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Ama-electrocatalyst asebenza kahle, angabizi futhi ahlala isikhathi eside enciphisa umoya-mpilo (ORR) abaluleke kakhulu kumabhethri esibili e-Zn-air.Umsebenzi we-ORR wama-oxide ensimbi eyodwa nexubile nama-carbon electrocatalysts waphenywa kusetshenziswa izilinganiso ze-rotating disk electrode (RDE), amathambeka e-Tafel, kanye neziza ze-Kutetsky-Levich.Kutholwe ukuthi inhlanganisela ye-MnOx ne-XC-72R ibonisa umsebenzi ophezulu we-PBP nokuzinza okuhle, kufika ku-100 mA cm–2.Ukusebenza kwama-electrode e-ORR akhethiwe kanye ne-electrode ye-oxygen evolution reaction (OER) eyenziwe kahle ngaphambili kwabe sekuhlolwa ebhethrini lomoya lesibili elakhiwe ngokwezifiso le-zinc-air ekucushweni kwama-electrode amathathu, kanye nokuminyana kwamanje, i-electrolyte molarity, izinga lokushisa, ubumsulwa komoyampilo. futhi ihlolwe.Izici ze-ORR ne-OERama-electrode.Ekugcineni, ukuqina kwesistimu ye-zinc-air yesibili kwahlolwa, okubonisa ukusebenza kahle kwamandla ka-58-61% ku-20 mA cm-2 ku-4 M NaOH + 0.3 M ZnO ku-333 K amahora angu-40.
Amabhethri ensimbi emoyeni ane-oxygen electrode athathwa njengezinhlelo ezikhangayo kakhulu ngoba izinto ezisebenza ngogesi zama-electrode komoyampilo zingatholakala kalula emkhathini ozungezile futhi azidingi ukugcinwa1.Lokhu kwenza idizayini yesistimu ibe lula ngokuvumela i-electrode yomoya-mpilo ukuthi ibe namandla angenamkhawulo, ngaleyo ndlela kwandise ukuminyana kwamandla ohlelo.Ngakho-ke, amabhethri omoya ensimbi asebenzisa izinto ze-anode ezifana ne-lithium, i-aluminium, insimbi, i-zinc, ne-magnesium avele ngenxa yomthamo wawo omuhle kakhulu othize.Phakathi kwawo, amabhethri omoya e-zinc akwazi ngempela ukuhlangabezana nesidingo semakethe sezindleko, ukuphepha, kanye nobungane bemvelo, njengoba i-zinc inezici eziningi ezifiselekayo njengempahla ye-anode, njengokuzinza okuhle kuma-electrolyte anamanzi, ukuminyana kwamandla aphezulu, nokulingana okuphansi.amandla., ukuguqulwa kwe-electrochemical, conductivity enhle kagesi, ukuchichima nokubamba kalula4,5.Njengamanje, nakuba amabhethri omoya we-zinc ayinhloko asetshenziselwa izinhlelo zokusebenza zezentengiselwano ezifana nezinsiza zokuzwa, amasiginali wesitimela nezibani zokuhamba, amabhethri omoya we-zinc yesibili anamandla okuba namandla aphezulu okuqhathaniswa namabhethri e-lithium-based.Lokhu kwenza kube wusizo ukuqhubeka nokucwaninga ngamabhethri omoya ezinc ukuze kusetshenziswe izinto zikagesi eziphathwayo, ezimotweni zikagesi, ukugcinwa kwamandla esikalini segridi kanye nokusekela ukukhiqizwa kwamandla avuselelekayo6,7.
Enye yezinjongo eziyinhloko ukuthuthukisa ukusebenza kahle kokusabela komoyampilo ku-electrode yomoya, okuyi-oxygen reduction reaction (ORR) kanye ne-oxygen evolution reaction (OER), ukuze kuthuthukiswe ukuthengiswa kwamabhethri esibili e-Zn-air.Kuze kube manje, ama-electrocatalyst asebenzayo angasetshenziswa ukwandisa izinga lokuphendula futhi ngaleyo ndlela andise ukusebenza kahle.Njengamanje, ama-electrode oksijini anama-catalysts angasebenzi kahle achazwe kahle ezincwadini8,9,10.Nakuba ama-catalyst asebenza kabili angenza kube lula ukwakheka kwama-electrode futhi anciphise ukulahlekelwa kokudluliswa kwenqwaba, okungasiza ukunciphisa izindleko zokukhiqiza, empeleni, ama-catalysts afaneleka kakhulu ku-ORR ngokuvamile awafaneleki i-OER, futhi ngokuphambene nalokho11.Lo mehluko emandleni okusebenza udala ukuthi i-catalyst ivezwe kububanzi obubanzi bamandla, okungashintsha ukwakheka kwayo kwendawo ngokuhamba kwesikhathi.Ngaphezu kwalokho, ukuncika kwamanye amandla amaphakathi abophayo kusho ukuthi amasayithi asebenzayo ku-catalyst angahluka ekuphenduleni ngakunye, okungase kube nzima ukwenza kahle.
Enye inkinga enkulu yamabhethri e-Zn-air yesibili ukwakhiwa kwe-oxygeni-electrode, ikakhulukazi ngenxa yokuthi ama-catalyst asebenzayo e-ORR kanye ne-OER asebenza kumidiya ehlukene yokusabela.I-ORR gas diffusion layer kumele ibe yi-hydrophobic ukuze ivumele igesi ye-oxygen ukuthi ingene kumasayithi e-catalytic, kuyilapho ku-OER indawo ye-electrode kufanele ibe yi-hydrophilic ukuze kube lula ukukhishwa kwamabhamuza omoya-mpilo.Emkhiwaneni.I-1 ibonisa imiklamo emithathu evamile ye-electrode ye-oksijeni yesibili ethathwe ekubuyekezweni ngu-Jorissen12, okungukuthi (i) ama-monolayer catalysts angasebenzi kahle, (ii) ama-catalyst aphindwe kabili noma ama-multilayer, kanye (iii) nokulungiswa kwama-electrode kathathu.
Ngomklamo wokuqala we-electrode, ohlanganisa kuphela isendlalelo esisodwa se-bifunctional catalyst esenza kanyekanye i-ORR ne-OER, uma ulwelwesi lufakiwe kulo mklamo, bese kwakheka umhlangano we-membrane-electrode (MEA) njengoba kubonisiwe.Uhlobo lwesibili luhlanganisa imibhede emibili (noma ngaphezulu) ye-catalyst ene-porosity ehlukene kanye ne-hydrophobicity ukuze kulandelwe umehluko ezindaweni zokusabela13,14,15.Kwezinye izimo, imibhede emibili ye-catalytic ihlukaniswe, uhlangothi lwe-hydrophilic lwe-OER lubheke i-electrolyte kanye nohlangothi lwe-semi-hydrophobic lwe-ORR lubheke emaphethelweni avulekile ama-electrode 16, 17, 18. iseli elihlanganisa ukusabela okubili- ama-electrode oksijini athile kanye ne-zinc electrode19,20.Ithebula i-S1 ibala izinzuzo kanye nokubi zomklamo ngamunye.
Ukuqaliswa komklamo we-electrode ohlukanisa ukusabela kwe-ORR kanye ne-OER ngaphambilini kubonise ukuzinza okuthuthukisiwe kwamabhayisikili19.Lokhu kuyiqiniso ikakhulukazi ekucushweni kwama-electrode amathathu, lapho ukuwohloka kwama-catalyst nezithasiselo ezihlangene kuncipha khona futhi ukukhipha umoya kulawulwa kakhulu kulo lonke uhla olungase lube khona.Ngenxa yalezi zizathu, sisebenzise ukucushwa kwe-Zn-air ye-electrode emithathu kulo msebenzi.
Kulesi sihloko, siqale sikhethe ama-catalyst e-ORR asebenza kahle ngokuqhathanisa ama-oxide ensimbi eshintshashintshayo, izinto ezisetshenziswa nge-carbonaceous, nama-catalysts ayireferensi ngokuhlolwa kwe-disk electrode (RDE).I-transition metal oxides ijwayele ukuba ama-electrocatalyst amahle ngenxa yezindawo zawo ezihlukene ze-oxidation;ukusabela kwenziwa kalula lapho kukhona lezi zinhlanganisela21.Isibonelo, ama-manganese oxides, ama-cobalt oxides, nama-oxide axubile asuselwa ku-cobalt (njenge-NiCo2O4 ne-MnCo2O4) angu-22,23,24 abonisa i-ORR enhle ezimweni ze-alkaline ngenxa ye-d-orbitals egcwele uhhafu, amazinga wamandla e-electron avumela i-electron. ukusebenza kanye nokunethezeka kokusika okuthuthukisiwe.Ngaphezu kwalokho, ziningi kakhulu emvelweni futhi zine-conductivity kagesi eyamukelekayo, ukusebenza kabusha okuphezulu nokuzinza okuhle.Ngokufanayo, izinto ezisetshenziselwa i-carbonaceous zisetshenziswa kabanzi, zinezinzuzo ze-conductivity ephezulu kagesi kanye nendawo enkulu.Kwezinye izimo, ama-heteroatom afana ne-nitrogen, i-boron, i-phosphorus, ne-sulfure afakwe kukhabhoni ukuze aguqule isakhiwo sayo, ngokuqhubekayo ngcono izici ze-ORR zalezi zinto.
Ngokusekelwe emiphumeleni yokuhlola, sifake ama-catalyst e-OVR akhethiwe kuma-electrode e-gas diffusion electrode (GDE) futhi sawahlola ngokuminyana okuhlukahlukene kwamanje.I-ORR GDE catalyst esebenza kahle kakhulu yabe isihlanganiswa yaba yibhethri lesibili le-Zn-air elesibili elenziwe ngama-electrode amathathu kanye nama-electrode e-OER aqondene nokusabela athuthukisiwe emsebenzini wethu wangaphambilini26,27.Amandla ama-electrode omoya-mpilo angawodwana aqashwa ngesikhathi sokukhishwa okuqhubekayo kanye nokuhlolwa kokuhamba ngebhayisikili ukuze kufundwe umthelela wezimo zokusebenza ezifana nokuminyana kwamanje, i-electrolyte molarity, izinga lokushisa lokusebenza kwamaseli, nokuhlanzeka komoyampilo.Ekugcineni, ukuzinza kwamabhethri esibili e-Zn-air kwahlolwa ngaphansi kokuhamba ngamabhayisikili ngaphansi kwezimo ezikahle zokusebenza.
I-MnOx28 yalungiswa ngendlela yekhemikhali ye-redox: 50 ml wesixazululo esingu-0.04 M KMnO4 (Fisher Scientific, 99%) yengezwe ku-100 ml ka-0.03 Mn(CH3COO)2 (Fisher Scientific, 98%) ukuze kwakheke imvula ensundu.Ingxube ilungiswa ku-pH 12 nge-dilute sodium hydroxide, bese i-centrifuged izikhathi ezi-3-5 ngo-2500 rpm ukuqoqa imvula.Imvula yayibe igezwa ngamanzi angcolile kuze kube yilapho umbala onsomi we-ion permanganate uphela.Ekugcineni, idiphozithi yomiswa emoyeni ku-333 K ngobusuku obubodwa bese icolishwa.
Ama-spinel oxides i-Co3O4, i-NiCo2O4, ne-MnCo2O4 ahlanganiswe ngokubola okushisayo.I-NiCo2O4 ne-MnCo2O4 zilungiswe ngokungeza u-0.5 M (14.5 g) nickel(II) nitrate hexahydrate, Ni(NO3)2⋅6H2O (Fisher Scientific, 99.9%) noma 0.5 M (12.6 g) tetrahydrate manganese(II) nitrate Mn(NO3) ).)2 4H2O (Sigma Aldrich, ≥ 97%) kanye ne-1 M (29.1 g) cobalt(II) nitrate hexahydrate, Co(NO3)2 6H2O (Fisher Scientific, 98+%, ACS reagents) ku-methanol (Fisher Scientific%, 99. ) ku-100 ml dilution vials.I-Methanol yengezwa ezingxenyeni ezincane ku-nitrate yensimbi yenguquko ngokugqugquzela okuqhubekayo kuze kube yilapho kutholakala isisombululo se-homogeneous.Isixazululo sabe sesidluliselwa ku-crucible futhi sishiswa epuleti elishisayo, lishiye okuqinile okubomvu okumnyama.Okuqinile kwabalwa ku-648 K amahora angu-20 emoyeni.Okuqinile okwaba umphumela kwabe kugaywa kube yimpushana ecolekile.Cha i-Ni(NO3)2 6H2O noma i-Mn(NO3)2 4H2O yengezwe ngesikhathi sokuhlanganiswa kwe-Co3O4.
Ama-graphene nanosheet anendawo engu-300 m2/g (Sigma Aldrich), igraphene efakwe i-nitrogen (Sigma Aldrich), i-carbon black powder (Vulcan XC-72R, Cabot Corp., 100%), MnO2 (Sigma Aldrich) kanye 5 wt.% Pt/C (Acros Organics) isetshenziswe njengoba injalo.
Izilinganiso ze-RDE (Pine Research Instrumentation) zasetshenziselwa ukuhlola umsebenzi wamacatalyst ahlukahlukene we-ORR ku-1 M NaOH.Uyinki we-catalytic ohlanganisa i-1 mg catalyst + 1 ml deionized (DI) H2O + 0.5 ml isopropanol (IPA) + 5 µl 5 wt% Nafion 117 (Sigma-Aldrich) wasetshenziswa njengoba kwenzeka.Ngenkathi i-Vulcan XC-72R yengezwa, upende we-catalytic ubuhlanganisa i-catalyst engu-0.5 mg + 0.5 mg Vulcan XC-72R + 1 ml DI HO + 0.5 ml IPA + 5 µl 5 wt% Nafion 117 ukuze kuqinisekiswe ukulayishwa kwezinto ezingaguquki .Ingxube yenziwe nge-sonicated imizuzu engama-20 futhi yahlanganiswa kusetshenziswa i-Cole-Parmer LabGen 7 Series homogenizer ku-28,000 rpm imizuzu emi-4.Uyinki wabe ususetshenziswa kuma-aliquots amathathu ka-8 μl ebusweni be-carbon electrode eyingilazi (Pine Instrument Company) enobubanzi obungu-4 mm (indawo yokusebenza ≈ 0.126 cm2) futhi yomiswa phakathi kwezingqimba ukuze kuhlinzekwe umthwalo ongu-≈120 μg cm. -2.Phakathi kwezinhlelo zokusebenza, indawo eyingilazi ye-electrode ye-carbon electrode yaba manzi ngokulandelana nge-MicroCloth (Buehler) kanye ne-1.0 mm ne-alumina powder engu-0.5 mm (MicroPolish, Buehler) elandelwa yi-sonication ku-H2O eyenziwe nge-deionized.
Amasampula e-electrode yokusabalalisa igesi ye-ORR alungiswa ngokuya ngephrothokholi yethu echazwe ngaphambilini28.Okokuqala, i-catalyst powder ne-Vulcan XC-72R zixutshwe ngesilinganiso sesisindo esingu-1: 1.Khona-ke ingxube yesisombululo se-polytetrafluoroethylene (PTFE) (60 wt.% ku-H2O) kanye ne-solvent ene-IPA/H2O ye-1: 1 yengezwe kungxube ye-powder eyomile.I-Sonicate upende we-catalytic cishe imizuzu engama-20 bese wenza i-homogenize cishe imizuzu emi-4 ngo-28,000 rpm.Uyinki wabe usugcotshwa kancane nge-spatula ephepheni lekhabhoni elisikwe ngaphambili elingu-13 mm ububanzi (AvCarb GDS 1120) futhi womiswa kuze kube yilapho kufinyelelwa khona okuqukethwe kwe-catalyst okungu-2 mg cm2.
Ama-electrode e-OER akhiwe nge-cathodic electrodeposition ye-Ni—Fe hydroxide catalysts kunsimbi engenasici engu-15 mm x 15 mm.Imeshi(DeXmet Corp, 4SS 5-050) njengoba kubikiwe26,27.I-Electrodeposition yenziwa kuhhafu yeseli elijwayelekile le-electrode emithathu (iseli lengilazi elivalwe nge-polymer elicishe libe ngu-20 cm3) elinegridi ye-Pt njenge-counter electrode kanye ne-Hg/HgO ku-1 M NaOH njenge-electrode eyireferensi.Vumela i-catalyst coated steel stainless mesh ukuthi yome emoyeni ngaphambi kokusika indawo ecishe ibe ngu-0.8 cm2 ngesibhakela sensimbi esiwugqinsi esingu-10 mm.
Ukuze uqhathanise, ama-electrode e-ORR kanye ne-OER yezohwebo asetshenziswe njengoba amukelwa futhi ahlolwa ngaphansi kwezimo ezifanayo.I-electrode ye-ORR yezohwebo (i-QSI Nano Gas Diffusion Electrode, Quantum Sphere, 0.35 mm ugqinsi) iqukethe imanganese ne-carbon oxide embozwe nge-nickel mesh collector yamanje, kuyilapho i-electrode ye-OER yokuhweba (uhlobo 1.7, i-Magneto anode ekhethekile, i-BV) inogqinsi ongu-1.3 mm.kuze kufike ku-1.6 mm inwetshiwe ye-titanium mesh ehlanganiswe ne-Ru-Ir exutshwe i-metal oxide.
Ukuma komhlaba kanye nokwakheka kwama-catalyst kwabonakala kusetshenziswa i-FEI Quanta 650 FEG scanning electron microscope (SEM) esebenza ngaphansi kwevacuum ephezulu kanye ne-voltage esheshayo engu-5 kV.Idatha ye-Powder X-ray diffraction (XRD) yaqoqwa ku-Bruker D8 Advance X-ray diffractometer enomthombo weshubhu yethusi (λ = 1.5418 Å) futhi yahlaziywa kusetshenziswa isofthiwe ye-Bruker Diffraction Suite EVA.
Zonke izilinganiso ze-electrochemical zenziwe kusetshenziswa i-Biologic SP-150 potentiostat nesofthiwe ye-EC-lab.Amasampuli e-RDE ne-GDE ahlolwe ekusetheni okujwayelekile kwama-electrode amathathu okuhlanganisa iseli lengilazi elinejakhethi elingu-200 cm3 kanye ne-Laggin capillary njenge-electrode eyireferensi.I-Pt mesh ne-Hg/HgO ku-1 M NaOH isetshenziswe njengama-electrodes ekhawunta nereferensi, ngokulandelanayo.
Ezilinganisweni ze-RDE ekuhloleni ngakunye, kusetshenziswe i-electrolyte engu-1 M NaOH entsha, izinga lokushisa eligcinwe lingashintshile liku-298 K kusetshenziswa ibhavu lamanzi elizungezayo (TC120, Grant).I-gaseous oxygen (BOC) ibigeleza ku-electrolyte ngokusebenzisa ingilazi ye-porosity engu-25–50 µm okungenani imizuzu engu-30 ngaphambi kokuhlolwa ngakunye.Ukuze kutholwe amajika e-ORR e-polarization, amandla askenwa kusukela ku-0.1 kuya ku- -0.5 V (okuhlobene ne-Hg/HgO) ngesilinganiso sokuskena esingu-5 mV s -1 ku-400 rpm.Ama-voltammograms e-cyclic atholwe ngokushanela amandla aphakathi kuka-0 kanye -1.0 V kanye ne-Hg/HgO ngenani elingu-50 mV s-1.
Ezilinganisweni ze-HDE, i-electrolyte engu-1 M NaOH iye yagcinwa iku-333 K nebhavu lamanzi elizungezayo.Indawo esebenzayo engu-0.8 cm2 yavezwa ku-electrolyte ngokunikezwa okuqhubekayo komoya-mpilo ohlangothini olungemuva lwe-electrode ngesilinganiso esingu-200 cm3/min.Ibanga elinqunyiwe phakathi kwe-electrode esebenzayo kanye ne-electrode eyireferensi lalingu-10 mm, futhi ibanga phakathi kwe-electrode esebenzayo ne-counter electrode lalingu-13-15 mm.Intambo ye-nickel kanye ne-mesh inikeza ukuthintana kukagesi ohlangothini lwegesi.Izilinganiso ze-Chronopotentiometric zithathwe ku-10, 20, 50 kanye ne-100 mA cm-2 ukuze kuhlolwe ukuzinza nokusebenza kahle kwe-electrode.
Izici zama-electrode e-ORR kanye ne-OER zihlolwe kuseli lengilazi elinejakhethi elingu-200 cm3 elifaka i-PTFE29.Umdwebo wohlelo lwesistimu uboniswa kuMfanekiso S1.Ama-electrode ebhethri axhunywe ohlelweni lwe-electrode emithathu.I-electrode esebenzayo yayihlanganisa ama-electrode ahlukene okusabela okuthize i-ORR kanye ne-OER exhunywe kumojula edluliselwe emuva (Ingoma, i-SRD-05VDC-SL-C) kanye nesilawuli esincane (i-Raspberry Pi 2014© imodeli B+V1.2) ene-anode ye-zinc.njengepheya Ama-electrode kanye ne-electrode eyireferensi Hg/HgO ku-4 M NaOH bekukude no-3 mm ukusuka ku-anode ye-zinc.Isikripthi se-Python sibhaliwe ukuze sisebenze futhi silawule i-Raspberry Pi ne-Relay Module.
Iseli lishintshiwe ukuze lifake i-anode ye-zinc foil (Goodfellow, 1 mm ukujiya, 99.95%) kanye nesembozo se-polymer savumela ama-electrode ukuthi abekwe ebangeni elingaguquki elicishe libe ngamamitha ayi-10.4 mm phakathi.Amapulagi enjoloba e-Nitrile alungisa ama-electrode esivaloni, nezintambo ze-nickel (Alfa Aesar, 0.5 mm ububanzi, annealed, 99.5% Ni) zasetshenziselwa ukuxhumana kukagesi kwama-electrode.I-anode ye-zinc foil yaqale yahlanzwa nge-isopropanol kwase kuba ngamanzi a-deionized, futhi ingaphezulu le-foil lambozwa nge-polypropylene tape (Avon, AVN9811060K, 25 µm ubukhulu) ukuze kuvezwe indawo esebenzayo ecishe ibe ngu-0.8 cm2.
Zonke izivivinyo zokuhamba ngebhayisikili zenziwe ku-4 M NaOH + 0.3 M ZnO electrolyte ngo-333 K ngaphandle kwalapho kuboniswe ngenye indlela.Emfanekisweni, i-Ewe ngokuphathelene ne-Hg/HgO ibhekisela emandleni e-electrode yomoya-mpilo (ORR kanye ne-OER), i-Ece ngokuphathelene ne-Hg/HgO imele amandla e-electrode ye-zinc, i-Ecell mayelana ne-Hg/HgO imelela ngokugcwele. amandla eseli noma umehluko ongaba khona.phakathi kwamandla amabili ebhethri.Ioksijeni noma umoya ocindezelwe wanikezwa ohlangothini olungemuva lwe-electrode ye-OPP ngesilinganiso sokugeleza esingaguquki esingu-200 cm3/min.Ukuzinza kokuhamba ngebhayisikili nokusebenza kwama-electrode kwacwaningwa ngokuminyana kwamanje okungu-20 mA cm-2, isikhathi somjikelezo esiyimizuzu engama-30, kanye nesikhathi sokuphumula se-OCV esiyiminithi elingu-1 phakathi komjikelezo ngamunye wesigamu.Okungenani imijikelezo eyi-10 yenziwa ekuhlolweni ngakunye, futhi idatha yakhishwa kumjikelezo 1, 5, no-10 ukuze kunqunywe isimo sama-electrode ngokuhamba kwesikhathi.
I-morphology ye-ORR catalyst ibonakala nge-SEM (Fig. 2), futhi izilinganiso ze-powder X-ray diffraction ziqinisekisa isakhiwo se-crystal samasampuli (Fig. 3).Amapharamitha esakhiwo samasampula e-catalyst anikezwe kuThebula 1. 1. Uma uqhathanisa ama-manganese oxides, i-MnO2 yokuhweba kufig.I-2a iqukethe izinhlayiya ezinkulu, futhi iphethini ye-diffraction ku-Fig. 3a ihambisana ne-JCPDS 24-0735 ye-tetragonal β-MnO2.Ngokuphambene nalokho, endaweni ye-MnOx ku-Fig. 2b ibonisa izinhlayiya ezicolekile nezicolekile, ezihambisana nephethini ye-diffraction ku-Fig. 66 ° zihambisana neziqongo (110), (220), (310), (211), kanye (541) ye-tetrahedral egxile ku-α-MnO2 hydrate, JCPDS 44-014028.
(a) MnO2, (b) MnOx, (c) Co3O4, (d) NiCo2O4, (e) MnCo2O4, (f) Vulcan XC-72R, (g) igraphene, (h) i-nitrogen doped graphene, (kanye) 5 wt .% Pt/C.
Amaphethini we-X-ray (a) MnO2, (b) MnOx, (c) Co3O4, (d) NiCo2O4, (e) MnCo2O4, (f) Vulcan XC-72R, i-nitrogen-doped graphene negraphene, kanye (g) 5 % iplatinum/carbon.
Emkhiwaneni.I-2c–e, i-surface morphology yama-oxides asekelwe ku-cobalt Co3O4, i-NiCo2O4, ne-MnCo2O4 iqukethe amaqoqo ezinhlayiya ezinosayizi ongajwayelekile.Emkhiwaneni.I-3c–e ikhombisa ukuthi zonke lezi zinguqukoinsimbiama-oxide anesakhiwo se-spinel kanye nesistimu ye-cubic crystal efanayo (JCPDS 01-1152, JCPDS 20-0781, ne-JCPDS 23-1237, ngokulandelana).Lokhu kubonisa ukuthi indlela yokubola okushisayo iyakwazi ukukhiqiza ama-oxide ensimbi ecwebe kakhulu, njengoba kuboniswa iziqongo eziqinile ezichazwe kahle kuphethini yokuhlukanisa.
Izithombe ze-SEM zezinto zekhabhoni zibonisa izinguquko ezinkulu.Emkhiwaneni.I-2f Vulcan XC-72R carbon black iqukethe ama-nanoparticles aminyene.Ngokuphambene nalokho, ukubonakala kwe-graphene ku-Fig. 2g amapuleti aphazamisekile kakhulu anama-agglomerations athile.Nokho, i-graphene ye-N-doped (Fig. 2h) ibonakala iqukethe izendlalelo ezincane.Amaphethini ahambisanayo we-X-ray diffraction we-Vulcan XC-72R, ama-graphene nanosheets okuhweba, kanye ne-N-doped graphene kumakhiwane.I-3f ibonisa izinguquko ezincane kumanani angu-2θ weziqongo zekhabhoni (002) kanye (100).I-Vulcan XC-72R ikhonjwa njenge-hexagonal graphite ku-JCPDS 41-1487 eneziqongo (002) kanye (100) ezibonakala ku-24.5° naku-43.2° ngokulandelanayo.Ngokufanayo, iziqongo ze-(002) kanye (100) ze-N-doped graphene zivela ku-26.7° naku-43.3°, ngokulandelana.Ukushuba kwangemuva okuphawulwe kumaphethini wokuhluka kwe-X-ray we-Vulcan XC-72R kanye ne-nitrogen-doped graphene kungenxa yemvelo ephazamisekile kakhulu yalezi zinto ku-morphology yazo.Ngokuphambene, iphethini ye-diffraction yama-graphene nanosheets ibonisa ukuphakama okubukhali, okuqinile (002) ku-26.5° kanye nenani elincane elincane elibanzi (100) ku-44°, okubonisa imvelo ecwebe kakhulu yalesi sampuli.
Ekugcineni, emkhiwaneni.Isithombe se-2i SEM esingu-5 wt.% Pt/C sibonisa izingcezu zekhabhoni ezimise okwenduku ezinama-void ayindilinga.I-Cubic Pt inqunywa kusukela eziqongweni eziningi zephethini ye-diffraction engu-5 wt% ye-Pt/C ku-Fig. 3g, futhi isiqongo esingu-23° sihambisana no-(002) wekhabhoni ekhona.
Umugqa woshanela we-ORR catalyst voltammogram urekhodwe ngenani lokushanela elingu-5 mV s-1.Ngenxa yemikhawulo yokudluliswa kwenqwaba, amamephu aqoqiwe (Fig. 4a) ngokuvamile anomumo we-S odlulela endaweni eyithafa enamandla amaningi amabi.Ukuminyana kwamanje okukhawulelayo, i-jL, i-E1/2 engaba khona (lapho j/jL = ½) namandla okuqalisa ku- -0.1 mA cm-2 akhishiwe kulezi ziqephu futhi akleliswa kuThebula 2. Kubalulekile ukuqaphela ukuthi kumfanekiso.4a, ama-catalysts angahlukaniswa ngokwamandla awo we-E1/2 abe yilokhu: (I) ama-oxide ensimbi, (II) izinto ze-carbonaceous, kanye (III) nezinsimbi ezinhle.
I-Linear sweep voltammograms (a) i-catalyst kanye (b) nefilimu ezacile ye-catalyst ne-XC-72R, ikalwa nge-RDE glassy carbon probe ngo-400 rpm ngesilinganiso sokuskena esingu-5 mV s-1 ekugcwalisweni kwe-O2 ku-298 K ku-1 M NaOH cf.
Ama-oxide ensimbi angawodwana we-Mn no-Co eqenjini I abonisa amandla okuqala ka- -0.17 V kanye -0.19 V ngokulandelana, namavelu e-E1/2 aphakathi kuka -0.24 kanye -0.26 V. Ukusabela kokunciphisa kwalawa ma-oxide ensimbi kuvezwa ngesibalo .(1) kanye no-(2), avela eduze kwamandla okuqala ku-Fig.4a ifanise amandla ajwayelekile esinyathelo sokuqala esingu-2e sendlela engaqondile ye-ORR esibalweni.(3).
Ama-oxide ensimbi axutshwe i-MnCo2O4 ne-NiCo2O4 eqenjini elifanayo abonisa amandla okuqala alungiswe kancane kokuthi -0.10 kanye -0.12 V ngokulandelanayo, kodwa agcina amanani we-E1/2 cishe angu-10.−0.23 volts.
Izinto zekhabhoni zeqembu II zibonisa amanani amahle kakhulu we-E1/2 kunama-oxide ensimbi eqembu I.I-graphene inamandla okuqala angu- -0.07 V kanye nevelu engu-E1/2 engu- -0.11 V, kuyilapho amandla okuqala kanye ne-E1/2 ye-72R Vulcan XC- kungu- -0.12V kanye -0.17V ngokulandelanayo.Eqenjini le-III, i-5 wt% i-Pt/C ibonise amandla okuqala amahle kakhulu ku-0.02 V, i-E1/2 ye- -0.055 V, kanye nomkhawulo omkhulu ku -0.4 V, njengoba ukuncishiswa kwe-oksijeni kwenzeke ngokusebenzisa ukuminyana kwamanje kwendlela ye-4e .Iphinde ibe ne-E1/2 ephansi kakhulu ngenxa yokuqhutshwa okuphezulu kwe-Pt/C kanye ne-kinetics ehlehliswayo yokusabela kwe-ORR.
Umfanekiso S2a wethula ukuhlaziywa kwemithambeka ye-Tafel kuma-catalyst ahlukahlukene.Isifunda esilawulwa nge-kinetically esingu-5 wt.% Pt/C siqala ku-0.02 V ngokuphathelene ne-Hg/HgO, kuyilapho isifunda sama-oxide ensimbi nezinto zekhabhoni zisebangeni lamandla angemahle ukusuka ku- -0.03 ukuya -0.1 V. Inani lemithambeka ku-Tafel Pt/C ngu--63.5 mV ss–1, okujwayelekile ku-Pt ekuminyanisweni okuphansi kwamanje dE/d log i = -2.3 RT/F31.32 lapho isinyathelo sokunquma izinga sibandakanya ukushintshwa komoya-mpilo usuka ku-physisorption uye ku-physisorption ikhemisorption33,34.Amanani emithambeka e-Tafel ezinto zekhabhoni asendaweni efanayo ne-Pt/C (-60 ukuya ku- -70 mV div-1), aphakamisa ukuthi lezi zinto ezisetshenziswayo zinezindlela ezifanayo ze-ORR.I-oxide yensimbi ngayinye ye-Co kanye ne-Mn ibika i-Tafel yemithambeka esukela ku- -110 kuya ku- -120 mV dec-1, okuyi-dE/d log i = -2.3 2RT/F, lapho isinyathelo sokunquma isilinganiso siyi-electron yokuqala.dlulisa isinyathelo esingu-35, 36. Amanani emithambeka aphakeme kancane aqoshwe ama-oxide ensimbi exubile i-NiCo2O4 ne-MnCo2O4, cishe -170 mV dec-1, abonisa ukuba khona kwama-ion we-OH- ne-H2O ebusweni be-oxide, okuvimbela ukungena komoyampilo futhi ukudluliswa kwama-electron, ngaleyo ndlela kuthinte umoya-mpilo.indlela yokunciphisa 35.
I-equation ye-Kutetsky-Levich (KL) isetshenziselwe ukunquma imingcele yokusabela kwe-kinetic yamasampuli e-catalyst ahlukahlukene ngaphandle kokudluliswa kwenqwaba.ku-equation.(4) isamba sokuminyana samanje esikaliwe j siyisamba sokuminyana kwamanje kokudluliswa kwama-electron nokudluliswa kwenqwaba.
kusuka ku-equation.(5) Ukuminyana kwamanje okukhawulela i-jL kuhambisana nempande eyisikwele yesivinini sokuzungezisa.Ngakho-ke, i-equation ye-KL.(6) ichaza igrafu yomugqa ka-j−1 uma iqhathaniswa no-ω−1//2, lapho iphoyinti lokuhlangana khona lingu-jk futhi umthambeka wegrafu ungu-K.
lapho u-ν kuyi-kinematic viscosity ye-electrolyte 1 M NaOH (1.1 × 10–2 cm2 s–1)37, D iyi-coefficient yokusabalalisa ye-O2 ku-1 M NaOH (1.89 × 10–5 cm2 s–1)38, ω i-rpm ijubane lokuzungeza, u-C ukugcwala komoyampilo kusixazululo senqwaba (8.4 × 10–7 mol cm–3)38.
Qoqa ama-voltammogram ashanelwe ngomugqa usebenzisa i-RDE ku-100, 400, 900, 1600, kanye no-2500 rpm.Amanani athathwe ku--0.4 V endaweni elinganiselwe yokudluliswa kwenqwaba ukuze ahlele umdwebo we-KL, okungukuthi -j-1 ngokumelene no-ω-1//2 we-catalyst (Fig. S3a).Sebenzisa izibalo.Ezilinganisweni (6) kanye (7), izinkomba zokusebenza ze-catalyst, njengokuminyana kwamanje kwe-kinetic ngaphandle kokucabangela imiphumela yokudluliswa kobuningi jk, kunqunywa indawo yokuphambana ne-eksisi ka-y, kanye nenombolo ukudluliswa kwama-electron kunqunywa i-gradient K yejika.Asohlwini lwethebula lesi-2.
I-5 wt% Pt/C ne-XC-72R inamanani aphansi we-jk aphelele, abonisa ama-kinetics asheshayo alezi zinto.Kodwa-ke, ukuthambeka kwejika le-XC-72R cishe kuphindwe kabili kunalokho ku-5 wt% Pt/C, okulindelekile njengoba i-K iyinkomba yenani lama-electron adluliswayo ngesikhathi sokusabela kokunciphisa umoya-mpilo.Ngokwethiyori, itulo le-KL le-5 wt% Pt/C kufanele lidlule kumsuka wama-39 ngaphansi kwezimo ezilinganiselwe zokudluliswa kwenqwaba, nokho lokhu akubonwa ku-Figure S3a, okuphakamisa imikhawulo ye-kinetic noma yokusabalalisa ethinta imiphumela.Lokhu kungase kube ngenxa yokuthi uGarsani et al.I-40 ibonise ukuthi ukungahambisani okuncane ku-topology kanye ne-morphology yamafilimu e-Pt/C e-catalytic kungathinta ukunemba kwamanani omsebenzi we-ORR.Kodwa-ke, njengoba wonke amafilimu e-catalyst alungiswa ngendlela efanayo, noma yimuphi umphumela emiphumeleni kufanele ufane nawo wonke amasampula.Iphoyinti eliphambanayo le-graphene KL lika-≈ -0.13 mA-1 cm2 liqhathaniswa nele-XC-72R, kodwa indawo enqamulayo -0.20 mA-1 cm2 yegrafu ye-N-doped graphene KL ikhombisa ukuthi ukuminyana kwamanje kukhulu kuncike ekutheni i-voltage ku-converter ye-catalytic.Lokhu kungase kube ngenxa yokuthi i-nitrogen doping ye-graphene inciphisa ukuqhutshwa kukagesi kukonke, okuholela ekudluliseni kwama-electron kancane kinetics.Ngokuphambene, inani eliphelele lika-K le-graphene ene-nitrogen-doped lincane kunele-graphene ngoba ukuba khona kwe-nitrogen kusiza ekudaleni amasayithi asebenza kakhulu we-ORR41,42.
Kuma-oxide asekelwe ku-manganese, indawo yokuhlangana yenani elikhulu kunawo wonke iyabonwa - 0.57 mA-1 cm2.Noma kunjalo, inani eliphelele lika-K le-MnOx liphansi kakhulu kunele-MnO2 futhi lisondele ku-5 wt %.%Pt/C.Izinombolo zokudlulisa ama-electron zinqunywe ukuthi zilinganiselwa.I-MnOx ingu-4 kanti i-MnO2 iseduze no-2. Lokhu kuhambisana nemiphumela eshicilelwe ezincwadini, ezibika ukuthi inani lokudluliselwa kwama-electron endleleni ye-α-MnO2 ORR ngu-4, kuyilapho u-β-MnO243 ngokuvamile engaphansi kuka-4. Ngakho Ngakho , izindlela ze-ORR ziyahlukahluka ezinhlotsheni ze-polymorphic ze-catalysts ezisekelwe ku-manganese oxide, nakuba amazinga ezinyathelo zamakhemikhali ahlala cishe afanayo.Ikakhulukazi, ama-catalysts we-MnOx kanye ne-MnCo2O4 anezinombolo zokudlulisa ama-electron eziphakeme kancane kuno-4 ngenxa yokuthi ukuncipha kwama-manganese oxide akhona kulawa ma-catalyst kwenzeka kanye kanye nokuncipha komoyampilo.Emsebenzini odlule, sithole ukuthi ukuncishiswa kwe-electrochemical kwe-manganese oxide kwenzeka ebangeni elingase libe khona njengokwehliswa komoyampilo esixazululweni esigcwele i-nitrogen28.Umnikelo wokusabela oseceleni uholela enanini elibaliwe lama-electron angaphezu kuka-4.
Impambanomgwaqo ye-Co3O4 ingu-≈ −0.48 mA-1 cm2, enegethivu encane kunezinhlobo ezimbili ze-manganese oxide, futhi inombolo yokudlulisa i-electron ebonakalayo inqunywa inani lika-K elilingana no-2. Ukushintsha i-Ni ku-NiCo2O4 kanye ne-Mn ku-MnCo2O4 ngo-Co kuholela ekwehleni kwamanani aphelele K, okubonisa ukuthuthukiswa kwe-kinetics yokudlulisa ama-electron kuma-oxide ensimbi exubile.
Ama-substrates ekhabhoni anezelwa kuyinki we-ORR we-catalyst ukuze kukhuliswe ukuqhutshwa kukagesi futhi kube lula ukwakheka komngcele ofanele wezigaba ezintathu kuma-electrode okusabalalisa igesi.I-Vulcan-XC-72R ikhethwe ngenxa yenani layo eliphansi, indawo enkulu engu-250 m2·g-1, kanye nokumelana okuphansi okungu-0.08 kuya ku-1 Ω·cm44.45.Isakhiwo se-LSV sesampula ye-catalyst exutshwe ne-Vulcan XC-72R ku-400 rpm siboniswa kuMfanekiso 1. 4b.Umphumela osobala kakhulu wokwengeza i-Vulcan XC-72R ukukhulisa ukuminyana kwamanje.Qaphela ukuthi lokhu kubonakala kakhulu kuma-oxide ensimbi, nge-0.60 mA cm-2 eyengeziwe kuma-oxide ensimbi eyodwa, u-0.40 mA cm-2 wama-oxide ensimbi exutshwe, kanye no-0.28 mA cm-2 we-graphene ne-graphene ene-doped.N. Engeza u-0.05 mA cm-2.−2.Ukwengezwa kwe-Vulcan XC-72R kuyinki ye-catalyst kuphinde kwaholela ekushintsheni okuhle kwamandla okuqala kanye namandla we-E1/2 wamagagasi ohhafu wawo wonke ama-catalyst ngaphandle kwe-graphene.Lezi zinguquko zingase zibe umphumela ongase ube umphumela wokwanda kokusetshenziswa kwendawo ye-electrochemical46 kanye nokuthuthukiswa kokuxhumana47 phakathi kwezinhlayiya ze-catalyst ku-catalyst ye-Vulcan XC-72R esekelwe.
Iziqephu ze-Tafel ezihambisanayo kanye nemingcele ye-kinetic yalezi zingxube ze-catalyst ziboniswa kuMfanekiso S2b kanye neThebula 3, ngokulandelanayo.Amanani emithambeka e-Tafel ayefana kuzinto ze-MnOx ne-graphene ezine-XC-72R nangaphandle kwayo, okubonisa ukuthi izindlela zabo ze-ORR azizange zithinteke.Nokho, ama-oxide asekelwe ku-cobalt i-Co3O4, i-NiCo2O4 ne-MnCo2O4 anikeze amanani amancane amancane anegethigethi emthambekeni we-Tafel phakathi kuka- -68 no- -80 mV dec-1 kuhlanganiswe ne-XC-72R ebonisa ukushintsha kwendlela ye-ORR.Umfanekiso we-S3b ubonisa isakhiwo se-KL sesampula ye-catalyst ehlanganiswe ne-Vulcan XC-72R.Ngokuvamile, ukwehla kwamanani aphelele we-jk kwabonwa kuwo wonke ama-catalysts ahlanganiswe ne-XC-72R.I-MnOx ibonise ukwehla okukhulu kunani eliphelele le-jk ngo-55 mA-1 cm2, kuyilapho i-NiCo2O4 iqophe ukwehla ngo-32 mA-1 cm-2, futhi i-graphene ibonise ukwehla okuncane kakhulu ngo-5 mA-1 cm2.Kungaphethwa ngokuthi umthelela we-Vulcan XC-72R ekusebenzeni kwe-catalyst ukhawulelwe umsebenzi wokuqala we-catalyst ngokuya nge-OVR.
I-Vulcan XC-72R ayiwathinti amanani we-K we-NiCo2O4, MnCo2O4, i-graphene, ne-nitrogen-doped graphene.Kodwa-ke, inani le-K le-Co3O4 lehle kakhulu ngokungezwa kwe-Vulcan XC-72R, okubonisa ukwanda kwenani lama-electron adluliswa yi-ORR.Ukuhlotshaniswa okunjalo kwe-Co3O4 nezingxenye zekhabhoni kubikwe kumarefs.48, 49. Uma kungekho ukwesekwa kwekhabhoni, i-Co3O4 kucatshangwa ukuthi ikhuthaza ukungafani kwe-HO2- kuya ku-O2 ne-OH-50.51, okuvumelana kahle nenombolo yokudlulisa i-electron ye-Co3O4 cishe engu-2 kuThebula 2. Ngakho, i ukukhangiswa ngokomzimba kwe-Co3O4 kuma-substrates e-carbon kulindeleke ukuthi kukhiqize indlela engu-2 + 2 yama-electron amane ORR52 eqala ngogesi i-O2 iye ku-HO2- ekuxhumaneni kwe-Co3O4 catalyst kanye ne-Vulcan XC-72R (i-equation 1) bese kuba yi-HO2 - I-Electoral ehlukanisayo ngokushesha. i-metal oxide surface iguqulwa ibe yi-O2 elandelwa yi-electroreduction.
Ngokuphambene, inani eliphelele le-K MnOx lenyuke ngokungezwa kwe-Vulcan XC-72R, emele ukwehla kwenombolo yokudlulisa ama-electron isuka ku-4.6 iye ku-3.3 (Ithebula 3).Lokhu kungenxa yokuba khona kwezingosi ezimbili ku-carbon catalyst composite yomzila we-electron wezigaba ezimbili.Ukwehliswa kokuqala kwe-O2 kuya ku-HO2- kwenzeka kalula kakhulu kuzisekeli zekhabhoni, okuholela ekwandeni okuncanyana kwendlela yama-electron amabili ye-ORR53.
Ukuzinza kwe-catalyst kwahlolwa kuhhafu yeseli ye-GDE ebangeni lokuminyana kwamanje.Emkhiwaneni.5 ibonisa iziqephu ezingaba khona uma kuqhathaniswa nesikhathi se-GDE MnOx, MnCo2O4, NiCo2O4, graphene, kanye ne-nitrogen-doped graphene.I-MnOx ikhombisa ukuzinza okuhle okuphelele kanye nokusebenza kwe-ORR ekuminyaneni okuphansi nokuphezulu kwamanje, okuphakamisa ukuthi ilungele ukwenziwa ngokugcwele.
I-Chronopotentiometry yamasampuli e-HDE okwamanje ukusuka ku-10 ukuya ku-100 mA/cm2 ku-1 M NaOH, 333 K, izinga lokugeleza kwe-O2 200 cm3/min.
I-MnCo2O4 futhi ibonakala igcina ukuzinza okuhle kwe-ORR kulo lonke ibanga lokuminyana kwamanje, kodwa ekuminyaniseni okuphezulu kwamanje okungu-50 kanye no-100 mA cm-2 ama-overvoltage amakhulu ayabonwa okubonisa ukuthi i-MnCo2O4 ayisebenzi kahle njenge-MnOx.I-Graphene GDE ibonisa ukusebenza kwe-ORR okuphansi kakhulu phezu kwebanga lamanje lokuminyana elihloliwe, okubonisa ukwehla okusheshayo kokusebenza ngo-100 mA cm-2.Ngakho-ke, ngaphansi kwezimo zokuhlola ezikhethiwe, i-MnOx GDE yakhethelwa ukuhlolwa okwengeziwe ohlelweni lwesibili lwe-Zn-air.