciam teb, ntug, thiab cov kauj ruam (83-85).Yeo thiab cov neeg ua haujlwm ua haujlwm (83) tau tshaj tawm cov kev xaiv C─C coupling ntawm electrodeposited Cu2O films nrog txawv thicknesses (Fig. 4F).Hauv qhov xwm txheej Raman spectroscopy tau qhia tias qhov chaw ntawm Cu2O cov yeeb yaj kiab raug txo kom ruaj khov Cu0 thaum ECR (83).Raws li qhov tshwm sim, nws yog xim hlau Cu0 tau lees paub tias yog lub chaw catalytic active chaw hloov Cu + hom lossis Cu + / Cu0 interface.Nyob rau hauv tus txheej txheem ntawm txo Cu2O rau nws yog xim hlau Cu0, lub catalyst nto yog zoo li nyob rau hauv situ daim ntawv cov kauj ruam, npoo, thiab terraces.Nws tau taw qhia tias cov kauj ruam tsim thiab cov npoo muaj zog dua li cov terraces, pib los ntawm lawv txoj kev ruaj khov nrog * CO, uas tuaj yeem txuas ntxiv hydrogenate * CO rau * CHO lossis * CH2O.Dhau li ntawd, ntug Cu atoms yog tus txhawb nqa * CHO thiab * CH2O tsim.Cov hauj lwm yav dhau los tau qhia tias * CHO thiab * CH2O intermediates yog qhov zoo dua rau C─C coupling dua * CO hauv kinetics (86).Los ntawm kev tswj cov morphology saum npoo, chemisorption energies ntawm * CHO thiab * CH2O intermediates tuaj yeem ua kom zoo dua.Hauv txoj kev tshawb no, cov kws sau ntawv pom tias FE ntawm C2H4 txo qis los ntawm 40 mus rau 22% thaum lawv nce lub thickness ntawm Cu2O nyias zaj duab xis los ntawm 0.9 mus rau 8.8 μm.Qhov no yog vim qhov concentration ntawm tsawg sib koom ua Cu uas nce nrog qhov nce hauv Cu2O thickness.Cov atoms undercoordinated tuaj yeem khi nrog H thiab, yog li, nyiam dua rau hydrogen evolution dua li C─C coupling.Qhov kev ua haujlwm no tau pom tias cov oxide-los ntawm tooj liab catalyst tuaj yeem txhim kho C2H4 kev xaiv ntawm qhov chaw morphology reconstruction es tsis txhob qhia cov nqi Cuδ + hom.Siv cov oxide-derived catalysts, ethane (C2H6) kuj tau xaiv los ntawm kev pab los ntawm palladium (II) chloride (PdCl2) additive nyob rau hauv electrolyte (34).Nws tau pom tias cov adsorbed PdClx ntawm qhov chaw ntawm Cu2O-derived Cu ua lub luag haujlwm tseem ceeb rau C2H6 evolution.Tshwj xeeb, CO2 thawj zaug raug txo rau C2H4 ntawm Cu2O-derived active Cu chaw, thiab tom qab ntawd cov tsim C2H4 yuav hydrogenated nrog kev pab los ntawm adsorbed PdClx los tsim C2H6.FE ntawm C2H6 tau nce los ntawm <1 txog 30.1% nrog kev pab ntawm PdCl2.Qhov kev ua haujlwm no qhia tias kev sib xyaw ua ke ntawm ECR catalyst thiab electrolyte additive tuaj yeem qhib cov hauv kev tshiab rau cov khoom tsim tshwj xeeb C2 +.

Morphology thiab / lossis cov qauv kev cai sawv cev rau lwm lub tswv yim los hloov cov kev xaiv catalytic thiab kev ua ub no.Kev tswj qhov loj me, cov duab, thiab nthuav dav ntawm cov catalyst tau nthuav dav rau kev txhim kho ECR (58, 87, 88).Piv txwv li, Cu(100) facet yog intrinsically nyiam rau C2H4 tiam, thaum lub dominated khoom los ntawm Cu(111) catalyst yog methane (CH4) (87).Hauv kev tshawb fawb ntawm Cu nanocrystals nrog ntau cov duab thiab qhov ntau thiab tsawg, Buonsanti thiab cov neeg ua haujlwm sib koom ua ke (58) tau qhia txog qhov loj me me ntawm C2H4 selectivity hauv lub voos xwmfab zoo li tooj liab nanocrystals (Fig. 5A).Intrinsically, cubic Cu nanocrystals nthuav tawm ntau dua C2H4 kev ua haujlwm thiab kev xaiv ntau dua spherical Cu nanocrystals vim qhov tseem ceeb ntawm (100) facet.Lub pob zeb me me ntawm cubic Cu tuaj yeem ua rau muaj kev ua haujlwm siab dua vim tias qhov nce siab ntawm qhov chaw qis qis, xws li cov fab, cov kauj ruam, thiab kinks.Txawm li cas los xij, qhov muaj zog chemisorption ntawm qhov chaw qis qis tau nrog H2 thiab CO xaiv ntau dua, ua rau qis dua hydrocarbon FE.Ntawm qhov tod tes, qhov sib piv ntawm ntug qhov chaw rau qhov chaw dav hlau poob nrog qhov nce ntawm qhov ntau thiab tsawg, uas tseem cuam tshuam rau kev ua haujlwm ntawm C2H4 ntau lawm.Cov kws sau ntawv tau pom tias qhov nruab nrab-qhov loj me ntawm tooj liab nanocube nrog 44-nm ntug ntev tau pom qhov siab tshaj plaws C2H4 xaiv vim qhov ua kom zoo sib npaug ntawm qhov loj me thiab qhov ntom ntawm ntug qhov chaw.Tsis tas li ntawd, morphology tseem tuaj yeem cuam tshuam rau pH hauv zos thiab kev thauj mus los loj thaum ECR.Nws tau raug pom tias qhov siab pH hauv cheeb tsam nyob ib puag ncig ntawm qhov chaw catalyst, uas yog tshwm sim los ntawm qhov chaw tsim tawm OH-, suppresses txoj kev tawm tsam proton.Raws li qhov tshwm sim, C2 + hydrocarbon tsim los ntawm * CO dimerization tuaj yeem txhim kho, thiab CH4 tsim los ntawm * COH nruab nrab yuav raug cuam tshuam.Copper nanowire arrays (Fig. 5B) tau ua kom pom tias ua kom muaj zog hauv zos pH (68).Raws li ib qho kev siv electrolyte, CO2 saturated potassium bicarbonate (KHCO3) tov yuav sai sai neutralize lub zos OH− (HCO3− + OH− = CO32− + H2O) thiab txo cov pH hauv zos.Nrog rau qhov elongated microstructure, qhov diffusion ntawm HCO3- rau hauv Cu nanowire arrays tuaj yeem ua rau qis qis kom qhov cuam tshuam tsis zoo rau hauv zos OH- yuav raug txwv rau qee qhov.Raws li lub hauv paus ntsiab lus zoo sib xws, tooj liab meshes nrog precisely tswj mesopores (Fig. 5C) ua kom pom kev txhim kho FE rau C2H4 lossis C2H6 ntau lawm (32).Nws tau pom tias pH hauv cheeb tsam hauv qhov chaw electrode tuaj yeem nce ntxiv los ntawm kev nqaim qhov pore dav, ua rau txo qis C1 khoom FE thiab txhim kho C2 khoom FE.Tsis tas li ntawd, los ntawm kev nce lub pore qhov tob, cov khoom txo qhov loj tuaj yeem raug kho los ntawm C2H4 mus rau C2H6.FE ntawm C2H6 yog siab li 46%.Txij li thaum cov tshuaj tau raug kaw nyob rau hauv lub pores thaum lub sij hawm ECR, lub sij hawm tuav lub sij hawm ntev ntawm cov intermediates tseem ceeb tshwm sim los ntawm qhov tob pores tau piav qhia tias yog vim li cas lub ntsiab ntawm lub siab xaiv rau saturated C2 hydrocarbon.CuI-derived Cu nanofibers kuj pom muaj kev xaiv siab rau C2H6 (FE = 30% ntawm −0.735 V piv rau RHE) (89).Lub anisotropic morphology thiab siab nto roughness ntawm CuI-derived Cu nanofibers tuaj yeem txhim kho cov cuab yeej ua haujlwm ntawm absorbed H2 thiab yog li nce FE ntawm C2H6.

(A txog C) Morphology lossis cov qauv kev cuam tshuam.(A) Qhov ntom ntawm atoms (sab laug axis) thiab qhov piv ntawm atoms ntawm ntug qhov chaw (Nedge) rau atoms ntawm (100) dav hlau (N100) (txoj cai axis) nyob rau hauv qhov cuam tshuam rau ntug ntev (d).Luam tawm nrog kev tso cai los ntawm John Wiley thiab Cov Tub (58).(B) Cov txheej txheem ntawm morphology ua rau pH hloov pauv.Rov ua dua nrog kev tso cai los ntawm John Wiley thiab Cov Tub (68).(C) Cov khoom xaiv ntawm mesopore tooj liab nrog qhov sib txawv ntawm qhov pore thiab qhov tob.Rov ua dua nrog kev tso cai los ntawm John Wiley thiab Cov Tub (32).(D txog H) Ligand cov teebmeem.(D thiab E) ECR ntawm tooj liab nanowire (Cu NW) nrog ntau hom amino acids (D) lossis hloov pauv (E) ntawm −1.9 V. Rov ua dua nrog kev tso cai los ntawm Royal Society of Chemistry (35).(F) Ntau lawm tus nqi ntawm C2H4 nyob rau hauv txawv halide electrolytes nrog txawv adsorption peev xwm ntawm Cu(35).Luam tawm nrog kev tso cai los ntawm American Chemical Society (91).NHE, ib txwm hydrogen electrode.(G) FE ntawm C2H4 thiab CO hauv qhov sib txawv ntawm KOH electrolytes thiab (H) Tafel txoj kab nqes ntawm C2H4 hauv ntau qhov sib txawv ntawm KOH electrolytes.(G) thiab (H) raug tsim tawm los ntawm American Association for the Advancement of Science (AAAS) (33).

Catalyst nto hloov kho siv cov me me molecules yog lwm lub tswv yim zoo los txhim kho electrochemical kev ua tau zoo ntawm ECR.Cov tswv yim no tuaj yeem cuam tshuam rau microenvironment nyob ze ntawm qhov chaw catalyst, uas tuaj yeem ua kom ruaj khov ntawm cov neeg nruab nrab tseem ceeb vim muaj kev cuam tshuam ntawm cov ligand nto thiab nruab nrab.Amine tau tshaj tawm tias yog tus hloov kho los txhawb ECR (35).Ntau yam amino acids, suav nrog glycine (Gly), dl-alanine (Ala), dl-leucine (Leu), dl-tryptophan (Tyr), dl-arginine (Arg), thiab dl-tryptophan (Trp), tau raug tshawb xyuas. kawm lawv cov teebmeem ntawm tooj liab nanowires (35).Raws li pom hauv daim duab 5D, tag nrho cov amino acid-raws li ligands muaj peev xwm los txhim kho cov kev xaiv ntawm C2 + hydrocarbons.Qhov kev txhim kho zoo li no qhia tias ─COOH thiab ─NH2 cov pab pawg ua haujlwm hauv cov amino acid tej zaum yog lub luag haujlwm rau kev txhim kho kev xaiv ntawm ECR.Cov ntaub ntawv dhau los qhia tau hais tias qhov adsorption ntawm cov amino acids ntawm Cu nto tau ua tiav los ntawm ob pawg ─COOH thiab ─NH2 pawg (35, 90).Stearic acid (C17H35COOH, RCO2H), uas muaj tsuas yog pawg ─COOH, raug xaiv los txheeb xyuas lub luag haujlwm ntawm ─COOH.Lwm cov kev hloov kho, xws li a-anthraquinone diazonium ntsev (AQ), o-nitrobenzene diazonium ntsev (PhNO2), thiab dodecyl mercaptan (C12H25SH, RSH), uas tsis muaj ─COOH lossis ─NH2 pawg, kuj tau tshawb xyuas.Txawm li cas los xij, tag nrho lawv tsis zoo rau C2 + hydrocarbon FE txhim kho (Fig. 5E).Kev suav cov theoretical qhia tau hais tias ─NH3+ pawg hauv cov adsorbed zwitterionic glycine tuaj yeem ua kom ruaj khov * CHO nruab nrab vim lawv cov kev sib cuam tshuam, xws li hydrogen bonds.Kev taw qhia ntawm halide ions rau hauv electrolyte yog lwm txoj hauv kev los hloov cov catalysts (91, 92).Raws li pom nyob rau hauv daim duab 5F, C2H4 ntau lawm tus nqi ntawm plasma-activated Cu tuaj yeem nce ntxiv nrog kev pab ntawm halide additives.Nws tau pom tias I- ion muaj zog dua Br- thiab Cl-, nyob rau hauv kev pom zoo nrog lub zog adsorption ntawm I-, Br-, thiab Cl- ntawm Cu(100) facet (91).Dhau li ntawm halides, hydroxide ion kuj pom muaj txiaj ntsig zoo ntawm C2H4 xaiv.Tsis ntev los no, Sargent thiab cov neeg ua haujlwm sib koom tes (33) tau tshaj tawm txog kev hloov pauv CO2-rau-C2H4 nrog ~ 70% FE siv cov concentrated potassium hydroxide (KOH) electrolyte (txog 10 M) hauv lub xov tooj ntawm tes.Raws li qhia hauv daim duab 5G, qhov pib muaj peev xwm ntawm CO thiab C2H4 hauv 10 M KOH electrolyte yog qis dua piv rau qhov ntawd hauv 1 M KOH.Tsis tas li ntawd, Tafel slopes (Fig. 5H) ntawm C2H4 tsim tau poob nrog qhov nce ntawm hydroxide concentration (135 mV xyoo caum-1 hauv 1 M KOH thiab 65 mV xyoo caum-1 hauv 10 M KOH), qhia txog kev hloov pauv ntawm tag nrho tus nqi- kev txiav txim kauj ruam.Kev ua haujlwm ceev ceev (DFT) cov txiaj ntsig tau ua pov thawj tias muaj cov concentrated hydroxides tuaj yeem txo qis lub zog ntawm CO intermediate thiab tseem ua rau kom tus nqi tsis sib npaug ntawm ob lub atoms hauv adsorbed OCCO intermediates.Raws li qhov tshwm sim, OCCO nruab nrab yuav tau ua kom ruaj khov ntxiv los ntawm qhov muaj zog dipole attraction, ua rau txo qis kev ua kom lub zog cuam tshuam rau CO dimerization, uas yuav ua rau kev ua tau zoo tag nrho.

C2 + oxygenates xws li ethanol (CH3CH2OH) yog lwm pawg loj ntawm ECR cov khoom muaj txiaj ntsig zoo.Kev lag luam synthesis ntawm ethanol yog cov txheej txheem siv hluav taws xob ntau, uas tseem siv ntau cov ethylene lossis cov khoom noj ua liaj ua teb (40).Yog li, electrocatalytic ntau lawm ntawm ethanol lossis lwm yam C2 + oxygenates los ntawm CO2 ua rau muaj kev lag luam thiab ib puag ncig zoo.Txij li thaum ethanol tiam los ntawm ECR tau sib koom ua ke nruab nrab nruab nrab nrog C2H4 uas yog * C2H3O (43), xaiv hydrogenation ntawm qhov nruab nrab tuaj yeem hloov ECR txoj hauv kev los ntawm C2H4 mus rau cawv (64).Txawm li cas los xij, hauv ntau lub tshuab, kev xaiv rau C2 + oxygenates qis dua li cov hydrocarbons (31, 37, 39, 41, 42, 67).Yog li, nyob rau hauv seem no, peb yuav qhia txog cov txheej txheem tsim electrocatalyst uas tuaj yeem ua tiav C2 + oxygenate FE ntawm ntau dua 25%.

Raws li tau hais los saum no, cov khoom siv hluav taws xob bimetallic zoo tsim tuaj yeem txhim kho kev xaiv thiab kev ua haujlwm rau C2 + hydrocarbon ntau lawm.Ib lub tswv yim zoo sib xws tab sis tsis zoo ib yam kuj tau siv los txhim kho cov kev ua haujlwm electrocatalytic rau C2 + oxygenates (38, 93, 94).Piv txwv li, Ag-incorporated Cu-Cu2O catalysts nthuav tawm tunable ethanol xaiv, thiab qhov siab tshaj ethanol FE yog 34.15% (95).Cov ciam teb biphasic nyob rau hauv theem sib xyaw Ag-Cu alloy, es tsis txhob Ag / Cu atomic piv, tau txheeb xyuas tias yog qhov tseem ceeb rau kev xaiv ntau lawm ntawm ethanol.Txij li thaum lub chaw Cu nyob ze rau ntawm qhov chaw Ag nyob rau hauv ib theem sib xyaw qauv (Ag-Cu2OPB), qhov kev tsim tus nqi ntawm ethanol intermediates rau cov theem sib xyaw qauv tuaj yeem nce qib piv rau theem sib cais (Ag-Cu2OPS. ), ua rau muaj kev ua tau zoo ntawm ethanol tiam.Dhau li ntawm ethanol, Cu-Ag bimetallic NPs kuj tau pom los hloov CO2 rau acetate nrog ntxiv ntawm benzotriazole (93).Ntawm −1.33 V piv rau RHE, FE ntawm acetate yog 21.2%.Ob txoj hauv kev muaj peev xwm tshwm sim tau raug npaj rau hauv qhov no: Ib qho yog ua raws li CO dimerization, thiab lwm qhov yog nyob ntawm CO nkag, qhia txog lub luag haujlwm tseem ceeb ntawm CO nruab nrab tsim ntawm cov chaw Ag.Ib qho kev soj ntsuam zoo sib xws tau tshaj tawm hauv Cu-Zn catalysts (Fig. 6, A thiab B) rau ethanol ntau lawm (38).Los ntawm kev kho cov ntsiab lus ntawm Zn hauv Zn-Cu alloyed catalysts, qhov piv ntawm ethanol piv rau C2H4 FE tuaj yeem tswj tau zoo nyob rau hauv thaj tsam ntawm 0.48 txog 6, qhia txog qhov tseem ceeb ntawm CO-evolving qhov chaw rau C2 + oxygenate tsim.Tsim cov alloyed catalysts yuav ua rau muaj kev cuam tshuam ntawm cov khoom siv matrix, uas tej zaum yuav tsis xav tau.Yog li, txoj kev ncaj qha mus rau bimetallic catalysts yuav tsim nyog rau qee cov khoom lag luam.Jaramillo thiab cov neeg ua haujlwm sib koom ua ke (96) tau tsim kom yooj yim Au-Cu bimetallic system, ua ke los ntawm kev tso nyiaj ncaj qha ntawm NPs mus rau polycrystalline Cu ntawv ci, txhawm rau tshawb xyuas cov nyhuv tandem catalysis.Lub bimetallic Au-Cu nthuav tawm kev sib koom ua ke thiab kev ua haujlwm rau C2 + cawv, ua haujlwm zoo tshaj plaws tooj liab thiab kub, thiab Au-Cu alloy.Piv nrog rau Cu foil, lub bimetallic Au-Cu system pom tau tias muaj zog CO hauv zos vim tias muaj Au NPs (Fig. 6C) uas tau ua haujlwm rau CO tiam.Txij li thaum kub tsis ua haujlwm rau CO txo qis, qhov txhim kho C2 + cawv ntau npaum li cas ntawm Au-Cu bimetallic catalysts tau ascribed rau tandem catalysis mechanism.Tshwj xeeb, kub NPs tuaj yeem tsim kom muaj CO hauv zos siab nyob ze ntawm Cu nto.Tom ntej no, ntau lub zos CO molecules tuaj yeem txo qis ntxiv rau C2 + cawv los ntawm Cu.

(A txog C) Alloy teebmeem.(A) Qhov siab tshaj plaws FE ntawm ethanol thiab C2H4 thiab FE piv ntawm ethanol thiab ethylene ntawm ntau yam Cu-Zn alloys.(B) Ib nrab tam sim no ceev ntawm ethanol ntawm ntau yam Cu-Zn alloys.(A) thiab (B) raug tsim tawm nrog kev tso cai los ntawm American Chemical Society (38).(C) txo CO2 thiab CO evolution tus nqi ntawm kub, tooj liab, thiab Au-Cu bimetallic system.Luam tawm nrog kev tso cai los ntawm Nature Publishing Group (96).(D txog L) Morphology lossis cov qauv kev cuam tshuam.(D) Schematic illustration ntawm hlau ion cycling txoj kev.(E thiab F) SEM cov duab ntawm 100-cycle Cu ua ntej (E) thiab tom qab (F) qhov prereduction nyob rau hauv ECR tej yam kev mob.(G) TEM thiab xaiv thaj chaw electron diffraction qhia tias Cu(100) raug nthuav tawm thiab (H) dawb zog rau * OCCO thiab * OCCHO tsim ntawm Cu(100), Cu(111), thiab Cu(211) facets.(D) rau (G) raug muab luam tawm nrog kev tso cai los ntawm Nature Publishing Group (42).(I) Qhov sib piv ntawm cov pa oxygenates thiab hydrocarbons ua haujlwm ntawm lub peev xwm ntawm Cu (111), Cu (751), thiab Cu (100).(J) Coordinates tooj Cu(111), Cu(100), and Cu(751).(I) thiab (J) raug luam tawm nrog kev tso cai los ntawm National Academy of Sciences (97).(K) Cov txheej txheem ntawm kev hloov pauv ntawm Cu NPs rau cubic zoo li tooj liab.Luam tawm nrog kev tso cai los ntawm National Academy of Sciences (98).(L) SEM cov duab ntawm nanodendritic tooj liab ua ntej thiab tom qab ECR.Luam tawm nrog kev tso cai los ntawm American Chemical Society (99).

Kev xaiv ntawm cov khoom siv lead ua rau cov electrocatalysts tau pom tias yog ib txoj hauv kev zoo thiab ncaj ncees kom ua tiav FE rau cov khoom tshwj xeeb ECR thiab ib txoj hauv kev tseem ceeb rau kev nkag siab zoo.Yooj yim tab sis scalable synthesis ntawm ib leeg-crystal catalysts yog qhov nyuaj.Kev tshoov siab los ntawm cov txheej txheem galvanostatic charging-discharging (GCD) rau cov roj teeb, peb pab pawg tau tsim cov txheej txheem hlau ion caij tsheb kauj vab (Fig. 6D) los xaiv nthuav tawm cov khoom siv lead ua ntawm Cu catalyst (42).Tom qab 100 GCD cycles, qhov ntom ntom Cu nanocube array tau tsim rau ntawm Cu ntawv ci nrog nthuav tawm (100) facets (Fig. 6, E rau G).Lub 100-cycle catalyst nthuav tawm tag nrho C2 + cawv FE ntawm ntau dua 30% thiab cov C2 + cawv tam sim no ntom ntom ntawm ntau dua 20 mA cm-2.Txawm li cas los xij, 10-cycle Cu nrog qis dua ntawm (100) facet tsuas yog muaj C2 + cawv FE ntawm ~ 10%.DFT simulation tau lees paub tias Cu(100) thiab stepped (211) facets tau zoo dua rau C─C coupling dhau Cu(111), raws li qhia hauv daim duab 6H.Ib tug qauv catalyst, epitaxial Cu zaj duab xis nrog txawv exposed facets, tau siv los txiav txim lub active-site motifs mus rau C2 + oxygenate ntau lawm (Fig. 6I) (97).Txij li nws tsis tshua muaj txiaj ntsig rau CO * dimer nyob ib sab ntawm H * atoms ntawm qhov chaw uas muaj cov neeg nyob ze tsawg dua, qhov chaw Cu hauv qis tuaj yeem cuam tshuam qhov tsim ntawm hydrocarbons thiab ua rau txhim kho C2 + oxygenate FE vim tias nws nyuaj rau hydrogenate. C─C txuas ECR intermediates ntawm nws qhov chaw (97).Hauv kev tshawb fawb epitaxial Cu zaj duab xis, cov kws sau ntawv tau lees paub tias ECR ntawm Cu(751) facet tau pom tias muaj kev txhim kho oxygenate / hydrocarbon piv.Qhov kev txhim kho no tuaj yeem raug sau rau saum npoo Cu atom geometry ntawm cov Cu facets sib txawv thiab qhov sib thooj qis nruab nrab ntawm tus lej sib koom (Fig. 6J), qhov twg Cu atom koom ua ke, feem, nrog ob, plaub, thiab rau cov neeg nyob ze ze ntawm Cu(751), Cu(100), thiab Cu(111) facets.Nyob rau hauv situ morphology reconstruction kuj tau siv los txhim kho C2 + oxygenate FE.Lub cube zoo li Cu catalyst tau tsim los ntawm Yang thiab cov neeg ua haujlwm sib koom ua ke (98), uas pom tau tias C─C coupling kev ua tau zoo.Hauv kev nthuav dav, monodisperse Cu NPs (6.7 nm) nrog cov khoom sib txawv tau muab tso rau hauv cov ntawv txhawb nqa los ua cov khoom siv rau ECR.Pom tseeb, nce FE ntawm C2 + oxygenates tau pom nrog qhov nce hauv Cu NP loading.Nws tau pom tias cov ntaub ntawv ntim tau ntim qis nyob rau hauv cov kev hloov pauv siab hauv situ morphological kev hloov pauv hauv ECROCHIIIIIELIE zoo li morphisies tau tsim kawg (Daim duab 6k).Cov qauv tsim tshiab no tau pom tias muaj ntau dua electrocatalytically nquag.Tafel tsom xam hais tias CO dimerization yog tus nqi-txhais kauj ruam rau C2 cov khoom tsim, whereas ntawm n-propanol qhia ib tug discrete txoj kev nyob rau hauv no catalytic system.Nanodendritic tooj liab yog lwm qhov piv txwv uas qhia tau hais tias qhov tseem ceeb ntawm kev tswj morphology rau C2 + oxygenate ntau lawm (99).Luv luv, tag nrho FE ntawm qhov zoo-txhais tooj liab nanodendrite (Fig. 6L) rau C2 + cawv yog kwv yees li 25% ntawm −1.0 V piv rau RHE.Qhov zoo tshaj plaws n-propanol FE ntawm 13% tuaj yeem ua tiav ntawm −0.9 V. Xav txog kev ua haujlwm siab ntawm Cu atom, tooj liab-raws li catalysts ib txwm raug kev txom nyem los ntawm cov txheej txheem degradation thaum ECR, tshwj xeeb tshaj yog nyob rau hauv siab overpotential, uas, nyob rau hauv lem, ua rau cov neeg pluag. ruaj khov.Txawm li cas los xij, xws li nanodendritic tooj liab pom zoo ruaj khov rau cawv ntau lawm, qhia txog cawv FE ntawm ~ 24% tshaj 6 teev.

Qhov tsis xws ntawm electrocatalysts, xws li atom vacancies thiab dopants, qhia tau tias muaj peev xwm ntawm adsorbing unconventional ECR intermediates thiab, yog li, xaiv los txhim kho txoj kev sib raug mus rau oxygenates (29, 43, 100).Noj *C2H3O ua piv txwv, uas yog lub peev xwm penultimate intermediate rau ethylene thiab ethanol ntau lawm, Sargent thiab cov neeg ua hauj lwm (43) tau kawm txog lub luag hauj lwm ntawm qhov tsis xws luag nyob rau hauv ib tug core-plhaub Cu electrocatalyst kom meej.Lawv theoretically qhia tau hais tias cov tshuaj tiv thaiv lub zog teeb meem rau ethylene thiab ethanol tsim tau zoo ib yam nyob rau hauv thaum ntxov C─C coupling theem (0.5-V overpotential) (Fig. 7A).Nyob rau hauv cov xwm txheej zoo li no, kev qhia txog tooj liab qhov chaw nyob yuav ua rau me ntsis ua rau lub zog thaiv kev tsim ethylene, tab sis nws tsis pom muaj kev cuam tshuam rau tiam ethanol (Fig. 7B).Txawm li cas los xij, raws li pom nyob rau hauv daim duab 7C, tooj liab catalysts nrog qhov chaw nyob thiab subsurface sulfur dopant tuaj yeem ua rau lub zog cuam tshuam rau txoj kev ethylene, ua rau nws tsis zoo rau thermodynamically.Txawm li cas los xij, qhov kev hloov kho no tau pom tias muaj kev cuam tshuam tsis zoo rau txoj hauv kev ethanol.Qhov tshwm sim no tau raug kuaj xyuas ntxiv.Cov tub ntxhais-plhaub qauv Cu2S-Cu nrog ntau qhov chaw ua haujlwm (Cu2S-Cu-V; Fig. 7D) tau ua ke.Qhov piv ntawm cawv rau ethylene nce los ntawm 0.18 ntawm liab Cu NPs rau 0.34 ntawm qhov tsis muaj Cu2S-Cu thiab tom qab ntawd mus rau 1.21 ntawm Cu2S-Cu-V, txawm hais tias tag nrho FE ntawm C2 + cov khoom rau tag nrho cov catalysts tseem zoo sib xws (Fig. 7E) .Qhov kev soj ntsuam no tau qhia tias kev nce qib ntawm kev xaiv cawv tau cuam tshuam nrog kev tawm tsam ntawm ethylene ntau lawm, raws li DFT cov txiaj ntsig.Tsis tas li ntawd, kev ua haujlwm tsis zoo ua lub luag haujlwm tseem ceeb dua rau cov hlau tsis muaj cov pa roj carbon catalyst vim cov ntaub ntawv carbon ntshiab tsis ua haujlwm rau ECR.Dopants xws li nitrogen thiab boron tau siv los hloov cov qauv hluav taws xob ntawm cov pa roj carbon-based catalyst (31, 43, 100).Piv txwv li, nitrogen-doped nanodiamond (NDD) zaj duab xis ntawm silicon substrate yog devolved los ntawm Quan li al.(29) rau kev xaiv acetate ntau lawm los ntawm ECR (Fig. 7F).acetate pib muaj peev xwm tsawg li −0.36 V piv rau RHE siv NDD catalyst, thiab FE rau acetate ntau dua 75% hauv qhov muaj peev xwm ntawm −0.8 txog −1.0 V piv rau RHE.Txhawm rau nkag siab txog keeb kwm ntawm qhov kev txhim kho zoo, NDD/Si ​​electrodes nrog cov ntsiab lus nitrogen sib txawv lossis hom nitrogen tau npaj thiab tshawb xyuas (Daim duab 7G).Cov kws sau ntawv tau xaus lus tias qhov kev ua tau zoo tshaj ntawm NDD / Si catalyst rau ECR tuaj yeem raug ntaus nqi rau nws qhov muaj peev xwm tshaj plaws rau hydrogen evolution thiab N doping, qhov twg N-sp3C hom muaj zog heev rau acetate ntau lawm.Electrokinetic cov ntaub ntawv thiab nyob rau hauv situ infrared spectrum qhia tau hais tias lub ntsiab txoj kev rau acetate tsim tej zaum yuav CO2 → * CO2− → * (COO) 2 → CH3COO−.Dhau li ntawm nitrogen, boron yog lwm qhov zoo tshawb nrhiav heteroatom los tswj cov qauv hluav taws xob ntawm nanodiamond.Txawm li cas los xij, boron-doped nanodiamond (BDD) nyiam txo CO2 rau formaldehyde lossis formate (101).Tsis tas li ntawd, Quan thiab cov neeg ua haujlwm sib koom ua ke (102) tau pom tias boron thiab nitrogen co-doped nanodiamond (BND) tau pom muaj kev sib koom ua ke ntawm ECR, uas tuaj yeem kov yeej qhov kev txwv ntawm BDD thiab tom qab ntawd xaiv tsim ethanol.BND1, BND2, thiab BND3 catalysts nrog cov ntsiab lus nitrogen sib txawv thiab zoo sib xws boron doping qib tau npaj.Raws li pom hauv daim duab 7H, qhov kev xaiv siab tshaj plaws ntawm ethanol mus txog 93% tuaj yeem ua tiav ntawm BND3 catalyst ntawm −1.0 V piv rau RHE, uas muaj nitrogen ntau tshaj plaws.Theoretical laij lej qhia tau hais tias C─C coupling txheej txheem ntawm BND yog qhov zoo tshaj plaws thermodynamically, qhov twg boron atom txhawb kev ntes ntawm CO2 thiab nitrogen dopant pab txhawb cov hydrogenation ntawm nruab nrab mus rau ethanol.Txawm hais tias heteroatom-doped nanodiamond muaj peev xwm hloov CO2 rau hauv cov pa roj carbon ntau nrog cov kev xaiv siab, nws txoj haujlwm ECR raug txwv vim tias cov txheej txheem hloov pauv qeeb qeeb (tam sim no qhov ceev tsawg dua 2 mA cm-2).Graphene-raws li cov ntaub ntawv yuav yog ib qho kev daws teeb meem los kov yeej qhov tsis txaus ntawm pob zeb diamond-based catalysts.Raws li txoj cai, cov ntug pyridinic N qhov chaw hauv graphene txheej tau raug coj los ua cov chaw ua haujlwm rau C─C coupling (103).Qhov no yog vim qhov tseeb tias muaj pyridinic N ntawm ntug qhov chaw tuaj yeem hloov CO2 rau hauv CO, uas tuaj yeem txuas ntxiv rau hauv C2 + molecule (Fig. 7I).Piv txwv li, * C2O2 nruab nrab tuaj yeem ruaj khov hauv nitrogen-doped carbon nyob rau hauv uas ob lub C atoms raug khi rau pyridinic N thiab nws cov C atom uas nyob ib sab, raws li (103).Qhov kev kwv yees theoretical tau raug lees paub siv nitrogen-doped graphene quantum dot (NGQD) catalysts (31).Tom qab pulverization ntawm nitrogen-doped graphene nplooj (1 mus rau 3 μm) (Daim duab 7J), 1- mus rau 3-nm NGQDs tau txais nyob rau hauv uas qhov ceev ntawm pyridinic N ntawm ntug qhov chaw tau nce los ntawm peb qhov kev txiav txim ntawm qhov loj.Ntawm −0.78 V piv rau RHE, qhov siab tshaj plaws FE rau C2 + oxygenates tuaj yeem ncav cuag 26%.Tsis tas li ntawd, raws li pom nyob rau hauv daim duab 7K, ib nrab tam sim no ceev rau C2 + oxygenates yog ze rau 40 mA cm−2 ntawm −0.86 V piv rau RHE, uas yog ntau dua li cov hloov kho nanodiamond.Hauv kev sib piv, N-dawb graphene quantum dots thiab N-doped graphene oxide, uas qhia ntau qhov chaw qis qis pyridinic N, feem ntau yielded H2, CO, thiab formate.

(A rau C) Gibbs dawb zog los ntawm * C2H3O rau ethylene thiab ethanol rau tooj liab, tooj liab nrog qhov tsis muaj, thiab tooj liab nrog tooj liab vacancy thiab subsurface sulfur.(D) Schematic illustration ntawm Cu2S-Cu-V catalyst.(E) FE ntawm C2 + cawv thiab ethylene, nrog rau FE piv ntawm cawv rau alkenes.(A) mus rau (E) raug luam tawm nrog kev tso cai los ntawm Nature Publishing Group (43).(F) SEM image of NDD.(G) Cov nqi ntau lawm ntawm acetate thiab formate ntawm NDD nrog cov ntsiab lus nitrogen sib txawv.ntawm %, atomic %.(F) thiab (G) raug luam tawm nrog kev tso cai los ntawm American Chemical Society (29).(H) FEs rau NDD, BDD, thiab BNDs ntawm −1.0 V. Rov ua dua nrog kev tso cai los ntawm John Wiley thiab Cov Tub (102).(I) Schematic illustration of the active sites for C─C coupling in NGQDs.(I) raug tsim dua tshiab nrog kev tso cai los ntawm American Chemical Society (103).(J) TEM image of NGQDs.Scale bar, 1 nm.(K) Ib feem tam sim no ntom rau ntau yam khoom siv NGQDs.(J) thiab (K) raug luam tawm nrog kev tso cai los ntawm Nature Publishing Group (31).

Tshaj li electrocatalysts, electrode thiab catalytic reactor architecture tsim nthuav tawm lwm txoj hauv kev los txhawb ECR kev ua tau zoo, tshwj xeeb tshaj yog rau cov nqi tsim khoom thiab kev siv hluav taws xob.Cov kev txhim kho tseem ceeb tau tsim los ntawm kev tsim thiab tsim cov tshuab electroreduction tshiab kom ua tau zoo C2 + ntau lawm.Hauv seem no, peb yuav tham txog ECR electrode / reactor tsim kom ntxaws.

H-hom hlwb tau siv dav hauv kev sim ntsuas ntsuas, xav txog lawv cov kev sib dhos yooj yim, ua haujlwm yooj yim, thiab tus nqi qis.Cov hlwb tau nruab nrog cov cathode ywj siab thiab cov anode chambers uas txuas nrog ion-exchange membrane (104, 105).Thawj qhov tsis zoo ntawm H-hom cell no yog qhov tsis tshua muaj CO2 solubility hauv aqueous electrolyte, uas tsuas yog 0.034 M nyob rau hauv ambient tej yam kev mob, ua rau txo qis CO2 tam sim no ntom ntawm j < 100 mA cm−2 (64).Ntxiv mus, lwm yam kev tsis txaus ntseeg, suav nrog thaj tsam ntawm thaj chaw electrode tsawg thiab qhov sib cuam tshuam loj loj, tau ua tsis tau raws li kev tshawb fawb loj hlob (105, 106).Rau C2 + cov khoom tsim, H-hom hlwb feem ntau qhia tau qis qis qis hauv cov khoom siv ntau dhau, piv txwv li, 32% rau ethylene ntawm −0.98 V piv rau RHE (107), 13.1% rau n-propanol ntawm −0.9 V piv rau RHE (99), thiab 20.4% rau ethanol ntawm −0.46 V piv rau RHE (108), vim muaj kev sib tw hydrogen evolution.

Txhawm rau hais txog cov teeb meem saum toj no, lub tshuab hluav taws xob ntws tau thov (15, 109).Nyob rau hauv cov hlwb khiav, gaseous CO2 kwj tuaj yeem siv ncaj qha los ua cov khoom noj ntawm cathode, yog li ua rau kev txhim kho huab hwm coj ntau thiab ntau lawm (104, 110).Daim duab 8A qhia tau hais tias tus qauv tsim ntawm lub xovtooj ntawm tes, qhov twg lub polymer electrolyte membrane (PEM) tau txais kev pabcuam raws li cov electrode separator uas yog sandwiched ntawm ob txoj kev ntws.Lub catalyst yog immobilized mus rau ib qho roj diffusion electrode (GDE) los ua cov cathode electrode, uas gaseous CO2 yog ncaj qha noj.Cov catholyte, xws li 0.5 M KHCO3, tsis tu ncua ntws hauv txheej nyias ntawm cov catalyst electrode thiab PEM.Tsis tas li ntawd, sab anode feem ntau yog circulated nrog aqueous electrolyte rau oxygen evolution cov tshuaj tiv thaiv (43, 110).Piv nrog rau H-hom hlwb, cov membrane-raws li cov hlwb no qhia ntau ECR kev ua tau zoo.Piv txwv li, Sargent thiab cov neeg ua haujlwm sib koom tes (43) tau soj ntsuam ECR kev ua tau zoo ntawm Cu2S-Cu-V catalyst nyob rau hauv ob qho tib si H-hom cell thiab flow cell, raws li tau piav qhia hauv daim duab 8 (B txog E).Siv H-hom hlwb, qhov siab tshaj plaws FE rau C2 + cov khoom yog 41% nrog tag nrho cov tam sim no ntom ntawm ~ 30 mA cm−2 nyob rau hauv −0.95 V piv rau RHE.Txawm li cas los xij, FE rau C2 + cov khoom tau nce mus rau 53% nrog tag nrho cov tam sim no ceev yooj yim tshaj 400 mA cm−2 nyob rau hauv −0.92 V piv rau RHE nyob rau hauv ib tug txaus system.Xws li kev txhim kho tseem ceeb ntawm kev siv cov dej ntws reactor tuaj yeem ua rau kev txhim kho CO2 diffusion thiab suppressed sab kev cuam tshuam, feem ntau yog los ntawm lub zos roj-electrolyte-catalyst triple-interface architecture.

(A) Ib daim duab ntawm cov dej electrolyzer nrog zoomed-hauv schematic ntawm electrode-electrolyte interface.(A) raug tsim tawm nrog kev tso cai los ntawm John Wiley thiab Cov Tub (30).(B txog E) Kev sib piv ntawm ECR kev ua tau zoo siv H-hom cell thiab ntws cell.(B) rau (E) raug muab luam tawm nrog kev tso cai los ntawm Nature Publishing Group (43).(F txog H) Cov khoom siv hluav taws xob sib txawv siv hauv cov hlwb khiav tawm piv rau ECR kev ua haujlwm.(F) rau (H) raug tsim tawm nrog kev tso cai los ntawm John Wiley thiab Cov Tub (30).(I mus rau K) Cov qauv thiab kev ruaj ntseg kev ua tau zoo ntawm polymer-based gas diffusion electrode.(I) rau (K) raug muab luam tawm nrog kev tso cai los ntawm AAAS (33).

Lub zero gap cell yog lwm cov chav kawm tshiab ntawm electrolyzers, uas ntxiv tshem tawm cov dej ntws hauv cov hlwb thiab nias ob lub electrodes ua ke nrog ib qho ion pauv membrane nyob nruab nrab.Qhov kev teeb tsa no tuaj yeem txo qhov kev hloov pauv loj thiab kev hloov hluav taws xob tsis zoo thiab yog li txhim kho lub zog ua haujlwm, ua kom muaj peev xwm ua tau zoo hauv kev siv tswv yim (110).Cov reactants pub rau cathode tuaj yeem yog CO2-saturated catholyte los yog humidified CO2 kwj.Dej vapor lossis aqueous electrolyte yuav tsum tau pub rau lub anode rau kev tso tawm proton los them tus nqi rau CO2 txo hom (111).Gutiérrez-Guerra et al.(109) soj ntsuam kev ua tau zoo ntawm Cu-AC hybrid catalyst nyob rau hauv lub zero gap cell thiab qhia tias acetaldehyde yog cov khoom tseem ceeb nrog ib tug siab selectivity ntawm 60%.Raws li lwm qhov txiaj ntsig ntawm cov cuab yeej no, nws yooj yim heev los ua kom lub zog reactant ntws thiab txhim kho cov CO2 concentration hauv zos, yog li ua rau muaj qhov loj tam sim no thiab cov tshuaj tiv thaiv siab (110).Txawm li cas los xij, qhov nrawm ion pauv tus nqi hauv xoom qhov sib txawv ntawm cov hlwb nyiam acidify cov catholyte, hloov cov tshuaj tiv thaiv mus rau H2 evolution es tsis txhob CO2 txo (112).Txhawm rau daws qhov teeb meem no, Zhou thiab cov neeg ua haujlwm sib koom ua ke (112, 113) tau muab cov txheej txheem tsis sib xws nrog cov dej ntws tawm ntawm cov cathode thiab daim nyias nyias kom tswj tau qhov pH zoo ze ntawm cathode rau CO2 txo cov tshuaj tiv thaiv.Txawm hais tias ntau yam C2 + cov khoom raug kuaj pom los ntawm lub hauv paus ntawm xoom qhov sib txawv ntawm lub hlwb, suav nrog acetone, ethanol, thiab n-propanol, FEs tseem tsawg.Cov kev tshawb fawb tshaj tawm feem ntau ib txwm tsom rau C1 cov khoom lag luam uas koom nrog tsawg tus lej ntawm proton thiab electron hloov pauv thaum txo cov tshuaj tiv thaiv.Yog li, qhov ua tau ntawm xoom qhov sib txawv ntawm tes rau C2 + cov khoom tseem nyob hauv kev sib cav (110).

Ntxiv mus, microfluidic electrolytic cells (MECs) yog ib hom kev tsim hluav taws xob zoo nkauj uas tsim los ntawm Kenis thiab cov neeg ua haujlwm sib koom ua ke (39, 114).Nyob rau hauv cov khoom no, lub membrane yog hloov los ntawm ib tug nyias qhov chaw (< 1 hli nyob rau hauv thickness) uas muaj ntws electrolyte kwj cais cov anode thiab cathode.Cov CO2 molecules tuaj yeem tawg sai sai rau hauv electrode-electrolyte interface nyob ze cathode, thiab ob lub GDE ruaj khov yog dej ntws los ntawm cov dej electrolyte.Piv nrog rau cov membrane-raws li cov hlwb khiav, MECs tsis tsuas yog zam cov nqi siab ntawm daim nyias nyias tab sis kuj txo cov kev tswj dej, tshwj xeeb tshaj yog hais txog cov anode qhuav-tawm thiab cathode dej nyab thaum ua haujlwm ntawm qhov kub tam sim no vim yog osmotic luag ntawm cov dej molecules nrog rau. proton thauj los ntawm anode mus rau cathode hla daim nyias nyias (115).Raws li peb paub, txawm tias muaj txiaj ntsig zoo thiab ua tiav, tsawg kawg ntawm cov kev tshawb fawb tau ua tiav C2 + cov khoom hauv thawj MECs.Qhov no yog tej zaum tshwm sim los ntawm "floating" nyhuv uas protons tsim nyob rau hauv lub anode yog yooj yim drained los ntawm lub cathode ib puag ncig los yog ntxuav tawm los ntawm ntws electrolyte, es tsis mus koom nyob rau hauv ntau yam proton yuav tsum tau C2 + tsim cov tshuaj tiv thaiv.Cov speculation tuaj yeem lees paub los ntawm cov piv txwv hauv qab no.Xyoo 2016, Kenis thiab cov neeg ua haujlwm sib koom ua ke (31) tau tshaj tawm txog kev txo qis CO2 rau C2 + cov khoom lag luam ntawm kev hloov kho thiab cov membrane-muaj MEC, uas NGQDs tuaj yeem txo CO2 molecules rau C2+ nrog 55% FE (31% rau ethylene, 14% rau ethanol, 6% rau acetate, thiab 4% rau n-propanol) ntawm kev siv peev xwm ntawm −0.75 V piv rau RHE hauv 1 M KOH kua.Nws yog ib qho tseem ceeb uas yuav tau taw qhia tias ib puag ncig electrolyte tuaj yeem cuam tshuam rau cov khoom xaiv thiab.Piv txwv li, Jiao thiab cov neeg ua haujlwm sib koom ua ke (30) tau tsim cov nanoporous Cu catalyst thiab tom qab ntawd sim nws cov kev ua haujlwm ECR siv cov electrolytes sib txawv (KHCO3, KOH, K2SO4, thiab KCl) hauv daim nyias nyias ntawm MEC.Lawv tau qhia tias CO2 txo qis hauv alkaline electrolyte (KOH) nthuav tawm qhov siab tshaj plaws C2 + selectivity thiab tam sim no ntom, raws li qhia hauv daim duab 8 (F thiab G).Ntawm −0.67 V piv rau RHE hauv 1 M KOH electrolyte, qhov tau txais FE rau C2 + nce mus txog 62% nrog ib nrab tam sim no ntom ntawm 653 mA cm-2, uas yog ib qho ntawm cov tam sim no siab tshaj plaws uas tau tshaj tawm hauv electrochemical CO2 txo. rau C2+ cov khoom.Ethylene (38.6%), ethanol (16.6%), thiab n-propanol (4.5%) yog cov khoom tseem ceeb C2 + nrog me me ntawm acetate.Lawv kuj tau taw qhia tias muaj kev sib raug zoo ntawm cov pH saum npoo av thiab FE rau C2 + cov khoom: Qhov siab dua pH saum npoo, qhov siab dua tam sim no thiab C2 + cov khoom tawm los, raws li tau piav qhia hauv daim duab 8H.Kev suav cov theoretical tau hais tias qhov ze-nto OH- ions tuaj yeem pab txhawb C─C coupling (31).

Ntxiv rau qhov kev teeb tsa electrolyzer, cov electrolyte siv rau hauv cov electrolyzers sib txawv kuj tuaj yeem hloov pauv cov khoom ECR kawg.Raws li peb tau hais los saum toj no, KOH cov kev daws teeb meem muaj alkaline ib txwm siv hauv cov hlwb uas muaj kev ua tau zoo heev dua li hauv H-hom hlwb.Nws yog ascribed rau lub fact tias KOH electrolyte yuav muab ntau dua electrolyte conductivity, txo ohmic kuj ntawm cov nyias electrolyte txheej ntawm catalyst thiab tej electrolyte, thiab ntxiv txo qhov yuav tsum tau overpotentials rau C2 + tsim (31).Cov txiaj ntsig DFT tau lees paub ntxiv tias qhov muaj OH- ions tuaj yeem txo lub zog teeb meem rau CO dimerization, yog li txhawb nqa C2 + tsim thiab txwv kev sib tw los ntawm C1 thiab H2 tsim (30, 33).Txawm li cas los xij, alkaline KOH tsis tuaj yeem siv los ua electrolyte hauv H-hom hlwb.Qhov no yog vim CO2 ntws sai sai nrog KOH cov kev daws teeb meem thiab thaum kawg tsim cov tshuaj bicarbonate nrog nruab nrab pH hauv H-hom hlwb (30).Hauv cov hlwb khiav, txawm li cas los xij, ib zaug CO2 diffuses los ntawm GDE, CO2 molecules yuav tau noj nyob rau theem peb zaug (CO2-catalyst-electrolyte) los tsim cov khoom txo tam sim ntawd.Tsis tas li ntawd, lub peev xwm tsis zoo ntawm cov electrolyte muaj peev xwm ua kom cov pH nyob ib ncig ntawm cov electrode nyob rau hauv qhov chaw nyob ruaj ruaj electrolyzer configurations, whereas lub ntws electrolyte yuav refresh lub nto thiab txo cov pH fluctuation nyob rau hauv cov electrolyte (33, 116).

Raws li tau hais los saum no, ECR yog cov tshuaj tiv thaiv diffusion-tswj, cov tshuaj tiv thaiv siab kuj tseem tuaj yeem txhim kho qhov ntau thiab sib cuam tshuam CO2 concentration.Cov khoom siv hluav taws xob siab ntau zoo ib yam li cov hlau tsis muaj steel autoclave, uas muaj cov pa roj carbon monoxide siab (txog 60 atm) tuaj yeem nkag mus rau hauv lub xov tooj ntawm tes, ua rau muaj qhov nce ntxiv hauv FE thiab qhov ceev tam sim no ntawm C2 + (117. , 118 ib.).Sakata thiab cov neeg ua haujlwm sib koom ua ke (119) tau pom tias qhov ceev tam sim no tuaj yeem txhim kho mus rau 163 mA cm−2 hauv qab 30 atm ntawm Cu electrode nrog ethylene ua cov khoom loj.Ntau cov hlau catalysts (piv txwv li, Fe, Co, thiab Ni), tsis muaj kev ua haujlwm rau C2 + ntau lawm ntawm ambient siab, tuaj yeem txo CO2 rau ethylene, ethane, propane, thiab lwm yam khoom lag luam siab C2 + ntawm qhov siab siab.Nws tau raug pom tias qhov kev xaiv ntawm cov khoom tau pom zoo nyob ntawm CO2 siab nyob rau hauv kev hloov pauv CO2 muaj nyob ntawm electrode nto (117, 120).Cov khoom lag luam txo qis yog hloov pauv los ntawm H2 mus rau hydrocarbons (C2 + suav nrog) thiab thaum kawg rau CO / HCOOH nrog nce CO2 siab.Qhov tseem ceeb, CO2 siab yuav tsum tau ua tib zoo saib xyuas vim tias CO2 siab ntau dhau los yog qis qis yuav ua rau muaj qhov tsis txaus siab lossis txwv CO2 diffusion tus nqi, uas nyiam ua rau CO / HCOOH lossis H2.Tsuas yog tus nqi sib xws ntawm nruab nrab CO thiab qhov ceev tam sim no uas tsim los ntawm electrode nto tuaj yeem pab txhawb C─C coupling cov tshuaj tiv thaiv thiab txhim kho C2 + cov khoom xaiv (119).

Tsim ib qho tshiab electrode nrog cov qauv siab heev yog lwm qhov kev taw qhia tseem ceeb los txhim kho cov kev xaiv C2 + ntau lawm.Nyob rau theem pib, cov electrodes ua haujlwm yog cov hlau tsis zoo thiab raug kev txom nyem los ntawm kev hloov pauv loj (26, 105).Raws li qhov tshwm sim, GDE tau thov kom txo qis kev ua haujlwm ntawm tes tsis zoo los ntawm kev muab cov kab hluav taws xob hydrophobic uas pab txhawb CO2 diffusion mus rau catalyst hais (121).Cov pa GDE feem ntau muaj cov txheej txheem catalyst (CL) thiab cov roj diffusion txheej (GDL), raws li qhia hauv qab ntawm daim duab 8A (30, 33).Gas-kua-catalyst interface tsim hauv GDE yog qhov tseem ceeb los txhim kho kev ua haujlwm ntawm tes.GDL sib sau ua ke nrog cov ntaub ntawv ntxeem tau (feem ntau cov ntawv carbon) tuaj yeem muab ntau txoj hauv kev CO2 thiab ua kom cov electrolyte diffusion sai.Nws kuj ua raws li qhov nruab nrab ntawm kev thauj mus los tsis zoo rau cov khoom siv hluav taws xob, cov khoom siv hluav taws xob, thiab cov khoom txo qis los ntawm CL rau hauv cov electrolyte (121).Poob casting, airbrushing, thiab electrodeposition yog cov yees siv rau kev npaj ntawm GDEs (122).Cov catalysts sib sau ua ke nrog GDEs tau tshawb xyuas ntau hauv CO2 electroreduction rau C2 + cov khoom.Qhov tseem ceeb, cov lus hais los saum toj no nrog kev ua tau zoo yog tag nrho nrog GDEs.Thaum ntxov li xyoo 1990, Sammells thiab cov neeg ua haujlwm ua haujlwm (123) tau tshaj tawm tias Cu-coated GDEs ua tiav FE ntawm 53% rau ethylene nrog qhov ntom ntom ntawm 667 mA cm-2.Txhim kho qhov kev xaiv ntawm ethylene thiab ethanol yog ib qho kev sib tw loj uas ib txwm ua los ntawm Cu-based catalysts vim tias lawv txoj kev siv tshuab zoo sib xws.Tsis tas li ntawd, nws yog ib qho tseem ceeb uas yuav tau taw qhia tias cov khoom tsim tau nce siab thiab kev xaiv ntawm ethylene piv rau ethanol tau pom ntawm Cu-based GDE (25, 36).Gewirth thiab cov neeg ua haujlwm sib koom ua ke (36) tau pom qhov zoo tshaj plaws FE ntawm 60% rau ethylene thiab FE suppressed rau ethanol ntawm 25% ntawm electrodeposited Cu-Ag GDE, thaum tag nrho cov tam sim no ceev mus txog ~ 300 mA cm-2 ntawm −0.7 V piv rau RHE.Nws yog ib qho kev ua haujlwm tsawg uas ua tiav qhov kev xaiv siab ntawm qhov loj tam sim no.Qhov kev tshawb pom no qhia tau hais tias GDE-incorporated electrode muab ib txoj hauv kev zoo rau kev kho cov txheej txheem tshuaj tiv thaiv, uas qhov kev xaiv ntawm cov khoom txo qis tuaj yeem tau txais ntawm qhov ceev tam sim no.

Kev ruaj ntseg ntawm GDEs kuj yog ib qho teeb meem tseem ceeb uas yuav tsum tau hais vim tias kev ua haujlwm ruaj khov mus sij hawm ntev yog qhov tseem ceeb kom paub txog kev siv tswv yim rau cov hlwb khiav.Txawm hais tias qhov ua tau zoo ntawm CO2-rau-C2 + ua tiav nrog GDEs, qhov kev ruaj ntseg tseem tsis zoo vim qhov tsis muaj zog ntawm cov khoom siv hluav taws xob, GDL, thiab binder txheej (77, 124).Cov pa roj carbon monoxide ntawm GDL tuaj yeem hloov pauv los ntawm hydrophobic mus rau hydrophilic thaum lub sijhawm cov tshuaj tiv thaiv electrochemical vim yog cov tshuaj tiv thaiv oxidation uas tshwm sim ntawm qhov siab tshaj, uas ua rau dej nyab hauv GDL thiab cuam tshuam CO2 diffusion txoj hauv kev (33).Txhawm rau daws qhov teeb meem no, cov kws tshawb fawb tau koom ua ke hydrophobic scaffold ntawm polytetrafluoroethylene (PTFE) rau hauv GDEs.Muab piv rau hydrophilic Nafion, ib txheej hydrophobic PTFE ua rau muaj kev ruaj ntseg zoo tshaj plaws (33).Sargent thiab cov neeg ua haujlwm sib koom ua ke (33) tau sib sau ua ke Cu catalyst ntawm cov PTFE thiab carbon NPs sib cais, uas cov txheej txheem hydrophobic PTFE tuaj yeem ua rau NPs thiab graphite txheej, yog li tsim kom muaj qhov ruaj khov electrode interface (Fig. 8, I thiab J).Yog li ntawd, FE rau ethylene ntau lawm tau nce mus rau 70% nyob rau hauv 7 M KOH tov ntawm tam sim no ntom ntawm 75 mus rau 100 mA cm-2.Lub neej ntev ntawm lub reactor ntws no tau txuas ntxiv mus rau ntau tshaj 150 teev nrog kev poob qis hauv ethylene selectivity, uas yog 300-fold ntev dua li ib txwm GDEs, raws li qhia hauv daim duab 8K.Xws li cov qauv qhaub cij tau pom tias yog GDE tsim zoo heev.Piv txwv li, Cui thiab cov neeg ua haujlwm ua haujlwm (124) tau tsim cov qauv trilayer nrog cov txheej txheem electrode clipped los ntawm ob lub yeeb yaj kiab hydrophobic nanoporous polyethylene.Cov txheej txheej hydrophobic sab nraud tuaj yeem ua rau qeeb ntawm cov electrolyte flux los ntawm cov kua ntau, ua rau kom ruaj khov, siab pH hauv zos nyob ib ncig ntawm cov electrode ua haujlwm.Kev ua kom zoo ntawm qhov chaw interlayer, uas tuaj yeem txhim kho CO2 thauj thiab adsorption, kuj tseem ceeb hauv kev tsim qauv (124).Tsis ntev los no, cov pa roj carbon nanotubes kuj tau muab tso rau hauv GDEs vim tias lawv cov porosity siab, zoo conductivity, thiab hydrophobicity, uas yuav pab tau electron thiab loj thauj mus los (77).

Txawm hais tias muaj kev vam meej ntawm ECR, cov tswv yim rau cov nqi qis, cov khoom lag luam loj C2+ tsis tshua muaj tam sim no (125).Nyob rau theem no, cov kev cov nyom thiab cov cib fim sib thooj kom nkag siab txog cov txheej txheem tshuaj tiv thaiv ntawm ECR thiab ua lag luam rau cov cuab yeej zoo no.

Raws li kev daws teeb meem zoo nkauj los kaw cov pa roj carbon monoxide thiab khaws cov hluav taws xob txuas ntxiv txuas ntxiv mus, xws li cua thiab hnub ci, kev nce qib ntau tau ua kom tau txais txiaj ntsig CO2 hloov dua siab tshiab nyob rau xyoo dhau los.Txawm hais tias kev nkag siab ntawm cov txheej txheem cuam tshuam nrog ECR tau dhau los ntev txij li nws cov hnub thaum ntxov (126), C─C txuas ntawm ECR mus rau C2 + cov khoom tseem nyob deb ntawm kev npaj rau kev siv tswv yim.Hauv kev tshuaj xyuas no, peb tau saib xyuas cov tswv yim tam sim no uas tuaj yeem txhawb qhov kev xaiv thiab ntau lawm tus nqi rau C2 + cov khoom ntawm ECR, nrog rau kev kho kom zoo-catalyst tuning, electrolyte cuam tshuam, electrochemical tej yam kev mob, thiab electrochemical electrode / reactor tsim.

Txawm hais tias tag nrho cov kev siv zog muab tso rau hauv ECR, tseem muaj ntau yam teeb meem nrog cov catalysts tam sim no thiab ECR system uas yuav tsum tau hais ua ntej ua lag luam ECR.Ua ntej, raws li tus thawj tswj hwm kom paub txog kev sib txuas ntawm C─C, Cu raug kev txom nyem los ntawm cov teeb meem kev ruaj ntseg, tshwj xeeb tshaj yog nyob rau hauv aqueous electrolyte, thiab muaj peev xwm tsis tshua muaj sia nyob rau 100 teev vim lawv lub zog atom siab, particle aggregation, thiab cov qauv deterioration nyob rau hauv ECR tej yam kev mob.Yog li, yuav ua li cas kom ua tiav lub sijhawm ntev kev ruaj ntseg siv Cu-based catalyst tseem yog qhov kev sib tw qhib.Anchoring Cu-based catalyst ntawm kev txhawb nqa tshwj xeeb nrog kev sib cuam tshuam zoo yuav yog lub tswv yim txhim khu kev qha los khaws cov qauv catalyst / morphology thiab yog li muab kev txhawb nqa lub neej ntev.Tsis tas li ntawd, siv cov polymer membrane electrolyte los hloov cov tshuaj aqueous thaum lub sij hawm ECR tuaj yeem txhim kho kev ruaj ntseg ntawm Cu-based catalyst.Tsis tas li ntawd, los ntawm kev xav ntawm catalysts, nyob rau hauv situ / nyob rau hauv operando characterization cov tswv yim thiab theoretical qauv yuav tsum tau siv los saib xyuas thiab nkag siab txog cov catalyst kev ua tau zoo lwj, yog li, nyob rau hauv lem, suppressing degradation thiab lom ntawm catalyst mus rau theem qis tshaj.Lwm qhov teeb meem tseem ceeb ntawm ECR catalysts uas yuav tsum tau hais txog yog ua kom cov txheej txheem synthesis siv tau rau ntau lawm.Txog rau qhov kawg no, streamlining cov txheej txheem hluavtaws siv cov khoom siv dav dav yog nyiam.

Qhov thib ob, C2 + oxygenated los ntawm ECR feem ntau yog tov nrog cov kua (piv txwv li, KHCO3 thiab KOH) nyob rau hauv cov electrolyte rau cov tshuaj H- lossis flow-cell reactors, uas, txawm li cas los xij, yuav tsum muaj kev sib cais ntxiv thiab cov txheej txheem kom rov qab tau cov roj ntshiab huv hauv siv tau.Nyob rau tib lub sijhawm, qhov hloov pauv C2 + hydrocarbons kuj sib xyaw nrog H2 thiab cov seem CO2.Yog li, cov txheej txheem sib cais raug nqi yog qhov tseem ceeb rau ECR thev naus laus zis tam sim no, uas ntxiv cuam tshuam ECR los ntawm kev siv tswv yim.Yog li ntawd, yuav ua li cas ncaj qha thiab tsis tu ncua tsim cov kua roj ntshiab thiab cov roj ntshiab hydrocarbons, tshwj xeeb tshaj yog nrog cov khoom lag luam siab, yog qhov tsim nyog rau kev xa tawm ntawm ECR.Peb yog li kwv yees qhov tseem ceeb ntawm kev tsim khoom ncaj qha ntawm ECR nyob rau yav tom ntej, uas yuav siv ECR thev naus laus zis ntau ze rau kev ua lag luam (127).

Thib peb, thaum tsim cov C─O thiab C─H daim ntawv cog lus, xws li ethanol, acetic acid, thiab ethylene, hauv ECR thev naus laus zis tau kawm ntau, kev tshawb nrhiav lwm hom khoom tseem ceeb rau ECR thev naus laus zis thiab qhia txog kev lag luam.Piv txwv li, tsis ntev los no, Han thiab cov neeg ua haujlwm ua haujlwm (128) tau tshaj tawm txog kev tsim 2-bromoethnol los ntawm ECR.Lub hauv paus tsim ntawm C─Br daim ntawv cog lus hloov cov khoom ntawm ethanol mus rau 2-bromoethnol, uas yog ib qho tseem ceeb lub tsev thaiv nyob rau hauv tshuaj thiab tshuaj synthesis thiab qhia tau hais tias ntau dua tus nqi ntxiv.Yog li, dhau ntawm cov khoom lag luam C2 + uas tau kawm zoo tam sim no, peb ntseeg tias lub hom phiaj ntawm lwm yam tsis tshua tshawb nrhiav cov khoom xws li oxalic acid (129) thiab kev sib txuas ntawm ntau cov C2 + molecules xws li cyclic compounds yog lwm txoj hauv kev rau kev tshawb fawb ECR yav tom ntej.

Qhov kawg tab sis tsis kawg, cov khoom siv hluav taws xob tshiab thiab cov reactor tsim xws li cov dej tsis zoo GDE, cov kua dej ntws, thiab PEM cell yuav tsum tau txais kev pom zoo los txhawb ECR ntau lawm rau qib kev lag luam (> 200 mA cm-2).Txawm li cas los xij, qhov sib txawv loj hauv kev ua haujlwm electrocatalytic yog ib txwm pom thaum electrocatalysts raug siv rau tag nrho cov xov tooj ntawm tes.Yog li, kev tshawb fawb ntau dua yuav tsum tau ua kom txo qis qhov sib txawv ntawm kev tshawb fawb ib nrab ntawm tes thiab daim ntawv thov siv tag nrho ntawm tes kom coj tau ECR los ntawm kev sim ntsuas ntsuas mus rau kev siv tswv yim.

Hauv cov ntsiab lus, electrochemical CO2 txo qis muaj lub sijhawm zoo rau peb los daws qhov teeb meem ib puag ncig los ntawm cov pa roj carbon monoxide tawm los ntawm tib neeg kev ua ub no.Nws kuj tseem qhia tau tias muaj peev xwm ua tiav cov roj huv huv thiab tshuaj siv lub zog tauj dua tshiab.Txawm hais tias muaj ntau qhov kev sib tw tseem nyob rau ECR thev naus laus zis nyob rau theem tam sim no, tshwj xeeb tshaj yog rau C─C coupling txheej txheem, nws ntseeg tau tias nrog kev tshawb fawb txuas ntxiv thiab kev txhim kho ntawm ob qho tib si catalyst optimization thiab cell perfection, qhov kev xav ntawm lub ntiaj teb tiag tiag CO2 electrolysis rau roj huv. thiab tshuaj lom neeg yuav raug pom nyob rau yav tom ntej.

Qhov no yog ib tsab xov xwm qhib tau muab faib raws li cov ntsiab lus ntawm Creative Commons Attribution-NonCommercial daim ntawv tso cai, uas tso cai rau siv, faib, thiab luam tawm nyob rau hauv ib qho nruab nrab, tsuav yog qhov tshwm sim ntawm kev siv tsis yog rau kev lag luam kom zoo dua thiab muab cov haujlwm qub kom zoo. hais.

CEEB TOOM: Peb tsuas yog thov koj qhov chaw nyob email kom tus neeg uas koj tab tom qhia nplooj ntawv kom paub tias koj xav kom lawv pom nws, thiab nws tsis yog ntawv xa tuaj.Peb tsis ntes ib qho email chaw nyob.

© 2020 American Association rau Advancement of Science.Txhua txoj cai.AAAS yog ib tug khub ntawm HINARI, AGORA, OARE, CHORUS, CLOCKSS, CrossRef thiab COUNTER.Science Advances ISSN 2375-2548.