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Kuchepetsa kwa carbon dioxide mu electrochemical kukhala formic acid ndi njira yabwino yowonjezerera kugwiritsa ntchito carbon dioxide ndipo ingagwiritsidwe ntchito ngati malo osungira hydrogen. Mu ntchitoyi, kapangidwe ka electrode ya nembanemba ya zero-gap kapangidwa kuti kaphatikizidwe mwachindunji kwa formic acid kuchokera ku carbon dioxide. Kupita patsogolo kwakukulu kwaukadaulo ndi membrane yolumikizana ndi mabowo, yomwe, ikagwiritsidwa ntchito mu kasinthidwe ka bipolar membrane, imalola formic acid yopangidwa pamalo olumikizirana ndi membrane kuti isunthidwe kudzera mu anodic flow field m'magulu otsika ngati 0.25 M. Popanda zigawo zina za sandwich pakati pa anode ndi cathode, lingaliroli likufuna kugwiritsa ntchito zida ndi mapangidwe a batri omwe alipo omwe amapezeka m'maselo amafuta ndi hydrogen electrolysis, zomwe zimapangitsa kuti kusintha kwachangu kukhale kokulirapo komanso kogulitsa. Mu selo la 25 cm2, kasinthidwe ka membrane yolumikizana ndi mabowo kamapereka >75% Faraday efficiency ya formic acid pa <2 V ndi 300 mA/cm2. Chofunika kwambiri, mayeso okhazikika a maola 55 pa 200 mA/cm2 adawonetsa efficiency yokhazikika ya Faraday ndi voltage ya maselo. Kusanthula kwa ukadaulo ndi zachuma kumagwiritsidwa ntchito pofotokoza njira zopezera kufanana kwa mtengo ndi njira zamakono zopangira formic acid.
Kuchepetsa kwa carbon dioxide mu electrochemical kukhala formic acid pogwiritsa ntchito magetsi obwezerezedwanso kwawonetsedwa kuti kumachepetsa ndalama zopangira ndi 75%1 poyerekeza ndi njira zachikhalidwe zopangira mafuta. Monga momwe zasonyezedwera m'mabuku2,3, formic acid ili ndi ntchito zosiyanasiyana, kuyambira njira yothandiza komanso yotsika mtengo yosungira ndikunyamula hydrogen kupita ku chakudya chamakampani opanga mankhwala4,5 kapena makampani opanga biomass6. Formic acid yadziwikanso ngati chakudya chosinthira kukhala zinthu zokhazikika za jet fuel intermediates pogwiritsa ntchito metabolic engineering7,8. Ndi chitukuko cha formic acid economics1,9, ntchito zingapo zofufuza zayang'ana kwambiri pakukonza catalyst selectivity10,11,12,13,14,15,16. Komabe, khama lalikulu likupitilira kuyang'ana kwambiri maselo ang'onoang'ono a H kapena maselo oyenda amadzimadzi omwe amagwira ntchito pamagetsi otsika (<50 mA/cm2). Kuti muchepetse ndalama, kuti malonda apitirire, ndikuwonjezera kulowa kwa msika pambuyo pake, kuchepetsa kwa carbon dioxide (CO2R) kuyenera kuchitika pamlingo wapamwamba wamagetsi (≥200 mA/cm2) ndi Faraday efficiency (FE)17 pomwe kugwiritsa ntchito bwino zinthu ndikugwiritsa ntchito zigawo za batri kuchokera ku ma cell amafuta a Technology ndi electrolysis yamadzi kumalola zida za CO2R kugwiritsa ntchito bwino mphamvu zake18. Kuphatikiza apo, kuti ziwonjezere kugwiritsidwa ntchito kwa kupanga ndikupewa kukonza kwina, formic acid iyenera kugwiritsidwa ntchito ngati chinthu chomaliza m'malo mwa kupanga mchere19.
Pachifukwa ichi, kuyesetsa kwaposachedwa kwapangidwa kuti pakhale zida za CO2R formate/formic acid based gas diffusion electrode (GDE) zofunikira m'mafakitale. Kuwunikanso kwathunthu kwa Fernandez-Caso et al.20 kukufotokoza mwachidule momwe maselo onse amagetsi amagwirira ntchito kuti CO2 isapitirire kukhala formic acid/formate ichepetsedwe. Kawirikawiri, ma configurations onse omwe alipo akhoza kugawidwa m'magulu atatu akuluakulu: 1. Flow-through catholytes19,21,22,23,24,25,26,27, 2. Single membrane (cation exchange membrane (CEM)28 kapena anion exchange membrane (AEM)29 ndi 3. Sandwich configuration15,30,31,32. Ma cross-sections osavuta a ma configurations awa akuwonetsedwa mu Chithunzi 1a. Pa flow configuration ya catholyte, chipinda cha electrolyte chimapangidwa pakati pa membrane ndi cathode ya GDE. Flow-through catholyte imagwiritsidwa ntchito popanga ma ion channels mu cathode layer ya catalyst33, ngakhale kuti kufunika kwake kolamulira formate selectivity kumakambidwa34. Komabe, ma configurations awa adagwiritsidwa ntchito ndi Chen et al. Pogwiritsa ntchito SnO2 cathode pa carbon substrate yokhala ndi catholyte layer ya 1.27 mm thick, mpaka 90% FE 35 pa 500 mA/cm2 adakwaniritsidwa. Kuphatikiza kwa thick catholyte layer ndi reverse-biased bipolar membrane (BPM) yomwe imaletsa kusamutsa ma ion imapereka mphamvu yogwira ntchito ya 6 V ndi mphamvu yogwira ntchito ya 15%. Pofuna kupititsa patsogolo mphamvu, Li et al., pogwiritsa ntchito kasinthidwe kamodzi ka CEM, adapeza FE 29 ya 93.3% pa ​​density ya fractional current ya 51.7 mA/cm2. Diaz-Sainz et al.28 adagwiritsa ntchito fyuluta yosindikizira yokhala ndi nembanemba imodzi ya CEM pa density ya 45 mA/cm2. Komabe, njira zonse zidapanga formate m'malo mwa chinthu chomwe chimakondedwa, formic acid. Kuphatikiza pa zofunikira zina zokonzera, mu kasinthidwe ka CEM, mawonekedwe monga KCOOH amatha kusonkhana mwachangu mu GDE ndi flow field, zomwe zimapangitsa kuti zoletsa zoyendera komanso kulephera kwa maselo zitheke.
Kuyerekeza kwa CO2R zitatu zodziwika bwino kwambiri ndi makonzedwe a chipangizo chosinthira ma formate/formic acid ndi kapangidwe kake komwe kaperekedwa mu kafukufukuyu. b Kuyerekeza kwa phindu lonse la current ndi formate/formic acid pa makonzedwe a catholyte, makonzedwe a sandwich, makonzedwe a single CEM m'mabuku (omwe akuwonetsedwa mu Supplementary Table S1) ndi ntchito yathu. Zizindikiro zotseguka zimasonyeza kupanga kwa formate solution, ndipo zizindikiro zolimba zimasonyeza kupanga kwa formic acid. *Kukonza kukuwonetsedwa pogwiritsa ntchito hydrogen pa anode. c Kukonza kwa Zero-gap MEA pogwiritsa ntchito membrane yolumikizana ndi bipolar yokhala ndi perforated cation exchange layer yomwe ikugwira ntchito mu forward bias mode.
Pofuna kupewa kupangika kwa mawonekedwe, Proietto ndi anzake 32 adagwiritsa ntchito makina osindikizira osasunthika omwe madzi oyeretsedwa amadutsa pakati pawo. Dongosololi likhoza kufika >70% CE mu kuchuluka kwa kachulukidwe ka 50–80 mA/cm2. Mofananamo, Yang ndi anzake 14 adapereka lingaliro logwiritsa ntchito solid electrolyte interlayer pakati pa CEM ndi AEM kuti alimbikitse kupangika kwa formic acid. Yang ndi anzake 31,36 adapeza 91.3% FE mu selo la 5 cm2 pa 200 mA/cm2, ndikupanga yankho la 6.35 wt% formic acid. Xia ndi anzake. Pogwiritsa ntchito njira yofanana, kusintha kwa 83% kwa carbon dioxide (CO2) kukhala formic acid FE kunapezeka pa 200 mA/cm2, ndipo kulimba kwa dongosololi kunayesedwa kwa maola 100 mphindi 30. Ngakhale zotsatira zazing'ono zili zabwino, kukwera mtengo ndi zovuta za ma resini osinthira ma ion okhala ndi porous zimapangitsa kuti zikhale zovuta kukulitsa ma configurations a interlayer ku machitidwe akuluakulu (monga, 1000 cm2).
Kuti tiwone zotsatira za mapangidwe osiyanasiyana, tinalemba mndandanda wa kupanga kwa formate/formic acid pa kWh ya machitidwe onse omwe atchulidwa kale ndipo tinawajambula mu Chithunzi 1b. Apa n'zoonekeratu kuti dongosolo lililonse lokhala ndi catholyte kapena interlayer lidzagwira ntchito bwino kwambiri pa kachulukidwe kochepa kwa mphamvu yamagetsi ndikuwonongeka pa kachulukidwe ka mphamvu yamagetsi, komwe malire a ohmic angadziwitse mphamvu yamagetsi ya maselo. Komanso, ngakhale kuti kasinthidwe ka CEM kogwiritsa ntchito mphamvu kochepa kamapereka kupanga kwa molar formic acid kwambiri pa kWh, kuchuluka kwa mchere kungayambitse kuwonongeka kwa magwiridwe antchito mwachangu pa kachulukidwe ka mphamvu yamagetsi.
Kuti tichepetse njira zolephera zomwe takambirana kale, tinapanga membrane electrode assembly (MEA) yokhala ndi composite forward biased BPM yokhala ndi perforated cation exchange membrane (PCEM). Kapangidwe kake kakuwonetsedwa pa Chithunzi 1c. Hydrogen (H2) imalowetsedwa mu anode kuti ipange ma proton kudzera mu hydrogen oxidation reaction (HOR). PCEM layer imalowetsedwa mu BPM system kuti ilole ma ion a formate opangidwa ku cathode kudutsa mu AEM, kuphatikiza ndi ma proton kuti apange formic acid pa BPM interface ndi interstitial pores a CEM, kenako kutuluka kudzera mu GDE anode ndi flow field. . Pogwiritsa ntchito kasinthidwe aka, tinapeza >75% FE ya formic acid pa <2 V ndi 300 mA/cm2 pa malo a 25 cm2 cell. Chofunika kwambiri, kapangidwe kake kamagwiritsa ntchito zigawo zomwe zimapezeka m'masitolo ndi zomangamanga za hardware za zomera zamafuta ndi madzi, zomwe zimathandiza kuti nthawi ifike mwachangu. Ma configurations a Catholyte ali ndi catholyte flow chambers zomwe zingayambitse kusalingana kwa mphamvu pakati pa gasi ndi madzi, makamaka m'ma configurations akuluakulu a cell. Pazinthu za sandwich zomwe zili ndi zigawo zoboola za madzi oyenda, pamafunika khama lalikulu kuti pakhale bwino gawo loboola pakati kuti muchepetse kutsika kwa mphamvu ndi kusonkhanitsa kaboni dioksidi mkati mwa gawo loboola pakati. Zonsezi zingayambitse kusokonezeka kwa kulumikizana kwa ma cell. N'kovutanso kupanga zigawo zoonda zoboola pakati pa malo omasuka pamlingo waukulu. Mosiyana ndi zimenezi, kasinthidwe katsopano komwe kakuperekedwa ndi kasinthidwe ka zero-gap MEA komwe kulibe chipinda choyendera kapena gawo loboola pakati. Poyerekeza ndi maselo ena amagetsi omwe alipo, kasinthidwe komwe kakuperekedwako ndi kapadera chifukwa kamalola kupanga mwachindunji formic acid mu kasinthidwe kosinthika, kogwiritsa ntchito mphamvu zochepa, komanso kopanda mipata yambiri.
Pofuna kuletsa kusintha kwa haidrojeni, khama lalikulu lochepetsa CO2 lagwiritsa ntchito mawonekedwe a nembanemba ya MEA ndi AEM pamodzi ndi ma electrolyte okwera kwambiri (monga, 1-10 M KOH) kuti apange zinthu za alkaline pa cathode (monga momwe zasonyezedwera pa Chithunzi 2a). Mu mawonekedwe awa, ma ion a formate omwe amapangidwa pa cathode amadutsa mu nembanemba ngati mitundu yoyipa, kenako KCOOH imapangidwa ndikutuluka mu dongosolo kudzera mumtsinje wa anodic KOH. Ngakhale kuti formate FE ndi voltage ya selo poyamba zinali zabwino monga momwe zasonyezedwera pa Chithunzi 2b, kuyesa kukhazikika kunapangitsa kuti FE ichepe pafupifupi 30% m'maola 10 okha (Chithunzi S1a–c). Tiyenera kudziwa kuti kugwiritsa ntchito 1 M KOH anolyte ndikofunikira kwambiri kuti muchepetse anodic overvoltage mu alkaline oxygen evolution reaction (OER) systems37 ndikukwaniritsa kupezeka kwa ion mkati mwa cathode catalyst bed33. Pamene kuchuluka kwa anolyte kwachepetsedwa kufika pa 0.1 M KOH, magetsi onse a maselo ndi oxidation ya formic acid (kutayika kwa formic acid) kumawonjezeka (Chithunzi S1d), kusonyeza kusintha kwa zero-sum. Mlingo wa oxidation ya formate unayesedwa pogwiritsa ntchito balance yonse ya mass; kuti mudziwe zambiri, onani gawo la "Njira". Kugwira ntchito pogwiritsa ntchito MEA ndi single CEM membrane configurations kunaphunziridwanso, ndipo zotsatira zake zikuwonetsedwa mu Chithunzi S1f,g. FE formate yosonkhanitsidwa kuchokera ku cathode inali >60% pa 200 mA/cm2 kumayambiriro kwa mayeso, koma inachepa mofulumira mkati mwa maola awiri chifukwa cha kuchuluka kwa mchere wa cathode womwe takambirana kale (Chithunzi S11).
Chithunzi cha zero-gap MEA yokhala ndi CO2R pa cathode, hydrogen oxidation reaction (HOR) kapena OER pa anode, ndi nembanemba imodzi ya AEM pakati. b FE ndi voteji ya selo pa kasinthidwe aka ndi 1 M KOH ndi OER zikuyenda pa anode. Mipiringidzo yolakwika ikuyimira kupotoka kwa miyezo itatu yosiyana. mu FE ndi voteji ya selo ya dongosolo yokhala ndi H2 ndi HOR pa anode. Mitundu yosiyanasiyana imagwiritsidwa ntchito kusiyanitsa kupanga kwa formate ndi formic acid. d Chithunzi cha Schematic cha MEA chokhala ndi BPM chosunthidwa patsogolo pakati. FE ndi voteji ya batri motsutsana ndi nthawi pa 200 mA/cm2 pogwiritsa ntchito kasinthidwe aka. f Chithunzi chodutsa cha BPM MEA yolunjika patsogolo pambuyo pa mayeso afupiafupi.
Kuti apange formic acid, hydrogen imaperekedwa ku chothandizira cha Pt-on-carbon (Pt/C) pa anode. Monga momwe zasonyezedwera pa Chithunzi 2d, ma protoni opanga BPM omwe ali ndi mbali yolunjika patsogolo pa anode adafufuzidwa kale kuti apange formic acid. BPM tuning unit idalephera pambuyo pa mphindi 40 yogwira ntchito pa 200 mA/cm2, limodzi ndi kuwonjezeka kwa voltage yoposa 5 V (Chithunzi 2e). Pambuyo poyesa, delamination yodziwikiratu idawonedwa pa CEM/AEM interface. Kupatula formate, ma anion monga carbonate, bicarbonate ndi hydroxide amathanso kudutsa mu nembanemba ya AEM ndikuchita ndi ma protoni pa CEM/AEM interface kuti apange mpweya wa CO2 ndi madzi amadzimadzi, zomwe zimapangitsa kuti BPM delamination (Chithunzi 2f) ndi , pamapeto pake zimapangitsa kuti maselo alephere kugwira ntchito.
Kutengera ndi magwiridwe antchito ndi kulephera kwa kapangidwe kamene kali pamwambapa, kapangidwe katsopano ka MEA kaperekedwa monga momwe kawonetsedwera pa Chithunzi 1c ndipo kafotokozedwa bwino pa Chithunzi 3a38. Pano, gawo la PCEM limapereka njira yosamutsira formic acid ndi anions kuchokera ku CEM/AEM interface, motero kuchepetsa kusonkhana kwa chinthucho. Nthawi yomweyo, njira ya PCEM interstitial imatsogolera formic acid kulowa mu diffusion medium ndi flow field, kuchepetsa kuthekera kwa formic acid oxidation. Zotsatira za polarization pogwiritsa ntchito AEMs zokhala ndi makulidwe a 80, 40 ndi 25 mm zikuwonetsedwa pa Chithunzi 3b. Monga momwe zikuyembekezeredwa, ngakhale kuti voteji yonse ya selo imawonjezeka ndi makulidwe a AEM akuwonjezeka, kugwiritsa ntchito AEM yokhuthala kumalepheretsa kufalikira kwa formic acid kumbuyo, motero kumawonjezera cathode pH ndikuchepetsa kupanga kwa H2 (Chithunzi 3c–e).
Chithunzi cha kapangidwe ka MEA ndi AEM ndi CEM yobowoka ndi njira zosiyanasiyana zoyendera za formic acid. b Voltage ya maselo pa kachulukidwe kosiyanasiyana ka current ndi makulidwe osiyanasiyana a AEM. mu EE pa kachulukidwe kosiyanasiyana ka current ndi makulidwe a AEM a 80 μm (d) 40 μm, e) 25 μm. Mipiringidzo yolakwika ikuyimira kupotoka kokhazikika komwe kumayesedwa kuchokera ku zitsanzo zitatu zosiyana. f Zotsatira zoyeserera za kuchuluka kwa formic acid ndi pH pa interface ya CEM/AEM pa makulidwe osiyanasiyana a AEM. f PC ndi pH mu cathode wosanjikiza wa catalyst ndi makulidwe osiyanasiyana a filimu ya AEM. g Kugawa kwa magawo awiri kwa kuchuluka kwa formic acid ndi interface ya CEM/AEM ndi kubowoka.
Chithunzi S2 chikuwonetsa kufalikira kwa kuchuluka kwa asidi a formic ndi pH kudutsa makulidwe a MEA pogwiritsa ntchito chitsanzo cha Poisson-Nernst-Planck finite element. Nzosadabwitsa kuti kuchuluka kwakukulu kwa asidi a formic, 0.23 mol/L, kumawonedwa pa CEM/AEM interface, popeza asidi wa formic amapangidwa pamtunduwu. Kuchuluka kwa asidi wa formic kudzera mu AEM kumachepa mofulumira pamene makulidwe a AEM akuwonjezeka, zomwe zikusonyeza kukana kwakukulu ku kusamutsa kwa mass ndi kuchepa kwa asidi wa formic chifukwa cha kufalikira kwa back. Zithunzi 3 f ndi g zikuwonetsa pH ndi formic acid values ​​​​mu cathode catalyst bed zomwe zimachitika chifukwa cha kufalikira kwa back ndi kufalikira kwa formic acid kwa magawo awiri, motsatana. Kaya AEM membrane ndi yopyapyala, kuchuluka kwa asidi wa formic pafupi ndi cathode kumawonjezeka, ndipo pH ya cathode imakhala acidic. Chifukwa chake, ngakhale kuti ma nembanemba okhuthala a AEM amachititsa kuti ma ohmic awonongeke kwambiri, ndizofunikira kwambiri poletsa kufalikira kwa formic acid kumbuyo kwa cathode ndikuwonjezera kuyera kwakukulu kwa FE formic acid system. Pomaliza, kuwonjezera makulidwe a AEM kufika pa 80 μm kunapangitsa kuti FE ikhale >75% ya formic acid pa <2 V ndi 300 mA/cm2 pa malo a selo la 25 cm2.
Pofuna kuyesa kukhazikika kwa kapangidwe kameneka kochokera ku PECM, mphamvu ya batri idasungidwa pa 200 mA/cm2 kwa maola 55. Zotsatira zonse zikuwonetsedwa mu Chithunzi 4, ndipo zotsatira za maola atatu oyamba zawonetsedwa mu Chithunzi S3. Pogwiritsa ntchito chothandizira cha anodic cha Pt/C, mphamvu ya selo idakwera kwambiri mkati mwa mphindi 30 zoyambirira (Chithunzi S3a). Kwa nthawi yayitali, mphamvu ya selo idakhalabe yofanana, zomwe zidapangitsa kuti chiwopsezo cha kuwonongeka kwa 0.6 mV/h chiwopsezo (Chithunzi 4a). Poyamba mayeso, PV ya formic acid yomwe idasonkhanitsidwa pa anode inali 76.5% ndipo PV ya hydrogen yomwe idasonkhanitsidwa pa cathode inali 19.2%. Pambuyo pa ola loyamba loyesa, hydrogen FE idatsika kufika pa 13.8%, zomwe zikusonyeza kusintha kwa kusankha kwa formate. Komabe, kuchuluka kwa okosijeni wa formic acid mu dongosolo kunatsika kufika pa 62.7% mu ola limodzi, ndipo kuchuluka kwa okosijeni wa anodic formic acid kunakwera kuchoka pafupifupi zero kumayambiriro kwa mayeso kufika pa 17.0%. Pambuyo pake, FE ya H2, CO, formic acid ndi kuchuluka kwa okosijeni wa formic acid kunakhalabe kokhazikika panthawi yoyesera. Kuwonjezeka kwa okosijeni wa formic acid mu ola loyamba kungakhale chifukwa cha kuchuluka kwa formic acid pa PCEM/AEM interface. Pamene kuchuluka kwa formic acid kumawonjezeka, sikuti kumangotuluka kudzera mu kubowola kwa nembanemba, komanso kumafalikira kudzera mu FEM yokha ndikulowa mu Pt/C anode layer. Popeza formic acid ndi madzi pa 60°C, kuchuluka kwake kungayambitse mavuto osuntha ndi kubweretsa okosijeni wosankhidwa kuposa hydrogen.
a Voltage ya selo motsutsana ndi nthawi (200 mA/cm2, 60 °C). Chithunzi cha mkati chikuwonetsa chithunzi cha maikulosikopu yowoneka bwino cha gawo lopingasa la MEA yokhala ndi EM yobowoka. Scale bar: 300 µm. b Kuyera kwa PE ndi formic acid ngati ntchito ya nthawi pa 200 mA/cm2 pogwiritsa ntchito anode ya Pt/C.
Kapangidwe ka zitsanzo kumayambiriro kwa mayeso (BOT) panthawi yokonzekera komanso kumapeto kwa mayeso (EOT) pambuyo pa maola 55 a kuyesa kokhazikika kunadziwika pogwiritsa ntchito nano-X-ray computed tomography (nano-CT), monga momwe zasonyezedwera pa Chithunzi 5 a. Chitsanzo cha EOT chili ndi kukula kwakukulu kwa tinthu tating'onoting'ono ta catalyst tokhala ndi mainchesi a 1207 nm poyerekeza ndi 930 nm ya BOT. Zithunzi za High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) ndi zotsatira za energy-dispersive X-ray spectroscopy (EDS) zikuwonetsedwa pa Chithunzi 5b. Ngakhale kuti BOT catalyst layer ili ndi tinthu tating'onoting'ono ta catalyst komanso ma agglomerates ena akuluakulu, mu gawo la EOT, catalyst layer ikhoza kugawidwa m'magawo awiri osiyana: limodzi ndi tinthu tating'onoting'ono tating'onoting'ono tating'onoting'ono ndipo lina ndi madera okhala ndi ma pore. Chiwerengero cha tinthu tating'onoting'ono tating'onoting'ono. Chithunzi cha EDS chikuwonetsa kuti tinthu tating'onoting'ono tating'onoting'ono ta Bi, mwina tachitsulo, ndipo madera okhala ndi ma pore ali ndi mpweya wochuluka. Pamene selo likugwiritsidwa ntchito pa 200 mA/cm2, mphamvu yoipa ya cathode idzapangitsa kuchepa kwa Bi2O3, monga momwe zasonyezedwera ndi zotsatira za in situ X-ray absorption spectroscopy zomwe zafotokozedwa pansipa. Zotsatira za HAADF-STEM ndi EDS mapping zikusonyeza kuti Bi2O3 imadutsa mu njira yochepetsera, zomwe zimapangitsa kuti ataye mpweya ndikusonkhana kukhala tinthu tating'onoting'ono tachitsulo. Ma X-ray diffraction pa ma cathode a BOT ndi EOT amatsimikizira kutanthauzira kwa deta ya EDS (Chithunzi 5c): crystalline Bi2O3 yokha ndiyo yomwe idapezeka mu BOT cathode, ndipo crystalline bimetal idapezeka mu EOT cathode. Kuti timvetse momwe cathode potential imakhudzira mkhalidwe wa okosijeni wa Bi2O3 cathode catalyst, kutentha kunasiyana kuyambira open circuit potential (+0.3 V vs RHE) mpaka -1.5 V (vs RHE). Zawonedwa kuti gawo la Bi2O3 limayamba kuchepetsedwa pa -0.85 V poyerekeza ndi RHE, ndipo kuchepa kwa mphamvu ya mzere woyera m'dera la m'mphepete mwa sipekitiramu kumasonyeza kuti Bi yachitsulo yachepetsedwa kufika pa 90% ya RHE pa -1.1. V motsutsana ndi RHE (Chithunzi 5d). Mosasamala kanthu za njira yake, kusankha konse kwa mawonekedwe pa cathode sikunasinthe kwenikweni, monga momwe zafotokozedwera kuchokera ku H2 ndi CO FE ndi mapangidwe a formic acid, ngakhale kusintha kwakukulu mu mawonekedwe a cathode, mkhalidwe wa catalyst oxidation, ndi kapangidwe ka microcrystalline.
Kapangidwe ka magawo atatu ka gawo la catalyst ndi kufalikira kwa tinthu ta catalyst tomwe timapezedwa pogwiritsa ntchito nano-X-ray CT. Scale bar: 10 µm. b Pamwamba 2: Zithunzi za HAADF-STEM za zigawo za cathode za BOT ndi EOT catalysts. Scale bar: 1 µm. Pansi 2: Zithunzi za HADF-STEM zokulirapo ndi EDX za gawo la cathode la EOT catalyst. Scale bar: 100 nm. c Ma X-ray diffraction patterns a BOT ndi EOT cathode samples. d In situ X-ray absorption spectra ya Bi2O3 electrode mu 0.1 M KOH ngati ntchito ya potential (0.8 V mpaka -1.5 V vs. RHE).
Kuti mudziwe bwino mwayi womwe ulipo wowongolera kugwiritsa ntchito mphamvu mwa kuletsa kusungunuka kwa formic acid, electrode yowunikira ya H2 idagwiritsidwa ntchito kuzindikira zomwe zimathandizira kutayika kwa magetsi39. Pa kuchuluka kwa magetsi komwe kuli pansi pa 500 mA/cm2, mphamvu ya cathode imakhalabe pansi pa -1.25 V. Mphamvu ya anodic imagawidwa m'magawo awiri akuluakulu: kuchuluka kwa magetsi osinthika HOR ndi overvoltage ya theoretical HOR 40 yomwe idanenedweratu ndi equation ya Bulter-Volmer yomwe idayesedwa kale, ndipo gawo lotsalalo limachokera ku oxidation formic acid. Chifukwa cha kinetics yocheperako poyerekeza ndi HOR41, kuchuluka kochepa kwa formic acid oxidation reaction pa anode kungayambitse kuwonjezeka kwakukulu kwa mphamvu ya anodic. Zotsatira zake zikuwonetsa kuti kuletsa kwathunthu kwa formic acid anodic oxidation kumatha kuchotsa pafupifupi 500 mV overvoltage.
Poyesa kuyerekezera kumeneku, kuchuluka kwa madzi osungunuka (DI) pamalo olowera anode kunasinthidwa kuti kuchepetse kuchuluka kwa asidi wa formic acid. Zithunzi 6b ndi c zikuwonetsa FE, kuchuluka kwa asidi wa formic, ndi magetsi a maselo monga momwe DI flux imagwirira ntchito pa anode pa 200 mA/cm2. Pamene kuchuluka kwa madzi osungunuka kunakwera kuchoka pa 3.3 mL/min kufika pa 25 mL/min, kuchuluka kwa asidi wa formic pa anode kunachepa kuchoka pa 0.27 mol/L kufika pa 0.08 mol/L. Poyerekeza, pogwiritsa ntchito kapangidwe ka sandwich komwe Xia et al. 30 adapereka, kuchuluka kwa asidi wa formic acid wa 1.8 mol/L kunapezeka pa 200 mA/cm2. Kuchepetsa kuchuluka kwa asidi wa formic acid kumawonjezera FE yonse ya formic acid ndikuchepetsa FE ya H2 pamene cathode pH imakhala ya alkaline kwambiri chifukwa cha kuchepa kwa kufalikira kwa asidi wa formic acid. Kuchepa kwa kuchuluka kwa formic acid pa DI flow yayikulu kunachotsanso kusungunuka kwa formic acid, zomwe zimapangitsa kuti magetsi onse a cell akhale pansi pa 1.7 V pa 200 mA/cm2. Kutentha kwa batri kumakhudzanso magwiridwe antchito onse, ndipo zotsatira zake zikuwonetsedwa mu Chithunzi S10. Komabe, mapangidwe ozikidwa pa PCEM amatha kusintha kwambiri mphamvu poletsa kusungunuka kwa formic acid, kaya pogwiritsa ntchito ma catalyst a anodic okhala ndi kusankha bwino kwa hydrogen kupita ku formic acid kapena kudzera mu ntchito ya chipangizocho.
a Kuwonongeka kwa magetsi a selo pogwiritsa ntchito ma electrode a H2 ofotokozera maselo omwe amagwira ntchito pa 60 °C, Pt/C anode ndi 80 µm AEM. b Kuchuluka kwa FE ndi formic acid komwe kumasonkhanitsidwa pa 200 mA/cm2 pogwiritsa ntchito kuchuluka kosiyanasiyana kwa madzi a anodic deionized. c Pamene anode ikusonkhanitsa formic acid m'magulu osiyanasiyana, magetsi a selo ndi 200 mA/cm2. Mipiringidzo yolakwika imayimira kupotoka kwa miyezo itatu yosiyana. d Mtengo wotsika wogulitsa womwe umagawidwa ndi magwiridwe antchito pamitengo yosiyanasiyana ya madzi a deionized pogwiritsa ntchito mitengo yamagetsi yapakati pa mafakitale ya US$0.068/kWh ndi US$4.5/kg hydrogen. (*: Mkhalidwe wocheperako wa oxidation wa formic acid pa anode ukuyembekezeka kukhala 10 M FA, mtengo wapakati wamagetsi wa mafakitale mdziko lonse ndi $0.068/kWh, ndipo hydrogen ndi $4.5/kg. **: Mkhalidwe wocheperako wa oxidation ndi formic acid. Kuchuluka kwa FA pa anode ndi 1.3 M anode, mtengo wamagetsi wamtsogolo womwe ukuyembekezeka ndi $0.03/kWh, ndipo mzere wokhala ndi madontho ukuyimira mtengo wamsika wa 85 wt% FA.
Kusanthula kwa ukadaulo ndi zachuma (TEA) kunachitika kuti apeze mtengo wotsika kwambiri wogulitsa wa ma assemblies amafuta pansi pa mikhalidwe yosiyanasiyana yogwirira ntchito, monga momwe zasonyezedwera pa Chithunzi 5d. Njira ndi deta yakumbuyo ya TEA zitha kupezeka mu SI. Pamene kuchuluka kwa LC mu utsi wa anode kuli kokwera, ngakhale kuti magetsi ambiri a maselo ali ndi mphamvu, mtengo wonse wa mafuta osonkhanitsira umachepetsedwa chifukwa cha kuchepa kwa mtengo wolekanitsa. Ngati anodic oxidation ya formic acid ingachepetsedwe kudzera mu catalyst development kapena electrode technology, kuphatikiza kwa magetsi otsika a maselo (1.66 V) ndi kuchuluka kwa FA m'madzi otuluka (10 M) kungachepetse mtengo wa kupanga electrochemical FA kufika pa 0.74 US dollars/kg (kutengera mtengo wamagetsi).) $0.068/kWh ndi $4.5/kg hydrogen42. Kuphatikiza apo, zikaphatikizidwa ndi mtengo wamtsogolo wamagetsi ongowonjezwdwanso wa $0.03/kWh ndi hydrogen wa $2.3/kg, cholinga cha madzi otayira a FA chimachepetsedwa kufika pa 1.3 miliyoni, zomwe zimapangitsa kuti mtengo womaliza wopangira ukhale US$0.66/kg43. Izi zikufanana ndi mitengo yamsika yomwe ilipo. Chifukwa chake, zoyesayesa zamtsogolo zomwe zikuyang'ana pa zipangizo ndi kapangidwe ka ma electrode zitha kuchepetsa kwambiri anodization pomwe zimalola kuti ntchito pamagetsi otsika a cell ipange kuchuluka kwa LC.
Mwachidule, taphunzira kapangidwe ka MEA ka zero-gap kuti CO2 ichepetse kukhala formic acid ndipo tapereka lingaliro la kapangidwe kamene kali ndi membrane ya bipolar yomwe imagwirizana ndi formic acid kuphatikizapo membrane ya perforated cation exchange (PECM) kuti ithandize membrane mass transfer interface ya formic acid yomwe yatuluka. . Kapangidwe kameneka kamapanga >96% formic acid pamlingo wofika 0.25 M (pa anode DI flow rate ya 3.3 mL/min). Pa kuchuluka kwa DI flow rate (25 mL/min), kapangidwe kameneka kamapereka current density ya >80% FE ya 200 mA/cm2 pa 1.7 V pogwiritsa ntchito malo a 25 cm2 cell. Pa kuchuluka kwa anodic DI (10 mL/min), kapangidwe ka PECM kadasunga voltage yokhazikika komanso milingo ya formic acid FE yapamwamba kwa maola 55 oyesera pa 200 mA/cm2. Kukhazikika kwakukulu ndi kusankha komwe kumachitika ndi ma catalysts omwe amapezeka m'masitolo ndi zinthu za polymeric membrane zitha kupitilizidwa poziphatikiza ndi ma electrocatalysts opangidwa bwino. Ntchito yotsatira idzayang'ana kwambiri pakusintha momwe ntchito ikuyendera, kusankha kwa anode catalyst, ndi kapangidwe ka MEA kuti muchepetse kusungunuka kwa formic acid, zomwe zimapangitsa kuti pakhale kutayikira kwamphamvu kwambiri pamagetsi otsika a cell. Njira yosavuta yogwiritsira ntchito carbon dioxide pa formic acid yomwe yaperekedwa pano imachotsa kufunikira kwa zipinda za anolyte ndi catholyte, zigawo za sandwich, ndi zinthu zapadera, motero zimawonjezera kugwiritsa ntchito bwino mphamvu za cell ndikuchepetsa zovuta za dongosolo, zomwe zimapangitsa kuti zikhale zosavuta kukulitsa. Kapangidwe kameneka kamapereka nsanja yopangira mtsogolo zomera zosinthira CO2 zomwe zimagwira ntchito bwino paukadaulo komanso pazachuma.
Pokhapokha ngati tanena mwanjira ina, zinthu zonse zoyezera mankhwala ndi zosungunulira zinagwiritsidwa ntchito monga momwe zinalandirira. Bismuth oxide catalyst (Bi2O3, 80 nm) inagulidwa kuchokera ku US Research Nanomaterials, Inc. Ufa wa polymer (AP1-CNN8-00-X) unaperekedwa ndi IONOMR. Omnisolv® mtundu wa N-propanol (nPA) ndi madzi oyera kwambiri (18.2 Ω, Milli–Q® Advantage A10 water cleansing system) zinagulidwa kuchokera ku Millipore Sigma. Methanol ndi acetone zovomerezeka ndi ACS zimagulidwa kuchokera ku VWR Chemicals BDH® ndi Fisher Chemical, motsatana. Ufa wa polymer unasakanizidwa ndi chisakanizo cha acetone ndi methanol mu chiŵerengero cha 1:1 polemera kuti mupeze kufalikira kwa polymer ndi kuchuluka kwa 6.5 wt.%. Konzani inki yothandizira posakaniza 20g Bi2O3, madzi oyera kwambiri, nPA ndi kufalikira kwa ionomer mu mtsuko wa 30ml. Kapangidwe kake kanali ndi 30 wt.% catalyst, chiŵerengero cha ionomer ndi catalyst cha 0.02 ndi chiŵerengero cha mowa ndi madzi cha 2:3 (40 wt.% nPA). Musanasakanize, 70g ya Glen Mills 5mm zirconia grinding material inawonjezedwa ku chisakanizocho. Zitsanzo zinayikidwa pa Fisherbrand™ digital bottle roller pa 80 rpm kwa maola 26. Lolani inki ikhale kwa mphindi 20 musanayike. Inki ya Bi2O3 inayikidwa pa Qualtech automatic applicator (QPI-AFA6800) pogwiritsa ntchito 1/2″ x 16″ labotale wirewound refill (RD Specialties - 60 mil diameter) pa 22°C. 5 mL ya inki catalytic inayikidwa pa 7.5 x 8 inch Sigraacet 39 BB carbon gas diffusion carrier (fuel cell storage) poika ndodo pa liwiro lokhazikika la 55 mm/sec. Tumizani ma electrode ophimbidwa awa ku uvuni ndipo muume pa 80 °C. Njira yophikira ndodo ndi zithunzi za chophimba cha GDE zikuwonetsedwa mu Zithunzi S4a ndi b. Chida cha X-ray fluorescence (XRF) (Fischerscope® XDV-SDD, Fischer-Technolgy Inc. USA) chinatsimikizira kuti katundu wa GDE wophimbidwa anali 3.0 mg Bi2O3/cm2.
Pa ma configuration a membrane okhala ndi anion exchange membrane (AEM) ndi CEM yoboola. Nafion NC700 (Chemours, USA) yokhala ndi makulidwe a 15 µm idagwiritsidwa ntchito ngati CEM layer. Anodic catalyst idapopedwa mwachindunji pa FEM ndi ionomer ku carbon ratio ya 0.83 ndi malo ophimbira a 25 cm2. Platinamu yothandizidwa yokhala ndi malo akuluakulu (50 wt.% Pt/C, TEC 10E50E, TANAKA precious metal) yokhala ndi load ya 0.25 mg Pt/cm2 idagwiritsidwa ntchito ngati anode catalyst. Nafion D2020 (Ion Power, USA) idagwiritsidwa ntchito ngati ionomer ya anode layer ya catalyst. CEM perforation imachitika podula mizere yofanana pa filimu ya CEM pa 3mm intervals. Tsatanetsatane wa njira yoboola ikuwonetsedwa mu Zithunzi S12b ndi c. Pogwiritsa ntchito X-ray computed tomography, zinatsimikiziridwa kuti kusiyana kwa kubowola kunali 32.6 μm, monga momwe zasonyezedwera pa Chithunzi S12d ndi e. Pa nthawi yosonkhanitsa maselo, nembanemba ya CEM yokhala ndi mabowo yophimbidwa ndi catalyst inayikidwa pa pepala la Toray la 25 cm2 (5 wt% PTFE treated, Fuel Cell Store, USA). Nembanemba ya AEM (PiperION, Versogen, USA) yokhala ndi makulidwe a 25, 40 kapena 80 μm inayikidwa pamwamba pa CEM kenako pa GDE cathode. Nembanemba ya AEM inadulidwa m'zidutswa za 7.5 × 7.5 cm kuti iphimbe malo onse oyenda ndipo inanyowetsedwa usiku wonse mu 1 M potassium hydroxide solution musanasonkhanitse. Anode ndi cathode zonse zimagwiritsa ntchito PTFE spacers zomwe ndi zokhuthala mokwanira kuti zikwaniritse GDE compression yabwino kwambiri ya 18%. Tsatanetsatane wa njira yosonkhanitsira batri wawonetsedwa pa Chithunzi S12a.
Pa nthawi yoyesera, selo lomwe linasonkhanitsidwa linasungidwa pa 60 °C (30, 60, ndi 80 °C kuti liphunzire za kutentha) ndi mpweya wa hydrogen wa 0.8 L/min womwe unaperekedwa ku anode ndi 2 L/min wa carbon dioxide womwe unaperekedwa ku cathode. Mitsinje yonse ya anodic ndi cathodic inanyowa pa chinyezi cha 100% komanso 259 kPa blurse cathodic pressure. Pa nthawi yogwira ntchito, mpweya wa cathode unasakanizidwa ndi yankho la 1 M KOH pamlingo wa 2 mL/min kuti mulimbikitse kugwiritsa ntchito cathode catalyst bed ndi ionic conduction. Sakanizani mpweya wa anode ndi madzi osungunuka pamlingo wa 10 ml/min kuti muchotse formic acid pa anode. Tsatanetsatane wa zolowetsa ndi zotuluka za chipangizochi zikuwonetsedwa mu Chithunzi S5. Mpweya wotulutsa mpweya wa cathode uli ndi CO2 ndipo umapanga CO ndi H2. Nthunzi ya madzi imachotsedwa kudzera mu condenser (chosinthira kutentha chotsika pa 2°C). Mpweya wotsalawo udzasonkhanitsidwa kuti uwonetse nthawi ya mpweya. Kuyenda kwa anode kudzadutsanso mu condenser kuti ilekanitse madzi ndi mpweya. Madzi otayira adzasonkhanitsidwa m'mabotolo oyera ndikuwunikidwa pogwiritsa ntchito chronometry yamadzimadzi kuti ayese formic acid yomwe imapangidwira. Mayeso a electrochemical adachitika pogwiritsa ntchito Garmy potentiostat (nambala yofotokozera 30K, Gamry, USA). Asanayese curve ya polarization, seloyo idakonzedwa nthawi 4 kuyambira 0 mpaka 250 mA/cm2 pogwiritsa ntchito linear voltammetry yokhala ndi scan rate ya 2.5 mA/cm2. Ma curve a polarization adapezeka mu galvanostatic mode ndi seloyo kusungidwa pamlingo winawake wamagetsi kwa mphindi 4 asanayese gasi wa cathode ndi madzi a anolyte.
Timagwiritsa ntchito electrode yowunikira ya hydrogen mu MEA kuti tilekanitse cathode ndi anodic potentials. Kapangidwe ka electrode yowunikira kakuwonetsedwa mu Chithunzi S6a. Nembanemba ya Nafion (Nafion 211, IonPower, USA) idagwiritsidwa ntchito ngati mlatho wa ionic kuti ilumikize nembanemba ya MEA ndi electrode yowunikira. Malekezero amodzi a Nafion strip adalumikizidwa ku electrode yowunikira ya 1 cm2 (GDE) yodzaza ndi 0.25 mg Pt/cm2 (50 wt% Pt/C, TEC10E50E, TANAKA Precious Metals) yolumikizidwa pa pepala la kaboni la 29BC (Fuel Cell Store, USA). ). Zipangizo zapadera za polyetheretherketone (PEEK) zimagwiritsidwa ntchito kutseka gasi ndikuwonetsetsa kuti GDE ndi Nafion strips zikugwirizana bwino, ndikulumikiza electrode yowunikira ku hardware ya fuel cell. Malekezero ena a Nafion strip amalumikizidwa ku m'mphepete mwa batri ya CEM. Chithunzi S6b chikuwonetsa gawo lopingasa la electrode yowunikira yolumikizidwa ndi MEA.
Mpweya wotulutsa utsi ukadutsa mu condenser ndi gas-liquid separator, zitsanzo za mpweya zimatengedwa kuchokera ku cathode. Mpweya wosonkhanitsidwawo unasanthulidwa katatu pogwiritsa ntchito 4900 Micro GC (10 μm molecular sieve, Agilent). Zitsanzo zinasonkhanitsidwa mu matumba a zitsanzo za gasi a inert multi-layer aluminium foil sample bags Supel™ (Sigma-Aldrich) kwa nthawi inayake (masekondi 30) ndikuyikidwa pamanja mu microgas chromatograph mkati mwa maola awiri kuchokera pamene zinasonkhanitsidwa. Kutentha kwa jekeseni kunayikidwa pa 110°C. Carbon monoxide (CO) ndi hydrogen (H2) zinalekanitsidwa pa column ya MS5A yotenthedwa (105 °C) ya 10 m MS5A pogwiritsa ntchito argon (Matheson Gas-Matheson Purity) ngati mpweya wonyamulira. Maulumikizidwe awa amapezeka pogwiritsa ntchito Thermal Conductivity Detector (TCD) yomangidwa mkati. Ma GC chromatograms ndi ma CO ndi ma calibration curve akuwonetsedwa mu Chithunzi S7. Zitsanzo za asidi wamadzimadzi wa formic acid zinasonkhanitsidwa kuchokera ku anode kwa nthawi inayake (masekondi 120) ndikusefedwa pogwiritsa ntchito fyuluta ya syringe ya 0.22 μm PTFE m'mabotolo a 2 mL. Zinthu zamadzimadzi zomwe zili m'mabotolo zinasanthulidwa pogwiritsa ntchito njira ya Agilent 1260 Infinity II bioinert high-performance liquid chromatography (HPLC), momwe 20 μl ya chitsanzo idalowetsedwa kudzera mu autosampler (G5668A) yokhala ndi gawo loyenda la 4 mM sulfuric acid (H2SO4). ) pamlingo woyenda wa 0.6 ml/min (quaternary pump G5654A). Zinthuzo zinalekanitsidwa pa uvuni wotentha (35°C, column oven G7116A) Aminex HPX-87H 300 × 7.8 mm (Bio-Rad) wotsogozedwa ndi Micro-Guard Cation H guard column. Formic acid idapezeka pogwiritsa ntchito diode array detector (DAD). pa kutalika kwa mafunde a 210 nm ndi bandwidth ya 4 nm. Chromatogram ya HPL ndi curve yokhazikika ya calibration ya formic acid zikuwonetsedwa mu Chithunzi S7.
Zinthu za mpweya (CO ndi H2) FE zimawerengedwa pogwiritsa ntchito equation yotsatirayi, ndipo ma mole onse a mpweya amawerengedwa pogwiritsa ntchito equation yoyenera ya mpweya:
Pakati pawo: \({n}_{i}\): chiwerengero cha ma elekitironi mu electrochemical reaction. \(F\): Chosasinthika cha Faraday. \({C}_{i}\): Kuchuluka kwa HPLC yamadzimadzi. \(V\): voliyumu ya chitsanzo chamadzimadzi chosonkhanitsidwa pa nthawi yokhazikika t. \(j\): kuchuluka kwa current. \(A\): Malo a geometric a electrode (25 cm2). \(t\): nthawi yosankha zitsanzo. \(P\): kuthamanga kwathunthu. \({x}_{i}\): Mole peresenti ya mpweya yotsimikiziridwa ndi GC. \(R\): chosasinthika cha mpweya. \(T\): kutentha.
Kuchuluka kwa ma anodic cations kunayesedwa pogwiritsa ntchito inductively combined plasma atomic emission spectroscopy (ICP-OES). Ma cations omwe angatuluke kapena kufalikira mu anode ndi monga Ti, Pt, Bi ndi K. Kupatula K, ma cations ena onse anali pansi pa malire ozindikira. Kupanga ma ayoni mu yankho kusiya anode kuti igwirizane ndi ma proton kapena ma cations ena. Chifukwa chake, kuyera kwa formic acid kumatha kuwerengedwa ngati
Kupanga kwa Formate/FA kumayimira kuchuluka kwa FA komwe kumapangidwa pa kWh yamagetsi omwe amagwiritsidwa ntchito pogwiritsa ntchito mawonekedwe enaake a MEA, mu mol/kWh. Kumawerengedwa kutengera kuchuluka kwa magetsi, magetsi a maselo ndi mphamvu ya Faraday pansi pa mikhalidwe inayake yogwirira ntchito.
Werengerani kuchuluka kwa asidi wa formic womwe wasungunuka pa anode kutengera kuchuluka kwa misa yonse. Zochitika zitatu zopikisana zimachitika pa cathode: kusintha kwa haidrojeni, kuchepetsa CO2 kukhala CO, ndi kuchepetsa CO2 kukhala formic acid. Chifukwa tili ndi njira yopangira oxidation ya formic acid mu Anton, formic acid FE ikhoza kugawidwa m'magawo awiri: kusonkhanitsa formic acid ndi oxidation ya formic acid. Kuchuluka kwa misa yonse kungalembedwe motere:
Tinagwiritsa ntchito GC kuti tiwerenge kuchuluka kwa formic acid, hydrogen, ndi CO zomwe HPLC yasonkhanitsa. Tiyenera kudziwa kuti formic acid yambiri idasonkhanitsidwa kuchokera ku anode pogwiritsa ntchito njira yomwe yawonetsedwa mu Supplementary Figure S5. Kuchuluka kwa formate komwe kudasonkhanitsidwa kuchokera ku cathode chamber ndi kochepa, pafupifupi kawiri kukula kwake, ndipo ndi kochepera 0.5% ya kuchuluka konse kwa SC.
Chitsanzo choyendera mosalekeza chomwe chagwiritsidwa ntchito pano chimachokera ku ntchito yakale pa machitidwe ofanana34. Dongosolo lolumikizana la ma equation a Poisson-Nerst-Planck (PNP) limagwiritsidwa ntchito kudziwa kuchuluka kwa madzi ndi mphamvu zamagetsi m'magawo oyendetsera zamagetsi ndi ma ionic. Chidule chatsatanetsatane cha ma equation oyambira ndi geometry ya chitsanzo chaperekedwa mu SI.
Dongosolo ili limazindikira kuchuluka kwa zinthu zisanu ndi zitatu zamadzi (\({{{{{\rm{C}}}}}}}{{{{{\rm{O}}}}}}}}_{2 \left ({{{{{\rm{aq}}}}}}}\right)}\), \({{{{{{\rm{H}}}}}}}}}^{+ }\ ), \ ({{{{\rm{O}}}}}}{{{{{\rm{H}}}}}}^{-}\), \({{{ {{ \rm{HCO}}}}}}}_{3}^{-}\), \({{{{{\rm{CO}}}}}}_{3}^{ 2-} \ ),\ ({{{{\rm{HCOOH}}}}}}}\), \({{{{{\rm{HCOO}}}}}}}}}^{- }\) ndi \({{{ {{\rm{K}}}}}}}^{+}\)), mphamvu yamagetsi mu gawo loyendetsa ma ionic (\({\phi }_{I}\ )) ndi mphamvu yamagetsi ya anodic ndi cathodic. Mphamvu yamagetsi mu magawo (\({\phi }_{A}\) ndi \({\phi }_{C}\) motsatana). M'malo mwake, ntchito zamagetsi zapafupi kapena kusagwirizana kwa ma charge sizimachitika, dera la charge la malo limathetsedwa mwachindunji pogwiritsa ntchito equation ya Poisson; Njira iyi imatithandiza kutengera mwachindunji zotsatira za Donnan repulsion pa ma interface a CEM|AEM, CEM|Pore, ndi AEM|Pore. Kuphatikiza apo, chiphunzitso cha electrode chopondapo (PET) chimagwiritsidwa ntchito pofotokoza kayendedwe ka charge mu zigawo za anodic ndi cathodic za catalyst. Monga momwe olembawo akudziwira, ntchitoyi ikuyimira kugwiritsa ntchito koyamba kwa PET m'makina omwe ali ndi madera ambiri operekera mphamvu.
Zitsanzo za GDE BOT ndi EOT cathode zinayesedwa pogwiritsa ntchito Zeiss Xradia 800 Ultra yokhala ndi gwero la X-ray la 8.0 keV, njira zoyamwitsa ndi njira zolumikizirana, komanso kusakanikirana kwa zithunzi1. Zithunzi 901 zinasonkhanitsidwa kuyambira -90° mpaka 90° ndi nthawi yowonekera ya masekondi 50. Kukonzanso kunachitika pogwiritsa ntchito fyuluta yowonera kumbuyo yokhala ndi kukula kwa voxel ya 64 nm. Kusanthula kwa kugawa magawo ndi kugawa kwa tinthu tating'onoting'ono kunachitika pogwiritsa ntchito code yolembedwa mwapadera.
Kuzindikira ma electron microscopic kumaphatikizapo kuyika ma MEA oyesera mu epoxy resin pokonzekera kugawa magawo ochepa kwambiri ndi mpeni wa diamondi. Gawo lopingasa la MEA iliyonse linadulidwa mpaka makulidwe a 50 mpaka 75 nm. Talos F200X transmission electron microscope (Thermo Fisher Scientific) idagwiritsidwa ntchito poyesa ma electron microscopy (STEM) ndi ma energy-dispersive X-ray spectroscopy (EDS). Maikulosikopu ili ndi dongosolo la EDS Super-X lokhala ndi ma SDD detectors anayi opanda mawindo ndipo limagwira ntchito pa 200 kV.
Mawonekedwe a ufa wa X-ray diffraction (PXRD) adapezeka pa Bruker Advance D8 powder X-ray diffractometer yokhala ndi Ni-filtered Cu Kα radiation yomwe imagwira ntchito pa 40 kV ndi 40 mA. Kusanthula kwa data ndi kuyambira 10° mpaka 60°, kukula kwa sitepe ndi 0.005°, ndipo liwiro lopeza deta ndi sekondi imodzi pa sitepe iliyonse.
Sipekitiramu ya RAS yomwe ili m'mphepete mwa chothandizira cha Bi2O3 Bi L3 inayesedwa ngati ntchito ya mphamvu pogwiritsa ntchito selo lopangidwa kunyumba. Inki ya ionoma ya Bi2O3 yothandiza kwambiri inakonzedwa pogwiritsa ntchito 26.1 mg ya Bi2O3 yosakanizidwa ndi yankho la ionoma la 156.3 μL (6.68%) ndipo inathetsedwa ndi 1 M KOH, madzi (157 μL) ndi isopropyl alcohol (104 μL) kuti ipeze inki ya ionoma. Chofunikira cha chothandizira ndi 0.4. Inkiyo inagwiritsidwa ntchito pamapepala a graphene m'malo ozungulira (10×4 mm) mpaka katundu wa chothandizira cha Bi2O3 atafika pa 0.5 mg/cm2. Pepala lotsala la graphene limakutidwa ndi Kapton kuti lilekanitse madera awa ndi electrolyte. Pepala la graphene lokhala ndi chothandizira linayikidwa pakati pa ma PTFE awiri ndikulumikizidwa ku thupi la selo (PEEK) ndi zomangira, Chithunzi S8. Hg/HgO (1 M NaOH) linagwiritsidwa ntchito ngati electrode yofotokozera, ndipo pepala la carbon linagwiritsidwa ntchito ngati electrode yotsutsana. Elekitirodi yowunikira ya Hg/HgO idayesedwa pogwiritsa ntchito waya wa platinamu woviikidwa mu hydrogen-saturated 0.1 M KOH kuti isinthe ma potential onse oyesedwa kukhala sikelo yosinthika ya hydrogen electrode (RHE). Ma XRD spectra adapezeka poyang'anira mphamvu ya electrode yogwira ntchito ya Bi2O3/graphene yoviikidwa mu 0.1 M KOH, yotenthedwa mpaka 30 °C. Elekitirodi imazungulira mu batire, ndi electrolyte inlet pansi pa selo ndi outlet pamwamba kuti zitsimikizire kuti electrolyte imalumikizana ndi catalyst layer pamene thovu likupanga. CH Instruments 760e potentiostat idagwiritsidwa ntchito kuwongolera mphamvu ya electrode yogwira ntchito. Potentiyo inali mphamvu yotseguka ya circuit: -100, -200, -300, -400, -500, -800, -850, -900, -1000, -1100, -1500 ndi +700 mV kutengera RHE. Ma potential onse a iR asinthidwa.
Kuyeza kwa Bi L3 m'mphepete (~13424 eV ya Bi metal) X-ray absorption fine structure (XAFS) spectroscopy kunachitika pa channel 10-ID, Advanced Photon Source (APS), Argonne National Fluorescence Laboratory. National Model Measurement Laboratory. Chojambulira cha Si(111) chokhala ndi makristalo awiri chozizira ndi nayitrogeni yamadzimadzi chinagwiritsidwa ntchito kukonza mphamvu ya X-ray, ndipo galasi lophimbidwa ndi rhodium linagwiritsidwa ntchito kuchepetsa kuchuluka kwa harmonic. Mphamvu zojambulira zinasiyanasiyana kuyambira 13200 mpaka 14400 eV, ndipo fluorescence inayesedwa pogwiritsa ntchito 5 × 5 silicon PIN diode array yopanda zosefera kapena Soller slits. Mphamvu yodutsa zero ya derivative yachiwiri imayesedwa pa 13271.90 eV kudzera m'mphepete mwa L2 ya pepala la Pt. Chifukwa cha makulidwe a selo la electrochemical, sizinatheke kuyeza nthawi imodzi spectrum ya muyezo wofotokozera. Motero, kusintha kowerengedwa kwa scan-to-scanning mu mphamvu ya X-ray ya incident ndi ±0.015 eV kutengera muyeso wobwerezabwereza mu kuyesa konse. Kukhuthala kwa Bi2O3 layer kumabweretsa ku mlingo winawake wa kudziyamwa kwa fluorescence; ma electrodes amakhala ndi mawonekedwe okhazikika poyerekeza ndi kuwala kwa incident ndi detector, zomwe zimapangitsa kuti ma scan onse akhale ofanana. Near-field XAFS spectrum idagwiritsidwa ntchito kudziwa momwe oxidation imakhalira ndi mtundu wa mankhwala wa bismuth poyerekeza ndi XANES region ya Bi ndi Bi2O3 standards pogwiritsa ntchito linear combination fitting algorithm ya Athena software (version 0.9.26). ndi code IFEFFIT 44.
Deta yothandizira ziwerengero zomwe zili munkhaniyi ndi mfundo zina za kafukufukuyu zikupezeka kwa wolemba woyenerera ngati pakufunika kutero.
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