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Tsarin lantarki na adipic acid (wanda ya fara samar da nailan 66) daga man CA (cakuda cyclohexanone da cyclohexanol) dabara ce mai dorewa wacce za ta iya maye gurbin hanyoyin gargajiya waɗanda ke buƙatar yanayi mai tsauri. Duk da haka, ƙarancin yawan wutar lantarki da kuma halayen juyin halittar iskar oxygen masu gasa suna iyakance aikace-aikacen masana'antu sosai. A cikin wannan aikin, muna gyara nickel double hydroxide tare da vanadium don haɓaka yawan wutar lantarki da kuma kula da ingantaccen aikin faradaic (>80%) akan kewayon yuwuwar mai faɗi (1.5–1.9 V idan aka kwatanta da hydrogen electrode mai juyawa). Nazarin gwaji da na ka'ida sun bayyana manyan ayyuka guda biyu na gyaran V, gami da hanzarta sake gina mai kara kuzari da inganta shaƙar cyclohexanone. A matsayin hujja ta ra'ayi, mun gina taro na membrane-electrode wanda ke samar da adipic acid tare da ingantaccen aikin faradaic (82%) da yawan aiki (1536 μmol cm-2 h-1) a wani yanki mai dacewa da masana'antu (300 mA cm-2), yayin da muke cimma daidaito >50 h. Wannan aikin ya nuna ingantaccen mai kara kuzari ga electrosynthesis na adipic acid mai yawan aiki da kuma karfin masana'antu.
Adipic acid (AA) yana ɗaya daga cikin mahimman aliphatic dicarboxylic acid kuma ana amfani da shi galibi wajen samar da nailan 66 da sauran polyamides ko polymers1. A fannin masana'antu, ana haɗa AA ta hanyar haɗa cakuda cyclohexanol da cyclohexanone (watau man AA) ta amfani da nitric acid mai girman vol 50-60 a matsayin mai hana iskar shaka. Wannan tsari yana da damuwa game da muhalli dangane da fitar da sinadarin nitric acid mai yawa da nitrogen oxides (N2O da NOx) a matsayin iskar gas mai dumama yanayi2,3. Kodayake ana iya amfani da H2O2 a matsayin madadin mai hana iskar shaka mai kore, tsadarsa mai yawa da yanayin haɗa shi mai tsauri yana sa ya zama da wahala a yi amfani da shi a zahiri, kuma ana buƙatar wata hanya mafi inganci da dorewa4,5,6.
A cikin shekaru goma da suka gabata, hanyoyin haɗa sinadarai da mai na lantarki sun jawo hankalin masana kimiyya saboda fa'idodin amfani da makamashin da ake sabuntawa da kuma aiki a ƙarƙashin yanayi mai sauƙi (misali, zafin ɗaki da matsin lamba na yanayi)7,8,9,10. A wannan fanni, haɓaka canza man KA zuwa AA yana da matuƙar muhimmanci don samun fa'idodin da ke sama da kuma kawar da hayakin nitric acid da nitrous oxide da aka fuskanta a cikin samarwa na al'ada (Hoto na 1a). Petrosyan et al. sun yi aikin farko, waɗanda suka ba da rahoton amsawar iskar gas na electrocatalytic na cyclohexanone (COR; cyclohexanone ko cyclohexanol an yi nazari akai-akai a matsayin wakiltar man KA) akan nickel oxyhydroxide (NiOOH), amma an sami ƙarancin yawan wutar lantarki (6 mA cm-2) da matsakaicin yawan AA (52%)11,12. Tun daga lokacin, an sami babban ci gaba a cikin haɓaka abubuwan da ke haifar da nickel don haɓaka aikin COR. Misali, an haɗa wani sinadarin nickel hydroxide mai sinadarin jan ƙarfe (Cu-Ni(OH)2) don haɓaka raba Cα–Cβ a cikin cyclohexanol13. Kwanan nan mun ba da rahoton wani sinadarin Ni(OH)2 da aka gyara tare da sodium dodecyl sulfonate (SDS) don ƙirƙirar yanayin da ke haifar da rashin ruwa wanda ke wadatar da cyclohexanone14.
a Kalubalen samar da AA ta hanyar amfani da man KA. b Kwatanta COR na electrocatalytic na masu haɓaka Ni da aka ruwaito a baya da kuma mai haɓaka mu a cikin tsarin lantarki uku da tsarin batirin kwarara11,13,14,16,26. An bayar da cikakkun bayanai game da sigogin amsawa da aikin amsawa a cikin Teburin Ƙarin 1 da 2. c Aikin catalytic na masu haɓaka NiV-LDH-NS ɗinmu don COR a cikin mai haɓaka H-cell da MEA, waɗanda ke aiki a kan kewayon yuwuwar mai yawa.
Duk da cewa hanyoyin da ke sama sun inganta aikin COR, abubuwan da aka bayyana na Ni sun nuna ingantaccen AA Faraday (FE) mai yawa (>80%) kawai a ƙananan ƙarfin lantarki, yawanci ƙasa da 1.6 V idan aka kwatanta da electrode hydrogen mai juyawa (RHE, wanda aka taƙaita VRHE). Don haka, yawan wutar lantarki da aka ruwaito (watau, jimlar yawan wutar lantarki da aka ninka ta FE) na AA koyaushe yana ƙasa da 60 mA cm−2 (Hoto na 1b da Tebur na Ƙarin 1). Ƙananan yawan wutar lantarki yana ƙasa da buƙatun masana'antu (>200 mA cm−2)15, wanda ke kawo cikas ga fasahar electrocatalytic don haɗakar AA mai ƙarfi (Hoto na 1a; sama). Don ƙara yawan wutar lantarki, ana iya amfani da ƙarin ƙarfin lantarki mai kyau (ga tsarin electrode uku) ko ƙarfin lantarki mafi girma (ga tsarin electrode biyu), wanda hanya ce mai sauƙi don sauye-sauyen electrocatalytic da yawa, musamman amsawar juyin halittar oxygen (OER). Duk da haka, ga COR mai yawan ƙarfin anodic, OER na iya zama babban mai fafatawa wajen rage FE na AA, ta haka ne rage ingancin kuzari (Hoto na 1a; ƙasa). Misali, idan muka yi bitar ci gaban da ya gabata (Hoto na 1b da Tebur na Ƙarin 1), mun ji takaici da muka ga cewa FE na AA akan Ni(OH)2 da aka gyara SDS ya ragu daga 93% zuwa 76% tare da ƙara ƙarfin da aka yi amfani da shi daga 1.5 VRHE zuwa 1.7 VRHE14, yayin da FE na AA akan CuxNi1-x(OH)2/CF ya ragu daga 93% zuwa 69% tare da ƙara ƙarfin daga 1.52 VRHE zuwa 1.62 VRHE16. Don haka, yawan halin yanzu da aka ruwaito na AA ba ya ƙaruwa daidai gwargwado a manyan ƙarfin da ke da ƙarfi, wanda galibi yana iyakance haɓaka aikin AA, ba tare da ambaton yawan amfani da makamashi mai yawa ba saboda ƙarancin FE na AA. Baya ga masu haɓaka nickel, masu haɓaka cobalt suma sun nuna aikin catalytic a cikin COR17,18,19. Duk da haka, ingancinsu yana raguwa a mafi girman ƙarfin aiki, kuma idan aka kwatanta da masu haɓaka kuzari na tushen Ni, suna da ƙarin ƙuntatawa a aikace-aikacen masana'antu, kamar hauhawar farashi da ƙananan kayayyaki. Saboda haka, yana da kyau a haɓaka masu haɓaka kuzari na tushen Ni tare da yawan ƙarfin lantarki mai yawa da FE a cikin COR don ya zama mai amfani don cimma babban yawan amfanin AA.
A cikin wannan aikin, mun bayar da rahoton nanosheets biyu na hydroxide mai nauyin vanadium (V) (NiV-LDH-NS) waɗanda aka gyara da nickel mai layer (AA) ta hanyar COR, waɗanda ke aiki a kan kewayon yuwuwar mai yawa tare da OER mai ƙarfi sosai, suna samun babban FE da yawan yanzu a cikin ƙwayoyin H da haɗuwar electrode na membrane (MEAs; Hoto na 1 b). Da farko mun nuna cewa ingancin oxidation na acetylene akan na yau da kullun na Ni(OH)2 nanosheet catalyst (Ni(OH)2-NS) yana raguwa, kamar yadda aka zata, a mafi girman yuwuwar, daga 80% a 1.5 VRHE zuwa 42% a 1.9 VRHE. Sabanin haka, bayan gyara Ni(OH)2 tare da V, NiV-LDH-NS ya nuna mafi girman yawan yanzu a wani ƙarfin da aka bayar kuma, mafi mahimmanci, ya kiyaye babban FE akan babban kewayon yuwuwar. Misali, a 1.9 VRHE, ya nuna yawan yanzu na 170 mA cm−2 da FE na 83%, wanda shine mafi kyawun mai kara kuzari ga COR a cikin tsarin electrode uku (Hoto na 1c da Tebur na Ƙarin 1). Bayanan gwaji da na ka'idoji sun nuna cewa gyaran V yana haɓaka rage kinetics daga Ni(OH)2 zuwa Ni oxyhydroxides masu yawan valent (Ni3+xOOH1-x), waɗanda ke aiki a matsayin matakin aiki na COR. Bugu da ƙari, gyaran V ya haɓaka shaƙar cyclohexanone akan saman mai kara kuzari, wanda ya taka muhimmiyar rawa wajen danne OER a manyan ƙarfin anodic. Don nuna yuwuwar NiV-LDH-NS a cikin yanayi mafi gaskiya, mun tsara mai kara kuzari na MEA kuma mun nuna FE na AA (82%) a wani yawan yanzu mai dacewa da masana'antu (300 mA cm−2), wanda ya fi girma fiye da sakamakon da muka samu a baya a cikin mai kara kuzari na membrane (Hoto na 1b da Tebur na Ƙarin 2). Yawan amfanin AA (1536 μmol cm−2 h−1) ya fi wanda aka samu ta amfani da tsarin thermal catalytic (<30 mmol gcatalyst−1 h−1)4. Bugu da ƙari, mai kara kuzari ya nuna kyakkyawan kwanciyar hankali lokacin amfani da MEA, yana kiyaye FE >80% AA na tsawon awanni 60 a 200 mA cm−2 da FE >70% AA na tsawon awanni 58 a 300 mA cm−2. A ƙarshe, wani bincike na farko (FEA) ya nuna ingancin dabarun electrocatalytic don samar da AA.
A cewar wallafe-wallafen da suka gabata, Ni(OH)2 wani abu ne da ke nuna kyakkyawan aiki ga COR, don haka an haɗa Ni(OH)2-NS13,14 a karon farko ta hanyar hanyar coprecipitation. Samfuran sun nuna tsarin β-Ni(OH)2, wanda aka tabbatar ta hanyar X-ray diffraction (XRD; Hoto na 2a), kuma an lura da nanosheets masu siriri sosai (kauri: 2-3 nm, girman gefe: 20-50 nm) ta hanyar ma'aunin electron transmission microscopy mai ƙuduri mai girma (HRTEM; Ƙarin Hoto na 1) da kuma ma'aunin atomic force microscopy (AFM) (Ƙarin Hoto na 2). An kuma lura da tarin nanosheets saboda yanayinsu na siriri sosai.
Tsarin watsa hasken X-ray na Ni(OH)2-NS da NiV-LDH-NS. FE, fitarwa, da yawan halin yanzu na AA akan b Ni(OH)2-NS da c NiV-LDH-NS a wurare daban-daban. Sandunan kuskure suna wakiltar karkacewar daidaitattun ma'auni guda uku masu zaman kansu ta amfani da mai kara kuzari iri ɗaya. hoton HRTEM na NV-LDH-NS. Sandunan sikelin: 20 nm. Hoton HAADF-STEM na NiV-LDH-NS da taswirar abubuwan da suka dace waɗanda ke nuna rarraba Ni (kore), V (rawaya), da O (shuɗi). Sandunan sikelin: 100 nm. f Ni 2p3/2, g O 1 s, da h V 2p3/2 bayanan XPS na Ni(OH)2-NS (sama) da NiV-LDH-NS (ƙasa). i FE da j sune ayyukan AA akan masu kara kuzari guda biyu a cikin zagayowar 7. Sandunan kuskure suna wakiltar karkacewar daidaitattun ma'auni guda uku masu zaman kansu ta amfani da mai kara kuzari iri ɗaya kuma suna cikin 10%. Ana bayar da bayanai na asali na a–c da f–j a cikin fayilolin bayanai na asali.
Sai muka kimanta tasirin Ni(OH)2-NS akan COR. Ta amfani da electrolysis mai yuwuwa akai-akai, mun sami 80% FE na AA a ƙarancin ƙarfin (1.5 VRHE) ba tare da OER ba (Hoto na 2b), wanda ke nuna cewa COR ya fi OER kyau a cikin kuzari a ƙarancin ƙarfin anodic. An gano babban abin da ya rage shine glutaric acid (GA) tare da FE na 3%. Hakanan HPLC ta ƙididdige kasancewar adadin succinic acid (SA), malonic acid (MA), da oxalic acid (OA) (duba Ƙarin Hoto na 3 don rarraba samfur). Ba a gano wani formic acid a cikin samfurin ba, yana nuna cewa carbonate na iya zama samfurin C1. Don gwada wannan hasashe, an ƙara acidity na electrolysis daga cikakken electrolysis na 0.4 M cyclohexanone kuma an wuce samfuran gas ta hanyar maganin Ca(OH)2. Sakamakon haka, maganin ya zama turbid, yana tabbatar da samuwar carbonate bayan electrolysis. Duk da haka, saboda ƙarancin wutar lantarki da aka samar a lokacin aikin electrolysis (Hoto na 2b, c), yawan carbonate yana da ƙasa kuma yana da wahalar ƙididdigewa. Bugu da ƙari, ana iya samar da wasu samfuran C2-C5, amma ba za a iya ƙididdige adadin su ba. Duk da cewa jimlar adadin samfuran yana da wahalar ƙididdigewa, kashi 90% na jimlar adadin electrochemical yana nuna cewa an gano yawancin hanyoyin electrochemical, wanda ke ba da tushe don fahimtar injinmu. Saboda ƙarancin yawan wutar lantarki (20 mA cm−2), yawan AA shine 97 μmol cm−2 h−1 (Hoto na 2b), daidai yake da 19 mmol h−1 g−1 bisa ga nauyin mai kara kuzari (5 mg cm−2), wanda ya yi ƙasa da yawan yawan mai kara kuzari na thermal (~30 mmol h−1 g−1)1. Lokacin da ƙarfin da aka yi amfani da shi ya ƙaru daga 1.5 zuwa 1.9 VRHE, kodayake yawan ƙarfin da aka yi amfani da shi ya ƙaru (daga 20 zuwa 114 mA cm−2), a lokaci guda an sami raguwa mai yawa a cikin AA FE, daga 80% zuwa 42%. Raguwar FE a mafi kyawun ƙarfin da aka samu galibi ya faru ne saboda gasar OER. Musamman a 1.7 VRHE, gasar OER ta haifar da raguwa mai yawa a cikin AA FE, wanda hakan ya rage aikin AA kaɗan tare da ƙara yawan ƙarfin da aka samu gaba ɗaya. Don haka, kodayake yawan ƙarfin da aka samu na AA ya ƙaru daga 16 zuwa 48 mA cm−2 kuma yawan aikin AA ya ƙaru (daga 97 zuwa 298 μmol cm−2 h−1), an cinye ƙarin kuzari mai yawa (ƙarin 2.5 W h gAA−1 daga 1.5 zuwa 1.9 VRHE), wanda ya haifar da ƙaruwar fitar da carbon na 2.7 g CO2 gAA−1 (an ba da cikakkun bayanai game da lissafi a cikin Ƙarin Bayani na 1). OER da aka ambata a baya a matsayin mai fafatawa da amsawar COR a babban ƙarfin anodic ya yi daidai da rahotannin da suka gabata kuma yana wakiltar babban ƙalubale don inganta yawan aiki na AA14,17.
Domin samar da ingantaccen mai kara kuzari na COR mai tushen Ni(OH)2-NS, da farko mun yi nazari kan matakin aiki. Mun lura da kololuwa a 473 cm-1 da 553 cm-1 a cikin sakamakon binciken mu na Raman a wuri (Hoto na Karin Bayani na 4), wanda ya yi daidai da lankwasawa da mikewa na haɗin Ni3+-O a cikin NiOOH, bi da bi. An rubuta cewa NiOOH sakamakon raguwar Ni(OH)2 da tarin Ni(OH)O a cikin ƙarfin anodic, kuma shine ainihin matakin aiki a cikin iskar gas mai guba ta lantarki20,21. Saboda haka, muna tsammanin hanzarta tsarin sake ginawa na Ni(OH)2 zuwa NiOOH zai iya haɓaka aikin catalytic na COR.
Mun yi ƙoƙarin gyara Ni(OH)2 da ƙarfe daban-daban tun da aka lura cewa gyaran heteroatom yana haɓaka sake ginawa a cikin oxides na ƙarfe na canzawa/hydroxides22,23,24. An haɗa samfuran ta hanyar haɗa Ni da wani abin da ya fara aiki na ƙarfe na biyu. Daga cikin samfuran da aka gyara ƙarfe daban-daban, samfurin da aka gyara V (rabo na atomic na V:Ni 1:8) (wanda ake kira NiV-LDH-NS) ya nuna yawan wutar lantarki mafi girma a cikin COR (Karin Hoto na 5) kuma mafi mahimmanci, babban AA FE akan taga mai faɗi. Musamman, a ƙarancin ƙarfin (1.5 VRHE), yawan NiV-LDH-NS na yanzu ya fi na Ni(OH)2-NS sau 1.9 (39 vs. 20 mA cm−2), kuma AA FE ya kasance daidai akan duka abubuwan haɓaka (83% vs. 80%). Saboda yawan ƙarfin lantarki da kuma irin wannan FE AA, yawan aikin NiV-LDH-NS ya fi na Ni(OH)2-NS sau 2.1 (204 vs. 97 μmol cm−2 h−1), yana nuna tasirin inganta gyaran V akan yawan ƙarfin lantarki a ƙananan ƙarfin lantarki (Hoto na 2c).
Tare da ƙaruwar ƙarfin da aka yi amfani da shi (misali, 1.9 VRHE), yawan ƙarfin da ke kan NiV-LDH-NS ya ninka na Ni(OH)2-NS sau 1.5 (170 vs. 114 mA cm−2), kuma ƙaruwar ta yi kama da ta ƙasan ƙarfin da ke akwai (sau 1.9 mafi girma). Abin lura shi ne, NiV-LDH-NS ya riƙe babban AA FE (83%) kuma an danne OER sosai (O2 FE 4%; Hoto na 2c), ya fi Ni(OH)2-NS aiki kuma an ruwaito abubuwan da ke haifar da ƙazanta tare da ƙarancin AA FE a manyan ƙarfin anodic (Tebur na Ƙarin 1). Saboda yawan FE na AA a cikin taga mai faɗi (1.5–1.9 VRHE), an cimma ƙimar samar da AA na 867 μmol cm−2 h−1 (daidai da 174.3 mmol g−1 h−1) a 1.9 VRHE, wanda ke nuna kyakkyawan aiki a cikin tsarin lantarki da ma thermocatalytic lokacin da aikin ya daidaita ta hanyar jimlar nauyin samfuran NiV-LDH-NS (Hoto na Ƙarin 6).
Domin fahimtar yawan wutar lantarki mai yawa da kuma yawan FE mai yawa a kan babban kewayon yuwuwar bayan gyara Ni(OH)2 tare da V, mun siffanta tsarin NiV-LDH-NS. Sakamakon XRD ya nuna cewa gyaran da V ya yi tare da V ya haifar da sauyawar lokaci daga β-Ni(OH)2 zuwa α-Ni(OH)2, kuma ba a gano nau'in kristal mai alaƙa da V ba (Hoto na 2a). Sakamakon HRTEM ya nuna cewa NiV-LDH-NS ya gaji yanayin zanen Ni(OH)2-NS mai siriri kuma yana da irin wannan girman gefe (Hoto na 2d). Ma'aunin AFM ya bayyana yanayin tarin zanen nano mai ƙarfi, wanda ya haifar da kauri mai aunawa na kimanin nm 7 (Hoto na Ƙari na 7), wanda ya fi na Ni(OH)2-NS girma (kauri: 2-3 nm). Binciken taswirar X-ray mai rarraba makamashi (EDS) (Hoto na 2e) ya nuna cewa abubuwan V da Ni sun bazu sosai a cikin zanen nano. Domin fayyace tsarin lantarki na V da tasirinsa akan Ni, mun yi amfani da na'urar daukar hoto ta X-ray photoelectron spectroscopy (XPS) (Hoto na 2f–h). Ni(OH)2-NS ya nuna halayen kololuwar juyawa-zuwa-kololuwar Ni2+ (kololuwar mace a 855.6 eV, kololuwar tauraron dan adam a 861.1 eV, Hoto na 2f)25. Za a iya raba siginar O1s XPS na Ni(OH)2-NS zuwa kololuwa uku, daga cikinsu ana danganta kololuwar a 529.9, 530.9 da 532.8 eV da iskar oxygen mai lattice (OL), ƙungiyar hydroxyl (Ni-OH) da iskar oxygen da aka shake akan lahani na saman (OAds), bi da bi (Hoto na 2g)26,27,28,29. Bayan gyaran da aka yi da V, kololuwar V 2p3/2 ta bayyana, wadda za a iya raba ta zuwa kololuwa uku da ke a 517.1 eV (V5+), 516.6 eV (V4+) da 515.8 eV (V3+), bi da bi, tana nuna cewa nau'in V a cikin tsarin galibi suna wanzuwa a cikin yanayin iskar shaka mai yawa (Hoto na 2h)25,30,31. Bugu da ƙari, kololuwar Ni 2p a 855.4 eV a cikin NiV-LDH-NS an canza ta da mummunan (da kusan 0.2 eV) idan aka kwatanta da na Ni(OH)2-NS, wanda ke nuna cewa an canja wutar lantarki daga V zuwa Ni. Yanayin valence na Ni da aka lura bayan gyaran V ya yi daidai da sakamakon Ni K-gefen X-ray absorption near-gedge spectroscopy (XANES) (duba sashen "Gyaran V Yana Inganta Rage Catalyst" a ƙasa don ƙarin bayani). An sanya NiV-LDH-NS bayan an yi wa COR magani na tsawon awa 1 a matsayin NiV-LDH-POST kuma an yi cikakken siffanta shi ta amfani da na'urar hangen nesa ta hanyar watsawa, taswirar EDS, bambancin hasken X-ray, Raman spectroscopy, da ma'aunin XPS (Hotunan Ƙarin 8 da 9). Masu haɓaka sun kasance a matsayin tarawa tare da yanayin nanosheet mai siriri (Hoto na Ƙarin 8a–c). Ƙirgar samfuran ta ragu kuma yawan V ya ragu saboda cirewar V da sake gina mai haɓaka (Hoto na Ƙarin 8d–f). Siffar XPS ta nuna raguwar ƙarfin V (Hoto na Ƙarin 9), wanda aka danganta da cirewar V. Bugu da ƙari, nazarin bakan O 1s (Ƙarin Hoto na 9d) da ma'aunin electron paramagnetic resonance (EPR) (Ƙarin Hoto na 10) sun nuna cewa adadin gurɓatattun iskar oxygen akan NiV-LDH-NS ya ƙaru bayan awa 1 na electrolysis, wanda zai iya haifar da canji mara kyau a cikin kuzarin ɗaure Ni 2p (duba Ƙarin Hoto na 9 da 10 don ƙarin bayani)26,27,32,33. Don haka, NiV-LDH-NS ya nuna ƙaramin canji a tsarin bayan awa 1 na COR.
Domin tabbatar da muhimmancin rawar da V ke takawa wajen haɓaka COR, mun haɗa ƙwayoyin NiV-LDH masu haɗaka da nau'ikan atom na V:Ni daban-daban (1:32, 1:16, da 1:4, waɗanda aka sanya su a matsayin NiV-32, NiV-16, da NiV-4, bi da bi) banda 1:8 ta hanyar amfani da wannan hanyar. Sakamakon taswirar EDS ya nuna cewa rabon atom na V:Ni a cikin mai haɗaka yana kusa da na mai haɗaka (Hoto na Ƙarin 11a–e). Tare da ƙaruwar gyaran V, ƙarfin bakan V 2p yana ƙaruwa, kuma kuzarin ɗaure yankin Ni 2p yana ci gaba da canzawa zuwa gefen mara kyau (Hoto na Ƙarin 12). A lokaci guda, rabon OL yana ƙaruwa a hankali. Sakamakon gwajin catalytic ya nuna cewa ana iya danne OER yadda ya kamata ko da bayan ƙaramin gyaran V (rabon atomic na V:Ni na 1:32), tare da raguwar O2 FE daga 27% zuwa 11% a 1.8 VRHE bayan gyaran V (Karin Hoto na 11f). Tare da ƙaruwar rabon V:Ni daga 1:32 zuwa 1:8, aikin catalytic ya ƙaru. Duk da haka, tare da ƙarin ƙaruwar gyaran V (rabon V:Ni na 1:4), yawan yanzu yana raguwa, wanda muke hasashe ya faru ne saboda raguwar yawan wuraren aiki na Ni (musamman matakin aiki na NiOOH; Ƙarin Hoto na 11f). Saboda tasirin haɓakawa na gyaran V da kiyaye wuraren aiki na Ni, mai haɓaka tare da rabon V:Ni na 1:8 ya nuna mafi girman aikin FE da AA a cikin gwajin tantance rabon V:Ni. Domin a fayyace ko rabon V:Ni ya kasance daidai bayan electrolysis, an gano abubuwan da ke cikin masu haɓaka da aka yi amfani da su. Sakamakon ya nuna cewa ga masu haɓaka sinadarai waɗanda suka fara da rabon V:Ni daga 1:16 zuwa 1:4, rabon V:Ni ya ragu zuwa kimanin 1:22 bayan amsawar, wanda zai iya zama saboda fitar V saboda sake gina mai haɓaka sinadarai (Hoto na 13). Lura cewa an lura da FEs masu kama da juna lokacin da rabon V:Ni na farko ya yi daidai da ko sama da 1:16 (Hoto na 11f na Ƙarin Bayani), wanda za a iya bayyana shi ta hanyar sake gina mai haɓaka sinadarai wanda ya haifar da irin wannan rabon V:Ni a cikin masu haɓaka sinadarai waɗanda ke nuna aikin mai haɓaka sinadarai masu kama da juna.
Domin ƙara tabbatar da mahimmancin Ni(OH)2 da aka gyara na V wajen haɓaka aikin COR, mun ƙirƙiro wasu hanyoyi guda biyu na roba don shigar da V cikin kayan Ni(OH)2-NS. Ɗaya hanyar haɗawa ce, kuma ana kiran samfurin da NiV-MIX; ɗayan kuma hanyar sputtering ce mai jere, kuma ana kiran samfurin da NiV-SP. Cikakkun bayanai game da haɗin an bayar da su a cikin sashin Hanyoyi. Taswirar SEM-EDS ta nuna cewa an yi nasarar gyara V akan saman Ni(OH)2-NS na samfuran biyu (Hoto na Ƙarin 14). Sakamakon electrolysis ya nuna cewa a 1.8 VRHE, ingancin AA akan lantarki na NiV-MIX da NiV-SP shine 78% da 79%, bi da bi, duka suna nuna inganci mafi girma fiye da Ni(OH)2-NS (51%). Bugu da ƙari, an danne OER akan lantarki na NiV-MIX da NiV-SP (FE O2: 7% da 2%, bi da bi) idan aka kwatanta da Ni(OH)2-NS (FE O2: 27%). Waɗannan sakamakon sun tabbatar da tasirin da gyaran V a cikin Ni(OH)2 ke da shi kan rage OER (Hoto na 14). Duk da haka, kwanciyar hankalin masu haɓaka ya lalace, wanda aka nuna ta hanyar raguwar FE AA akan NiV-MIX zuwa 45% da kuma kan NiV-SP zuwa 35% bayan zagayowar COR guda bakwai, wanda ke nuna buƙatar ɗaukar hanyoyin da suka dace don daidaita nau'ikan V, kamar gyaran V a cikin layin Ni(OH)2 a cikin NiV-LDH-NS, wanda shine babban mai haɓaka a cikin wannan aikin.
Mun kuma kimanta daidaiton Ni(OH)2-NS da NiV-LDH-NS ta hanyar sanya COR zuwa zagaye da yawa. An gudanar da martanin na tsawon awa 1 a kowace zagaye kuma an maye gurbin electrolyte bayan kowace zagaye. Bayan zagaye na 7, aikin FE da AA akan Ni(OH)2-NS ya ragu da kashi 50% da 60%, bi da bi, yayin da aka lura da ƙaruwa a OER (Hoto na 2i, j). Bayan kowane zagaye, mun yi nazarin lanƙwasa na voltammetry (CV) na masu haɓaka kuma mun lura cewa kololuwar oxidation na Ni2+ ya ragu a hankali, yana nuna raguwar ikon redox na Ni (Hoto na Ƙarin 15a–c). Tare da ƙaruwar yawan Nication a cikin electrolyte yayin electrolysis (Hoto na Ƙarin 15d), mun danganta raguwar aiki (rage yawan FE da AA) ga fitar da Ni daga mai haɓaka, wanda ya haifar da ƙarin fallasa na substrate mai kumfa na Ni wanda ke nuna aikin OER. Sabanin haka, NiV-LDH-NS ya rage raguwar yawan aiki na FE da AA zuwa 10% (Hoto na 2i, j), yana nuna cewa gyaran V ya hana Ni leaching yadda ya kamata (Hoto na Ƙari na 15d). Don fahimtar ingantaccen kwanciyar hankali na gyaran V, mun yi lissafin ka'idoji. Dangane da wallafe-wallafen da suka gabata34,35, canjin enthalpy na tsarin demetallization na ƙwayoyin ƙarfe akan saman aiki na mai kara kuzari za a iya amfani da shi azaman bayanin da ya dace don kimanta kwanciyar hankali na mai kara kuzari. Saboda haka, an kiyasta canje-canjen enthalpy na tsarin demetallization na ƙwayoyin Ni akan saman (100) na Ni(OH)2-NS da NiV-LDH-NS da aka sake ginawa (NiOOH da NiVOOH, bi da bi) (an bayyana cikakkun bayanai game da tsarin ƙirar a cikin Ƙarin Bayani na 2 da Ƙarin Hoto na 16). An kwatanta tsarin demetallization na Ni daga NiOOH da NiVOOH (Hoto na Ƙari na 17). Kudin makamashin da Ni ke kashewa a kan NiVOOH (0.0325 eV) ya fi na NiOOH (0.0005 eV) tsada, wanda ke nuna cewa gyaran V yana ƙara kwanciyar hankali na NiOOH.
Domin tabbatar da tasirin hana OER akan NiV-LDH-NS, musamman a manyan ƙarfin anodic, an yi gwajin mass spectrometry na electrochemical differential (DEMS) don bincika samuwar O2 mai dogaro da yuwuwar akan samfura daban-daban. Sakamakon ya nuna cewa idan babu cyclohexanone, O2 akan NiV-LDH-NS ya bayyana a farkon yuwuwar 1.53 VRHE, wanda ya ɗan yi ƙasa da na O2 akan Ni(OH)2-NS (1.62 VRHE) (Hoto na Ƙarin 18). Wannan sakamakon ya nuna cewa hana OER na NiV-LDH-NS a lokacin COR bazai kasance saboda ƙarancin aikin OER na ciki ba, wanda ya yi daidai da ɗan ƙaramin yawan halin yanzu a cikin lanƙwasa voltammetry (LSV) akan NiV-LDH-NS fiye da wanda ke kan Ni(OH)2-NS ba tare da cyclohexanone ba (Hoto na Ƙarin 19). Bayan gabatar da cyclohexanone, jinkirin juyin halittar O2 (mai yiwuwa saboda fa'idar thermodynamic na COR) ya bayyana babban FE na AA a cikin yankin da ke da ƙarancin yuwuwar. Mafi mahimmanci, yuwuwar farawar OER akan NiV-LDH-NS (1.73 VRHE) ya fi jinkiri fiye da na Ni(OH)2-NS (1.65 VRHE), wanda ya yi daidai da babban FE na AA da ƙarancin FE na O2 akan NiV-LDH-NS a mafi kyawun yuwuwar (Hoto na 2c).
Domin ƙarin fahimtar tasirin inganta gyaran V, mun yi nazarin tasirin amsawar OER da COR akan Ni(OH)2-NS da NiV-LDH-NS ta hanyar auna gangaren Tafel ɗinsu. Ya kamata a lura cewa yawan da ake samu a yankin Tafel ya faru ne sakamakon iskar shaka ta Ni2+ zuwa Ni3+ yayin gwajin LSV daga ƙarancin ƙarfin zuwa babban ƙarfin. Don rage tasirin iskar shaka ta Ni2+ akan ma'aunin gangaren COR Tafel, da farko mun yi oxidizing mai kara kuzari a 1.8 VRHE na tsawon mintuna 10 sannan muka yi gwajin LSV a yanayin duba baya, watau, daga babban ƙarfin zuwa ƙaramin ƙarfin (Karin Hoto na 20). An gyara lanƙwasa na asali na LSV da diyya 100% iR don samun gangaren Tafel. Idan babu cyclohexanone, gangaren Tafel na NiV-LDH-NS (41.6 mV dec−1) ya yi ƙasa da na Ni(OH)2-NS (65.5 mV dec−1), wanda ke nuna cewa ana iya inganta kinetics na OER ta hanyar gyaran V (Hoto na Ƙari 20c). Bayan gabatar da cyclohexanone, gangaren Tafel na NiV-LDH-NS (37.3 mV dec−1) ya yi ƙasa da na Ni(OH)2-NS (127.4 mV dec−1), wanda ke nuna cewa gyaran V yana da tasirin kinetics mafi bayyana akan COR idan aka kwatanta da OER (Hoto na Ƙari 20d). Waɗannan sakamakon sun nuna cewa kodayake gyaran V yana haɓaka OER zuwa wani mataki, yana hanzarta kinetics na COR sosai, wanda ke haifar da ƙaruwa a cikin FE na AA.
Domin fahimtar tasirin inganta gyaran V da ke sama akan aikin FE da AA, mun mayar da hankali kan nazarin tsarin. Wasu rahotannin da suka gabata sun nuna cewa gyaran heteroatom na iya rage yawan masu kara kuzari da kuma ƙara yankin saman electrochemically active (EAS), ta haka ne za a ƙara yawan wuraren aiki da kuma inganta aikin catalytic36,37. Don bincika wannan yiwuwar, mun gudanar da ma'aunin ECSA kafin da kuma bayan kunna electrochemical, kuma sakamakon ya nuna cewa ECSA na Ni(OH)2-NS da NiV-LDH-NS sun yi kama da juna (Karin Hoto na 21), ban da tasirin yawan wurin aiki bayan gyaran V akan haɓaka catalytic.
Bisa ga ilimin da aka yarda da shi gabaɗaya, a cikin electrooxidation na Ni(OH)2-catalyzed na alcohols ko wasu substrates na nucleophilic, Ni(OH)2 da farko yana rasa electrons da protons sannan a rage shi zuwa NiOOH ta hanyar matakan electrochemical a wani takamaiman ƙarfin anodic38,39,40,41. Sai NiOOH da aka samar ya zama ainihin nau'in COR mai aiki don cire hydrogen da electrons daga substrate na nucleophilic ta hanyar matakan sinadarai don samar da samfurin oxidized20,41. Duk da haka, kwanan nan an ruwaito cewa kodayake ragewa zuwa NiOOH na iya zama matakin ƙayyade ƙimar (RDS) don electrooxidation na barasa akan Ni(OH)2, kamar yadda aka ba da shawara a cikin wallafe-wallafen baya-bayan nan, oxidation na Ni3+ alcohols na iya zama tsari na bazata ta hanyar canja wurin electron mara redox ta hanyar orbitals mara shagaltuwa na Ni3+41,42. An yi wahayi zuwa gare mu daga binciken injiniya da aka ruwaito a cikin wannan wallafe-wallafen, mun yi amfani da dimethylglyoxime disodium gishiri octahydrate (C4H6N2Na2O2 8H2O) a matsayin kwayar bincike don kama duk wani samuwar Ni2+ da ya samo asali daga raguwar Ni3+ yayin COR (Ƙarin Hoto na 22 da Ƙarin Bayani na 3). Sakamakon ya nuna samuwar Ni2+, yana tabbatar da cewa rage sinadarai na NiOOH da electrooxidation na Ni(OH)2 sun faru a lokaci guda yayin aikin COR. Saboda haka, aikin catalytic na iya dogara sosai akan kinetics na rage Ni(OH)2 zuwa NiOOH. Dangane da wannan ƙa'ida, mun sake bincika ko gyaran V zai hanzarta rage Ni(OH)2 don haka inganta COR.
Da farko mun yi amfani da dabarun Raman a wuri don nuna cewa NiOOH shine matakin aiki na COR akan Ni(OH)2-NS da NiV-LDH-NS ta hanyar lura da samuwar NiOOH a cikin ƙarfin da ya dace da kuma amfani da shi bayan gabatar da cyclohexanone, bin tsarin "electrochemical-chemical" da aka ambata a sama (Hoto na 3a). Bugu da ƙari, amsawar NiV-LDH-NS da aka sake ginawa ya wuce na Ni(OH)2-NS, kamar yadda aka tabbatar ta hanyar ɓacewar siginar Ni3+–O Raman cikin sauri. Daga nan muka nuna cewa NiV-LDH-NS ya nuna ƙarancin ƙarfin da ya dace don samuwar NiOOH idan aka kwatanta da Ni(OH)2-NS a gaban ko babu cyclohexanone (Hoto na 3b, c da Hoto na Ƙarin 4c, d). Abin lura shi ne, mafi kyawun aikin OER na NiV-LDH-NS yana haifar da ƙarin kumfa da ke manne a kan gilashin gaba na ma'aunin Raman, wanda ke sa kololuwar Raman a 1.55 VRHE ta ɓace (Hoto na Ƙarin 4d). Bisa ga sakamakon DEMS (Ƙarin Hoto na 18), yawan halin yanzu a ƙananan ƙarfin lantarki (VRHE < 1.58 don Ni(OH)2-NS da VRHE < 1.53 don NiV-LDH-NS) ya faru ne saboda sake gina ions na Ni2+ maimakon OER idan babu cyclohexanone. Don haka, kololuwar iskar oxygen na Ni2+ a cikin lanƙwasa na LSV ya fi ƙarfi fiye da na NiV-LDH-NS, yana nuna cewa gyaran V yana ba NiV-LDH-NS damar haɓaka iyawar gyara (duba Ƙarin Hoto na 19 don cikakken nazarin).
a In situ Raman spectra na Ni(OH)2-NS (hagu) da NiV-LDH-NS (dama) a ƙarƙashin yanayin OCP bayan preoxidation a 1.5 VRHE a cikin 0.5 M KOH da 0.4 M cyclohexanone na 60 s. b In situ Raman spectra na Ni(OH)2-NS da c NiV-LDH-NS a cikin 0.5 M KOH + 0.4 M cyclohexanone a cikin 0.5 M KOH + 0.4 M cyclohexanone a cikin potentials daban-daban. d In situ XANES spectra na Ni(OH)2-NS da NiV-LDH-NS a Ni K-gedge a cikin 0.5 M KOH da e 0.5 M KOH da 0.4 M cyclohexanone. Inset ɗin yana nuna yankin spectral mai girma tsakanin 8342 da 8446 eV. f Yanayin Valence na Ni a cikin Ni(OH)2-NS da NiV-LDH-NS a cikin potentials daban-daban. g In situ Ni EXAFS spectra na NiV-LDH-NS kafin da kuma bayan saka cyclohexanone a cikin iyakoki daban-daban. h Samfuran ka'idoji na Ni(OH)2-NS da NiV-LDH-NS. Sama: A kan Ni(OH)2-NS, gyaran da aka yi a hankali daga Ni(OH)2-NS zuwa NiOOH yana aiki azaman RDS, yayin da cyclohexanone ke rage nau'in Ni mai yawan valent ta hanyar matakan sinadarai don kiyaye yanayin Ni mai ƙarancin valent don samar da AA. Ƙasa: A kan NiV-LDH-NS, matakin gyaran yana sauƙaƙe ta hanyar gyaran V, wanda ke haifar da canja wurin RDS daga matakin gyara zuwa matakin sinadarai. i Ƙarfin Gibbs kyauta yana canzawa bayan sake gina Ni(OH)2-NS da NiV-LDH-NS. Ana samar da bayanai na asali na aj da i a cikin fayil ɗin bayanai na asali.
Domin bincika juyin halittar tsarin atomic da na lantarki yayin rage yawan sinadarin catalyst, mun yi gwaje-gwajen X-ray absorption spectroscopy (XAS) a situ, wanda ya samar da kayan aiki mai ƙarfi don bincika yanayin nau'in Ni a matakai uku a jere: OER, allurar cyclohexanone, da COR a buɗewar da'ira (OCP). Wannan hoton yana nuna K-gefen XANES spectra na Ni tare da ƙaruwar yuwuwar kafin da bayan allurar cyclohexanone (Hoto na 3d, e). A daidai wannan yuwuwar, kuzarin gefen sha na NiV-LDH-NS ya fi kyau fiye da na Ni(OH)2-NS (Hoto na 3d, e, shigarwa). An kiyasta matsakaicin ƙimar Ni a ƙarƙashin kowane yanayi ta hanyar haɗakar daidaiton layin XANES spectra da kuma komawa ga canjin kuzarin sha na Ni K (Hoto na 3f), tare da bakan tunani da aka ɗauka daga wallafe-wallafen da aka buga (Hoto na 23)43.
A mataki na farko (kafin gabatar da cyclohexanone, wanda ya dace da tsarin OER; Hoto na 3f, hagu), a cikin yuwuwar mai kara kuzari mara sake ginawa (<1.3 VRHE), yanayin kuzarin Ni a cikin NiV-LDH-NS (+1.83) ya ɗan yi ƙasa da na NiV-LDH-NS (+1.97), wanda za'a iya danganta shi da canja wurin lantarki daga V zuwa Ni, daidai da sakamakon XPS da aka ambata a sama (Hoto na 2f). Lokacin da ƙarfin ya wuce wurin ragewa (1.5 VRHE), yanayin kuzarin Ni a cikin NiV-LDH-NS (+3.28) yana nuna ƙaruwa mafi bayyana idan aka kwatanta da na Ni(OH)2-NS (+2.49). A mafi girman ƙarfin (1.8 VRHE), yanayin kuzarin Ni da aka samu akan NiV-LDH-NS (+3.64) ya fi na Ni(OH)2-NS (+3.47). A cewar rahotannin da suka gabata, wannan tsari ya yi daidai da samuwar nau'ikan Ni4+ masu yawan valent a cikin tsarin Ni3+xOOH1-x (Ni3+x nau'in Ni3+ ne gauraye na Ni4+), wanda a baya ya nuna ingantaccen aikin catalytic a cikin dehydrogenation na barasa38,39,44. Saboda haka, mafi kyawun aikin NiV-LDH-NS a cikin COR na iya kasancewa saboda haɓaka ragewa don samar da nau'ikan Ni mai yawan valent mai yawan catalytic.
A mataki na biyu (gabatar da cyclohexanone bayan buɗewar zobe, Hoto na 3f), yanayin ƙarfin Ni akan duka abubuwan haɓaka guda biyu ya ragu sosai, wanda ya yi daidai da tsarin rage Ni3+xOOH1-x ta hanyar cyclohexanone, wanda ya yi daidai da sakamakon in situ Raman spectroscopy (Hoto na 3a), kuma yanayin ƙarfin Ni ya kusan dawo da shi zuwa yanayin farko (mataki na farko a ƙarancin ƙarfin), yana nuna sake juyawar tsarin redox na Ni zuwa Ni3+xOOH1-x.
A mataki na uku (tsarin COR) a ƙarfin COR (1.5 da 1.8 VRHE; Hoto na 3f, dama), yanayin ƙarfin Ni a cikin Ni(OH)2-NS ya ƙaru kaɗan kawai (+2.16 da +2.40), wanda ya yi ƙasa da ƙarfin iri ɗaya a matakin farko (+2.49 da +3.47). Waɗannan sakamakon sun nuna cewa bayan allurar cyclohexanone, COR yana da iyaka ta hanyar iskar oxygen a hankali na Ni2+ zuwa Ni3+x (watau, sake gina Ni) maimakon matakin sinadarai tsakanin NiOOH da cyclohexanone akan Ni(OH)2-NS, wanda ke barin Ni a cikin yanayin ƙarancin kuzari. Don haka, mun kammala da cewa sake gina Ni na iya zama RDS a cikin tsarin COR akan Ni(OH)2-NS. Sabanin haka, NiV-LDH-NS ta ci gaba da samun babban ƙarfin Ni (>3) a lokacin aikin COR, kuma ƙarfin ya ragu sosai (ƙasa da 0.2) idan aka kwatanta da matakin farko a wannan ƙarfin (1.65 da 1.8 VRHE), wanda ke nuna cewa gyaran V ya haɓaka iskar Ni2+ zuwa Ni3+x ta hanyar lantarki, wanda hakan ya sa tsarin rage Ni ya fi sauri fiye da matakin sinadarai na rage cyclohexanone. Sakamakon tsarin X-ray mai tsawo (EXAFS) ya kuma bayyana cikakken canji na haɗin Ni–O2 (daga 1.6 zuwa 1.4 Å) da Ni–Ni(V) (daga 2.8 zuwa 2.4 Å) a gaban cyclohexanone. Wannan ya yi daidai da sake gina matakin Ni(OH)2 zuwa matakin NiOOH da rage sinadaran matakin NiOOH ta hanyar cyclohexanone (Hoto na 3g). Duk da haka, cyclohexanone ya kawo cikas sosai ga rage tasirin Ni(OH)2-NS (duba Ƙarin Bayani na 4 da Ƙarin Hoto na 24 don ƙarin bayani).
Gabaɗaya, akan Ni(OH)2-NS (Hoto na 3h, sama), matakin ragewa a hankali daga matakin Ni(OH)2 zuwa matakin NiOOH na iya zama RDS na tsarin COR gabaɗaya maimakon matakin sinadarai na samuwar AA daga cyclohexanone yayin rage sinadarai na NiOOH. A kan NiV-LDH-NS (Hoto na 3h, ƙasa), gyaran V yana haɓaka motsin iskar shaka na Ni2+ zuwa Ni3+x, ta haka yana hanzarta samuwar NiVOOH (maimakon amfani da rage sinadarai), wanda ke canza RDS zuwa matakin sinadarai. Don fahimtar sake gina Ni wanda gyaran V ya haifar, mun yi ƙarin lissafin ka'idoji. Kamar yadda aka nuna a Hoto na 3h, mun kwaikwayi tsarin sake gina Ni(OH)2-NS da NiV-LDH-NS. Ƙungiyoyin hydroxyl na lattice akan Ni(OH)2-NS da NiV-LDH-NS ana cire su ta hanyar cire OH- a cikin electrolyte don samar da iskar oxygen mai ƙarancin electron. Halayen sinadarai masu dacewa sune kamar haka:
An ƙididdige canjin makamashin Gibbs kyauta na sake ginawa (Hoto na 3i), kuma NiV-LDH-NS (0.81 eV) ya nuna ƙaramin canjin makamashin Gibbs kyauta fiye da Ni(OH)2-NS (1.66 eV), yana nuna cewa gyaran V ya rage ƙarfin lantarki da ake buƙata don sake gina Ni. Mun yi imanin cewa haɓaka sake ginawa na iya rage shingen makamashi na dukkan COR (duba nazarin tsarin amsawar da ke ƙasa don cikakkun bayanai), ta haka ne ke hanzarta amsawar a mafi girman yawan wutar lantarki.
Binciken da ke sama ya nuna cewa gyaran V yana haifar da saurin sake fasalin Ni(OH)2, wanda hakan ke ƙara yawan amsawar, sannan kuma, yawan COR. Duk da haka, wuraren Ni3+x suma suna iya haɓaka aikin OER. Daga lanƙwasa LSV ba tare da cyclohexanone ba, a bayyane yake cewa yawan NiV-LDH-NS na yanzu ya fi na Ni(OH)2-NS girma (Hoto na Ƙari na 19), wanda ke sa halayen COR da OER su samar da halayen gasa. Saboda haka, ba za a iya bayyana cikakken FE na AA mafi girma fiye da na NiV-LDH-NS ta hanyar gyaran V wanda ke haɓaka sake fasalin lokaci ba.
An yarda cewa a cikin kafofin watsa labarai na alkaline, halayen electrooxidation na substrates na nucleophilic yawanci suna bin tsarin Langmuir-Hinshelwood (LH). Musamman, substrate da OH− anions suna haɗuwa cikin gasa a saman catalyst, kuma an haɗa OH− da aka shaƙa zuwa ƙungiyoyin hydroxyl masu aiki (OH*), waɗanda ke aiki azaman electrophiles don oxidation na nucleophiles, wata hanya da aka nuna a baya ta hanyar bayanan gwaji da/ko ƙididdigar ka'idoji45,46,47. Don haka, yawan masu amsawa da rabonsu (substrate na halitta da OH−) na iya sarrafa murfin mai amsawa na saman catalyst, ta haka yana shafar FE da yawan samfurin da aka yi niyya14,48,49,50. A yanayinmu, muna tsammanin cewa babban murfin saman cyclohexanone a cikin NiV-LDH-NS yana fifita tsarin COR, kuma akasin haka, ƙarancin murfin saman cyclohexanone a cikin Ni(OH)2-NS yana fifita tsarin OER.
Domin gwada hasashen da ke sama, da farko mun gudanar da gwaje-gwaje guda biyu da suka shafi yawan sinadaran da ke cikin sinadaran (C, cyclohexanone, da COH−). An gudanar da gwajin farko da electrolysis a wani ƙarfin da ba ya canzawa (1.8 VRHE) akan Ni(OH)2-NS da NiV-LDH-NS masu dauke da abubuwan da ke cikin cyclohexanone C daban-daban (0.05 ~ 0.45 M) da kuma adadin COH− da aka kayyade (0.5 M). Sannan, an ƙididdige yawan amfanin FE da AA. Ga mai kara kuzari na NiV-LDH-NS, dangantakar da ke tsakanin yawan amfanin AA da cyclohexanone C ta nuna lanƙwasa ta yau da kullun ta "nau'in dutsen mai aman wuta" a yanayin LH (Hoto na 4a), wanda ke nuna cewa babban murfin cyclohexanone yana fafatawa da sharar OH−. Duk da yake ga Ni(OH)2-NS, yawan amfanin AA ya ƙaru da sauri tare da ƙaruwar C na cyclohexanone daga 0.05 zuwa 0.45 M, wanda ke nuna cewa duk da yawan cyclohexanone yana da yawa (0.45 M), rufin saman sa har yanzu yana da ƙasa. Bugu da ƙari, tare da ƙaruwar COH− zuwa 1.5 M, an lura da lanƙwasa "nau'in dutsen mai aman wuta" akan Ni(OH)2-NS dangane da C na cyclohexanone, kuma an jinkirta wurin juyawa na aikin idan aka kwatanta da NiV-LDH-NS, wanda hakan ya ƙara tabbatar da raunin shaƙar cyclohexanone akan Ni(OH)2-NS (Ƙarin Hoto na 25a da Bayani na 5). Bugu da ƙari, FE na AA akan NiV-LDH-NS yana da matuƙar tasiri ga C-cyclohexanone kuma ya karu da sauri zuwa fiye da 80% lokacin da aka ƙara C-cyclohexanone daga 0.05 M zuwa 0.3 M, wanda ke nuna cewa cyclohexanone ya sami wadatar NiV-LDH-NS cikin sauƙi (Hoto na 4b). Sabanin haka, ƙara yawan C-cyclohexanone bai hana OER sosai akan Ni(OH)2-NS ba, wanda ƙila ya kasance saboda rashin isasshen shaƙar cyclohexanone. Akasin haka, ƙarin bincike kan dogaro da COH− akan ingancin catalytic ya kuma tabbatar da cewa an inganta shaƙar cyclohexanone idan aka kwatanta da NiV-LDH-NS, wanda zai iya jure wa mafi girman COH− yayin aikin COR ba tare da rage FE na AA ba (Hoto na Ƙari na 25b, c da Bayani na 5).
Yawan aiki na AA da EF na b Ni(OH)2-NS da NiV-LDH-NS akan cyclohexanone tare da C daban-daban a cikin 0.5 M KOH. c Ƙarfin shaye-shaye na cyclohexanone akan NiOOH da NiVOOH. d FE na AA akan Ni(OH)2-NS da NiV-LDH-NS a cikin 0.5 M KOH da 0.4 M cyclohexanone a 1.80 VRHE ta amfani da dabarun yuwuwar da ba sa tsayawa da ci gaba. Sandunan kuskure suna wakiltar karkacewar daidaitattun ma'auni guda uku masu zaman kansu ta amfani da samfurin iri ɗaya kuma suna cikin 10%. e Sama: A kan Ni(OH)2-NS, cyclohexanone mai ƙaramin yanki na saman C yana shaye-shaye da rauni ta hanyar cyclohexanone, wanda ke haifar da gasa mai ƙarfi don OER. Ƙasa: A kan NiV-LDH-NS, ana lura da yawan cyclohexanone C mai yawa a saman tare da ƙaruwar shaye-shaye na cyclohexanone, wanda ke haifar da danne OER. Ana bayar da bayanai na asali na a–d a cikin fayil ɗin bayanai na asali.
Domin gwada ingantaccen shaƙar cyclohexanone akan NiV-LDH-NS, mun yi amfani da na'urar auna ma'aunin kristal mai haɗin lantarki (E-QCM) don sa ido kan canjin taro na nau'in da aka sha a ainihin lokacin. Sakamakon ya nuna cewa ƙarfin shaƙar cyclohexanone na farko akan NiV-LDH-NS ya fi girma sau 1.6 fiye da na Ni(OH)2-NS a cikin yanayin OCP, kuma wannan bambancin ƙarfin shaƙar ya ƙara ƙaruwa yayin da ƙarfin ya ƙaru zuwa 1.5 VRHE (Hoto na Ƙari na 26). An gudanar da lissafin DFT mai juyawa don bincika halayen shaƙar cyclohexanone akan NiOOH da NiVOOH (Hoto na 4c). Cyclohexanone yana shiga cikin cibiyar Ni akan NiOOH tare da kuzarin sha (Eads) na -0.57 eV, yayin da cyclohexanone zai iya shiga cikin cibiyar Ni ko cibiyar V akan NiVOOH, inda cibiyar V ke samar da ƙananan Eads (-0.69 eV), daidai da ƙarfin shaƙar cyclohexanone da aka lura akan NiVOOH.
Don ƙara tabbatar da cewa ƙaruwar shaƙar cyclohexanone na iya haɓaka samuwar AA da kuma hana OER, mun yi amfani da dabarun yuwuwar da ba ta ci gaba ba don wadatar da cyclohexanone akan saman mai haɓaka (don Ni(OH)2-NS da NiV-LDH-NS), wanda rahotannin da suka gabata suka yi wahayi zuwa gare shi. 51, 52 Musamman, mun yi amfani da yuwuwar 1.8 VRHE zuwa COR, sannan muka canza shi zuwa yanayin OCP, sannan muka mayar da shi zuwa 1.8 VRHE. A wannan yanayin, cyclohexanone na iya taruwa a saman mai haɓaka a cikin yanayin OCP tsakanin electrolyses (duba sashin Hanyoyi don cikakkun hanyoyin). Sakamakon ya nuna cewa ga Ni(OH)2-NS da NiV-LDH-NS, amfani da electrolysis mai yuwuwar da ba ta ci gaba ba ya inganta aikin mai haɓaka idan aka kwatanta da electrolysis mai yuwuwar da ba ta ci gaba ba (Hoto na 4d). Abin lura shi ne, Ni(OH)2-NS ya nuna ci gaba mai mahimmanci a COR (AA FE: daga 51% zuwa 82%) da kuma danne OER (O2 FE: daga 27% zuwa 4%) fiye da NiV-LDH-NS, wanda aka danganta shi da gaskiyar cewa tarin cyclohexanone zai iya ingantawa sosai akan mai kara kuzari mai raunin ƙarfin sha (watau, Ni(OH)2-NS) ta hanyar electrolysis mai yuwuwa na lokaci-lokaci.
Gabaɗaya, hana OER akan NiV-LDH-NS za a iya danganta shi da ƙaruwar shaƙar cyclohexanone (Hoto na 4e). A kan Ni(OH)2-NS (Hoto na 4e, sama), raunin shaƙar cyclohexanone ya haifar da ƙarancin shaƙar cyclohexanone da kuma babban shaƙar OH* akan saman mai kara kuzari. Saboda haka, yawan nau'in OH* zai haifar da gasa mai tsanani ga OER da rage FE na AA. Sabanin haka, a kan NiV-LDH-NS (Hoto na 4e, ƙasa), gyaran V ya ƙara ƙarfin shaƙar cyclohexanone, ta haka yana ƙara saman C na cyclohexanone da kuma amfani da nau'in OH* da aka shaƙar don COR, yana haɓaka samuwar AA da kuma hana OER.
Baya ga binciken tasirin gyaran V akan sake gina nau'in Ni da kuma shaƙar cyclohexanone, mun kuma bincika ko V yana canza hanyar samuwar AA daga COR. An gabatar da hanyoyi daban-daban na COR a cikin wallafe-wallafen, kuma mun yi nazarin yuwuwarsu a cikin tsarin amsawarmu (duba Ƙarin Hoto na 27 da Ƙarin Bayani na 6 don ƙarin bayani)13,14,26. Da farko, an ruwaito cewa matakin farko na hanyar COR na iya haɗawa da farkon oxidation na cyclohexanone don samar da babban matsakaici na 2-hydroxycyclohexanone (2)13,14. Don tabbatar da tsarin, mun yi amfani da 5,5-dimethyl-1-pyrrolidine N-oxide (DMPO) don kama tsaka-tsakin aiki masu aiki da aka lulluɓe a saman mai haɓaka kuma muka yi nazarin EPR. Sakamakon EPR ya nuna kasancewar radicals masu tsakiya na C (R) da radicals masu hydroxyl (OH) a kan duka masu haɓaka sinadarai a lokacin aikin COR, yana nuna cewa rage yawan sinadarin Cα −H na cyclohexanone yana samar da radicals masu tsaka-tsaki na enolate (1), wanda daga nan sai OH* ya ƙara oxidize shi don samar da 2 (Hoto na 5a da Hoto na Ƙari na 28). Kodayake an gano tsaka-tsaki iri ɗaya akan duka masu haɓaka sinadarai, ɓangaren yanki na siginar R akan NiV-LDH-NS ya fi na Ni(OH)2-NS girma, wanda wataƙila ya faru ne saboda ƙarfin shaye-shaye na cyclohexanone (Tebur na Ƙari na 3 da Bayani na 7). Mun ƙara amfani da 2 da 1,2-cyclohexanedione (3) azaman masu amsawa na farko don electrolysis don gwada ko V zai canza matakin oxidation na gaba. Sakamakon electrolysis na matsakaicin yiwuwar (2 da 3) akan Ni(OH)2-NS da NiV-LDH-NS ya nuna zaɓin samfuri iri ɗaya, yana nuna cewa amsawar COR akan Ni(OH)2-NS ko NiV-LDH-NS ta ci gaba ta hanyoyi iri ɗaya (Hoto na 5b). Bugu da ƙari, AA ita ce babban samfurin kawai lokacin da aka yi amfani da 2 azaman mai amsawa, yana nuna cewa an sami AA ta hanyar tsarin oxidation kai tsaye ta hanyar raba haɗin Cα − Cβ na 2 maimakon oxidation na gaba zuwa 3 akan duka masu haɓaka, tunda galibi an canza shi zuwa GA lokacin da aka yi amfani da 3 azaman mai amsawa na farko (Karin Hotuna 29, 30).
Siginar EPR na NiV-LDH-NS a cikin 0.5 M KOH + 0.4 M cyclohexanone. b Sakamakon nazarin electrocatalytic na 2-hydroxycyclohexanone (2) da 1,2-cyclohexanedione (3). An gudanar da electrolysis a cikin 0.5 M KOH da 0.1 M 2 ko 3 a 1.8 VRE na tsawon awa ɗaya. Sandunan kuskure suna wakiltar daidaitaccen karkacewar ma'auni guda biyu masu zaman kansu ta amfani da mai kara kuzari iri ɗaya. c Hanyoyin amsawa da aka gabatar na COR akan masu kara kuzari guda biyu. d Zane-zanen tsari na hanyar COR akan Ni(OH)2-NS (hagu) da d NiV-LDH-NS (dama). Kibiyoyi ja suna nuna matakan da gyaran V ke haɓakawa a cikin tsarin COR. An samar da bayanai na asali na a da b a cikin fayil ɗin bayanai na asali.
Gabaɗaya, mun nuna cewa Ni(OH)2-NS da NiV-LDH-NS suna haɓaka COR ta hanyar hanya iri ɗaya: cyclohexanone yana shaƙa a saman mai haɓaka, yana narkewar ruwa kuma yana rasa electrons don samar da 1, wanda daga nan sai OH* ya yi oxidize don samar da 2, sannan canje-canje matakai da yawa don samar da AA (Hoto na 5c). Duk da haka, lokacin da aka yi amfani da cyclohexanone azaman mai amsawa, an lura da gasar OER kawai akan Ni(OH)2-NS, yayin da aka tattara mafi ƙarancin adadin oxygen lokacin da aka yi amfani da 2 da 3 azaman masu amsawa. Don haka, bambance-bambancen da aka lura a cikin aikin mai amsawa na iya zama saboda canje-canje a cikin shingen makamashi na RDS da ƙarfin shaƙar cyclohexanone wanda gyaran V ya haifar maimakon canje-canje a cikin hanyar amsawa. Saboda haka mun bincika RDS na hanyoyin amsawa akan duka masu haɓaka. Sakamakon binciken acoustic X-ray da aka ambata a sama ya nuna cewa gyaran V yana canza RDS a cikin amsawar COR daga matakin sake ginawa zuwa matakin sinadarai, yana kiyaye matakin NiOOH da nau'in Ni mai yawan valentine a kan NiV-LDH-NS (Hoto na 3f, Hoto na Ƙarin 24, da Bayani na 4). Mun ƙara yin nazarin hanyoyin amsawar da aka wakilta ta yawan yanzu a kowane ɓangare na yankuna daban-daban na yuwuwar yayin auna CV (duba Hoto na Ƙarin 31 da Bayani na 8 don cikakkun bayanai) kuma mun yi gwaje-gwajen musayar isotope na H/D, waɗanda suka nuna cewa RDS na COR akan NiV-LDH-NS ya ƙunshi raba haɗin Cα − H a matakin sinadarai maimakon matakin ragewa (duba Hoto na Ƙarin 32 da Bayani na 8 don ƙarin bayani).
Dangane da binciken da ke sama, an nuna tasirin gyaran V gaba ɗaya a cikin Hoto na 5d. Masu haɓaka Ni(OH)2-NS da NiV-LDH-NS suna yin sake gina saman ƙasa a manyan ƙarfin anodic kuma suna haɓaka COR ta hanyar hanya iri ɗaya. A kan Ni(OH)2-NS (Hoto na 5d, hagu), matakin sake ginawa shine RDS yayin tsarin COR; yayin da akan NiV-LDH-NS (Hoto na 5d, dama), gyaran V ya hanzarta tsarin sake ginawa sosai kuma ya canza RDS zuwa dehydrogenation na Cα−H na cyclohexanone zuwa 1. Bugu da ƙari, shaƙar cyclohexanone ya faru a wurin V kuma an inganta shi akan NiV-LDH-NS, wanda ya ba da gudummawa ga dakatar da OER.
Idan aka yi la'akari da kyakkyawan aikin lantarki na NiV-LDH-NS tare da babban FE a kan kewayon yuwuwar da yawa, mun tsara MEA don cimma ci gaba da samar da AA. An haɗa MEA ta amfani da NiV-LDH-NS a matsayin anode, PtRu/C na kasuwanci a matsayin cathode53 da membrane na musayar anion (nau'in: FAA-3-50) (Hoto na 6a da Hoto na Ƙarin 33)54. Tunda ƙarfin lantarki na tantanin halitta ya ragu kuma FE na AA ya yi daidai da 0.5 M KOH a cikin binciken da ke sama, an inganta yawan anolyte zuwa 1 M KOH (Hoto na Ƙarin 25c). An nuna lanƙwasa LSV da aka rubuta a cikin Hoto na Ƙarin 34, yana nuna cewa ingancin COR na NiV-LDH-NS ya fi na Ni(OH)2-NS girma sosai. Domin nuna fifikon NiV-LDH-NS, an gudanar da electrolysis na lantarki mai ɗorewa tare da yawan wutar lantarki mai mataki daga 50 zuwa 500 mA cm−2 kuma an rubuta ƙarfin wutar lantarki mai dacewa da ƙwayoyin halitta. Sakamakon ya nuna cewa NiV-LDH-NS ya nuna ƙarfin wutar lantarki na 1.76 V a yawan wutar lantarki na 300 mA cm−2, wanda ya yi ƙasa da kusan 16% fiye da na Ni(OH)2-NS (2.09 V), yana nuna ingantaccen makamashinsa a samar da AA (Hoto na 6b).
Tsarin zane na batirin kwarara. b Ƙarfin tantanin halitta ba tare da diyya ta iR akan Ni(OH)2-NS da NiV-LDH-NS a cikin 1 M KOH da 0.4 M cyclohexanone a cikin yawan yanzu daban-daban. c AA da FE suna samarwa akan Ni(OH)2-NS da NiV-LDH-NS a yawan yanzu daban-daban. Sandunan kuskure suna wakiltar daidaitaccen karkacewar ma'auni guda biyu masu zaman kansu ta amfani da mai kara kuzari iri ɗaya. d Kwatanta aikin mai kara kuzari na aikinmu tare da sauran tsarin batirin kwarara da aka ruwaito14,17,19. Sigogin amsawa da halayen amsawa an jera su dalla-dalla a cikin Tebur na Ƙarin 2. e Ƙarfin tantanin halitta da FE na AA akan NiV-LDH-NS a 200 da 300 mA cm−2 a cikin gwajin dogon lokaci, bi da bi. An bayar da bayanai na asali don zama azaman fayil ɗin bayanai na asali.
A halin yanzu, kamar yadda aka nuna a Hoto na 6c, NiV-LDH-NS ya kiyaye kyakkyawan FE (83% zuwa 61%) a mafi girman yawan wutar lantarki (200 zuwa 500 mA cm-2), ta haka ne ya inganta yawan aikin AA (1031 zuwa 1900 μmol cm-2 h-1). A halin yanzu, kashi 0.8% ne kawai na adipic acid anions aka lura a cikin sashin cathode bayan electrolysis, wanda ke nuna cewa canjin cyclohexanone bai yi wani tasiri ba a yanayinmu (Karin Hoto na 35). Sabanin haka, tare da ƙaruwar yawan wutar lantarki iri ɗaya, FE na AA akan Ni(OH)2-NS ya ragu daga 61% zuwa 34%, wanda ya sa ya zama da wahala a inganta yawan aikin AA (762 zuwa 1050 μmol cm-2 h-1). Musamman ma, aikin AA ya ragu kaɗan saboda ƙarfin gasa daga OER, don haka FE na AA ya ragu sosai tare da ƙaruwar yawan yanzu (daga 200 zuwa 250 mA cm−2, Ƙarin Hoto na 5). A gwargwadon iliminmu, sakamakon catalytic ta amfani da MEA tare da catalysts na NiV-LDH-NS ya fi ƙarfin aikin reactors kwarara da aka ruwaito a baya tare da catalysts na tushen Ni (Jadawali na Ƙarin 2). Bugu da ƙari, kamar yadda aka nuna a Hoto na 6d, NiV-LDH-NS ya nuna fa'idodi masu mahimmanci dangane da yawan yanzu, ƙarfin tantanin halitta, da FE na AA idan aka kwatanta da mafi kyawun catalyst na tushen Co, watau, Co3O4 da graphene ke tallafawa (Co3O4/GDY)17. Bugu da ƙari, mun kimanta yawan amfani da makamashin da aka samar a AA kuma mun nuna cewa yawan amfani da AA ya yi ƙasa sosai, 2.4 W h gAA-1 kawai a yawan yanzu na 300 mA cm-2 da kuma ƙarfin tantanin halitta na 1.76 V (an bayar da cikakkun bayanai a cikin Ƙarin Bayani na 1). Idan aka kwatanta da mafi kyawun sakamakon 4.1 W h gAA-1 don Co3O4/GDY da aka ruwaito a baya, yawan amfani da makamashin da aka samu don samar da AA a cikin aikinmu ya ragu da kashi 42% kuma yawan aiki ya karu da sau 4 (1536 vs. 319 μmol cm-2 h-1)17.
An kimanta kwanciyar hankali na mai haɓaka NiV-LDH-NS don samar da AA na dogon lokaci a cikin MEA a yawan da ake samu a yanzu na 200 da 300 mA cm-2, bi da bi (Hoto na 6e). Tunda ana cinye OH− da sauri a yawan da ake samu a yanzu, ƙimar sabunta electrolyte a 300 mA cm-2 ya fi na 200 mA cm-2 (duba ƙaramin sashe na "Ma'aunin Electrochemical" don ƙarin bayani). A yawan da ake samu a yanzu na 200 mA cm-2, matsakaicin ingancin COR ya kasance 93% a cikin awanni 6 na farko, sannan ya ragu kaɗan zuwa 81% bayan awanni 60, yayin da ƙarfin tantanin halitta ya ɗan ƙaru da 7% (daga 1.62 V zuwa 1.73 V), yana nuna kyakkyawan kwanciyar hankali. Da yawan wutar lantarki ya karu zuwa 300 mA cm−2, ingancin AA ya kasance kusan ba a canza shi ba (ya ragu daga 85% zuwa 72%), amma ƙarfin wutar lantarki na tantanin halitta ya ƙaru sosai (daga 1.71 zuwa 2.09 V, wanda ya yi daidai da 22%) a lokacin gwajin awanni 46 (Hoto na 6e). Mun yi hasashen cewa babban dalilin lalacewar aiki shine tsatsawar membrane na musayar anion (AEM) ta hanyar cyclohexanone, wanda ke haifar da ƙaruwar juriyar tantanin halitta da ƙarfin lantarki na tantanin lantarki (Hoto na Ƙari na 36), tare da ɗan zubar da electrolyte daga anode zuwa cathode, wanda ke haifar da raguwar girman anolyte da buƙatar dakatar da electrolysis. Bugu da ƙari, raguwar FE na AA na iya kasancewa saboda fitar da abubuwan kara kuzari, wanda ke fifita buɗewar kumfa Ni don OER. Domin nuna tasirin AEM da ya lalace akan lalacewar kwanciyar hankali a 300 mA cm−2, mun maye gurbinsa da sabon AEM bayan awanni 46 na electrolysis. Kamar yadda aka zata, an dawo da ingancin catalytic a bayyane, tare da raguwar ƙarfin lantarki na tantanin halitta sosai zuwa ƙimar farko (daga 2.09 zuwa 1.71 V) sannan kuma ya ɗan ƙaru a cikin awanni 12 na gaba na electrolysis (daga 1.71 zuwa 1.79 V, ƙaruwar 5%; Hoto na 6e).
Gabaɗaya, mun sami damar cimma daidaiton samar da AA na tsawon awanni 60 a yawan yanzu na 200 mA cm−2, wanda ke nuna cewa ƙarfin wutar lantarki na FE da ƙwayoyin halitta na AA suna da kyau. Mun kuma gwada yawan wutar lantarki mafi girma na 300 mA cm−2 kuma mun sami daidaiton gabaɗaya na awanni 58, inda muka maye gurbin AEM da sabo bayan awanni 46. Nazarin da ke sama ya nuna daidaiton mai haɓaka kuma ya nuna a sarari buƙatar haɓaka AEM masu ƙarfi a nan gaba don inganta daidaiton dogon lokaci na MEA don ci gaba da samar da AA a yawan yanzu da ya dace da masana'antu.
Dangane da aikin MEA ɗinmu, mun gabatar da cikakken tsarin samar da AA wanda ya haɗa da ciyar da substrate, electrolysis, neutralization, da rabe-raben abubuwa (Hoto na Ƙarin 37). An gudanar da nazarin aiki na farko don tantance yuwuwar tattalin arziki na tsarin ta amfani da samfurin samar da electrolyte electrocatalytic carboxylate alkaline55. A wannan yanayin, farashi ya haɗa da jari, ayyuka, da kayan aiki (Hoto na 7a da Hoto na Ƙarin 38), kuma kudaden shiga sun fito ne daga samar da AA da H2. Sakamakon TEA ya nuna cewa a ƙarƙashin yanayin aikinmu (yawan yanzu 300 mA cm-2, ƙarfin tantanin halitta 1.76 V, FE 82%), jimillar kuɗaɗen da kudaden shiga sune US$2429 da US$2564, bi da bi, wanda ke fassara zuwa ribar dalar Amurka $135 kowace tan na AA da aka samar (duba Ƙarin Bayani 9 don cikakkun bayanai).
Jimlar kuɗin tsarin lantarki na AA a ƙarƙashin yanayin tushe tare da FE na 82%, yawan yanzu na 300 mA cm−2, da ƙarfin lantarki na tantanin halitta na 1.76 V. Binciken hankali na farashi uku zuwa yawan b FE da c. A cikin nazarin hankali, an bambanta sigogin da aka yi nazari kawai kuma an kiyaye sauran sigogi daidai bisa ga samfurin TEA. d Tasirin FE daban-daban da yawan yanzu akan ribar electrosynthesis na AA da ribar ta amfani da Ni(OH)2-NS da NiV-LDH-NS, ana ɗauka cewa ƙarfin tantanin halitta yana kasancewa daidai a 1.76 V. Bayanan shigarwa na a–d an bayar da su a cikin fayil ɗin bayanai na asali.
Dangane da wannan hujja, mun ƙara bincika tasirin FE da yawan yanzu akan ribar lantarki ta AA. Mun gano cewa ribar tana da matuƙar tasiri ga FE na AA, tunda raguwar FE yana haifar da ƙaruwa mai yawa a cikin farashin aiki, wanda hakan ke ƙara yawan kuɗin gaba ɗaya (Hoto na 7b). Dangane da yawan yanzu, yawan wutar lantarki mafi girma (>200 mA cm-2) yana taimakawa wajen rage farashin jari da farashin ginin masana'antu, galibi ta hanyar rage yankin ƙwayoyin lantarki, wanda hakan ke ba da gudummawa ga ƙaruwar riba (Hoto na 7c). Idan aka kwatanta da yawan yanzu, FE yana da tasiri mai mahimmanci akan riba. Ta hanyar kwatanta tasirin FE da yawan yanzu akan riba, mun ga a sarari mahimmancin cimma babban FE (>60%) a yawan yanzu da ya dace da masana'antu (>200 mA cm-2) don tabbatar da riba. Saboda yawan ƙimar FE na AA, tsarin amsawa tare da NiV-LDH-NS a matsayin mai haɓaka ya kasance mai kyau a cikin kewayon 100-500 mA cm−2 (digogi na pentagram; Hoto na 7d). Duk da haka, ga Ni(OH)2-NS, rage FE a babban yawan wutar lantarki (>200 mA cm−2) ya haifar da sakamako mara kyau (da'ira; Hoto na 7d), yana nuna mahimmancin abubuwan da ke haifar da catalysts masu babban FE a babban yawan wutar lantarki.
Baya ga mahimmancin abubuwan da ke haifar da haɓaka aiki wajen rage farashin jari da aiki, kimantawarmu ta TEA ta nuna cewa za a iya ƙara inganta ribar ta hanyoyi biyu. Na farko shine a haɗa da sayar da potassium sulfate (K2SO4) a kasuwa a matsayin wani ɓangare na ɓangaren rage yawan amfani da sinadarai, amma tare da yuwuwar samun kuɗin shiga na US $828/t AA-1 (Bayani na Ƙarin Bayani na 9). Na biyu shine a inganta fasahar sarrafawa, gami da sake amfani da kayan aiki ko haɓaka fasahar rabuwar AA mai inganci (madadin raka'o'in rage yawan amfani da sinadarai). Tsarin rage yawan amfani da sinadarai na acid-base da ake amfani da shi a halin yanzu na iya haifar da hauhawar farashin kayan aiki (wanda ya kai babban kaso a 85.3%), wanda kashi 94% ya faru ne saboda cyclohexanone da KOH ($2069/t AA-1; Hoto na 7a), amma kamar yadda aka ambata a sama, tsarin har yanzu yana da riba gaba ɗaya. Muna ba da shawarar cewa za a iya ƙara rage farashin kayan aiki ta hanyar hanyoyin da suka fi ci gaba don dawo da KOH da cyclohexanone mara amsawa, kamar su electrodialysis don cikakken dawo da KOH14 (ƙiyasin farashin US $1073/t AA-1 ta hanyar electrodialysis; Ƙarin Bayani na 9).
A taƙaice, mun sami ingantaccen aikin electrolysis na atom na aluminum a babban yawan wutar lantarki ta hanyar shigar da V cikin nanosheets na Ni(OH)2. A ƙarƙashin kewayon yuwuwar 1.5–1.9 VRHE da yawan wutar lantarki mai yawa na 170 mA cm−2, AA FE akan NiV-LDH-NS ya kai 83–88%, yayin da aka rage OER sosai zuwa 3%. Gyaran V ya haɓaka rage Ni2+ zuwa Ni3+x kuma ya haɓaka shaƙar cyclohexanone. Bayanan gwaji da na ka'idoji sun nuna cewa sake ginawa da aka ƙarfafa yana ƙara yawan halin yanzu don iskar shaƙa ta cyclohexanone kuma yana canza RDS na COR daga sake ginawa zuwa dehydrogenation wanda ya haɗa da scission na Cα − H, yayin da haɓaka shaƙar cyclohexanone yana hana OER. Ci gaban MEA ya sami ci gaba da samar da AA a yawan halin yanzu na masana'antu na 300 mA cm−2, rikodin ingancin AA na 82%, da kuma yawan aiki na 1536 μmol cm−2 h−1. Gwaji na tsawon awanni 50 ya nuna cewa NiV-LDH-NS yana da kyakkyawan kwanciyar hankali domin yana iya riƙe babban AA FE a cikin MEA (> 80% na tsawon awanni 60 a 200 mA cm−2; > 70% na tsawon awanni 58 a 300 mA cm−2). Ya kamata a lura cewa akwai buƙatar haɓaka ƙarin AEMs masu ƙarfi don cimma kwanciyar hankali na dogon lokaci a cikin yawan wutar lantarki mafi kyau a masana'antu. Bugu da ƙari, TEA tana nuna fa'idodin tattalin arziki na dabarun amsawa don samar da AA da mahimmancin abubuwan haɓaka aiki masu ƙarfi da fasahar rabuwa ta zamani don ƙara rage farashi.