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ʻO ka hoʻemi electrochemical o ke kalapona dioxide i ka waikawa formic he ala hoʻohiki ia e hoʻomaikaʻi ai i ka hoʻohana ʻana i ke kalapona dioxide a he mau noi kūpono hoʻi ma ke ʻano he medium mālama hydrogen. Ma kēia hana, ua hoʻomohala ʻia kahi hoʻolālā hui electrode membrane zero-gap no ka synthesis electrochemical pololei o ka waikawa formic mai ke kalapona dioxide. ʻO kahi holomua ʻenehana koʻikoʻi ka membrane hoʻololi cation perforated, kahi, i ka wā e hoʻohana ʻia ai i kahi hoʻonohonoho membrane bipolar i mua, e ʻae i ka waikawa formic i hana ʻia ma ka interface membrane e hoʻoneʻe ʻia ma o ke kahua kahe anodic i nā ʻano haʻahaʻa e like me 0.25 M. Me ka ʻole o nā ʻāpana sandwich hou aʻe ma waena o ka anode a me ka cathode, manaʻo ka manaʻo e hoʻohana i nā mea pākaukau e kū nei a me nā hoʻolālā maʻamau i nā cell wahie a me ka electrolysis hydrogen, e ʻae ana i kahi hoʻololi wikiwiki i ka scale-up a me ke kālepa ʻana. I loko o kahi cell 25 cm2, hāʻawi ka hoʻonohonoho membrane hoʻololi cation perforated i ka pono >75% Faraday no ka waikawa formic ma <2 V a me 300 mA/cm2. ʻOi aku ka mea nui, ua hōʻike kahi hoʻāʻo paʻa 55-hola ma 200 mA/cm2 i ka pono Faraday paʻa a me ka voltage cell. Hoʻohana ʻia kahi loiloi techno-economic e hōʻike i nā ala e hoʻokō ai i ke kaulike o nā kumukūʻai me nā ʻano hana hana waikawa formic o kēia manawa.
Ua hōʻike ʻia ka hōʻemi electrochemical o ke kalapona dioxide i ka waikawa formic me ka hoʻohana ʻana i ka uila hou e hōʻemi i nā kumukūʻai hana a hiki i ka 75%1 i hoʻohālikelike ʻia me nā ʻano hana kuʻuna e pili ana i ka wahie fossil. E like me ka mea i hōʻike ʻia ma ka palapala2,3, he ākea nā noi o ka waikawa formic, mai kahi ala kūpono a hoʻokele waiwai hoʻi o ka mālama ʻana a me ka lawe ʻana i ka hydrogen i kahi feedstock no ka ʻoihana kemika4,5 a i ʻole ka ʻoihana biomass6. Ua ʻike ʻia ka waikawa formic ma ke ʻano he feedstock no ka hoʻololi ʻana ma hope i nā wahie jet hoʻomau me ka hoʻohana ʻana i ka ʻenekinia metabolic7,8. Me ka hoʻomohala ʻana o ka hoʻokele waiwai waikawa formic1,9, ua kālele kekahi mau hana noiʻi i ka hoʻonui ʻana i ke koho catalyst10,11,12,13,14,15,16. Eia nō naʻe, ke hoʻomau nei ka nui o nā hana e kālele ana i nā cell H liʻiliʻi a i ʻole nā ​​​​​​kelepona kahe wai e hana ana ma nā densities haʻahaʻa o kēia manawa (<50 mA/cm2). No ka hōʻemi ʻana i nā kumukūʻai, hoʻokō i ke kālepa ʻana a hoʻonui i ka komo ʻana o ka mākeke ma hope, pono e hana ʻia ka hoʻemi ʻana o ke kalapona carbon dioxide electrochemical (CO2R) ma nā densities o kēia manawa kiʻekiʻe (≥200 mA/cm2) a me ka Faraday efficiency (FE)17 ʻoiai e hoʻonui ana i ka hoʻohana ʻana i nā mea a me ka hoʻohana ʻana i nā ʻāpana pila mai ka ʻenehana ʻana i nā cell wahie a me ka electrolysis wai e ʻae i nā mea hana CO2R e hoʻohana pono i nā hoʻokele waiwai o ka unahi18. Eia kekahi, no ka hoʻonui ʻana i ka pono o ka hana ʻana a pale i ka hana hou ʻana ma lalo, pono e hoʻohana ʻia ka waikawa formic ma ke ʻano he huahana hope loa ma mua o nā paʻakai formate19.
Ma kēia ala, ua hana ʻia nā hoʻoikaika hou e hoʻomohala i nā mea hana electrode diffusion gas (GDE) e pili ana i ka ʻoihana CO2R formate/formic acid. Hōʻuluʻulu kahi loiloi piha e Fernandez-Caso et al.20 i nā hoʻonohonoho cell electrochemical āpau no ka hoʻemi mau ʻana o CO2 i ka formic acid/formate. Ma keʻano laulā, hiki ke hoʻokaʻawale ʻia nā hoʻonohonoho āpau i kēia manawa i ʻekolu mau ʻāpana nui: 1. Nā catholytes kahe-ma o19,21,22,23,24,25,26,27, 2. Membrane hoʻokahi (membrane hoʻololi cation (CEM)28 a i ʻole ka membrane hoʻololi anion (AEM)29 a me 3. Hoʻonohonoho Sandwich15,30,31,32. Hōʻike ʻia nā ʻāpana keʻa maʻalahi o kēia mau hoʻonohonoho ma ke Kiʻi 1a. No ke hoʻonohonoho kahe o ka catholyte, ua hana ʻia kahi keʻena electrolyte ma waena o ka membrane a me ka cathode o ka GDE. Hoʻohana ʻia ka catholyte kahe-ma o e hana i nā kahawai ion i loko o ka papa cathode o ka catalyst33, ʻoiai ke kūkākūkā ʻia nei kona pono no ka kaohi ʻana i ke koho formate34. Eia naʻe, ua hoʻohana ʻia kēia hoʻonohonoho e Chen et al. Ma ka hoʻohana ʻana i kahi cathode SnO2 ma kahi substrate kalapona me kahi papa catholyte mānoanoa 1.27 mm, a hiki i ka 90% FE 35 ma 500 mA/cm2 ua hoʻokō ʻia. ʻO ka hui pū ʻana o kahi mānoanoa ʻO ka papa catholyte a me kahi membrane bipolar reverse-biased (BPM) e kaupalena ana i ka hoʻoili ion e hāʻawi i kahi volta hana o 6 V a me ka pono ikehu o 15%. No ka hoʻomaikaʻi ʻana i ka pono ikehu, ua hoʻokō ʻo Li et al., me ka hoʻohana ʻana i kahi hoʻonohonoho CEM hoʻokahi, i kahi FE 29 o 93.3% ma kahi fractional current density o 51.7 mA/cm2. Ua hoʻohana ʻo Diaz-Sainz et al.28 i kahi kaomi kānana me kahi membrane CEM hoʻokahi ma kahi density o 45 mA/cm2. Eia nō naʻe, ua hana nā ʻano hana āpau i ka formate ma mua o ka huahana makemake ʻia, ka waikawa formic. Ma waho aʻe o nā koi hana hou aʻe, i nā hoʻonohonoho CEM, hiki i nā ʻano e like me KCOOH ke hōʻiliʻili koke i loko o ke kahua GDE a me ke kahe, e hana ana i nā palena o ka lawe ʻana a me ka hāʻule ʻana o nā cell.
Hoʻohālikelike ʻia o nā hoʻonohonoho ʻekolu o ka CO2R koʻikoʻi loa i nā hoʻonohonoho mea hoʻololi formate/formic acid a me ke ʻano hana i manaʻo ʻia ma kēia haʻawina. b Hoʻohālikelike ʻia o ka huina o kēia manawa a me ka hua formate/formic acid no nā hoʻonohonoho catholyte, nā hoʻonohonoho sandwich, nā hoʻonohonoho CEM hoʻokahi ma ka palapala (i hōʻike ʻia ma ka Papa Hoʻohui S1) a me kā mākou hana. Hōʻike nā māka hāmama i ka hana ʻana o ka hopena formate, a hōʻike nā māka paʻa i ka hana ʻana o ka waikawa formic. * Hōʻike ʻia ka hoʻonohonoho ʻana me ka hoʻohana ʻana i ka hydrogen ma ka anode. c Hoʻonohonoho MEA Zero-gap me ka hoʻohana ʻana i kahi membrane bipolar composite me kahi papa hoʻololi cation perforated e hana ana ma ke ʻano bias mua.
I mea e pale aku ai i ka hoʻokumu ʻana o ka formate, ua hoʻohana ʻo Proietto et al. 32 i kahi hoʻonohonoho kaomi kānana splitless kahi e kahe ai ka wai deionized ma o ka interlayer. Hiki i ka ʻōnaehana ke hoʻokō i ka >70% CE ma ka pae density o kēia manawa o 50-80 mA/cm2. Pēlā nō, ua hāpai ʻo Yang et al. 14 i ka hoʻohana ʻana i kahi interlayer electrolyte paʻa ma waena o ka CEM a me AEM e hoʻolaha i ka hoʻokumu ʻana o ka waikawa formic. Ua hoʻokō ʻo Yang et al.31,36 i ka 91.3% FE i loko o kahi cell 5 cm2 ma 200 mA/cm2, e hana ana i kahi hopena waikawa formic 6.35 wt%. Xia et al. Ma ka hoʻohana ʻana i kahi hoʻonohonoho like, ua hoʻokō ʻia ka hoʻololi ʻana o 83% o ke kalapona dioxide (CO2) i ka waikawa formic FE ma 200 mA/cm2, a ua hoʻāʻo ʻia ka lōʻihi o ka ʻōnaehana no 100 hola 30 mau minuke. ʻOiai he mea hoʻohiki nā hopena liʻiliʻi, ʻo ka hoʻonui ʻia o ke kumukūʻai a me ka paʻakikī o nā resins hoʻololi ion porous e paʻakikī ai ke hoʻonui i nā hoʻonohonoho interlayer i nā ʻōnaehana nui (e laʻa, 1000 cm2).
No ka ʻike ʻana i ka hopena o nā hoʻolālā like ʻole, ua helu mākou i ka hana ʻana o ka waikawa formate/formic i kēlā me kēia kWh no nā ʻōnaehana āpau i ʻōlelo ʻia ma mua a ua hoʻolālā iā lākou ma ke Kiʻi 1b. Ua maopopo ma ʻaneʻi e hoʻokiʻekiʻe ana kekahi ʻōnaehana i loaʻa kahi catholyte a i ʻole interlayer i kāna hana ma nā densities o kēia manawa haʻahaʻa a hoʻohaʻahaʻa i nā densities o kēia manawa kiʻekiʻe, kahi e hoʻoholo ai ka palena ohmic i ka voltage cell. Eia kekahi, ʻoiai ʻo ka hoʻonohonoho CEM ikehu-e hāʻawi i ka hana ʻana o ka waikawa formic molar kiʻekiʻe loa i kēlā me kēia kWh, hiki i ka hōʻiliʻili paʻakai ke alakaʻi i ka hoʻohaʻahaʻa wikiwiki ʻana i nā densities o kēia manawa kiʻekiʻe.
No ka hoʻēmi ʻana i nā ʻano hāʻule i kūkākūkā mua ʻia, ua hoʻomohala mākou i kahi hui electrode membrane (MEA) e loaʻa ana kahi BPM i hoʻopili ʻia i mua me kahi membrane hoʻololi cation perforated (PCEM). Hōʻike ʻia ke ʻano hana ma ke Kiʻi 1c. Hoʻokomo ʻia ka hydrogen (H2) i loko o ka anode e hana i nā protons ma o kahi hopena hydrogen oxidation (HOR). Hoʻokomo ʻia kahi papa PCEM i loko o ka ʻōnaehana BPM e ʻae i nā ion formate i hana ʻia ma ka cathode e hele ma waena o ka AEM, hui pū me nā protons e hana i ka waikawa formic ma ka interface BPM a me nā pores interstitial o ka CEM, a laila puka i waho ma o ka anode GDE a me ke kahua kahe. . Ma ka hoʻohana ʻana i kēia hoʻonohonoho ʻana, ua hoʻokō mākou i ka >75% FE o ka waikawa formic ma <2 V a me 300 mA/cm2 no kahi cell 25 cm2. ʻO ka mea nui loa, hoʻohana ka hoʻolālā i nā ʻāpana i loaʻa ma ke kālepa a me nā hoʻolālā lako no nā mea kanu electrolysis cell wahie a me ka wai, e ʻae ana i ka manawa wikiwiki e hoʻonui. Loaʻa i nā hoʻonohonoho Catholyte nā keʻena kahe catholyte hiki ke hana i kahi kaulike ʻole o ke kaomi ma waena o nā pae kinoea a me nā wai, ʻoi aku hoʻi i nā hoʻonohonoho cell nui. No nā ʻano hana sandwich me nā papa porous o ke kahe wai, pono nā hana koʻikoʻi e hoʻomaikaʻi i ka papa waena porous e hōʻemi i ka hāʻule ʻana o ke kaomi a me ka hōʻiliʻili ʻana o ke kalapona dioxide i loko o ka papa waena. Hiki i kēia mau mea ʻelua ke alakaʻi i ka hoʻopilikia ʻana i nā kamaʻilio kelepona. He mea paʻakikī hoʻi ke hana i nā papa porous lahilahi kūʻokoʻa ma kahi pae nui. I ka hoʻohālikelike ʻana, ʻo ka hoʻonohonoho hou i manaʻo ʻia he hoʻonohonoho MEA zero-gap ʻaʻohe ona keʻena kahe a i ʻole ka papa waena. Ke hoʻohālikelike ʻia me nā cell electrochemical ʻē aʻe, he kū hoʻokahi ka hoʻonohonoho i manaʻo ʻia no ka mea e ʻae ana i ka synthesis pololei o ka waikawa formic i loko o kahi hoʻonohonoho scalable, ikehu-effective, zero-gap.
No ke kāohi ʻana i ka ulu ʻana o ka hydrogen, ua hoʻohana nā hana hoʻemi nui o ka CO2 i nā hoʻonohonoho membrane MEA a me AEM i hui pū ʻia me nā electrolytes molar kiʻekiʻe (e laʻa, 1-10 M KOH) e hana i nā kūlana alkaline ma ka cathode (e like me ka mea i hōʻike ʻia ma ke Kiʻi 2a). Ma kēia mau hoʻonohonoho ʻana, hele nā ​​​​iona formate i hana ʻia ma ka cathode ma o ka membrane ma ke ʻano he ʻano i hoʻopiʻi maikaʻi ʻole ʻia, a laila hoʻokumu ʻia ʻo KCOOH a puka i waho o ka ʻōnaehana ma o ke kahawai anodic KOH. ʻOiai ua maikaʻi mua ka formate FE a me ka voltage cell e like me ka mea i hōʻike ʻia ma ke Kiʻi 2b, ua hopena ka hoʻāʻo paʻa i ka emi ʻana o FE ma kahi o 30% i loko o 10 h wale nō (Kiʻi S1a–c). Pono e hoʻomaopopo ʻia he mea koʻikoʻi ka hoʻohana ʻana o 1 M KOH anolyte e hōʻemi i ka overvoltage anodic i nā ʻōnaehana alkaline oxygen evolution reaction (OER)37 a hoʻokō i ka hiki ke komo i ka ion i loko o ka moena catalyst cathode33. Ke hoʻemi ʻia ka nui o ka anolyte i 0.1 M KOH, piʻi ka volta o ke kelepona a me ka hoʻomake ʻana o ka waikawa formic (nalowale o ka waikawa formic) (Kiʻi S1d), e hōʻike ana i kahi kālepa zero-sum. Ua loiloi ʻia ke kekelē o ka hoʻomake ʻana o ka formate me ka hoʻohana ʻana i ke kaulike nuipa holoʻokoʻa; no nā kikoʻī hou aku, e ʻike i ka ʻāpana "Methods". Ua aʻo ʻia hoʻi ka hana me ka hoʻohana ʻana i ka MEA a me nā hoʻonohonoho membrane CEM hoʻokahi, a ua hōʻike ʻia nā hopena ma ke Kiʻi S1f,g. ʻO ka FE formate i hōʻiliʻili ʻia mai ka cathode he >60% ma 200 mA/cm2 i ka hoʻomaka ʻana o ka hoʻāʻo, akā ua hoʻohaʻahaʻa koke ʻia i loko o ʻelua hola ma muli o ka hōʻiliʻili ʻana o ka paʻakai cathode i kūkākūkā ʻia ma mua (Kiʻi S11).
ʻO ke kiʻikuhi o kahi MEA zero-gap me CO2R ma ka cathode, ka hopena hydrogen oxidation (HOR) a i ʻole OER ma ka anode, a hoʻokahi membrane AEM ma waena. b ʻO FE a me ke kelepona uila no kēia hoʻonohonoho ʻana me 1 M KOH a me OER e kahe ana ma ka anode. Hōʻike nā kaha hewa i ka ʻokoʻa maʻamau o ʻekolu mau ana like ʻole. ma FE a me ke kelepona uila ʻōnaehana me H2 a me HOR ma ka anode. Hoʻohana ʻia nā kala like ʻole e hoʻokaʻawale i ka hana formate a me ka formic acid. d ʻO ke kiʻikuhi o MEA me BPM i neʻe ʻia i mua ma waena. ʻO FE a me ke kelepona uila e kūʻē i ka manawa ma 200 mA/cm2 me ka hoʻohana ʻana i kēia hoʻonohonoho. f Kiʻi cross-sectional o kahi BPM MEA i hoʻohālikelike ʻia i mua ma hope o kahi hoʻāʻo pōkole.
No ka hana ʻana i ka waikawa formic, ua hoʻolako ʻia ka hydrogen i kahi mea hoʻouluulu Pt-on-carbon (Pt/C) ma ka anode. E like me ka mea i hōʻike ʻia ma ke Kiʻi 2d, ua noiʻi mua ʻia kahi protons e hana ana i ka BPM i hoʻohālikelike ʻia i mua ma ka anode e hoʻokō i ka hana ʻana o ka waikawa formic. Ua hāʻule ka ʻāpana hoʻonohonoho BPM ma hope o 40 mau minuke o ka hana ma ke au o 200 mA/cm2, me ka piʻi ʻana o ka voltage ma mua o 5 V (Kiʻi 2e). Ma hope o ka hoʻāʻo ʻana, ua ʻike ʻia ka delamination maopopo ma ka interface CEM/AEM. Ma waho aʻe o ka formate, hiki i nā anions e like me ka carbonate, bicarbonate a me ka hydroxide ke hele ma waena o ka membrane AEM a pane me nā protons ma ka interface CEM/AEM e hana i ke kinoea CO2 a me ka wai wai, e alakaʻi ana i ka delamination BPM (Kiʻi 2f) a , i ka hopena e alakaʻi ana i ka hāʻule ʻana o ke kelepona.
Ma muli o ka hana a me nā ʻano hana hāʻule o ka hoʻonohonoho ʻana ma luna, ua hāpai ʻia kahi hoʻolālā MEA hou e like me ka mea i hōʻike ʻia ma ke Kiʻi 1c a ua kikoʻī ʻia ma ke Kiʻi 3a38. Maanei, hāʻawi ka papa PCEM i kahi ala no ka neʻe ʻana o ka waikawa formic a me nā anions mai ka interface CEM/AEM, no laila e hōʻemi ana i ka hōʻiliʻili ʻana o ka mea. I ka manawa like, kuhikuhi ke ala interstitial PCEM i ka waikawa formic i loko o ka medium diffusion a me ke kahua kahe, e hōʻemi ana i ka hiki ke hoʻopau ʻia ka waikawa formic. Hōʻike ʻia nā hopena polarization me ka hoʻohana ʻana i nā AEM me nā mānoanoa o 80, 40 a me 25 mm ma ke Kiʻi 3b. E like me ka mea i manaʻo ʻia, ʻoiai ke piʻi nei ka volta o ke kelepona holoʻokoʻa me ka hoʻonui ʻana i ka mānoanoa o AEM, ʻo ka hoʻohana ʻana i kahi AEM mānoanoa e pale aku i ka hoʻolaha hope o ka waikawa formic, no laila e hoʻonui ana i ka pH cathode a e hōʻemi ana i ka hana H2 (Kiʻi 3c–e).
a Kiʻi o ke ʻano MEA me AEM a me CEM perforated a me nā ala halihali waikawa formic like ʻole. b Ka uila o ke kelepona ma nā ʻano densities o kēia manawa like ʻole a me nā mānoanoa AEM like ʻole. ma EE ma nā ʻano densities o kēia manawa like ʻole me ka mānoanoa AEM o 80 μm (d) 40 μm, e) 25 μm. Hōʻike nā kaha hewa i ka ʻokoʻa maʻamau i ana ʻia mai ʻekolu mau laʻana kaʻawale. f Nā hopena simulation o ka hoʻohuihui waikawa formic a me ka waiwai pH ma ka interface CEM/AEM ma nā mānoanoa AEM like ʻole. f PC a me pH ma ka papa cathode o ka catalyst me nā mānoanoa kiʻiʻoniʻoni AEM like ʻole. g Ka hoʻolaha ʻelua-dimensional o ka hoʻohuihui waikawa formic me ka interface CEM/AEM a me ka perforation.
Hōʻike ka Kiʻi S2 i ka hoʻolaha ʻana o ka nui o ka waikawa formic a me ka pH ma waena o ka mānoanoa MEA me ka hoʻohana ʻana i ka hoʻohālike ʻana o nā mea finite Poisson-Nernst-Planck. ʻAʻole ia he mea kupanaha i ʻike ʻia ka nui kiʻekiʻe loa o ka waikawa formic, 0.23 mol/L, ma ka interface CEM/AEM, ʻoiai ua hoʻokumu ʻia ka waikawa formic ma kēia interface. ʻOi aku ka wikiwiki o ka emi ʻana o ka nui o ka waikawa formic ma o ka AEM i ka piʻi ʻana o ka mānoanoa o ka AEM, e hōʻike ana i ka pale nui ʻana i ka hoʻoili nui ʻana a me ka emi ʻana o ka flux waikawa formic ma muli o ka hoʻolaha hope. Hōʻike nā Kiʻi 3 f a me g i nā waiwai pH a me ka waikawa formic i loko o ka moena catalyst cathode i hoʻokumu ʻia e ka hoʻolaha hope a me ka hoʻolaha ʻelua-dimensional o ka nui o ka waikawa formic, kēlā me kēia. ʻO ka lahilahi o ka membrane AEM, ʻoi aku ka kiʻekiʻe o ka nui o ka waikawa formic kokoke i ka cathode, a lilo ka pH o ka cathode i acidic. No laila, ʻoiai ʻo nā membrane AEM mānoanoa e hopena i nā pohō ohmic kiʻekiʻe, he mea nui lākou i ka pale ʻana i ka hoʻolaha hope o ka waikawa formic i ka cathode a me ka hoʻonui ʻana i ka maʻemaʻe kiʻekiʻe o ka ʻōnaehana waikawa formic FE. ʻO ka mea hope loa, ʻo ka hoʻonui ʻana i ka mānoanoa o ka AEM i 80 μm i hopena i ka FE >75% no ka waikawa formic ma <2 V a me 300 mA/cm2 no kahi ʻāpana cell 25 cm2.
No ka hoʻāʻo ʻana i ke kūpaʻa o kēia hoʻolālā e pili ana i ka PECM, ua mālama ʻia ke au o ka pila ma 200 mA/cm2 no 55 mau hola. Hōʻike ʻia nā hopena holoʻokoʻa ma ke Kiʻi 4, me nā hopena mai nā hola 3 mua i hōʻike ʻia ma ke Kiʻi S3. I ka hoʻohana ʻana i ka mea hoʻouluulu anodic Pt/C, ua piʻi nui ka volta o ke kelepona i loko o nā minuke 30 mua (Kiʻi S3a). I loko o kahi manawa lōʻihi, ua noho mau ka volta o ke kelepona, e hāʻawi ana i ka helu hōʻino o 0.6 mV/h (Kiʻi 4a). I ka hoʻomaka ʻana o ka hoʻāʻo, ʻo ka PV o ka waikawa formic i hōʻiliʻili ʻia ma ka anode he 76.5% a ʻo ka PV o ka hydrogen i hōʻiliʻili ʻia ma ka cathode he 19.2%. Ma hope o ka hola mua o ka hoʻāʻo ʻana, ua hāʻule ka hydrogen FE i 13.8%, e hōʻike ana i ka hoʻomaikaʻi ʻana i ke koho formate. Eia nō naʻe, ua hāʻule ka helu oxidation o ka waikawa formic i loko o ka ʻōnaehana i 62.7% i loko o 1 hola, a ua piʻi ka helu oxidation o ka waikawa formic anodic mai ka aneane ʻole i ka hoʻomaka ʻana o ka hoʻāʻo a i 17.0%. Ma hope mai, ua noho paʻa ka FE o H2, CO, ka waikawa formic a me ka wikiwiki o ka oxidation anodic o ka waikawa formic i ka wā o ka hoʻokolohua. ʻO ka piʻi ʻana o ka oxidation waikawa formic i ka hola mua ma muli paha o ka hōʻiliʻili ʻana o ka waikawa formic ma ka interface PCEM/AEM. I ka piʻi ʻana o ka nui o ka waikawa formic, ʻaʻole ia e puka wale ma o ka perforation o ka membrane, akā e hoʻolaha pū kekahi ma o ka FEM ponoʻī a komo i loko o ka papa anode Pt/C. ʻOiai he wai ka waikawa formic ma 60°C, hiki i kona hōʻiliʻili ʻana ke hana i nā pilikia hoʻoili nui a hopena i ka oxidation makemake ʻia ma mua o ka hydrogen.
ʻO ke anakahi uila o ke kelepona e kūʻē i ka manawa (200 mA/cm2, 60 °C). Hōʻike ka inset i kahi kiʻi microscope optical o kahi ʻāpana kea o kahi MEA me kahi EM perforated. Pā unahi: 300 µm. b Ka maʻemaʻe o PE a me ka waikawa formic ma ke ʻano he hana o ka manawa ma 200 mA/cm2 me ka hoʻohana ʻana i kahi anode Pt/C.
Ua wehewehe ʻia ke ʻano o nā laʻana i ka hoʻomaka ʻana o ka hoʻāʻo ʻana (BOT) i ka wā hoʻomākaukau a ma ka hopena o ka hoʻāʻo ʻana (EOT) ma hope o 55 h o ka hoʻāʻo paʻa me ka hoʻohana ʻana i ka nano-X-ray computed tomography (nano-CT), e like me ka mea i hōʻike ʻia ma ke Kiʻi 5 a. ʻOi aku ka nui o ka nui o ka ʻāpana catalyst o ka laʻana EOT me ke anawaena o 1207 nm i hoʻohālikelike ʻia me 930 nm no BOT. Hōʻike ʻia nā kiʻi microscopy electron transmission scanning dark-field high-angle annular (HAADF-STEM) a me nā hopena spectroscopy X-ray dispersive ikehu (EDS) ma ke Kiʻi 5b. ʻOiai aia ka papa catalyst BOT i ka hapa nui o nā ʻāpana catalyst liʻiliʻi a me kekahi mau agglomerates nui aʻe, ma ke kahua EOT hiki ke hoʻokaʻawale ʻia ka papa catalyst i ʻelua mau ʻāpana like ʻole: hoʻokahi me nā ʻāpana paʻa nui a ʻo kekahi me nā ʻāpana porous. Helu o nā ʻāpana liʻiliʻi. Hōʻike ke kiʻi EDS ua waiwai nā ʻāpana paʻa nui i ka Bi, hiki ke metala Bi, a waiwai nā ʻāpana porous i ka oxygen. Ke hoʻohana ʻia ke kelepona ma 200 mA/cm2, ʻo ka hiki maikaʻi ʻole o ka cathode e hoʻemi i ka Bi2O3, e like me ka hōʻike ʻana o nā hopena spectroscopy absorption X-ray in situ i kūkākūkā ʻia ma lalo nei. Hōʻike nā hopena palapala ʻāina HAADF-STEM a me EDS e hele ana ʻo Bi2O3 i kahi kaʻina hana hōʻemi, e hoʻolilo ana iā lākou i ka oxygen a hoʻopili i loko o nā ʻāpana metala nui. Hōʻoia nā ʻano diffraction X-ray o nā cathodes BOT a me EOT i ka wehewehe ʻana o ka ʻikepili EDS (Kiʻi 5c): ʻo ka crystalline Bi2O3 wale nō i ʻike ʻia i loko o ka cathode BOT, a ua loaʻa ka bimetal crystalline i loko o ka cathode EOT. No ka hoʻomaopopo ʻana i ka hopena o ka hiki cathode ma ke kūlana oxidation o ka mea hoʻoulu cathode Bi2O3, ua hoʻololi ʻia ka mahana mai ka hiki ke kaapuni hāmama (+0.3 V vs RHE) a i -1.5 V (vs RHE). Ua ʻike ʻia ua hoʻomaka ka emi ʻana o ka pae Bi2O3 ma -0.85 V e pili ana iā RHE, a ʻo ka emi ʻana o ka ikaika o ka laina keʻokeʻo ma ka ʻāpana lihi o ka spectrum e hōʻike ana ua hoʻemi ʻia ka Bi metala i 90% o RHE ma -1.1. V e kūʻē iā RHE (Kiʻi 5d). Me ka nānā ʻole i ke ʻano hana, ʻaʻole i loli iki ke koho holoʻokoʻa o ka formate ma ka cathode, e like me ka mea i manaʻo ʻia mai ka H2 a me CO FE a me ka hoʻokumu ʻana o ka waikawa formic, ʻoiai nā loli koʻikoʻi i ke ʻano o ka cathode, ke kūlana oxidation catalyst, a me ke ʻano microcrystalline.
ʻO ke ʻano ʻekolu-dimensional o ka papa catalyst a me ka hoʻolaha ʻana o nā ʻāpana catalyst i loaʻa me ka hoʻohana ʻana i ka nano-X-ray CT. Pā unahi: 10 µm. b Luna 2: Nā kiʻi HAADF-STEM o nā papa cathode o nā catalysts BOT a me EOT. Pā unahi: 1 µm. Lalo 2: Nā kiʻi HADF-STEM a me EDX i hoʻonui ʻia o ka papa cathode o ka catalyst EOT. Pā unahi: 100 nm. c Nā ʻano diffraction X-ray o nā laʻana cathode BOT a me EOT. d Nā spectra absorption X-ray in situ o ka electrode Bi2O3 ma 0.1 M KOH ma ke ʻano he hana o ka hiki (0.8 V a i -1.5 V vs. RHE).
No ka hoʻoholo pono ʻana i nā manawa kūpono e loaʻa ana no ka hoʻomaikaʻi ʻana i ka pono o ka ikehu ma o ka pale ʻana i ka oxidation waikawa formic, ua hoʻohana ʻia kahi electrode kuhikuhi H2 e ʻike i ka hāʻawi ʻana o ka pohō voltage39. Ma nā densities o kēia manawa ma lalo o 500 mA/cm2, noho ka cathode potential ma lalo o -1.25 V. Ua māhele ʻia ka anodic potential i ʻelua mau ʻāpana nui: ka exchange current density HOR a me ka theoretical overvoltage HOR 40 i wānana ʻia e ka equation Bulter-Volmer i ana mua ʻia, a ʻo ke koena ma muli o ka oxidation formic acid. Ma muli o ke kinetics pane lohi loa i hoʻohālikelike ʻia me HOR41, ʻo ka liʻiliʻi o ka hopena oxidation waikawa formic ma ka anode hiki ke hopena i ka hoʻonui nui ʻana o ka anodic potential. Hōʻike nā hopena e hiki i ka pale piha ʻana o ka formic acid anodic oxidation ke hoʻopau i ka aneane 500 mV overvoltage.
No ka hoʻāʻo ʻana i kēia kuhi, ua hoʻololi ʻia ka nui o ke kahe o ka wai deionized (DI) ma ke komo ʻana o ka anode e hōʻemi i ka nui o ka waikawa formic effluent. Hōʻike nā kiʻi 6b a me c i ka FE, ka nui o ka waikawa formic, a me ke kahe o ke kelepona ma ke ʻano he hana o ka DI flux ma ka anode ma 200 mA/cm2. I ka piʻi ʻana o ka nui o ke kahe o ka wai deionized mai 3.3 mL/min a i 25 mL/min, ua emi ka nui o ka waikawa formic ma ka anode mai 0.27 mol/L a i 0.08 mol/L. I ka hoʻohālikelike ʻana, me ka hoʻohana ʻana i ke ʻano sandwich i hāpai ʻia e Xia et al. 30 ua loaʻa kahi nui o ka waikawa formic o 1.8 mol/L ma 200 mA/cm2. ʻO ka hoʻemi ʻana i ka nui e hoʻomaikaʻi i ka FE holoʻokoʻa o ka waikawa formic a hoʻemi i ka FE o H2 i ka wā e lilo ai ka pH cathode i mea alkaline ma muli o ka emi ʻana o ka hoʻolaha hope o ka waikawa formic. ʻO ka hoʻemi ʻia ʻana o ka nui o ka waikawa formic ma ke kahe DI kiʻekiʻe loa ua hoʻopau loa i ka oxidation waikawa formic, e hopena ana i ka volta cell holoʻokoʻa ma lalo iki o 1.7 V ma 200 mA/cm2. Hoʻopilikia pū ka mahana o ka pākaukau i ka hana holoʻokoʻa, a hōʻike ʻia nā hopena ma ke Kiʻi S10. Eia nō naʻe, hiki i nā hoʻolālā PCEM-based ke hoʻomaikaʻi nui i ka pono o ka ikehu i ka pale ʻana i ka oxidation waikawa formic, inā paha ma o ka hoʻohana ʻana i nā mea hoʻouluulu anodic me ka koho hydrogen i hoʻomaikaʻi ʻia i ka waikawa formic a i ʻole ma o ka hana ʻana o ka hāmeʻa.
a Ka haki ʻana o ke anakahi uila o ke kelepona me ka hoʻohana ʻana i ka electrode kuhikuhi kelepona H2 e hana ana ma 60 °C, Pt/C anode a me 80 µm AEM. b Nā ʻāpana FE a me nā waikawa formic i hōʻiliʻili ʻia ma 200 mA/cm2 me ka hoʻohana ʻana i nā kahe like ʻole o ka wai deionized anodic. c Ke hōʻiliʻili ka anode i ka waikawa formic i nā ʻano like ʻole, ʻo ke anakahi uila o ke kelepona he 200 mA/cm2. Hōʻike nā kaha hewa i ka ʻokoʻa maʻamau o ʻekolu mau ana like ʻole. d ʻO ke kumukūʻai kūʻai haʻahaʻa loa i wāwahi ʻia e ka hana ma nā kahe kahe wai deionized like ʻole me ka hoʻohana ʻana i nā kumukūʻai uila awelika ʻoihana aupuni o US$0.068/kWh a me US$4.5/kg hydrogen. (*: ʻO ke kūlana oxidation haʻahaʻa loa o ka waikawa formic ma ka anode ua manaʻo ʻia he 10 M FA, ʻo ke kumukūʻai uila ʻoihana awelika aupuni he $0.068/kWh, a ʻo ka hydrogen he $4.5/kg. **: ʻO ke kūlana oxidation haʻahaʻa loa ua manaʻo ʻia he waikawa formic. ʻO ka nui o FA ma ka anode he 1.3 M anode, ʻo ke kumukūʻai uila e hiki mai ana i manaʻo ʻia he $0.03/kWh, a ʻo ka laina kiko e hōʻike ana i ke kumukūʻai mākeke o 85 wt% FA.
Ua hana ʻia kahi loiloi techno-economic (TEA) e loaʻa ai ke kumukūʻai kūʻai haʻahaʻa loa o nā ʻākoakoa wahie ma lalo o nā ʻano hana like ʻole, e like me ka mea i hōʻike ʻia ma ke Kiʻi 5d. Hiki ke loaʻa nā ʻano hana a me nā ʻikepili hope no TEA ma ka SI. Ke kiʻekiʻe aʻe ka nui o ka LC ma ka hoʻopau anode, ʻoiai ke kiʻekiʻe o ka voltage cell, ua hoʻemi ʻia ke kumukūʻai holoʻokoʻa o ka ʻākoakoa wahie ma muli o ka emi ʻana o ke kumukūʻai hoʻokaʻawale. Inā hiki ke hoʻemi ʻia ka oxidation anodic o ka waikawa formic ma o ka hoʻomohala ʻana i ka catalyst a i ʻole ka ʻenehana electrode, ʻo ka hui pū ʻana o ka voltage cell haʻahaʻa (1.66 V) a me ke kiʻekiʻe o ka nui o ka FA ma ka effluent (10 M) e hōʻemi i ke kumukūʻai o ka hana electrochemical FA i 0.74 US kālā/kg (ma muli o ka uila). kumukūʻai) $0.068/kWh a me $4.5/kg hydrogen42. Eia kekahi, i ka hui pū ʻana me ke kumukūʻai i manaʻo ʻia no ka uila hou o $0.03/kWh a me ka hydrogen o $2.3/kg, ua hoʻemi ʻia ka pahuhopu wai hoʻoneoneo FA i 1.3 miliona, e hopena ana i ke kumukūʻai hana hope loa i manaʻo ʻia he US$0.66/kg43. Ua like kēia me nā kumukūʻai mākeke o kēia manawa. No laila, ʻo nā hana e hiki mai ana e kālele ana i nā mea electrode a me nā ʻano hana hiki ke hōʻemi hou i ka anodization ʻoiai e ʻae ana i ka hana ma nā voltages cell haʻahaʻa e hana i nā ʻano LC kiʻekiʻe.
I ka hōʻuluʻulu manaʻo, ua aʻo mākou i kekahi mau ʻano MEA zero-gap no ka hoʻemi ʻana o CO2 i ka waikawa formic a ua hāpai i kahi ʻano e loaʻa ana kahi membrane bipolar i hoʻopili ʻia i mua me kahi membrane hoʻololi cation perforated (PECM) e hoʻomaʻamaʻa i ka interface hoʻoili nuipa membrane no ka waikawa formic hopena. . Hoʻopuka kēia hoʻonohonoho i ka >96% waikawa formic ma nā ʻano a hiki i ka 0.25 M (ma ka nui o ke kahe ʻana o ka anode DI o 3.3 mL/min). Ma nā nui o ke kahe ʻana o DI kiʻekiʻe (25 mL/min), ua hāʻawi kēia hoʻonohonoho i kahi density o kēia manawa o >80% FE o 200 mA/cm2 ma 1.7 V me ka hoʻohana ʻana i kahi wahi cell 25 cm2. Ma nā helu anodic DI maʻamau (10 mL/min), ua mālama ka hoʻonohonoho PECM i ka voltage paʻa a me nā pae FE waikawa formic kiʻekiʻe no 55 h o ka hoʻāʻo ʻana ma 200 mA/cm2. Hiki ke hoʻonui hou ʻia ke kūpaʻa kiʻekiʻe a me ke koho ʻana i loaʻa e nā catalysts i loaʻa ma ke kālepa a me nā mea membrane polymeric ma ka hoʻohui ʻana iā lākou me nā electrocatalysts i hoʻomaikaʻi ʻia. E kālele ana ka hana ma hope aku i ka hoʻoponopono ʻana i nā kūlana hana, ke koho ʻana o ka mea hoʻouluulu anode, a me ke ʻano MEA e hōʻemi i ka hoʻoheheʻe ʻana o ka waikawa formic, e hopena ana i kahi effluent i ʻoi aku ka nui ma nā voltages cell haʻahaʻa. ʻO ke ʻano maʻalahi o ka hoʻohana ʻana i ke kalapona dioxide no ka waikawa formic i hōʻike ʻia ma ʻaneʻi e hoʻopau i ka pono no nā keʻena anolyte a me catholyte, nā ʻāpana sandwich, a me nā mea kūikawā, no laila e hoʻonui ai i ka pono o ka ikehu cell a me ka hōʻemi ʻana i ka paʻakikī o ka ʻōnaehana, e maʻalahi ai ka hoʻonui ʻana. Hāʻawi ka hoʻonohonoho i manaʻo ʻia i kahi kahua no ka hoʻomohala ʻana i ka wā e hiki mai ana o nā hale hana hoʻololi CO2 kūpono i ka ʻenehana a me ka hoʻokele waiwai.
Inā ʻaʻole i ʻōlelo ʻia, ua hoʻohana ʻia nā mea kemika a me nā mea hoʻoheheʻe āpau e like me ka mea i loaʻa. Ua kūʻai ʻia ka mea hoʻouluulu Bismuth oxide (Bi2O3, 80 nm) mai US Research Nanomaterials, Inc. Ua hāʻawi ʻia ka pauka Polymer (AP1-CNN8-00-X) e IONOMR. Ua kūʻai ʻia ka inoa ʻo Omnisolv® N-propanol (nPA) a me ka wai ultrapure (18.2 Ω, Milli–Q® Advantage A10 water purification system) mai Millipore Sigma. Ua kūʻai ʻia ka methanol a me ka acetone i hōʻoia ʻia e ACS mai VWR Chemicals BDH® a me Fisher Chemical. Ua hui pū ʻia ka pauka polymer me ka hui ʻana o ka acetone a me ka methanol ma ka lakio o 1:1 ma ke kaumaha e loaʻa ai kahi polymer dispersion me ka nui o 6.5 wt.%. E hoʻomākaukau i ka ʻīnika catalytic ma ke kāwili ʻana i 20g Bi2O3, ka wai ultrapure, nPA a me ka ionomer dispersion i loko o kahi ʻōmole 30ml. Aia i loko o ka hui ʻana he 30 wt.% catalyst, kahi lakio nui o ka ionomer i ka catalyst o 0.02 a me kahi lakio nui o ka waiʻona i ka wai o 2:3 (40 wt.% nPA). Ma mua o ke kāwili ʻana, ua hoʻohui ʻia he 70g o ka mea wili zirconia 5mm Glen Mills i ka hui ʻana. Ua kau ʻia nā laʻana ma luna o kahi ʻōwili ʻōmole kikohoʻe Fisherbrand™ ma 80 rpm no 26 mau hola. E ʻae i ka ʻīnika e noho no 20 mau minuke ma mua o ka hoʻopili ʻana. Ua hoʻopili ʻia ka ʻīnika Bi2O3 i kahi mea hoʻopili aunoa ʻo Qualtech (QPI-AFA6800) me ka hoʻohana ʻana i kahi 1/2″ x 16″ laboratory wirewound refill (RD Specialties - 60 mil diameter) ma 22°C. Ua hoʻopili ʻia he 5 mL o ka ʻīnika catalytic i kahi mea lawe diffusion gas carbon Sigraacet 39 BB 7.5 x 8 ʻīniha (waihona cell wahie) ma o ka waiho ʻana o ke koʻokoʻo ma kahi wikiwiki awelika paʻa o 55 mm/sec. E hoʻololi i kēia mau electrodes i uhi ʻia i ka umu a hoʻomaloʻo ma 80°C. Ua hōʻike ʻia ke kaʻina hana uhi koʻokoʻo a me nā kiʻi o ka uhi ʻana o GDE ma nā Kiʻi S4a a me b. Ua hōʻoia kahi mea hana X-ray fluorescence (XRF) (Fischerscope® XDV-SDD, Fischer-Technolgy Inc. USA) ʻo ka ukana GDE i uhi ʻia he 3.0 mg Bi2O3/cm2.
No nā hoʻonohonoho membrane hui pū ʻia e loaʻa ana ka membrane hoʻololi anion (AEM) a me ka CEM perforated. Ua hoʻohana ʻia ʻo Nafion NC700 (Chemours, USA) me ka mānoanoa nominal o 15 µm ma ke ʻano he papa CEM. Ua pīpī pololei ʻia ka mea hoʻoulu anodic ma luna o ka FEM me ka lakio ionomer i ke kalapona o 0.83 a me kahi uhi o 25 cm2. Ua hoʻohana ʻia ka platinum i kākoʻo ʻia me kahi ʻili nui (50 wt.% Pt/C, TEC 10E50E, TANAKA metala makamae) me ka hoʻouka ʻana o 0.25 mg Pt/cm2 ma ke ʻano he mea hoʻoulu anode. Ua hoʻohana ʻia ʻo Nafion D2020 (Ion Power, USA) ma ke ʻano he ionomer no ka papa anode o ka mea hoʻoulu. Hana ʻia ka perforation CEM ma ka ʻoki ʻana i nā laina like ma ka kiʻiʻoniʻoni CEM ma nā manawa 3mm. Hōʻike ʻia nā kikoʻī o ke kaʻina hana perforation ma nā Kiʻi S12b a me c. Ma ka hoʻohana ʻana i ka X-ray computed tomography, ua hōʻoia ʻia he 32.6 μm ka hakahaka perforation, e like me ka mea i hōʻike ʻia ma ke Kiʻi S12d a me e. I ka wā o ka ʻākoakoa ʻana o nā cell, ua kau ʻia kahi membrane CEM perforated i uhi ʻia me ka catalyst ma luna o kahi pepa Toray 25 cm2 (5 wt% PTFE i mālama ʻia, Fuel Cell Store, USA). Ua kau ʻia kahi membrane AEM (PiperION, Versogen, USA) me ka mānoanoa o 25, 40 a i ʻole 80 μm ma luna o ka CEM a laila ma ka cathode GDE. Ua ʻoki ʻia ka membrane AEM i mau ʻāpana 7.5 × 7.5 cm e uhi i ke kahua kahe holoʻokoʻa a hoʻomoʻa ʻia i ka pō i loko o ka hopena potassium hydroxide 1 M ma mua o ka ʻākoakoa ʻana. Hoʻohana ka anode a me ka cathode i nā mea hoʻokaʻawale PTFE i lawa ka mānoanoa e hoʻokō ai i kahi compression GDE kūpono o 18%. Hōʻike ʻia nā kikoʻī o ke kaʻina hana ʻākoakoa pākahiko ma ke Kiʻi S12a.
I ka wā o ka hoʻāʻo ʻana, ua mālama ʻia ke kelepona i hōʻuluʻulu ʻia ma 60 °C (30, 60, a me 80 °C no nā haʻawina hilinaʻi mahana) me 0.8 L/min o ke kinoea hydrogen i hoʻolako ʻia i ka anode a me 2 L/min o ke kalapona dioxide i hoʻolako ʻia i ka cathode. Ua hoʻomaʻū ʻia nā kahawai ea anodic a me cathodic ma ka 100% humidity pili a me 259 kPa kaomi cathodic paʻa. I ka wā o ka hana, ua hui pū ʻia ke kahawai kinoea cathode me ka hopena 1 M KOH ma ka wikiwiki o 2 mL/min e hoʻolaha i ka hoʻohana ʻana o ka moena catalyst cathode a me ka conduction ionic. E kāwili i kahi kahawai o ke kinoea anode me ka wai deionized ma ka wikiwiki o 10 ml/min e wehe i ka waikawa formic ma ka anode. Hōʻike ʻia nā kikoʻī o nā mea hoʻokomo a me nā mea hoʻopuka ma ka Kiʻi S5. Loaʻa i ke kinoea hoʻopau cathode ka CO2 a hoʻopuka i ka CO a me H2. Hoʻoneʻe ʻia ka mahu wai ma o kahi condenser (mea hoʻololi wela haʻahaʻa ma 2°C). E hōʻiliʻili ʻia ke kinoea i koe no ka nānā ʻana i ka manawa kinoea. E hele pū ke kahe anode ma o kahi condenser e hoʻokaʻawale i ka wai mai ke kinoea. E hōʻiliʻili ʻia ka wai hoʻoneoneo i loko o nā vials maʻemaʻe a kālailai ʻia me ka hoʻohana ʻana i ka chronometry wai e helu i ka waikawa formic i hana ʻia. Ua hana ʻia nā hoʻāʻo electrochemical me ka hoʻohana ʻana i kahi Garmy potentiostat (helu kuhikuhi 30K, Gamry, USA). Ma mua o ke ana ʻana i ka piʻo polarization, ua hoʻomaʻamaʻa ʻia ke kelepona i 4 mau manawa ma ka laulā mai 0 a 250 mA/cm2 me ka hoʻohana ʻana i ka linear voltammetry me ka helu scan o 2.5 mA/cm2. Ua loaʻa nā piʻo polarization ma ke ʻano galvanostatic me ke kelepona i paʻa ʻia ma kahi density o kēia manawa no 4 mau minuke ma mua o ka laʻana ʻana i ke kinoea cathode a me ka wai anolyte.
Hoʻohana mākou i kahi electrode kuhikuhi hydrogen i loko o ka MEA e hoʻokaʻawale i nā cathode a me nā anodic potentials. Hōʻike ʻia ke ʻano o ka electrode kuhikuhi ma ke Kiʻi S6a. Ua hoʻohana ʻia kahi membrane Nafion (Nafion 211, IonPower, USA) ma ke ʻano he alahaka ionic e hoʻohui i ka membrane MEA a me ka electrode kuhikuhi. Ua hoʻopili ʻia kekahi ʻaoʻao o ke kaha Nafion i kahi electrode diffusion gas 1 cm2 (GDE) i hoʻouka ʻia me 0.25 mg Pt/cm2 (50 wt% Pt/C, TEC10E50E, TANAKA Precious Metals) i pīpī ʻia ma luna o ka pepa kalapona 29BC (Fuel Cell Store, USA). ). Hoʻohana ʻia nā lako polyetheretherketone kūikawā (PEEK) e sila i ke kinoea a hōʻoia i ka pilina maikaʻi ma waena o nā kaha GDE a me Nafion, a e hoʻopili i ka electrode kuhikuhi i ka lako cell wahie. Ua hoʻopili ʻia kekahi ʻaoʻao o ke kaha Nafion i ka ʻaoʻao e puka ana o ka pākahiko CEM. Hōʻike ke Kiʻi S6b i ka ʻāpana kea o ka electrode kuhikuhi i hoʻohui ʻia me ka MEA.
Ma hope o ka hala ʻana o ke kinoea hoʻopau ma o ka condenser a me ka mea hoʻokaʻawale kinoea-wai, lawe ʻia nā laʻana kinoea mai ka cathode. Ua kālailai ʻia ke kinoea i hōʻiliʻili ʻia ma ka liʻiliʻi he ʻekolu mau manawa me ka hoʻohana ʻana i ka 4900 Micro GC (10 μm molecular sieve, Agilent). Ua hōʻiliʻili ʻia nā laʻana i loko o nā ʻeke laʻana kinoea pepa alumini multi-layer inert Supel™ (Sigma-Aldrich) no kahi manawa i kuhikuhi ʻia (30 kekona) a hoʻokomo lima ʻia i loko o ka microgas chromatograph i loko o ʻelua hola o ka hōʻiliʻili ʻana. Ua hoʻonohonoho ʻia ka mahana injection ma 110°C. Ua hoʻokaʻawale ʻia ke kalapona monoxide (CO) a me ka hydrogen (H2) ma kahi kolamu MS5A 10 m i hoʻomehana ʻia (105°C) me ka hoʻohana ʻana i ka argon (Matheson Gas-Matheson Purity) ma ke ʻano he kinoea lawe. ʻIke ʻia kēia mau pilina me ka hoʻohana ʻana i ka Thermal Conductivity Detector (TCD) i kūkulu ʻia. Hōʻike ʻia nā chromatograms GC a me nā piʻo calibration CO a me H2 ma ke Kiʻi S7. Ua hōʻiliʻili ʻia nā hāpana waikawa formic wai mai ka anode no kahi manawa i kuhikuhi ʻia (120 kekona) a kānana ʻia me ka hoʻohana ʻana i kahi kānana syringe PTFE 0.22 μm i loko o nā vials 2 mL. Ua kālailai ʻia nā huahana wai i loko o nā vials me ka hoʻohana ʻana i kahi ʻōnaehana Agilent 1260 Infinity II bioinert high-performance liquid chromatography (HPLC), kahi i hoʻokomo ʻia ai he 20 μl o ka hāpana ma o kahi autosampler (G5668A) me kahi pae mobile o 4 mM sulfuric acid (H2SO4). ) ma kahi kahe o 0.6 ml/min (quaternary pump G5654A). Ua hoʻokaʻawale ʻia nā huahana ma kahi Aminex HPX-87H 300 × 7.8 mm (Bio-Rad) i hoʻomehana ʻia (35°C, umu kolamu G7116A) i mua o kahi kolamu kiaʻi Micro-Guard Cation H. Ua ʻike ʻia ka waikawa formic me ka hoʻohana ʻana i kahi mea ʻike diode array (DAD). ma kahi nalu o 210 nm a me kahi bandwidth o 4 nm. Ua hōʻike ʻia ka chromatogram HPL a me ka piʻo hoʻoponopono maʻamau waikawa formic ma ke Kiʻi S7.
Ua helu ʻia nā huahana kinoea (CO a me H2) FE me ka hoʻohana ʻana i ka hoohalike ma lalo nei, a ua helu ʻia nā mole āpau o ke kinoea me ka hoʻohana ʻana i ka hoohalike kinoea kūpono:
Ma waena o lākou: \({n}_{i}\): ka helu o nā electrons i loko o kahi hopena electrochemical. \(F\): Ke kūpaʻa o Faraday. \({C}_{i}\): Ka nui o ka huahana wai HPLC. \(V\): ka nui o ka hāpana wai i hōʻiliʻili ʻia ma luna o kahi manawa paʻa t. \(j\): ka nui o ke au. \(A\): ʻĀpana geometric o ka electrode (25 cm2). \(t\): ka manawa hāpana. \(P\): kaomi paʻa. \({x}_{i}\): Mole pakeneka o ke kinoea i hoʻoholo ʻia e GC. \(R\): ke kūpaʻa kinoea. \(T\): mahana.
Ua helu ʻia ka nui o nā cation anodic me ka hoʻohana ʻana i ka inductively coupled plasma atomic emission spectroscopy (ICP-OES). ʻO nā cation e hiki ke leach a diffuse paha i loko o ka anode e komo pū me Ti, Pt, Bi a me K. Me ka ʻokoʻa o K, aia nā cation ʻē aʻe a pau ma lalo o ka palena ʻike. Hoʻokumu i nā ions i loko o ka hopena e waiho ana i ka anode e hui pū me nā protons a i ʻole nā ​​cation ʻē aʻe. No laila, hiki ke helu ʻia ka maʻemaʻe o ka waikawa formic e like me
Hōʻike ka hana ʻana o Formate/FA i ka nui o ka FA i hana ʻia no kēlā me kēia kWh o ka uila i hoʻopau ʻia me ka hoʻohana ʻana i kahi hoʻonohonoho MEA kikoʻī, ma mol/kWh. Ua helu ʻia ia ma muli o ka nui o kēia manawa, ka uila o ke kelepona a me ka pono o Faraday ma lalo o nā kūlana hana kikoʻī.
E helu i ka nui o ka waikawa formic i hoʻomake ʻia ma ka anode ma muli o ke kaulike nuipa holoʻokoʻa. ʻEkolu mau hopena hoʻokūkū e kū mai ana ma ka cathode: ka ulu ʻana o ka hydrogen, ka hoʻemi ʻana o CO2 i CO, a me ka hoʻemi ʻana o CO2 i ka waikawa formic. No ka mea, he kaʻina hana hoʻomake ʻana o ka waikawa formic ko mākou ma Anton, hiki ke hoʻokaʻawale ʻia ka waikawa formic FE i ʻelua ʻāpana: ka hōʻiliʻili waikawa formic a me ka hoʻomake ʻana o ka waikawa formic. Hiki ke kākau ʻia ke kaulike nuipa holoʻokoʻa penei:
Ua hoʻohana mākou i ka GC e helu i ka nui o ka waikawa formic, hydrogen, a me CO i hōʻiliʻili ʻia e HPLC. Pono e hoʻomaopopo ʻia ua hōʻiliʻili ʻia ka hapa nui o ka waikawa formic mai ka anode me ka hoʻohana ʻana i ka hoʻonohonoho i hōʻike ʻia ma ke Kiʻi Hoʻohui S5. ʻAʻole nui ka nui o ka formate i hōʻiliʻili ʻia mai ke keʻena cathode, ma kahi o ʻelua mau kauoha o ka nui i emi iho, a ʻoi aku ka liʻiliʻi ma mua o 0.5% o ka nui o SC.
ʻO ke kumu hoʻohālike halihali hoʻomau i hoʻohana ʻia ma ʻaneʻi e pili ana i ka hana ma mua ma nā ʻōnaehana like34. Hoʻohana ʻia kahi ʻōnaehana i hoʻopili ʻia o nā kaulike Poisson-Nerst-Planck (PNP) e hoʻoholo ai i ka nui o ka wai a me ka hiki ke electrostatic i nā pae alakaʻi uila a me ka ionic. Hāʻawi ʻia kahi ʻike kikoʻī o nā kaulike ma lalo a me ke geometry kumu hoʻohālike i loko o ka SI.
Hoʻoholo kēia ʻōnaehana i ka nui o nā mea wai ʻewalu (\({{{{{{\rm{C}}}}}}}{{{{{{\rm{O}}}}}}}}}_{2 \left ({{{{{{\rm{aq}}}}}}}\right)}\), \({{{{{{\rm{H}}}}}}}}^{+ }\ ), \ ({{{{{\rm{O}}}}}}{{{{{{\rm{H}}}}}}^{-}\), \({{{ {{{ \rm{ HCO}}}}}}}}_{3}^{-}\), \({{{{{{\rm{CO}}}}}}}_{3}^{ 2-} \ ),\ ({{{{{\rm{HCOOH}}}}}}}\), \({{{{{{{\rm{HCOO}}}}}}}}^{- }\) a me \({{{ {{{\rm{K}}}}}}}^{+}\)), ka hiki ke electrostatic i loko o ke kahua alakaʻi ionic (\({\phi }_{I}\ )) a me ka conductivity electron anodic a me cathodic. Nā hiki ke electrostatic i nā pae (\({\phi }_{A}\) a me \({\phi }_{C}\) pakahi). Akā, ʻaʻole i hoʻokō ʻia ka neutrality uila kūloko a i ʻole nā ​​hana hoʻokaʻawale uku, ua hoʻoponopono pololei ʻia ka ʻāpana uku hakahaka me ka hoʻohana ʻana i ka equation Poisson; ʻAe kēia ʻano hana iā mākou e hoʻohālike pololei i nā hopena repulsion Donnan ma nā interfaces CEM|AEM, CEM|Pore, a me AEM|Pore. Eia kekahi, hoʻohana ʻia ke kumumanaʻo electrode porous (PET) e wehewehe i ka lawe ʻana o ka uku ma nā papa anodic a me cathodic o ka catalyst. I ka ʻike maikaʻi loa o nā mea kākau, hōʻike kēia hana i ka hoʻohana mua ʻana o PET i nā ʻōnaehana me nā ʻāpana uku hakahaka he nui.
Ua hoʻāʻo ʻia nā laʻana cathode GDE BOT a me EOT me ka hoʻohana ʻana i kahi Zeiss Xradia 800 Ultra me kahi kumu X-ray 8.0 keV, nā ʻano absorption a me ke kahua ākea, a me ka image fusion1. Ua hōʻiliʻili ʻia nā kiʻi 901 mai -90° a i 90° me ka manawa hōʻike o 50 kekona. Ua hana ʻia ke kūkulu hou ʻana me ka hoʻohana ʻana i kahi kānana projection hope me ka nui voxel o 64 nm. Ua hana ʻia ka nānā ʻana o ka segmentation a me ka hoʻolaha ʻana o ka nui o ka ʻāpana me ka hoʻohana ʻana i ke code i kākau kūikawā ʻia.
ʻO ke ʻano microscope electron e pili ana i ka hoʻokomo ʻana i nā MEA hoʻāʻo i loko o ka resin epoxy i ka hoʻomākaukau ʻana no ka ʻoki ʻana i nā ʻāpana lahilahi loa me ka pahi daimana. Ua ʻoki ʻia ka ʻāpana kea o kēlā me kēia MEA i ka mānoanoa o 50 a 75 nm. Ua hoʻohana ʻia kahi microscope electron transmission Talos F200X (Thermo Fisher Scientific) no ke ana ʻana i ka microscopy electron transmission scanning (STEM) a me nā ana ʻana o ka spectroscopy X-ray dispersive ikehu (EDS). Ua lako ka microscope me kahi ʻōnaehana EDS Super-X me 4 mau mea ʻike SDD windowless a hana ma 200 kV.
Ua loaʻa nā ʻano diffraction X-ray pauka (PXRD) ma kahi diffractometer X-ray pauka Bruker Advance D8 me ka radiation Cu Kα i kānana ʻia e hana ana ma 40 kV a me 40 mA. ʻO ka laulā scan mai 10° a 60°, ʻo ka nui o ke kaʻina hana he 0.005°, a ʻo ka wikiwiki o ka loaʻa ʻikepili he 1 kekona no kēlā me kēia kaʻina hana.
Ua ana ʻia ke kiʻikuhi RAS ma ka lihi o ka mea hoʻoulu Bi2O3 Bi L3 ma ke ʻano he hana o ka hiki ke hoʻohana i kahi cell i hana ʻia ma ka home. Ua hoʻomākaukau ʻia ka ʻīnika ionomer catalytic Bi2O3 me ka hoʻohana ʻana i 26.1 mg Bi2O3 i hui pū ʻia me 156.3 μL ionomer solution (6.68%) a ua hoʻokaʻawale ʻia me 1 M KOH, ka wai (157 μL) a me ka waiʻona isopropyl (104 μL) e loaʻa ai ka ʻīnika ionomer. ʻO ke koina catalyst he 0.4. Ua hoʻopili ʻia ka ʻīnika i nā pepa graphene ma nā wahi ʻehā (10 × 4 mm) a hiki i ka hiki ʻana o ka hoʻouka ʻana o ka mea hoʻoulu Bi2O3 i 0.5 mg / cm2. Ua uhi ʻia ke koena o ka pepa graphene me Kapton e hoʻokaʻawale i kēia mau wahi mai ka electrolyte. Ua hoʻokomo ʻia ka pepa graphene i uhi ʻia me ka catalyst ma waena o ʻelua PTFE a hoʻopaʻa ʻia i ke kino cell (PEEK) me nā wili, Kiʻi S8. ʻO Hg / HgO (1 M NaOH) i lawelawe ʻia ma ke ʻano he electrode kuhikuhi, a ʻo ka pepa kalapona i lawelawe ʻia ma ke ʻano he electrode counter. Ua hoʻoponopono ʻia ka electrode kuhikuhi Hg/HgO me ka hoʻohana ʻana i kahi uea platinum i hoʻokomo ʻia i loko o ka hydrogen-saturated 0.1 M KOH e hoʻololi i nā potentials āpau i ana ʻia i kahi pālākiō hydrogen reversible (RHE). Ua loaʻa nā spectra XRD ma ka nānā ʻana i ka potential o kahi electrode hana pepa Bi2O3/graphene i hoʻokomo ʻia i loko o 0.1 M KOH, i hoʻomehana ʻia i 30 °C. Hoʻopuni ka electrolyte i loko o ka pila, me ka electrolyte inlet ma lalo o ke kelepona a me ka puka ma luna e hōʻoia i ka hoʻopili ʻana o ka electrolyte i ka papa catalyst ke hana ʻia nā pehu. Ua hoʻohana ʻia kahi potentiostat CH Instruments 760e e kāohi i ka potential electrode hana. ʻO ke kaʻina potential he potential circuit open: -100, -200, -300, -400, -500, -800, -850, -900, -1000, -1100, -1500 a me +700 mV ma muli o RHE. Ua hoʻoponopono ʻia nā potentials iR āpau.
Ua hana ʻia ka Bi L3 edge (~13424 eV no ka Bi metal) X-ray absorption fine structure (XAFS) spectroscopy ma ke kahawai 10-ID, Advanced Photon Source (APS), Argonne National Fluorescence Laboratory. National Model Measurement Laboratory. Ua hoʻohana ʻia kahi monochromator Si(111) ʻelua-crystal i hoʻomaʻalili ʻia me ka naikokene wai e hoʻoponopono i ka ikehu X-ray, a ua hoʻohana ʻia kahi aniani i uhi ʻia me ka rhodium e hoʻēmi i ka ʻike harmonic. Ua hoʻololi ʻia nā ikehu scan mai 13200 a i 14400 eV, a ua ana ʻia ka fluorescence me ka hoʻohana ʻana i kahi 5 × 5 silicon PIN diode array me ka ʻole o nā kānana a i ʻole nā ​​​​​​slits Soller. Ua hoʻoponopono ʻia ka ikehu keʻa ʻole o ka derivative ʻelua ma 13271.90 eV ma o ka lihi L2 o ka foil Pt. Ma muli o ka mānoanoa o ke kelepona electrochemical, ʻaʻole hiki ke ana like i ka spectrum o ke kūlana kuhikuhi. No laila, ʻo ka loli scan-to-scan i helu ʻia i ka ikehu X-ray incident he ±0.015 eV e pili ana i nā ana hou ʻana ma o ka hoʻokolohua. ʻO ka mānoanoa o ka papa Bi2O3 e alakaʻi ai i kahi kekelē o ka omo ponoʻī o ka fluorescence; mālama nā electrodes i kahi kuhikuhi paʻa e pili ana i ke kukuna hanana a me ka mea ʻike, e hana ana i nā scan āpau i aneane like. Ua hoʻohana ʻia ka spectrum XAFS kokoke-kahua e hoʻoholo i ke kūlana oxidation a me ke ʻano kemika o bismuth ma ka hoʻohālikelike ʻana me ka ʻāpana XANES o nā kūlana Bi a me Bi2O3 e hoʻohana ana i ka algorithm hoʻopili hui linear o ka polokalamu Athena (mana 0.9.26). ma ke code IFEFFIT 44.
Loaʻa ka ʻikepili e kākoʻo ana i nā helu ma kēia ʻatikala a me nā hopena ʻē aʻe o kēia haʻawina mai ka mea kākau pili ma ke noi kūpono.
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