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Ukunciphisa i-carbon dioxide kwi-formic acid nge-electrochemical yindlela ethembisayo yokuphucula ukusetyenziswa kwe-carbon dioxide kwaye inezicelo ezinokubakho njengendawo yokugcina i-hydrogen. Kulo msebenzi, uyilo lwe-zero-gap membrane electrode assembly luye lwaphuhliswa ukuze kuhlanganiswe i-formic acid ngqo kwi-carbon dioxide. Inkqubela phambili kwezobuchwepheshe yi-perforated cation exchange membrane, ethi, xa isetyenziswa kwi-forward bias bipolar membrane configuration, ivumele i-formic acid eyenziwe kwi-membrane interface ukuba ifuduke ngokusebenzisa i-anodic flow field kwii-concentrations eziphantsi njenge-0.25 M. Ngaphandle kwezinto ezongezelelweyo zesandwich phakathi kwe-anode kunye ne-cathode, le ngcamango ijolise ekusebenziseni izixhobo zebhetri ezikhoyo kunye noyilo oluqhelekileyo kwiiseli zepetroli kunye ne-hydrogen electrolysis, okuvumela utshintsho olukhawulezayo ukuya ekukhuleni nasekuthengisweni. Kwiseli engama-25 cm2, ulungiselelo lwe-perforated cation exchange membrane lubonelela nge->75% Faraday efficiency ye-formic acid kwi-<2 V kunye ne-300 mA/cm2. Okubaluleke ngakumbi, uvavanyo lokuzinza lweeyure ezingama-55 kwi-200 mA/cm2 lubonise ukusebenza kakuhle kweFaraday kunye ne-voltage yeseli. Uhlalutyo lwetekhnoloji-economic lusetyenziswa ukubonisa iindlela zokufezekisa ukulingana kweendleko neendlela zangoku zokuvelisa i-formic acid.
Ukunciphisa i-carbon dioxide kwi-formic acid kusetyenziswa umbane ohlaziyekayo nge-electrochemical kuye kwabonakala kunciphisa iindleko zemveliso ukuya kuthi ga kwi-75%1 xa kuthelekiswa neendlela zemveli ezisekelwe kwi-fossil fuel. Njengoko kubonisiwe kwiincwadi2,3, i-formic acid ineendlela ezahlukeneyo zokusetyenziswa, ukusuka kwindlela esebenzayo neyongayo yokugcina nokuthutha i-hydrogen ukuya kwi-feedstock yeshishini leekhemikhali4,5 okanye imboni ye-biomass6. I-Formic acid iye yachongwa njenge-feedstock yokuguqulwa okulandelayo ibe yi-established jet fuel intermediates kusetyenziswa ubunjineli be-metabolic7,8. Ngophuhliso lwe-formic acid economics1,9, imisebenzi emininzi yophando igxile ekuphuculeni ukhetho lwe-catalyst10,11,12,13,14,15,16. Nangona kunjalo, imizamo emininzi iyaqhubeka nokugxila kwii-H-cells ezincinci okanye ii-liquid flow cells ezisebenza kwi-low current densities (<50 mA/cm2). Ukunciphisa iindleko, ukufikelela kwintengiso kunye nokwandisa ukungena kwemarike okulandelayo, ukunciphisa i-electrochemical carbon dioxide (CO2R) kufuneka kwenziwe kwi-current densities ephezulu (≥200 mA/cm2) kunye nokusebenza kakuhle kweFaraday (FE)17 ngelixa kusetyenziswa kakhulu izinto kunye nokusebenzisa izixhobo zebhetri ezivela kwiiseli zamafutha zeTekhnoloji kunye ne-electrolysis yamanzi kuvumela izixhobo zeCO2R ukuba zisebenzise amathuba oqoqosho oluphezulu18. Ukongeza, ukwandisa ukusetyenziswa kwemveliso kunye nokuphepha ukucutshungulwa okongezelelweyo, i-formic acid kufuneka isetyenziswe njengemveliso yokugqibela endaweni yokwenza iityuwa19.
Kule ndlela, kuye kwenziwa imizamo yakutshanje yokuphuhlisa izixhobo ze-CO2R formate/formic acid based gas diffusion electrode (GDE) ezifanelekileyo kwimizi-mveliso. Uphononongo olupheleleyo lukaFernandez-Caso et al.20 lushwankathela zonke ii-electrochemical cell configurations zokunciphisa okuqhubekayo kwe-CO2 kwi-formic acid/formate. Ngokubanzi, zonke ii-configurations ezikhoyo zinokwahlulwa zibe ziindidi ezintathu eziphambili: 1. Ii-catholytes ezihamba nge-flow-through19,21,22,23,24,25,26,27, 2. I-membrane enye (i-cation exchange membrane (CEM)28 okanye i-anion exchange membrane (AEM)29 kunye ne-3. I-Sandwich configuration15,30,31,32. Ii-cross-sections ezilula zezi configurations ziboniswe kuMfanekiso 1a. Kwi-flow configuration ye-catholyte, kwenziwa igumbi le-electrolyte phakathi kwe-membrane kunye ne-cathode ye-GDE. I-Flow-through catholyte isetyenziselwa ukudala ii-ion channels kumaleko we-catholyte we-catalyst33, nangona imfuneko yayo yokulawula ukukhetha kwe-formate ixoxwa34. Nangona kunjalo, olu lungiselelo lusetyenziswe nguChen et al. Ukusebenzisa i-SnO2 cathode kwi-carbon substrate ene-catholyte maleko eyi-1.27 mm ubukhulu, ukuya kuthi ga kwi-90% FE 35 kwi-500 mA/cm2 kwafezwa. Ukudibanisa umaleko we-catholyte otyebileyo kunye ne-reverse-biased bipolar membrane (BPM) ethintela ukudluliselwa kwe-ion inika i-voltage yokusebenza ye-6 V kunye nokusebenza kakuhle kwamandla kwe-15%. Ukuphucula ukusebenza kakuhle kwamandla, uLi et al., besebenzisa ulungiselelo olunye lwe-CEM, bafumene i-FE 29 ye-93.3% kwi-fractional current density ye-51.7 mA/cm2. UDiaz-Sainz et al.28 basebenzise i-filter press ene-single CEM membrane kwi-current density ye-45 mA/cm2. Nangona kunjalo, zonke iindlela zivelise i-formate endaweni yemveliso ekhethwayo, i-formic acid. Ukongeza kwiimfuno ezongezelelweyo zokucubungula, kwi-CEM configurations, iifomathi ezifana ne-KCOOH zinokuqokelelana ngokukhawuleza kwi-GDE nakwi-flow field, nto leyo ebangela imida yokuthutha kunye nokusilela kweseli ekugqibeleni.
Uthelekiso lwe-CO2R ezintathu ezibalaseleyo kwiindlela zokuguqula isixhobo sokuguqula i-formate/formic acid kunye noyilo olucetywayo kolu phononongo. b Uthelekiso lwe-total current kunye ne-formate/formic acid yield kwiindlela zokulungisa i-catholyte, iindlela zokulungisa isandwich, iindlela zokulungisa i-single CEM kwiincwadi (eziboniswe kwiTheyibhile eyoNgezelelweyo S1) kunye nomsebenzi wethu. Amanqaku avulekileyo abonisa ukuveliswa kwesisombululo se-formate, kwaye amanqaku aqinileyo abonisa ukuveliswa kwe-formic acid. *Uqwalaselo luboniswe kusetyenziswa i-hydrogen kwi-anode. c Uqwalaselo lwe-Zero-gap MEA kusetyenziswa i-composite bipolar membrane ene-perforated cation exchange layer esebenza kwi-forward bias mode.
Ukuthintela ukwakheka kwe-formate, uProietto nabanye 32 basebenzise ulungiselelo lwe-splitless filter press apho amanzi angena kwi-interlayer ahamba khona. Inkqubo inokufikelela kwi->70% CE kuluhlu lwangoku lwe-density ye-50–80 mA/cm2. Ngokufanayo, uYang nabanye 14 bacebise ukusetyenziswa kwe-solid electrolyte interlayer phakathi kwe-CEM kunye ne-AEM ukukhuthaza ukwakheka kwe-formic acid. UYang nabanye 31,36 bafumene i-91.3% FE kwiseli ye-5 cm2 kwi-200 mA/cm2, bevelisa isisombululo se-formic acid ye-6.35 wt%. UXia nabanye 32 Besebenzisa ulungiselelo olufanayo, ukuguqulwa kwe-carbon dioxide (CO2) ye-83% kwi-formic acid ye-FE kufezekiswe kwi-200 mA/cm2, kwaye ukuqina kwenkqubo kuhlolwe iiyure ezili-100 nemizuzu engama-30. Nangona iziphumo ezincinci zithembisa, iindleko ezonyukileyo kunye nobunzima bee-resin zokutshintshiselana ngee-ion ezinemingxuma kwenza kube nzima ukulinganisa ulungelelwaniso lwe-interlayer kwiinkqubo ezinkulu (umz., i-1000 cm2).
Ukuze sibone isiphumo esipheleleyo seedizayini ezahlukeneyo, sidwelise imveliso ye-formate/formic acid nge-kWh kuzo zonke iinkqubo ezikhankanyiweyo ngaphambili saza sazidweba kuMfanekiso 1b. Kucacile apha ukuba nayiphi na inkqubo equlethe i-catholyte okanye i-interlayer iya kufikelela kwinqanaba eliphezulu lokusebenza kwayo kwi-low current densities kwaye yonakale kwi-high current densities, apho umda we-ohmic unokumisela i-voltage yeseli. Ngaphezu koko, nangona ulungiselelo lwe-CEM olusebenzisa amandla lubonelela ngemveliso ephezulu ye-molar formic acid nge-kWh, ukwakheka kwetyuwa kunokukhokelela ekuwohlokeni kokusebenza ngokukhawuleza kwi-high current densities.
Ukuze sinciphise iindlela zokusilela ebezixoxwe ngazo ngaphambili, senze i-membrane electrode assembly (MEA) equlethe i-composite forward biased BPM ene-perforated cation exchange membrane (PCEM). Uyilo luboniswe kuMfanekiso 1c. I-Hydrogen (H2) ingeniswa kwi-anode ukuvelisa ii-protons nge-hydrogen oxidation reaction (HOR). Umaleko we-PCEM ungeniswa kwinkqubo ye-BPM ukuvumela ii-ion ze-formate ezenziwe kwi-cathode ukuba zidlule kwi-AEM, zidityaniswe nee-protons ukwenza i-formic acid kwi-BPM interface kunye nee-interstitial pores ze-CEM, kwaye emva koko ziphume nge-GDE anode kunye ne-flow field. . Sisebenzisa olu lungiselelo, sifumene i->75% ye-formic acid kwi-<2 V kunye ne-300 mA/cm2 kwindawo yeseli ye-25 cm2. Okubaluleke kakhulu, uyilo lusebenzisa izinto ezifumanekayo zorhwebo kunye noyilo lwehardware kwizityalo ze-fuel cell kunye ne-water electrolysis, okuvumela ixesha elikhawulezayo lokukhula. Ulungiselelo lwe-Catholyte luqulathe amagumbi okuhamba kwe-catholyte anokubangela ukungalingani koxinzelelo phakathi kwezigaba zegesi kunye nolwelo, ingakumbi kwiindlela ezinkulu zolungiselelo lweseli. Kwizakhiwo zesandwich ezineengqimba ezineengqimba zokuhamba kolwelo, kufuneka imizamo ebalulekileyo yokuphucula ungqimba oluphakathi olunezingqimba ukunciphisa ukuhla koxinzelelo kunye nokuqokelelwa kwekhabhoni diokside ngaphakathi kongqimba oluphakathi. Zombini ezi zinto zinokukhokelela ekuphazamisekeni konxibelelwano lweselula. Kunzima nokuvelisa iingqimba ezincinci ezinezingqimba ezizimeleyo ngomlinganiselo omkhulu. Ngokwahlukileyo koko, uqwalaselo olutsha olucetywayo luqwalaselo lwe-MEA olungenamngxuma olungenagumbi lokuhamba okanye ungqimba oluphakathi. Xa kuthelekiswa nezinye iiseli ze-electrochemical ezikhoyo, uqwalaselo olucetywayo luhlukile kuba luvumela ukwenziwa ngokuthe ngqo kwe-formic acid kuqwalaselo olunokulinganiswa, olusebenzisa amandla kakuhle, nolungenamngxuma.
Ukuze kuthintelwe ukuvela kwehydrogen, imizamo emikhulu yokunciphisa i-CO2 isebenzise ulungelelwaniso lwe-MEA kunye ne-AEM membrane kunye ne-electrolytes ephezulu ye-molar concentration (umz., 1-10 M KOH) ukudala iimeko ze-alkaline kwi-cathode (njengoko kubonisiwe kuMfanekiso 2a). Kule mimiselo, ii-ion ze-formate ezenziwe kwi-cathode zidlula kwi-membrane njengeentlobo ezitshajiswe kakubi, emva koko i-KCOOH yenziwa kwaye iphume kwinkqubo ngomlambo we-anodic KOH. Nangona i-formate FE kunye ne-voltage yeseli ekuqaleni zazilungile njengoko kubonisiwe kuMfanekiso 2b, uvavanyo lozinzo lubangele ukwehla kwe-FE malunga ne-30% kwiiyure ezili-10 kuphela (Umfanekiso S1a–c). Kufuneka kuqatshelwe ukuba ukusetyenziswa kwe-anolyte ye-1 M KOH kubalulekile ukunciphisa i-anodic overvoltage kwiinkqubo ze-alkaline oxygen evolution reaction (OER)37 kunye nokufezekisa ukufikelela kwe-ion ngaphakathi kwe-cathode catalyst bed33. Xa uxinzelelo lwe-anolyte luncitshisiwe ukuya kwi-0.1 M KOH, zombini i-voltage yeseli kunye ne-formic acid oxidation (ukulahleka kwe-formic acid) ziyanda (Umfanekiso S1d), okubonisa ukurhweba kwe-zero-sum. Umgangatho we-formate oxidation uvavanywe kusetyenziswa ibhalansi yobunzima iyonke; ukuze ufumane iinkcukacha ezithe vetshe, jonga icandelo elithi "Iindlela". Ukusebenza kusetyenziswa i-MEA kunye noqwalaselo lwe-single CEM membrane nako kufundwe, kwaye iziphumo ziboniswe kuMfanekiso S1f,g. I-FE formate eqokelelwe kwi-cathode yayingaphezulu kwama-60% kwi-200 mA/cm2 ekuqaleni kovavanyo, kodwa yonakala ngokukhawuleza kwiiyure ezimbini ngenxa yokuqokelelwa kwetyuwa ye-cathode ekuthethwe ngayo ngaphambili (Umfanekiso S11).
I-Schematic ye-zero-gap MEA ene-CO2R kwi-cathode, i-hydrogen oxidation reaction (HOR) okanye i-OER kwi-anode, kunye ne-membrane enye ye-AEM phakathi. b I-FE kunye ne-voltage yeseli kolu qwalaselo kunye ne-1 M KOH kunye ne-OER ehamba kwi-anode. Iibha zempazamo zimele ukuphambuka okuqhelekileyo kwemilinganiselo emithathu eyahlukeneyo. kwi-FE kunye ne-voltage yeseli yenkqubo ene-H2 kunye ne-HOR kwi-anode. Imibala eyahlukeneyo isetyenziselwa ukwahlula i-formate kunye ne-formic acid production. d I-Schematic diagram ye-MEA ene-BPM itshintshelwe phambili embindini. I-FE kunye ne-voltage yebhetri ngokuchasene nexesha kwi-200 mA/cm2 kusetyenziswa olu qwalaselo. f Umfanekiso onqamlezileyo we-BPM MEA ebhekiswa phambili emva kovavanyo olufutshane.
Ukuze kuveliswe i-formic acid, i-hydrogen inikezelwa kwi-catalyst ye-Pt-on-carbon (Pt/C) kwi-anode. Njengoko kubonisiwe kuMfanekiso 2d, i-protons evelisa i-BPM ebhekisiwe phambili kwi-anode ikhe yaphandwa ngaphambili ukuze kufezekiswe imveliso ye-formic acid. Iyunithi yokulungisa i-BPM yasilela emva kwemizuzu engama-40 yokusebenza kumbane we-200 mA/cm2, ehamba nokunyuka kwevolthi engaphezulu kwe-5 V (Umfanekiso 2e). Emva kovavanyo, i-delamination ecacileyo yabonwa kwi-interface ye-CEM/AEM. Ngaphandle kwe-formate, ii-anions ezifana ne-carbonate, i-bicarbonate kunye ne-hydroxide nazo zinokudlula kwi-membrane ye-AEM kwaye zisebenze nee-protons kwi-interface ye-CEM/AEM ukuvelisa igesi ye-CO2 kunye namanzi angamanzi, okukhokelela kwi-delamination ye-BPM (Umfanekiso 2f) kunye ne-, ekugqibeleni okukhokelela ekusileleni kweseli.
Ngokusekelwe kwindlela yokusebenza kunye nokusilela kolu qwalaselo lungentla, kucetywa uyilo olutsha lwe-MEA njengoko kubonisiwe kuMfanekiso 1c kwaye kuchazwe kuMfanekiso 3a38. Apha, umaleko we-PCEM ubonelela ngendlela yokufuduka kwe-formic acid kunye nee-anions ukusuka kwi-interface ye-CEM/AEM, ngaloo ndlela kunciphisa ukuqokelelwa kwento. Kwangaxeshanye, indlela ye-PCEM interstitial ikhokelela i-formic acid kwindawo yokusasazwa kwe-diffusion medium kunye ne-flow field, inciphisa amathuba okuba i-formic acid oxidation. Iziphumo ze-polarization zisebenzisa ii-AEM ezinobukhulu obuyi-80, 40 kunye ne-25 mm ziboniswe kuMfanekiso 3b. Njengoko kulindelekile, nangona i-voltage iyonke yeseli inyuka ngokwanda kobukhulu be-AEM, ukusebenzisa i-AEM etyebileyo kuthintela ukusasazwa kwe-formic acid, ngaloo ndlela kwandisa i-cathode pH kunye nokunciphisa imveliso ye-H2 (Umfanekiso 3c–e).
Umzobo wesakhiwo se-MEA esine-AEM kunye ne-CEM eneembobo kunye neendlela ezahlukeneyo zokuthutha i-formic acid. b I-voltage yeseli kwiingxinano ezahlukeneyo zamandla ombane kunye nobukhulu obahlukeneyo be-AEM. kwi-EE kwiingxinano ezahlukeneyo zamandla ombane kunye nobukhulu be-AEM obuyi-80 μm (d) 40 μm, e) 25 μm. Iibha zempazamo zimele ukuphambuka okuqhelekileyo okulinganiswe kwiisampuli ezintathu ezahlukeneyo. f Iziphumo zokulinganisa zoxinzelelo lwe-formic acid kunye nexabiso le-pH kwi-interface ye-CEM/AEM kwiingxinano ezahlukeneyo ze-AEM. f I-PC kunye ne-pH kumaleko we-cathode we-catalyst enobukhulu obahlukeneyo befilimu ye-AEM. g Ukusasazwa kwe-two-dimensional of formic acid concentration with CEM/AEM interface and perforation.
Umfanekiso S2 ubonisa ukusasazwa koxinzelelo lwe-formic acid kunye ne-pH kulo lonke ubukhulu be-MEA kusetyenziswa i-Poisson-Nernst-Planck finite element modeling. Akumangalisi ukuba uxinzelelo oluphezulu lwe-formic acid, i-0.23 mol/L, lubonwa kwi-interface ye-CEM/AEM, kuba i-formic acid yenziwa kule interface. Uxinzelelo lwe-formic acid nge-AEM luyancipha ngokukhawuleza njengoko ubukhulu be-AEM bukhula, nto leyo ebonisa ukumelana okukhulu nokudluliselwa kobunzima kunye nokuguquguquka okuncinci kwe-formic acid ngenxa yokusasazwa komqolo. Imifanekiso 3 f kunye no-g ibonisa amaxabiso e-pH kunye ne-formic acid kwi-cathode catalyst bed ebangelwa kukusasazwa komqolo kunye nokusasazwa kwe-formic acid okunemilinganiselo emibini, ngokulandelelana. Okukhona i-membrane ye-AEM incinci, kokukhona uxinzelelo lwe-formic acid kufutshane ne-cathode, kwaye i-pH ye-cathode iba yi-acidic. Ke ngoko, nangona i-membranes ye-AEM etyebileyo ibangela ukulahleka okuphezulu kwe-ohmic, zibalulekile ekuthinteleni ukusasazwa komqolo kwe-formic acid kwi-cathode kunye nokwandisa ubumsulwa obuphezulu benkqubo ye-FE formic acid. Ekugqibeleni, ukwandisa ubukhulu be-AEM ukuya kwi-80 μm kwaphumela kwi-FE >75% ye-formic acid kwi-<2 V kunye ne-300 mA/cm2 kwindawo yeseli ye-25 cm2.
Ukuvavanya uzinzo lolu lwakhiwo olusekwe kwi-PECM, amandla ebhetri agcinwe kwi-200 mA/cm2 kangangeeyure ezingama-55. Iziphumo zizonke ziboniswe kuMfanekiso 4, kunye neziphumo ezivela kwiiyure zokuqala ezi-3 eziboniswe kuMfanekiso S3. Xa usebenzisa i-Pt/C anodic catalyst, i-voltage yeseli inyuke kakhulu kwimizuzu engama-30 yokuqala (Umfanekiso S3a). Kwixesha elide, i-voltage yeseli yahlala ifana, inika izinga lokubola kwe-0.6 mV/h (Umfanekiso 4a). Ekuqaleni kovavanyo, i-PV ye-formic acid eqokelelwe kwi-anode yayiyi-76.5% kwaye i-PV ye-hydrogen eqokelelwe kwi-cathode yayiyi-19.2%. Emva kweyure yokuqala yovavanyo, i-hydrogen FE yehla yaya kwi-13.8%, nto leyo ebonisa ukuphuculwa kokukhetha kwe-formate. Nangona kunjalo, izinga lokuxovwa kwe-formic acid kwinkqubo lehle laya kwi-62.7% kwiyure e-1, kwaye izinga lokuxovwa kwe-anodic formic acid lenyuke ukusuka phantse kwi-zero ekuqaleni kovavanyo laya kwi-17.0%. Emva koko, i-FE ye-H2, i-CO, i-formic acid kunye nezinga lokuxovwa kwe-anodic ye-formic acid kwahlala kuzinzile ngexesha lovavanyo. Ukwanda kwe-formic acid oxidation kwiyure yokuqala kusenokuba ngenxa yokuqokelelwa kwe-formic acid kwi-PCEM/AEM interface. Njengoko uxinzelelo lwe-formic acid lukhula, aluphumi kuphela ngokugqobhoka kwe-membrane, kodwa lusasazeka nge-FEM ngokwayo kwaye lungene kumaleko we-Pt/C anode. Ekubeni i-formic acid ilulwelo kwi-60°C, ukuqokelelwa kwayo kunokubangela iingxaki zokudluliselwa kobuninzi kwaye kubangele ukuxovwa okukhethwayo ngaphezu kwe-hydrogen.
i-voltage yeseli xa ithelekiswa nexesha (200 mA/cm2, 60 °C). I-inset ibonisa umfanekiso we-optical microscope we-cross-section ye-MEA ene-EM eneembobo. I-scale bar: 300 µm. b Ubumsulwa be-PE kunye ne-formic acid njengomsebenzi wexesha kwi-200 mA/cm2 kusetyenziswa i-Pt/C anode.
Imo yeesampuli ekuqaleni kovavanyo (i-BOT) ngexesha lokulungiselela kunye nasekupheleni kovavanyo (i-EOT) emva kweeyure ezingama-55 zovavanyo lokuzinza yachazwa kusetyenziswa i-nano-X-ray computed tomography (i-nano-CT), njengoko kubonisiwe kuMfanekiso 5 a. Isampulu ye-EOT inobukhulu obukhulu be-catalyst particle enobubanzi obuyi-1207 nm xa kuthelekiswa ne-930 nm ye-BOT. Imifanekiso ye-high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) kunye neziphumo ze-energy-dispersive X-ray spectroscopy (EDS) ziboniswe kuMfanekiso 5b. Ngelixa umaleko we-BOT catalyst uqulethe uninzi lwee-catalyst particles ezincinci kunye nezinye ii-agglomerates ezinkulu, kwinqanaba le-EOT umaleko we-catalyst unokwahlulwa ube ziingingqi ezimbini ezahlukeneyo: enye ene-solid particles ezinkulu kakhulu kwaye enye ine-porous regions ezingaphezulu. Inani le-porous particles. Umfanekiso we-EDS ubonisa ukuba ii-solid particles ezinkulu zizityebi kwi-Bi, mhlawumbi i-metallic Bi, kwaye iindawo ezine-porous zizityebi kwi-oxygen. Xa iseli isebenza kwi-200 mA/cm2, amandla angalunganga e-cathode aya kubangela ukwehla kwe-Bi2O3, njengoko kuboniswe ziziphumo ze-in situ X-ray absorption spectroscopy ezixutyushwe ngezantsi. Iziphumo zemephu ye-HAADF-STEM kunye ne-EDS zibonisa ukuba i-Bi2O3 idlula kwinkqubo yokunciphisa, ebangela ukuba ilahlekelwe yi-oxygen kwaye ihlangane ibe ngamasuntswana amakhulu esinyithi. Iipateni ze-X-ray diffraction zee-BOT kunye nee-EOT cathodes ziqinisekisa ukutolikwa kwedatha ye-EDS (Umzobo 5c): yi-crystalline Bi2O3 kuphela efunyenwe kwi-BOT cathode, kwaye i-crystalline bimetal yafunyanwa kwi-EOT cathode. Ukuqonda impembelelo ye-cathode potential kwimeko ye-oxidation ye-Bi2O3 cathode catalyst, ubushushu bahluka ukusuka kwi-open circuit potential (+0.3 V vs RHE) ukuya kwi--1.5 V (vs RHE). Kuqatshelwe ukuba isigaba seBi2O3 siqala ukuncitshiswa kwi -0.85 V xa kuthelekiswa ne-RHE, kwaye ukwehla kobunzima bomgca omhlophe kummandla osemaphethelweni we-spectrum kubonisa ukuba i-metallic Bi incitshisiwe ukuya kwi-90% ye-RHE kwi -1.1. V ngokuchasene ne-RHE (Umzobo 5d). Nokuba yeyiphi indlela, ukukhetha ngokubanzi kwe-formate kwi-cathode akutshintshi, njengoko kucingelwa kwi-H2 kunye ne-CO FE kunye nokwakheka kwe-formic acid, nangona utshintsho olukhulu kwi-cathode morphology, imeko ye-catalyst oxidation, kunye nesakhiwo se-microcrystalline.
a Ulwakhiwo olunemilinganiselo emithathu lwe-catalyst layer kunye nokusasazwa kwee-catalyst particles ezifunyenwe kusetyenziswa i-nano-X-ray CT. I-scale bar: 10 µm. b Phezulu 2: Imifanekiso ye-HAADF-STEM yee-cathode layers ze-BOT kunye ne-EOT catalysts. I-scale bar: 1 µm. Ezantsi 2: Imifanekiso ye-HADF-STEM kunye ne-EDX eyandisiweyo ye-cathode layer ye-EOT catalyst. I-scale bar: 100 nm. c Iipateni ze-X-ray diffraction zeesampuli ze-BOT kunye ne-EOT cathode. d I-In situ X-ray absorption spectra ye-Bi2O3 electrode kwi-0.1 M KOH njengomsebenzi we-potential (0.8 V ukuya kwi--1.5 V vs. RHE).
Ukuze kuchongwe ngqo amathuba akhoyo okuphucula ukusebenza kakuhle kwamandla ngokuthintela i-formic acid oxidation, i-H2 reference electrode isetyenzisiwe ukuchonga igalelo lokulahleka kwe-voltage39. Kwi-current densities engaphantsi kwe-500 mA/cm2, i-cathode potential ihlala ingaphantsi kwe--1.25 V. I-anodic potential yahlulwe yangamacandelo amabini aphambili: i-exchange current density HOR kunye ne-theory overvoltage HOR 40 eqikelelwe yi-Bulter-Volmer equation eyayilinganiswe ngaphambili, kwaye inxalenye eseleyo ibangelwa yi-oxidation formic acid. Ngenxa ye-reaction kinetics ecothayo kakhulu xa kuthelekiswa ne-HOR41, izinga elincinci le-formic acid oxidation reaction kwi-anode linokubangela ukwanda okukhulu kwi-anodic potential. Iziphumo zibonisa ukuba ukuthintelwa okupheleleyo kwe-formic acid anodic oxidation kunokususa phantse i-500 mV overvoltage.
Ukuvavanya olu qikelelo, izinga lokuhamba kwamanzi angena kwi-ion (DI) kwindawo yokungena ye-anode lahlulwe ukuze kuncitshiswe uxinzelelo lwe-effluent formic acid. Imifanekiso 6b kunye no-c ibonisa i-FE, uxinzelelo lwe-formic acid, kunye ne-voltage yeseli njengomsebenzi we-DI flux kwi-anode kwi-200 mA/cm2. Njengoko izinga lokuhamba kwamanzi angena kwi-ion linyuka ukusuka kwi-3.3 mL/min ukuya kwi-25 mL/min, uxinzelelo lwe-formic acid kwi-anode lwehla ukusuka kwi-0.27 mol/L ukuya kwi-0.08 mol/L. Xa kuthelekiswa, kusetyenziswa isakhiwo sesandwich esicetyiswe nguXia et al. 30, uxinzelelo lwe-formic acid lwe-1.8 mol/L lufunyenwe kwi-200 mA/cm2. Ukunciphisa uxinzelelo kuphucula i-FE iyonke ye-formic acid kwaye kunciphisa i-FE ye-H2 njengoko i-cathode pH iba yi-alkaline ngakumbi ngenxa yokuncipha kokusasazwa kwe-back formic acid. Uxinzelelo oluphantsi lwe-formic acid kwi-DI flow ephezulu lukwasuse phantse i-formic acid oxidation, nto leyo ebangela i-total cell voltage engaphantsi nje kwe-1.7 V kwi-200 mA/cm2. Ubushushu bebhetri bukwachaphazela ukusebenza ngokubanzi, kwaye iziphumo ziboniswe kuMfanekiso S10. Nangona kunjalo, uyilo olusekwe kwi-PCEM lunokuphucula kakhulu ukusebenza kakuhle kwamandla ekuthinteleni i-formic acid oxidation, nokuba kukusetyenziswa kwee-anodic catalysts ezinokukhetha ngcono i-hydrogen kwi-formic acid okanye ngokusebenzisa isixhobo.
a Ukwahlulwa kwevolthi yeseli kusetyenziswa i-electrode yesalathiso seseli ye-H2 esebenza kwi-60 °C, i-anode ye-Pt/C kunye ne-80 µm AEM. b Ii-FE kunye nee-formic acid concentrations eziqokelelwe kwi-200 mA/cm2 kusetyenziswa amazinga ahlukeneyo okuhamba kwamanzi a-anodic deionized. c Xa i-anode iqokelela i-formic acid kwii-concentrations ezahlukeneyo, i-voltage yeseli yi-200 mA/cm2. Ii-error bars zimele ukuphambuka okuqhelekileyo kwemilinganiselo emithathu eyahlukeneyo. d Ixabiso elincinci lokuthengisa lihlukaniswe ngokusebenza kwii-deionized water flow rates ezahlukeneyo kusetyenziswa amaxabiso ombane aphakathi kwemizi-mveliso kazwelonke e-US$0.068/kWh kunye ne-US$4.5/kg ye-hydrogen. (*: Imeko encinci ye-oxidation ye-formic acid kwi-anode ithathwa njenge-10 M FA, ixabiso eliqhelekileyo lombane wemizi-mveliso likazwelonke yi-$0.068/kWh, kwaye i-hydrogen yi-$4.5/kg. **: Imeko encinci ye-oxidation yi-formic acid ethathwa njenge-formic acid. Uxinzelelo lwe-FA kwi-anode yi-1.3 M anode, ixabiso lombane elilindelweyo kwixesha elizayo yi-$0.03/kWh, kwaye umgca onamachaphaza umele ixabiso lemarike le-85 wt% FA.
Uhlalutyo lwe-techno-economic (TEA) lwenziwe ukuze kufunyanwe ixabiso elincinci lokuthengisa leendibano zamafutha phantsi kweemeko ezahlukeneyo zokusebenza, njengoko kubonisiwe kuMfanekiso 5d. Iindlela kunye nedatha yangasemva ye-TEA inokufumaneka kwi-SI. Xa uxinzelelo lwe-LC kwi-anode exhaust luphezulu, nangona i-voltage ephezulu yeseli, iindleko zizonke zendibano yamafutha ziyancitshiswa ngenxa yokunciphisa iindleko zokwahlulahlula. Ukuba i-anodic oxidation ye-formic acid inokuncitshiswa ngophuhliso lwe-catalyst okanye iteknoloji ye-electrode, indibaniselwano ye-voltage ephantsi yeseli (1.66 V) kunye noxinzelelo oluphezulu lwe-FA kwi-effluent (10 M) kuya kunciphisa iindleko zemveliso ye-electrochemical FA ukuya kwi-0.74 US dollars/kg (ngokusekelwe kumbane). ixabiso) $0.068/kWh kunye ne-$4.5/kg ye-hydrogen42. Ngaphezu koko, xa zidityaniswe neendleko zexesha elizayo zombane ohlaziyekayo ze-$0.03/kWh kunye ne-hydrogen ye-$2.3/kg, ithagethi yamanzi amdaka ye-FA incitshiswa ukuya kwi-1.3 yezigidi, nto leyo ekhokelela ekubeni iindleko zokugqibela zemveliso eziqikelelweyo zibe yi-US$0.66/kg43. Oku kuthelekiswa namaxabiso emarike akhoyo ngoku. Ngoko ke, imizamo yexesha elizayo egxile kwizixhobo ze-electrode kunye nezakhiwo zinokunciphisa ngakumbi i-anodization ngelixa zivumela ukusebenza kwii-voltages ezisezantsi zeeseli ukuvelisa amazinga aphezulu e-LC.
Ngamafutshane, sifunde izakhiwo ezininzi ze-ZERO-gap MEA zokunciphisa i-CO2 ibe yi-formic acid kwaye sicebise isakhiwo esiqulethe i-composite forward-biased bipolar membrane equka i-perforated cation exchange membrane (PECM) ukuze kube lula ukujongana nokudluliselwa kobunzima be-membrane kwi-formic acid ephumayo. . Olu lwakhiwo luvelisa i-formic acid engaphezulu kwama-96% kwiindawo ezifikelela kwi-0.25 M (kwizinga lokuhamba kwe-anode DI le-3.3 mL/min). Kwizinga lokuhamba kwe-DI eliphezulu (25 mL/min), olu lwakhiwo lubonelele ngoxinano lwangoku lwe->80% FE ye-200 mA/cm2 kwi-1.7 V kusetyenziswa indawo yeseli ye-25 cm2. Kwizinga eliphakathi le-anodic DI (10 mL/min), ulungiselelo lwe-PECM lugcine i-voltage ezinzileyo kunye namanqanaba aphezulu e-formic acid FE kangangeeyure ezingama-55 zovavanyo kwi-200 mA/cm2. Uzinzo oluphezulu kunye nokukhetha okufunyenwe zii-catalysts ezifumaneka kurhwebo kunye nezixhobo ze-polymeric membrane zinokuphuculwa ngakumbi ngokuzidibanisa nee-electrocatalysts ezilungisiweyo. Umsebenzi olandelayo uza kugxila ekulungiseni iimeko zokusebenza, ukukhetha i-anode catalyst, kunye nolwakhiwo lwe-MEA ukunciphisa i-formic acid oxidation, okubangela ukungcola okuxineneyo kwi-voltages ezisezantsi zeeseli. Indlela elula yokusebenzisa i-carbon dioxide kwi-formic acid evezwe apha isusa imfuneko ye-anolyte kunye nee-catholyte chambers, izinto zesandwich, kunye nezixhobo ezikhethekileyo, ngaloo ndlela kwandisa ukusebenza kakuhle kwamandla eseli kunye nokunciphisa ubunzima benkqubo, okwenza kube lula ukwandisa. Ulwakhiwo olucetywayo lubonelela ngeqonga lophuhliso lwexesha elizayo lwezityalo zokuguqula i-CO2 ezisebenzayo kwezobuchwepheshe nakwezoqoqosho.
Ngaphandle kokuba kuchazwe ngenye indlela, zonke izixhobo kunye nezinyibilikisi ezikumgangatho weekhemikhali zisetyenzisiwe njengoko zifunyenwe. I-Bismuth oxide catalyst (Bi2O3, 80 nm) ithengwe kwi-US Research Nanomaterials, Inc. I-Polymer powder (AP1-CNN8-00-X) inikezelwe yi-IONOMR. I-Omnisolv® brand N-propanol (nPA) kunye namanzi acocekileyo kakhulu (18.2 Ω, Milli–Q® Advantage A10 water cleansing system) zithengwe kwi-Millipore Sigma. I-methanol kunye ne-acetone eziqinisekiswe yi-ACS zithengwa kwi-VWR Chemicals BDH® kunye ne-Fisher Chemical, ngokwahlukeneyo. I-polymer powder ixutywe nomxube we-acetone kunye ne-methanol kumlinganiselo we-1:1 ngobunzima ukuze kufunyanwe i-polymer dispersion enoxinzelelo lwe-6.5 wt.%. Lungisa i-inki ye-catalytic ngokuxuba i-20g ye-Bi2O3, amanzi acocekileyo kakhulu, i-nPA kunye ne-ionomer dispersion kwijari ye-30ml. Umxube wawune-30 wt.% catalyst, umlinganiselo wobunzima be-ionomer kwi-catalyst ye-0.02 kunye nomlinganiselo wobunzima botywala kumanzi we-2:3 (40 wt.% nPA). Ngaphambi kokuxuba, i-70g yeGlen Mills 5mm zirconia grinding material yongezwa kumxube. Iisampulu zabekwa kwi-roller yebhotile yedijithali yeFisherbrand™ kwi-80 rpm iiyure ezingama-26. Vumela i-inki ihlale imizuzu engama-20 ngaphambi kokufaka. I-inki ye-Bi2O3 ifakwe kwi-applicator ye-Qualtech automatic (QPI-AFA6800) kusetyenziswa i-1/2″ x 16″ wirewound refill yelabhoratri (RD Specialties - 60 mil diameter) kwi-22°C. I-5 mL ye-inki catalytic yafakwa kwi-7.5 x 8 intshi Sigraacet 39 BB carbon diffusion carrier (fuel cell storage) ngokubeka induku kwisantya esimiselweyo se-55 mm/sec. Dlulisa ezi electrodes zigqunyiweyo kwi-oven uze zome kwi-80 °C. Inkqubo yokugqunywa kwentonga kunye nemifanekiso yokugqunywa kwe-GDE iboniswe kwiMifanekiso S4a kunye no-b. Isixhobo se-X-ray fluorescence (XRF) (Fischerscope® XDV-SDD, Fischer-Technolgy Inc. USA) siqinisekisile ukuba umthwalo we-GDE ogqunyiweyo yi-3.0 mg Bi2O3/cm2.
Kwimilo ye-composite membrane equlethe i-anion exchange membrane (AEM) kunye ne-CEM eneembobo. I-Nafion NC700 (Chemours, USA) enobukhulu obuqhelekileyo be-15 µm yasetyenziswa njengomaleko we-CEM. I-anodic catalyst yatshizwa ngqo kwi-FEM ngomlinganiselo we-ionomer kwi-carbon we-0.83 kunye nommandla wokugubungela we-25 cm2. I-platinum exhaswayo enendawo enkulu yomphezulu (50 wt.% Pt/C, TEC 10E50E, TANAKA precious metal) enomthwalo we-0.25 mg Pt/cm2 yasetyenziswa njenge-anode catalyst. I-Nafion D2020 (Ion Power, USA) yasetyenziswa njenge-inomer yomaleko we-anode we-catalyst. I-CEM perforation yenziwa ngokusika imigca ehambelanayo kwifilimu ye-CEM ngamaxesha angama-3mm. Iinkcukacha zenkqubo yokugqobhoza ziboniswe kwiMifanekiso S12b kunye no-c. Ukusebenzisa i-X-ray computed tomography, kwaqinisekiswa ukuba umsantsa wokugqobhoza wawuyi-32.6 μm, njengoko kubonisiwe kuMfanekiso S12d kunye no-e. Ngexesha lokuhlanganiswa kweeseli, i-membrane ye-CEM egqobhozekileyo ene-catalyst yabekwa kwiphepha le-Toray elingama-25 cm2 (5 wt% PTFE treated, Fuel Cell Store, USA). I-membrane ye-AEM (PiperION, Versogen, USA) enobukhulu obuyi-25, 40 okanye 80 μm yabekwa phezu kwe-CEM yaza yabekwa kwi-GDE cathode. I-membrane ye-AEM yanqunyulwa yaba ziingcezu ze-7.5 × 7.5 cm ukugubungela yonke indawo yokuhamba kwaye yafakwa ubusuku bonke kwisisombululo se-potassium hydroxide se-1 M ngaphambi kokuhlanganiswa. Zombini i-anode kunye ne-cathode zisebenzisa ii-PTFE spacers ezinobukhulu obaneleyo ukufezekisa uxinzelelo lwe-GDE olufanelekileyo lwe-18%. Iinkcukacha zenkqubo yokuhlanganiswa kwebhetri ziboniswe kuMfanekiso S12a.
Ngexesha lovavanyo, iseli edibeneyo igcinwe kwi-60 °C (30, 60, kunye ne-80 °C kwizifundo zokuxhomekeka kubushushu) kunye ne-0.8 L/min yegesi yehydrogen enikwe kwi-anode kunye ne-2 L/min yekhabhoni diokside enikwe kwi-cathode. Zombini i-anodic kunye ne-cathodic air streams zafunyiswa kwi-100% yomswakama ohambelanayo kunye ne-259 kPa absolute cathodic pressure. Ngexesha lokusebenza, i-cathode gas stream yaxutywa nesisombululo se-1 M KOH ngesantya se-2 mL/min ukukhuthaza ukusetyenziswa kwe-cathode catalyst bed kunye ne-ionic conduction. Xuba i-anode gas stream kunye namanzi acocekileyo ngesantya se-10 ml/min ukususa i-formic acid kwi-anode. Iinkcukacha zezixhobo ezifakwayo kunye neziphumo ziboniswe kuMfanekiso S5. I-cathode exhaust gas iqulethe i-CO2 kwaye ivelisa i-CO2 kunye ne-H2. Umphunga wamanzi ususwa nge-condenser (i-low temperature heat exchanger kwi-2°C). Igesi eseleyo iya kuqokelelwa ukuze kuhlalutywe ixesha legesi. Ukuhamba kwe-anode kuya kudlula kwi-condenser ukuze kwahlulwe ulwelo kwigesi. Amanzi amdaka aya kuqokelelwa kwiibhotile ezicocekileyo aze ahlalutywe kusetyenziswa i-liquid chronometry ukuze kulinganiswe i-formic acid eveliswayo. Uvavanyo lwe-electrochemical lwenziwe kusetyenziswa i-Garmy potentiostat (inombolo yesalathiso 30K, eGamry, e-USA). Ngaphambi kokulinganisa i-polarization curve, iseli yalungiswa amaxesha ama-4 ukusuka kwi-0 ukuya kwi-250 mA/cm2 kusetyenziswa i-linear voltammetry enesantya sokuskena se-2.5 mA/cm2. Ii-polarization curves zifunyenwe kwi-galvanostatic mode kunye neseli ebanjwe kuxinano oluthile lwamandla imizuzu emi-4 ngaphambi kokuba kuthathwe isampuli yegesi ye-cathode kunye nolwelo lwe-anolyte.
Sisebenzisa i-electrode yereferensi ye-hydrogen kwi-MEA ukwahlula i-cathode kunye ne-anodic potentials. Ulwakhiwo lwe-electrode yereferensi luboniswe kuMfanekiso S6a. I-membrane ye-Nafion (Nafion 211, IonPower, USA) yasetyenziswa njengebhulorho ye-ionic ukudibanisa i-membrane ye-MEA kunye ne-electrode yereferensi. Isiphelo esinye se-strip ye-Nafion saqhagamshelwa kwi-electrode ye-1 cm2 ye-gas diffusion (GDE) elayishwe yi-0.25 mg Pt/cm2 (50 wt% Pt/C, TEC10E50E, TANAKA Precious Metals) ethe tyaba kwiphepha le-carbon le-29BC (iFuel Cell Store, USA). ). I-hardware ekhethekileyo ye-polyetherketone (PEEK) isetyenziselwa ukuvala igesi nokuqinisekisa unxibelelwano oluhle phakathi kwe-GDE kunye ne-Nafion strips, kunye nokudibanisa i-electrode yereferensi kwi-hardware ye-fuel cell. Esinye isiphelo se-strip ye-Nafion siqhagamshelwe kumda ophumayo webhetri ye-CEM. Umfanekiso S6b ubonisa icandelo elinqamlezileyo le-electrode yereferensi edityaniswe ne-MEA.
Emva kokuba igesi ephumayo idlule kwi-condenser kunye ne-gas-liquid separator, iisampulu zegesi zithathwa kwi-cathode. Igesi eqokelelweyo ihlalutywe ubuncinane kathathu kusetyenziswa i-4900 Micro GC (10 μm molecular sieve, Agilent). Iisampulu ziqokelelwe kwiibhegi zesampulu zegesi ze-aluminium foil ezine-inert multi-layer Supel™ (Sigma-Aldrich) kangangexesha elithile (imizuzwana engama-30) kwaye zifakwe ngesandla kwi-microgas chromatograph kwiiyure ezimbini emva kokuqokelelwa. Ubushushu be-injection bubekwe kwi-110°C. I-Carbon monoxide (CO) kunye ne-hydrogen (H2) zahlulwe kwikholamu ye-MS5A eshushu (105 °C) ene-pressurized (28 psi) ye-10 m kusetyenziswa i-argon (Matheson Gas-Matheson Purity) njengegesi ethwalayo. Olu qhagamshelo lufunyanwa kusetyenziswa i-Thermal Conductivity Detector (TCD) eyakhelwe ngaphakathi. Ii-GC chromatograms kunye nee-CO kunye nee-H2 calibration curves ziboniswe kuMfanekiso S7. Iisampulu ze-asidi ye-liquid formic acid zaqokelelwa kwi-anode ixesha elithile (imizuzwana eli-120) zaza zahluzwa kusetyenziswa isihluzo sesirinji se-PTFE se-0.22 μm kwiibhotile ze-2 mL. Iimveliso ze-liquid kwiibhotile zahlalutywa kusetyenziswa inkqubo ye-Agilent 1260 Infinity II bioinert high-performance liquid chromatography (HPLC), apho i-20 μl yesampulu yafakwa nge-autosampler (G5668A) ene-mobile phase ye-4 mM sulfuric acid (H2SO4). ) ngesantya sokuhamba se-0.6 ml/min (ipompo ye-quaternary G5654A). Iimveliso zahlulwe kwi-heated (35°C, column oven G7116A) Aminex HPX-87H 300 × 7.8 mm (Bio-Rad) eyandulelwa yi-Micro-Guard Cation H guard column. I-asidi ye-Formic yafunyanwa kusetyenziswa i-diode array detector (DAD). kwi-wavelength ye-210 nm kunye ne-bandwidth ye-4 nm. I-chromatogram ye-HPL kunye ne-formic acid standard calibration curve ziboniswe kuMfanekiso S7.
Iimveliso zegesi (CO kunye ne-H2) FE zibalwa kusetyenziswa le equation ilandelayo, kwaye i-total moles yegesi ibalwa kusetyenziswa i-equation yegesi efanelekileyo:
Phakathi kwazo: \({n}_{i}\): inani lee-electron kwi-electrochemical reaction. \(F\): I-Faraday's constant. \({C}_{i}\): Uxinzelelo lwemveliso yolwelo lwe-HPLC. \(V\): umthamo wesampulu yolwelo eqokelelwe kwixesha elimiselweyo t. \(j\): uxinano lwangoku. \(A\): Indawo yejiyometri ye-electrode (25 cm2). \(t\): ixesha lesampulu. \(P\): uxinzelelo olupheleleyo. \({x}_{i}\): Ipesenti ye-mole yegesi emiselwe yi-GC. \(R\): i-gas constant. \(T\): ubushushu.
Uxinaniso lwee-anodic cations lulinganiswe kusetyenziswa i-inductively coupled plasma atomic emission spectroscopy (ICP-OES). Ii-Cations ezinokuphuma okanye zisasazeke kwi-anode ziquka i-Ti, i-Pt, i-Bi kunye ne-K. Ngaphandle kwe-K, zonke ezinye ii-cations bezingaphantsi komda wokufunyanwa. Yenza ii-ions kwisisombululo zishiya i-anode idibene nee-protons okanye ezinye ii-cations. Ke ngoko, ubumsulwa be-formic acid bunokubalwa njenge
Imveliso yeFormate/FA imele ubungakanani be-FA eveliswayo nge-kWh nganye yombane osetyenzisiweyo kusetyenziswa ulungiselelo oluthile lwe-MEA, kwi-mol/kWh. Ibalwa ngokusekelwe kuxinano lwangoku, i-voltage yeseli kunye nokusebenza kakuhle kweFaraday phantsi kweemeko ezithile zokusebenza.
Bala ubungakanani be-formic acid e-oxidized kwi-anode ngokusekelwe kwibhalansi yobunzima iyonke. Iimpendulo ezintathu ezikhuphisanayo zenzeka kwi-cathode: i-hydrogen evolution, ukunciphisa i-CO2 ukuya kwi-CO2, kunye nokunciphisa i-CO2 ukuya kwi-formic acid. Ngenxa yokuba sinenkqubo ye-formic acid oxidation e-Anton, i-formic acid FE inokwahlulwa ibe ngamacandelo amabini: ukuqokelelwa kwe-formic acid kunye ne-formic acid oxidation. Ibhalansi yobunzima iyonke ingabhalwa ngolu hlobo:
Sisebenzise i-GC ukubala ubungakanani be-formic acid, i-hydrogen, kunye ne-CO eqokelelwe yi-HPLC. Kufuneka kuqatshelwe ukuba uninzi lwe-formic acid luqokelelwe kwi-anode kusetyenziswa indlela eboniswe kwi-Supplementary Figure S5. Ubungakanani be-formate eqokelelwe kwigumbi le-cathode abubalulekanga, bungaphantsi ngama-oda amabini ngobukhulu, kwaye bufikelela ngaphantsi kwe-0.5% yenani lilonke le-SC.
Imodeli yokuthutha eqhubekayo esetyenzisiweyo apha isekelwe kumsebenzi wangaphambili kwiinkqubo ezifanayo34. Inkqubo edibeneyo yee-Poisson-Nerst-Planck (PNP) equations isetyenziselwa ukumisela uxinzelelo lwamanzi kunye nekhono le-electrostatic kwizigaba zokuqhuba nge-elektroniki kunye ne-ionically. Isishwankathelo esineenkcukacha zee-equations ezisisiseko kunye ne-geometry yemodeli inikwe kwi-SI.
Le nkqubo imisela uxinaniso lwezinto ezisibhozo zamanzi (\({{{{{\rm{C}}}}}}}{{{{{\rm{O}}}}}}}}_{2 \left ({{{{{\rm{aq}}}}}}}\right)}\), \({{{{{{\rm{H}}}}}}}}}^{+ }\ ), \ ({{{{\rm{O}}}}}}{{{{{{\rm{H}}}}}}^{-}\), \({{{ {{ \rm{HCO}}}}}}_{3}^{-}\), \({{{{{\rm{CO}}}}}}_{3}^{ 2-} \ ),\ ({{{{\rm{HCOOH}}}}}}}\), \({{{{{\rm{HCOO}}}}}}}}}^{- }\) kunye \({{ {{{\rm{K}}}}}}}^{+}\)), amandla e-electrostatic kwisigaba sokuqhuba i-ionic (\({\phi }_{I}\ )) kunye nokuqhuba i-electron ye-anodic kunye ne-cathodic. Amandla e-electrostatic kwizigaba (\({\phi }_{A}\) kunye \({\phi }_{C}\) ngokwahlukeneyo). Endaweni yoko, imisebenzi yombane yengingqi okanye yokusasazwa kwe-charge ayifezekiswa, ummandla we-space charge usonjululwa ngokuthe ngqo kusetyenziswa i-equation kaPoisson; Le ndlela isivumela ukuba sibonise ngokuthe ngqo iziphumo zokurhoxiswa kukaDonnan kwi-CEM|AEM, CEM|Pore, kunye ne-AEM|Pore interfaces. Ukongeza, ithiyori ye-porous electrode (PET) isetyenziselwa ukuchaza ukuthuthwa kwe-charge kwi-anodic kunye ne-cathodic layers ze-catalyst. Ngokolwazi lwababhali, lo msebenzi umele ukusetyenziswa kokuqala kwe-PET kwiinkqubo ezineendawo ezininzi zokutshaja isithuba.
Iisampulu ze-GDE BOT kunye ne-EOT cathode zivavanyiwe kusetyenziswa i-Zeiss Xradia 800 Ultra enomthombo we-X-ray we-8.0 keV, iindlela zokufunxa kunye neendlela zentsimi ebanzi, kunye ne-image fusion1. Imifanekiso engama-901 iqokelelwe ukusuka kwi--90° ukuya kwi-90° kunye nexesha lokuvezwa lemizuzwana engama-50. Ukwakhiwa ngokutsha kwenziwe kusetyenziswa isihluzi se-back projection esinobukhulu be-voxel obuyi-64 nm. Uhlalutyo lokwahlulwahlulwa kunye nokusasazwa kobukhulu be-particle lwenziwe kusetyenziswa ikhowudi ebhalwe ngokukodwa.
Ukuchazwa kwe-electron microscopic kubandakanya ukufaka ii-MEA zovavanyo kwi-epoxy resin ukulungiselela ukuhlukaniswa okuncinci kakhulu ngemela yedayimani. Icandelo elinqamlezileyo le-MEA nganye lisikwe laya kubukhulu obuyi-50 ukuya kwi-75 nm. I-Talos F200X transmission electron microscope (Thermo Fisher Scientific) isetyenziselwe ukuskena i-transmission electron microscopy (STEM) kunye ne-energy-dispersive X-ray spectroscopy (EDS) measurements. I-microscope ixhotyiswe nge-EDS Super-X system ene-4 windowless SDD detectors kwaye isebenza kwi-200 kV.
Iipateni ze-diffraction ye-Powder X-ray (PXRD) zifunyenwe kwi-Bruker Advance D8 powder X-ray diffractometer ene-Ni-filtered Cu Kα radiation esebenza kwi-40 kV kunye ne-40 mA. Uluhlu lokuskena luqala kwi-10° ukuya kwi-60°, ubungakanani benyathelo yi-0.005°, kwaye isantya sokufumana idatha singumzuzwana omnye ngenyathelo.
I-RAS spectrum emphethweni we-Bi2O3 Bi L3 catalyst ilinganiswe njengomsebenzi we-potential kusetyenziswa iseli eyenziwe ekhaya. I-inki ye-ionomer ye-Bi2O3 catalytic ilungiswe kusetyenziswa i-26.1 mg ye-Bi2O3 exutywe nesisombululo se-ionomer se-156.3 μL (6.68%) kwaye yasuswa nge-1 M KOH, amanzi (157 μL) kunye ne-isopropyl alcohol (104 μL) ukuze kufunyanwe i-inki ye-ionomer. I-catalyst coefficient yi-0.4. I-inki isetyenziswe kumaphepha e-graphene kwiindawo eziziingxande (10×4 mm) de umthwalo we-Bi2O3 catalyst ufikelele kwi-0.5 mg/cm2. Inxalenye eseleyo yephepha le-graphene igqunywe nge-Kapton ukuze yahlulwe ezi ndawo kwi-electrolyte. Iphepha le-graphene eligqunywe nge-catalyst lifakwe phakathi kwe-PTFE ezimbini kwaye laqiniswa emzimbeni weseli (PEEK) ngezikrufu, Umfanekiso S8. I-Hg/HgO (1 M NaOH) isetyenzisiwe njenge-electrode yokubhekisa, kwaye iphepha le-carbon lisetyenzisiwe njenge-electrode yokuchasana. I-electrode yesalathiso se-Hg/HgO ilinganiswe kusetyenziswa intambo yeplatinum efakwe kwi-hydrogen-saturated 0.1 M KOH ukuguqula zonke ii-potentials ezilinganisiweyo zibe yi-reversible hydrogen electrode (RHE) scale. Ii-XRD spectra zifunyenwe ngokujonga amandla e-Bi2O3/graphene sheet working electrode efakwe kwi-0.1 M KOH, eshushu ukuya kwi-30 °C. I-electrolyte ijikeleza kwibhetri, kunye ne-electrolyte inlet ezantsi kweseli kunye ne-outlet phezulu ukuqinisekisa ukuba i-electrolyte iqhagamshelana nomaleko we-catalyst xa kusenziwa amaqamza. I-CH Instruments 760e potentiostat yasetyenziswa ukulawula amandla e-electrode asebenzayo. Ulandelelwano olunokwenzeka yayiyi-open circuit potential: -100, -200, -300, -400, -500, -800, -850, -900, -1000, -1100, -1500 kunye ne-+700 mV kuxhomekeke kwi-RHE. Zonke ii-potentials ze-iR zilungisiwe.
I-Bi L3 edge (~13424 eV yeBi metal) i-X-ray absorption fine structure (XAFS) spectroscopy yenziwe kwi-channel 10-ID, Advanced Photon Source (APS), Argonne National Fluorescence Laboratory. I-National Model Measurement Laboratory. I-monochromator ye-Si(111) yekristale ezimbini epholiswe yi-nitrogen engamanzi yasetyenziswa ukulungisa amandla e-X-ray, kwaye isibuko esine-rhodium-coated sasetyenziswa ukunciphisa umxholo we-harmonic. Amandla okuskena ahluka ukusuka kwi-13200 ukuya kwi-14400 eV, kwaye i-fluorescence yalinganiswa kusetyenziswa i-5 × 5 silicon PIN diode array ngaphandle kwezihluzi okanye ii-Soller slits. Amandla okuwela i-zero ye-derivative yesibini alinganiswa kwi-13271.90 eV ngomda we-L2 we-Pt foil. Ngenxa yobukhulu beseli ye-electrochemical, kwakungenakwenzeka ukulinganisa ngaxeshanye i-spectrum yomgangatho ongqinisisiweyo. Ngoko ke, utshintsho olubaliweyo lwe-scan-to-scan kumandla e-X-ray angalindelekanga yi-±0.015 eV ngokusekelwe kumlinganiselo ophindaphindwayo kulo lonke uvavanyo. Ubukhulu beleyara ye-Bi2O3 bukhokelela kwinqanaba elithile lokuzifunxa ngokwalo kwe-fluorescence; ii-electrodes zigcina i-orientation esisigxina ngokumalunga ne-incident beam kunye ne-detector, okwenza zonke ii-scan zifane phantse. I-Near-field XAFS spectrum yasetyenziswa ukumisela imeko ye-oxidation kunye nefom yekhemikhali ye-bismuth ngokuthelekisa nommandla we-XANES wemigangatho ye-Bi kunye ne-Bi2O3 kusetyenziswa i-linear combination fitting algorithm yesoftware ye-Athena (inguqulelo 0.9.26). ngekhowudi ye-IFEFFIT 44.
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