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ʻO nā slider e hōʻike ana i ʻekolu ʻatikala ma kēlā me kēia paheʻe.E hoʻohana i nā pihi hope a i hope no ka neʻe ʻana i nā paheʻe, a i ʻole nā ​​pihi hoʻokele paheʻe ma ka hopena e neʻe i kēlā me kēia paheʻe.
He mea koʻikoʻi nā mea electrocatalysts maikaʻi, kūʻai ʻole a paʻa i ka oxygen reduction reaction (ORR) no nā pākahi lua Zn-air.Ua noiʻi ʻia ka hana ORR o nā oxide metala hoʻokahi a me ka carbon electrocatalysts me ka hoʻohana ʻana i nā ana rotating disk electrode (RDE), nā pali Tafel, a me nā ʻāpana Kutetsky-Levich.Ua ʻike ʻia ʻo ka hui pū ʻana o MnOx a me XC-72R e hōʻike ana i ka hana PBP kiʻekiʻe a me ke kūpaʻa maikaʻi, a hiki i 100 mA cm-2.Ua hoʻāʻo ʻia ka hana o nā electrodes ORR i koho ʻia a me ka electrode oxygen evolution reaction (OER) i hoʻopaʻa mua ʻia i loko o kahi pākaukau zinc-air lua i kūkulu ʻia i loko o kahi hoʻonohonoho ʻekolu-electrode, a me ka nui o kēia manawa, electrolyte molarity, wela, oxygen maʻemaʻe. hoʻāʻo ʻia.Nā hiʻohiʻona o ORR a me OERnā electrodes.ʻO ka hope, ua loiloi ʻia ka lōʻihi o ka ʻōnaehana zinc-air lua, e hōʻike ana i ka ikaika o ka ikehu o 58-61% ma 20 mA cm-2 ma 4 M NaOH + 0.3 M ZnO ma 333 K no 40 mau hola.
ʻO nā ʻanuʻu metala-ea me nā electrodes oxygen ua manaʻo ʻia nā ʻōnaehana maikaʻi loa no ka mea hiki ke loaʻa maʻalahi nā mea uila no nā electrodes oxygen mai ka lewa a puni a ʻaʻole pono e mālama.Hoʻomaʻamaʻa kēia i ka hoʻolālā ʻōnaehana ma ka ʻae ʻana i ka electrode oxygen e loaʻa ka mana palena ʻole, a laila e hoʻonui ai i ka ikehu o ka ʻōnaehana.No laila, ua puka mai nā pahu metala-ea e hoʻohana ana i nā mea anode e like me ka lithium, aluminika, hao, zinc, a me ka magnesium ma muli o ko lākou mana kikoʻī maikaʻi loa.Ma waena o lākou, hiki ke hoʻokō ʻia nā pihi ea zinc i ke koi o ka mākeke no ke kumukūʻai, palekana, a me ke aloha o ke kaiapuni, no ka mea he nui nā hiʻohiʻona makemake o ka zinc ma ke ʻano he anode mea, e like me ke kūpaʻa maikaʻi i nā electrolytes aqueous, kiʻekiʻe ikehu kiʻekiʻe, a me ka haʻahaʻa equilibrium.hiki., hiki ke hoʻololi i ka electrochemical, conductivity uila maikaʻi, ka nui a me ka maʻalahi o ka lawelawe ʻana4,5.I kēia manawa, ʻoiai ke hoʻohana ʻia nei nā ʻeke ea zinc mua i nā noi kalepa e like me nā mea hoʻolohe pepeiao, nā hōʻailona o ke kaʻaahi a me nā kukui hoʻokele, loaʻa i nā ʻeke ea zinc lua ka hiki ke kiʻekiʻe o ka ikehu kiʻekiʻe e hoʻohālikelike ʻia me nā pā lithium-based.He mea pono kēia e hoʻomau i ka noiʻi ʻana i nā ʻenekini ea zinc no nā noi i nā uila uila, nā kaʻa uila, ka mālama ʻana i ka ikehu ma ka laulā a me ke kākoʻo ʻana i ka hana ʻenehana hou6,7.
ʻO kekahi o nā pahuhopu nui, ʻo ia ka hoʻomaikaʻi ʻana i ka hopena o ka oxygen i ka ea electrode, ʻo ia hoʻi ka oxygen reduction reaction (ORR) a me ka oxygen evolution reaction (OER), i mea e hoʻoikaika ai i ka hoʻolaha ʻana o nā ʻāpana lua Zn-air.I kēia hopena, hiki ke hoʻohana ʻia nā electrocatalysts maikaʻi e hoʻonui i ka wikiwiki o ka hopena a pēlā e hoʻonui ai i ka pono.I kēia manawa, wehewehe maikaʻi ʻia nā electrodes oxygen me nā catalysts bifunctional i ka palapala8,9,10.ʻOiai hiki i nā catalysts bifunctional ke hoʻohaʻahaʻa i ke ʻano o nā electrodes a hoʻemi i nā poho hoʻoili nui, hiki ke kōkua i ka hōʻemi ʻana i nā kumukūʻai hana, ma ka hoʻomaʻamaʻa, ʻaʻole kūpono nā catalysts i kūpono no ORR no OER, a me ka versa11.ʻO kēia ʻokoʻa i ka hiki ke hoʻohana i ke kumu e ʻike ʻia ai ka catalyst i kahi ākea ākea o nā mea hiki ke hoʻololi i kona ʻano ʻili i ka manawa.Eia kekahi, ʻo ka pili ʻana o nā ʻenehana paʻa waena, ʻo ia ka mea hiki ke ʻokoʻa nā wahi hana ma ka catalyst no kēlā me kēia pane, hiki ke hoʻopili i ka optimization.
ʻO kekahi pilikia nui no nā pākahi Zn-air lua ʻo ka hoʻolālā ʻana o ka oxygenelectrode, no ka mea, ke hana nei nā catalysts monofunctional no ORR a me OER i loko o nā pāpaho like ʻole.Pono ka hydrophobic o ke kinoea diffusion layer o ORR e hiki ai ke komo i ke kinoea oxygen i loko o nā wahi catalytic, ʻoiai no ka OER he hydrophilic ka ʻili electrode e hoʻomaʻamaʻa i ka wehe ʻana i nā ʻōpū oxygen.Ma ka fig.Hōʻike ʻo 1 i ʻekolu mau hoʻolālā electrode oxygen lua maʻamau i lawe ʻia mai ka loiloi a Jorissen12, ʻo ia hoʻi (i) nā mea hoʻoheheʻe monolayer bifunctional, (ii) nā mea hoʻoheheʻe pālua a i ʻole multilayer, a (iii) nā hoʻonohonoho electrode triple.
No ka hoʻolālā electrode mua, ʻo ia hoʻi kahi papa hoʻokahi bifunctional catalyst i hoʻopaʻa ʻia i ka ORR a me OER i ka manawa like, inā hoʻokomo ʻia kahi membrane i kēia hoʻolālā, a laila hoʻokumu ʻia kahi hui membrane-electrode (MEA) e like me ka mea i hōʻike ʻia.ʻO ka lua o nā ʻano he ʻelua (a ʻoi aku paha) nā moena catalyst me nā porosity ʻokoʻa a me ka hydrophobicity e helu i nā ʻokoʻa i nā ʻāpana hopena13,14,15.I kekahi mau hihia, ua hoʻokaʻawale ʻia nā moena catalytic ʻelua, me ka ʻaoʻao hydrophilic o ka OER e kū pono ana i ka electrolyte a me ka ʻaoʻao semi-hydrophobic o ka ORR e kū pono ana i nā welau hāmama o nā electrodes 16, 17, 18. he cell i loaʻa i ʻelua pane- nā electrodes oxygen kūikawā a me kahi electrode zinc19,20.Hōʻike ka papa S1 i nā pono a me nā pōʻino o kēlā me kēia hoʻolālā.
ʻO ka hoʻokō ʻana i kahi hoʻolālā electrode e hoʻokaʻawale ana i nā hopena ORR a me OER ua hōʻike mua ʻia ka hoʻomaikaʻi ʻana i ka paʻa paikikala19.He ʻoiaʻiʻo loa kēia no ka hoʻonohonoho electrode ʻekolu, kahi e hōʻemi ʻia ai ka hoʻohaʻahaʻa ʻana o nā catalysts paʻa ʻole a me nā co-additives a ʻoi aku ka maʻalahi o ka hoʻokuʻu ʻana ma luna o ka pae āpau.No kēia mau kumu, ua hoʻohana mākou i kahi hoʻonohonoho Zn-air ʻekolu-electrode i kēia hana.
Ma kēia ʻatikala, koho mua mākou i nā mea hoʻoheheʻe ORR hana kiʻekiʻe ma ka hoʻohālikelike ʻana i nā ʻenekini metala hoʻololi like ʻole, nā mea carbonaceous, a me nā catalysts kuhikuhi me nā hoʻokolohua rotating disk electrode (RDE).He mau electrocatalysts maikaʻi nā mea hoʻoneʻe metala ma muli o ko lākou mau ʻano hoʻokahe ʻokoʻa;ʻoi aku ka maʻalahi o ka hoʻopili ʻana i nā hopena i mua o kēia mau pūhui21.No ka laʻana, ʻo ka manganese oxides, cobalt oxides, a me ka cobalt-based mixed oxides (e like me NiCo2O4 a me MnCo2O4)22,23,24 hōʻike i ka ORR maikaʻi ma nā kūlana alkaline ma muli o kā lākou mau d-orbitals piha piha, nā pae ikehu electron e hiki ai i ka electron. hana a hoʻomaikaʻi i ka ʻoki ʻana.Eia kekahi, ʻoi aku ka nui o lākou i ke kaiapuni a loaʻa iā lākou ka conductivity uila, kiʻekiʻe reactivity a me ke kūpaʻa maikaʻi.Pēlā nō, hoʻohana nui ʻia nā mea carbonaceous, loaʻa nā mea maikaʻi o ka conductivity uila kiʻekiʻe a me kahi ākea ākea.I kekahi mau hihia, ua hoʻokomo ʻia nā heteroatoms e like me ka nitrogen, boron, phosphorus, a me ka sulfur i loko o ke kalapona e hoʻololi i kona ʻano, e hoʻomaikaʻi hou i nā ʻano ORR o kēia mau mea.
Ma muli o nā hopena hoʻokolohua, ua hoʻokomo mākou i nā catalysts OVR i koho ʻia i loko o nā electrodes diffusion gas (GDE) a hoʻāʻo iā lākou ma nā ʻano like ʻole o kēia manawa.ʻO ka mea hoʻoheheʻe ORR GDE maikaʻi loa i hui pū ʻia i loko o kā mākou pahu uila Zn-air maʻamau ʻekolu-electrode a me nā electrodes OER e hoʻohālikelike ʻia i kā mākou hana mua26,27.Ua nānā ʻia nā mana o kēlā me kēia oxygen electrodes i ka wā e hoʻokuʻu mau ai a hoʻopaʻa i nā hoʻokolohua kaʻa uila e aʻo i ka hopena o nā kūlana hana e like me ka density o kēia manawa, electrolyte molarity, cell operating temperature, a me ka hoʻomaʻemaʻe oxygen.ʻO ka mea hope loa, ua loiloi ʻia ke kūpaʻa o nā ʻeke lua Zn-air ma lalo o ke kaʻa kaʻa mau ma lalo o nā kūlana hana maikaʻi loa.
Ua hoʻomākaukau ʻia ʻo MnOx28 e ke ʻano redox kemika: 50 ml o 0.04 M KMnO4 solution (Fisher Scientific, 99%) i hoʻohui ʻia i 100 ml o 0.03 M Mn(CH3COO)2 (Fisher Scientific, 98%) e hana i kahi ʻeleʻele brown.Hoʻoponopono ʻia ka hui ʻana i ka pH 12 me ka dilute sodium hydroxide, a laila centrifuged 3-5 mau manawa ma 2500 rpm e hōʻiliʻili i ka precipitate.Holoi ʻia ka ʻeke me ka wai deionized a hiki i ka nalo ʻana o ke kala poni o ka ion permanganate.ʻO ka hope, ua maloʻo ʻia nā waihona i ka ea ma 333 K i ka pō a laila hoʻoheheʻe ʻia.
Ua hoʻohui ʻia nā spinel oxides Co3O4, NiCo2O4, a me MnCo2O4 e ka decomposition thermal.Ua hoʻomākaukau ʻia ʻo NiCo2O4 a me MnCo2O4 ma ka hoʻohui ʻana i 0.5 M (14.5 g) nickel(II) nitrate hexahydrate, Ni(NO3)2⋅6H2O (Fisher Scientific, 99.9%) a i ʻole 0.5 M (12.6 g) tetrahydrate manganese(II) nitrate Mn. ).)2 4H2O (Sigma Aldrich, ≥ 97%) a me 1 M (29.1 g) cobalt(II) nitrate hexahydrate, Co(NO3)2 6H2O (Fisher Scientific, 98+%, ACS reagents) i ka methanol (Fisher Scientific, 99.9% ) i loko o 100 ml dilution hue.Hoʻohui ʻia ka Methanol i nā ʻāpana liʻiliʻi i ka nitrate metala hoʻololi me ka hoʻoulu ʻana a hiki i ka loaʻa ʻana o kahi hopena homogeneous.A laila, hoʻoneʻe ʻia ka hopena i loko o kahi crucible a hoʻomehana ʻia ma kahi pā wela, e waiho ana i kahi paʻa ʻulaʻula ʻeleʻele.Hoʻopili ʻia ka paʻa ma 648 K no 20 mau hola i ka lewa.ʻO ka paʻa paʻa i hoʻopau ʻia a laila ʻeli ʻia a hiki i ka pauka maikaʻi.ʻAʻole i hoʻohui ʻia ʻo Ni(NO3)2 6H2O a i ʻole Mn(NO3)2 4H2O i ka hoʻohui ʻana o Co3O4.
Graphene nanosheets me kahi ili o 300 m2/g (Sigma Aldrich), graphene doped me ka nitrogen (Sigma Aldrich), kalapona ʻeleʻele pauka (Vulcan XC-72R, Cabot Corp., 100%), MnO2 (Sigma Aldrich) a me 5 wt.% Pt/C (Acros Organics) i hoʻohana ʻia e like me ia.
Ua hoʻohana ʻia nā ana RDE (Pine Research Instrumentation) no ka loiloi ʻana i ka hana o nā mea hoʻokalakupua ORR like ʻole ma 1 M NaOH.Ua hoʻohana ʻia kahi ʻīnika catalytic me 1 mg catalyst + 1 ml deionized (DI) H2O + 0.5 ml isopropanol (IPA) + 5 µl 5 wt% Nafion 117 (Sigma-Aldrich) e like me ia.I ka hoʻohui ʻia ʻana o Vulcan XC-72R, ua loaʻa i ka pena catalytic he 0.5 mg catalyst + 0.5 mg Vulcan XC-72R + 1 ml DI HO + 0.5 ml IPA + 5 µl 5 wt% Nafion 117 e hōʻoia i ka hoʻouka ʻana o nā mea.Ka hui 'ana i sonicated no 20 minuke a homogenized ka hoʻohana 'ana i ka Cole-Parmer LabGen 7 Series homogenizer ma 28,000 rpm no 4 minuke.A laila ua hoʻohana ʻia ka ʻīnika i ʻekolu aliquots o 8 μl i ka ʻili o kahi electrode kalapona aniani (Pine Instrument Company) me ke anawaena o 4 mm (wahi hana ≈ 0.126 cm2) a maloʻo ma waena o nā papa e hāʻawi i kahi ukana o ≈120 μg cm. -2.Ma waena o nā noi, ua hoʻomaʻemaʻe ʻia ke aniani kalapona electrode ʻili me MicroCloth (Buehler) a me 1.0 mm a me 0.5 mm alumina pauka (MicroPolish, Buehler) a ukali ʻia e ka sonication i ka H2O deionized.
Ua hoʻomākaukau ʻia nā laʻana electrode diffusion gas ORR e like me kā mākou protocol28 i wehewehe mua ʻia.ʻO ka mea mua, ua hui pū ʻia ka pauka catalyst a me Vulcan XC-72R i kahi ratio paona 1:1.A laila ua hoʻohui ʻia kahi hui ʻana o kahi hopena o polytetrafluoroethylene (PTFE) (60 wt.% i H2O) a me kahi mea hoʻoheheʻe me ka ratio o IPA/H2O o 1:1 i ka hui ʻana o ka pauka maloʻo.Sonicate ka catalytic pena no ma kahi o 20 minuke a homogenize no ma kahi o 4 minuke ma 28,000 rpm.A laila, hoʻopili ʻia ka ʻīnika me kahi spatula ma luna o ka pepa kalapona i ʻoki mua ʻia he 13 mm ke anawaena (AvCarb GDS 1120) a maloʻo a hiki i ka loaʻa ʻana o kahi mea catalyst o 2 mg cm2.
Ua hana ʻia nā electrodes OER e ka cathodic electrodeposition o Ni-Fe hydroxide catalysts ma luna o ke kila kila 15 mm x 15 mm.makaʻu(DeXmet Corp, 4SS 5-050) i hōʻike ʻia26,27.Ua lawe 'ia ka Electrodeposition i loko o ka ma'amau 'ekolu-electrode half-cell (he polymer-coated glass cell o kahi 20 cm3) me ka Pt grid as a counter electrode and Hg/HgO in 1 M NaOH as a reference electrode.E ʻae i ka wīwī i hoʻopaʻa ʻia i ka catalyst e hoʻomaloʻo i ka ea ma mua o ka ʻoki ʻana i kahi ʻāpana ma kahi o 0.8 cm2 me kahi punch kila kalapona mānoanoa 10 mm.
No ka hoʻohālikelike, ua hoʻohana ʻia nā electrodes ORR a me OER i loaʻa a hoʻāʻo ʻia ma lalo o nā kūlana like.ʻO ka electrode ORR pāʻoihana (QSI Nano Gas Diffusion Electrode, Quantum Sphere, 0.35 mm mānoanoa) he manganese a me ka carbon oxide i uhi ʻia me kahi ʻohi nickel mesh o kēia manawa, aʻo ka electrode OER pāʻoihana (type 1.7, anode Magneto kūikawā, BV) he mānoanoa 1.3 mm.a hiki i ka 1.6 mm i hoʻonui ʻia i ka mesh titanium i uhi ʻia me ka Ru-Ir i hui ʻia me ka oxide metala.
ʻO ka morphology o ka ʻili a me ka hoʻohui ʻana o nā catalysts i hōʻike ʻia me ka FEI Quanta 650 FEG scanning electron microscope (SEM) e hana ana ma lalo o ka momi kiʻekiʻe a me ka uila wikiwiki o 5 kV.Ua hōʻiliʻili ʻia ka ʻikepili pauka X-ray diffraction (XRD) ma kahi Bruker D8 Advance X-ray diffractometer me kahi puna keleawe keleawe (λ = 1.5418 Å) a nānā ʻia me ka polokalamu Bruker Diffraction Suite EVA.
Ua hana ʻia nā ana electrochemical a pau me ka Biologic SP-150 potentiostat a me ka polokalamu EC-lab.Ua hoʻāʻo ʻia nā laʻana o RDE a me GDE ma kahi hoʻonohonoho ʻekolu-electrode maʻamau i loaʻa i kahi cell glass jacketed 200 cm3 a me kahi capillary Laggin ma ke ʻano he electrode kuhikuhi.Pt mesh a me Hg/HgO i 1 M NaOH ua hoʻohana 'ia e like me ka counter a me ka kuhikuhi electrodes, pakahi.
No nā ana RDE i kēlā me kēia hoʻokolohua, ua hoʻohana ʻia ka 1 M NaOH electrolyte hou, ka mahana o ia mea i mālama mau ʻia ma 298 K me ka hoʻohana ʻana i ka wai ʻauʻau wai (TC120, Grant).ʻO ke kinoea oxygen (BOC) e hū ana i loko o ka electrolyte ma o ke aniani frit me ka porosity o 25-50 µm no ka liʻiliʻi loa he 30 min ma mua o kēlā me kēia hoʻokolohua.No ka loaʻa ʻana o nā pihi polarization ORR, ua nānā ʻia ka mea hiki mai ka 0.1 a i ka -0.5 V (e pili ana iā Hg/HgO) ma ka helu scan o 5 mV s -1 ma 400 rpm.Ua loaʻa nā voltammograms cyclic ma ke kāhili ʻana i ka hiki ma waena o 0 a me -1.0 V a me Hg/HgO ma ka wikiwiki o 50 mV s-1.
No nā ana HDE, mālama ʻia ka 1 M NaOH electrolyte ma 333 K me ka ʻauʻau wai kahe.ʻO kahi wahi ikaika o 0.8 cm2 i hōʻike ʻia i ka electrolyte me ka hāʻawi mau ʻana o ka oxygen i ka ʻaoʻao hope o ka electrode ma ka wikiwiki o 200 cm3 / min.ʻO ka mamao paʻa ma waena o ka electrode hana a me ka electrode kuhikuhi he 10 mm, a ʻo ka mamao ma waena o ka electrode hana a me ka electrode counter he 13-15 mm.Hāʻawi ka uea nickel a me ka mesh i ka pili uila ma ka ʻaoʻao kinoea.Ua lawe ʻia nā ana Chronopotentiometric ma 10, 20, 50 a me 100 mA cm-2 e loiloi i ka paʻa a me ka pono o ka electrode.
ʻO nā hiʻohiʻona o nā electrodes ORR a me OER i loiloi ʻia i loko o kahi pahu aniani 200 cm3 jacketed me kahi hoʻokomo PTFE29.Hōʻike ʻia kahi kiʻi schematic o ka ʻōnaehana ma ke Kiʻi S1.Hoʻopili ʻia nā electrodes i loko o ka pākaukau i kahi ʻōnaehana ʻekolu-electrode.ʻO ka electrode hana he mau electrodes ORR a me OER hoʻokaʻawale i hoʻohui ʻia i kahi module relay (Songle, SRD-05VDC-SL-C) a me kahi microcontroller (Raspberry Pi 2014© model B+V1.2) me kahi anode zinc.e like me ka lua ʻO nā electrodes a me ka electrode kuhikuhi Hg/HgO ma 4 M NaOH aia ma kahi mamao o 3 mm mai ka anode zinc.Ua kākau ʻia kahi palapala Python e hana a hoʻokele i ka Raspberry Pi a me ka Relay Module.
Ua hoʻololi ʻia ke kelepona e hoʻokomo i kahi anode zinc foil (Goodfellow, 1 mm mānoanoa, 99.95%) a me kahi uhi polymer i ʻae ʻia nā electrodes e kau ʻia ma kahi mamao paʻa ma kahi o 10 m.4 mm kaawale.Ua hoʻopaʻa ʻo Nitrile rubber plugs i nā electrodes i loko o ke poʻi, a ua hoʻohana ʻia nā uea nickel (Alfa Aesar, 0.5 mm anawaena, annealed, 99.5% Ni) no nā pilina uila o nā electrodes.Ua hoʻomaʻemaʻe mua ʻia ka anode zinc foil me ka isopropanol a laila me ka wai deionized, a ua uhi ʻia ka ʻili o ka foil me ka tape polypropylene (Avon, AVN9811060K, 25 µm mānoanoa) e hōʻike i kahi wahi ikaika ma kahi o 0.8 cm2.
Ua hana ʻia nā hoʻokolohua holo kaʻa a pau ma 4 M NaOH + 0.3 M ZnO electrolyte ma 333 K ke ʻole i ʻike ʻia.Ma ke kiʻi, ʻo Ewe me ka Hg/HgO e pili ana i ka hiki o ka oxygen electrode (ORR a me OER), Ece me ka Hg/HgO e hōʻike ana i ka hiki o ka zinc electrode, Ecell me ka Hg/HgO e hōʻike ana i ka piha piha. hiki ke kelepona a ʻokoʻa paha.ma waena o ʻelua mau mana pākahi.Hāʻawi ʻia ka oxygen a i ʻole ka ea i hoʻopili ʻia i ka ʻaoʻao hope o ka electrode OPP ma kahi kahe mau o 200 cm3 / min.Ua aʻo ʻia ke kūpaʻa kaʻa a me ka hana ʻana o nā electrodes i ka nui o kēia manawa o 20 mA cm-2, kahi manawa pōkole o 30 min, a me kahi manawa hoʻomaha OCV o 1 min ma waena o kēlā me kēia hapalua pōʻai.Ua hana ʻia ka liʻiliʻi o 10 pōʻai no kēlā me kēia hoʻāʻo, a lawe ʻia ka ʻikepili mai nā pōʻai 1, 5, a me 10 e hoʻoholo ai i ke ʻano o nā electrodes i ka manawa.
ʻO ka morphology o ka ORR catalyst ua hōʻike ʻia e SEM (Fig. 2), a ua hōʻoia ʻia nā ana ʻokoʻa o ka pauka X-ray i ke ʻano aniani o nā laʻana (Fig. 3).Hāʻawi ʻia nā ʻāpana hoʻonohonoho o nā mea hoʻohālike catalyst ma ka Papa 1. 1. Ke hoʻohālikelike ʻia i nā oxide manganese, MnO2 pāʻoihana ma fig.Aia ka 2a i nā ʻāpana nui, a ʻo ke ʻano ʻokoʻa ma ke kiʻi 3a e pili ana me JCPDS 24-0735 no ka tetragonal β-MnO2.Ma ka ʻaoʻao ʻē aʻe, ma ka ʻili MnOx ma Fig. 2b e hōʻike ana i nā ʻāpana ʻoi aku ka ʻoi aku ka maikaʻi a me ka ʻoi aku ka maikaʻi, e pili ana i ke ʻano ʻokoʻa ma ka Fig. 66° pili i nā piko (110), (220), (310), (211), a (541) o ka hydrate α-MnO2 tetrahedrally kikowaena, JCPDS 44-014028.
(a) MnO2, (b) MnOx, (c) Co3O4, (d) NiCo2O4, (e) MnCo2O4, (f) Vulcan XC-72R, (g) graphene, (h) nitrogen doped graphene, (a) 5 wt .% Pt/C.
Nā hiʻohiʻona X-ray o (a) MnO2, (b) MnOx, (c) Co3O4, (d) NiCo2O4, (e) MnCo2O4, (f) Vulcan XC-72R, graphene a me ka graphene nitrogen-doped, a me (g) 5 % platinum / kalapona.
Ma ka fig.2c–e, o ka morphology ili o na oxides e pili ana i ka cobalt Co3O4, NiCo2O4, a me MnCo2O4 he mau puu o na mea like ole ka nui.Ma ka fig.3c–e hōʻike i kēia mau hoʻololi a paumetalaʻO nā oxides he ʻano spinel a me kahi ʻōnaehana kristal cubic like (JCPDS 01-1152, JCPDS 20-0781, a me JCPDS 23-1237, kēlā me kēia).Hōʻike kēia i ka hiki i ke ʻano hoʻoheheʻe wela ke hana i nā ʻokiʻoki metala nui loa, e like me ka mea i ʻike ʻia e nā piko ikaika i wehewehe maikaʻi ʻia i ke ʻano ʻokoʻa.
Hōʻike nā kiʻi SEM o nā mea kalapona i nā loli nui.Ma ka fig.2f Vulcan XC-72R kalapona ʻeleʻele i loko o nā nanoparticles paʻa paʻa.ʻO ka mea ʻē aʻe, ʻo ka hiʻohiʻona o ka graphene ma Fig. 2g he mau papa ʻino loa me kekahi mau agglomerations.Eia naʻe, ʻike ʻia nā graphene N-doped (Fig. 2h) i nā ʻāpana lahilahi.ʻO nā hiʻohiʻona ʻokoʻa X-ray like o Vulcan XC-72R, nā graphene nanosheets kalepa, a me ka graphene N-doped ma Fig.Hōʻike ʻo 3f i nā loli liʻiliʻi i nā koina 2θ o ka (002) a me (100) mau piko kalapona.ʻIke ʻia ʻo Vulcan XC-72R he graphite hexagonal ma JCPDS 41-1487 me nā piko (002) a me (100) e ʻike ʻia ana ma 24.5° a me 43.2°.Pēlā nō, ʻike ʻia nā piko (002) a me (100) o N-doped graphene ma 26.7° a me 43.3°.ʻO ka ikaika hope i ʻike ʻia ma nā ʻano ʻokoʻa X-ray o Vulcan XC-72R a me ka nitrogen-doped graphene ma muli o ke ʻano ʻino loa o kēia mau mea i loko o kā lākou morphology ili.ʻO ka ʻokoʻa, ʻo ke ʻano ʻokoʻa o ka graphene nanosheets e hōʻike ana i kahi kiʻekiʻe ʻoi loa (002) ma 26.5° a me kahi piko ākea liʻiliʻi (100) ma 44 °, e hōʻike ana i kahi ʻano crystalline ʻoi aʻe o kēia hāpana.
ʻO ka hope, ma ka fig.2i SEM kiʻi o 5 wt.% Pt/C hōʻike i nā ʻāpana kalapona me ke ʻano o ke koʻokoʻo me nā hakahaka poepoe.Hoʻoholo ʻia ʻo Cubic Pt mai ka hapa nui o nā piko i ka 5 wt% Pt/C diffraction pattern ma Fig. 3g, a ʻo ka piko ma 23° pili i ka (002) peak o ke kalapona i loaʻa.
Ua hoʻopaʻa ʻia kahi laina sweep ORR catalyst voltammogram ma kahi sweep rate o 5 mV s-1.Ma muli o nā palena hoʻoili nui, ʻo nā palapala ʻāina i hōʻiliʻili ʻia (Fig. 4a) maʻamau ka loaʻa ʻana o kahi ʻano-S e hoʻonui ana i kahi pāpū me ka ʻoi aku ka maikaʻi ʻole.ʻO ka palena palena o kēia manawa, jL, hiki E1/2 (kahi j/jL = ½) a me ka hiki ke hoʻomaka ma -0.1 mA cm-2 i unuhi ʻia mai kēia mau ʻāpana a helu ʻia ma ka Papa 2. Pono e ʻike ʻia ma ka fig.4a, hiki ke hoʻokaʻawale ʻia nā mea hoʻoheheʻe e like me ko lākou mau mea hiki E1/2 i: (I) metala oxides, (II) mea kalapona, a me (III) metala hanohano.
Linear sweep voltammograms o (a) catalyst a me (b) kahi kiʻiʻoniʻoni lahilahi o ka catalyst a me XC-72R, i ana ʻia ma kahi ʻimi kalapona aniani RDE ma 400 rpm me ka helu scan o 5 mV s-1 ma O2 saturation ma 298 K i 1 M NaOH cf.
ʻO nā mea hoʻoheheʻe metala pākahi o Mn a me Co ma ka hui I hōʻike i nā hiki mua o -0.17 V a me -0.19 V i kēlā me kēia, a aia nā koina E1/2 ​​ma waena o -0.24 a me -0.26 V. Hōʻike ʻia nā hopena hoʻemi o kēia mau oxide metala ma ka hoohalike. .(1) a me (2), e ʻike ʻia ma ka ʻaoʻao o ka hiki ke hoʻomaka ma Fig.4a hoʻohālikelike i ka pono maʻamau o ka ʻanuʻu mua 2e o ke ala pololei ORR ma ka hoohalike.(3).
ʻO nā mea hoʻoheheʻe metala MnCo2O4 a me NiCo2O4 i loko o ka hui like e hōʻike ana i nā hiki mua i hoʻoponopono ʻia ma -0.10 a me -0.12 V pākahi, akā mālama ʻia nā waiwai E1/2 ma kahi o 10.−0.23 volts.
Hōʻike nā mea kalapona i ka hui II i nā waiwai E1/2 maikaʻi ma mua o ka hui I metala oxides.Loaʻa i ka mea graphene ka mana mua o -0.07 V a me ka waiwai E1/2 o -0.11 V, aʻo ka hiki mua a me ka E1/2 o 72R Vulcan XC- he -0.12V a me -0.17V pakahi.Ma ka hui III, 5 wt% Pt/C i hōʻike i ka hiki mua maikaʻi loa ma 0.02 V, he E1/2 o -0.055 V, a me ka palena kiʻekiʻe loa ma -0.4 V, no ka mea, ua hoʻemi ʻia ka oxygen ma o ka nui o kēia manawa o ke ala 4e. .Loaʻa iā ia ka E1 / 2 haʻahaʻa ma muli o ka conductivity kiʻekiʻe o Pt / C a me nā kinetics reversible o ka pane ORR.
Hōʻike ke Kiʻi S2a i ka nānā ʻana o Tafel slope no nā catalysts like ʻole.Hoʻomaka ka ʻāpana kinetically controlled o 5 wt.% Pt/C ma 0.02 V e pili ana i ka Hg/HgO, ʻoiai ʻo ka ʻāpana o nā oxides metala a me nā mea kalapona aia ma ka laulā o nā mea hiki ʻole mai -0.03 a -0.1 V. ʻO ka waiwai slope. no Tafel Pt/C he –63.5 mV ss–1, he mea maʻamau ia no Pt ma nā haʻahaʻa haʻahaʻa o kēia manawa dE/d log i = –2.3 RT/F31.32 i loko o ka hoʻololi ʻana o ka oxygen mai ka physisorption a chemisorption33,34.Aia nā koina slope ʻo Tafel no nā mea kalapona ma ka ʻāina like me Pt/C (-60 a -70 mV div-1), e hōʻike ana he like nā ala ORR o kēia mau mea.Hōʻike ʻia nā ʻokikene metala pākahi o Co a me Mn i nā pali Tafel mai ka -110 a i ka -120 mV dec-1, ʻo ia ka dE/d log i = -2.3 2RT/F, kahi o ka pae hoʻoholo helu ka electron mua.hoʻololi i kaʻanuʻu 35, 36. Ua hoʻopaʻa ʻia nā koina slope kiʻekiʻe aʻe no nā ʻokikene metala hui ʻia ʻo NiCo2O4 a me MnCo2O4, e pili ana i -170 mV dec-1, e hōʻike ana i ka hiki ʻana o nā OH- a me H2O i nā ion ma ka ʻili o ka oxide, ka mea e pale ai i ka adsorption oxygen a ka hoʻoili electron, a laila e pili ana i ka oxygen.ala hoemi 35.
Ua hoʻohana ʻia ka hoohalike Kutetsky-Levich (KL) no ka hoʻoholo ʻana i nā ʻāpana hoʻohālikelike kinetic no nā laʻana catalyst like ʻole me ka hoʻoili ʻole ʻana.ma ka hoohalike.(4) ʻo ka huina o ka nui o kēia manawa j ka huina o nā densities o kēia manawa o ka hoʻoili electron a me ka hoʻoili nuipaʻa.
mai ka hoohalike.(5) Ua like ka palena palena o keia manawa jL me ke kumu huinahalike o ka wikiwiki o ka huli ana.No laila, ka hoohalike KL.(6) wehewehe i ka pakuhi laina o ka j−1 me ka ω−1//2, kahi i jk ka piko o ka pakuhi a o K ka pali o ka pakuhi.
kahi o ν ka viscosity kinematic o ka electrolyte 1 M NaOH (1.1 × 10–2 cm2 s–1)37, ʻo D ka diffusion coefficient o O2 ma 1 M NaOH (1.89 × 10–5 cm2 s–1)38, ω ʻO ka rpm ka wikiwiki o ka hoʻololi ʻana, ʻo C ka neʻe ʻana o ka oxygen i loko o ka hopena nui (8.4 × 10–7 mol cm–3)38.
E hōʻiliʻili i nā voltammograms laina laina me RDE ma 100, 400, 900, 1600, a me 2500 rpm.Ua lawe ʻia nā waiwai mai -0.4 V ma ka palena hoʻoili nuipaʻa e hoʻolālā i ke kiʻi KL, ʻo ia hoʻi -j-1 kūʻē i ka ω-1//2 no ka catalyst (Fig. S3a).E hoohana i na hoohalike.Ma na hoohalike (6) a me (7), ua hooholoia na hoailona hana o ka catalyst, e like me ke kinikini kinetic current density me ka noonoo ole i na hopena o ka hoololi nuipa jk, e ke kiko o ka hui ana me ke axis y, a me ka helu o Hoʻoholo ʻia nā hoʻoili electron e ka gradient K o ka pihi.Ua helu ʻia lākou ma ka papa 2.
ʻO 5 wt% Pt/C a me XC-72R nā waiwai jk piha haʻahaʻa loa, e hōʻike ana i nā kinetics wikiwiki no kēia mau mea.Eia nō naʻe, ʻaneʻane ʻelua ka piʻi o ka pihi XC-72R no ka 5 wt% Pt/C, i manaʻo ʻia ʻoiai ʻo K he hōʻailona o ka helu o nā electrons i hoʻoili ʻia i ka wā o ka hoʻemi ʻana o ka oxygen.ʻO ka manaʻo manaʻo, pono e hele ka pā KL no 5 wt% Pt/C ma ke kumu 39 ma lalo o nā kūlana hoʻoili lehulehu, akā naʻe, ʻaʻole ʻike ʻia kēia ma ke Kiʻi S3a, e hōʻike ana i nā palena kinetic a diffusional e pili ana i nā hopena.Ma muli paha o Garsani et al.Ua hōʻike ʻo 40 i nā ʻano like ʻole liʻiliʻi i ka topology a me ka morphology o nā kiʻi catalytic Pt / C hiki ke hoʻopili i ka pololei o nā koina hana ORR.Eia nō naʻe, ʻoiai ua hoʻomākaukau ʻia nā kiʻiʻoniʻoni catalyst a pau ma ke ʻano like, pono e like nā hopena i nā hopena no nā laʻana a pau.Ua like ke kiko kea graphene KL o ≈ -0.13 mA-1 cm2 i ko ka XC-72R, aka, o ke kiko kea -0.20 mA-1 cm2 no ka graphene KL graphene N-doped e hoike mai ana ua oi aku ka nui o keia manawa ma muli o ka uila ma ka mea hoʻololi catalytic.Ma muli paha kēia o ka hoʻemi ʻana o ka doping nitrogen o ka graphene i ka conductivity uila holoʻokoʻa, e hopena i nā kinetics hoʻoili electron lohi.I ka hoʻohālikelike ʻana, ʻoi aku ka liʻiliʻi o ka waiwai K piha o ka graphene nitrogen-doped ma mua o ka graphene no ka mea ʻo ka loaʻa ʻana o ka nitrogen e kōkua i ka hana ʻana i nā pūnaewele ʻoi aku ka ikaika no ORR41,42.
No nā oxides e pili ana i ka manganese, ʻike ʻia ka helu intersection o ka waiwai nui loa - 0.57 mA-1 cm2.Eia naʻe, ʻoi aku ka haʻahaʻa o ka waiwai K piha o MnOx ma mua o ka MnO2 a kokoke i 5 wt%.%Pt/C.Ua hoʻoholo ʻia nā helu hoʻoili electron ma kahi o.ʻO ka MnOx ka 4 a me ka MnO2 kokoke i ka 2. Ua kūlike kēia me nā hopena i paʻi ʻia ma ka palapala, e hōʻike ana i ka helu o nā hoʻololi electron ma ke ala α-MnO2 ORR he 4, ʻoiai ʻo β-MnO243 ma lalo o 4. No laila , ʻokoʻa nā ala ORR no nā ʻano polymorphic like ʻole o nā catalysts e pili ana i ka manganese oxide, ʻoiai e mau ana ka nui o nā pae kemika.ʻO ka mea nui, loaʻa nā helu hoʻololi electron i ka MnOx a me MnCo2O4 ma mua o 4 no ka mea ʻo ka hoʻemi ʻana o ka manganese oxides i loko o kēia mau catalysts i ka manawa like me ka emi ʻana o ka oxygen.Ma kahi hana mua, ua ʻike mākou ua hiki mai ka hoʻemi electrochemical o ka manganese oxide ma ke ʻano like me ka hoʻemi ʻana o ka oxygen i loko o kahi hopena i hoʻopiha ʻia me ka nitrogen28.ʻO ka hāʻawi ʻana o nā ʻaoʻao ʻaoʻao e alakaʻi i kahi helu helu o nā electrons ma mua o 4.
ʻO ke kuʻina o Co3O4 he ≈ −0.48 mA-1 cm2, ʻoi aku ka maikaʻi ma mua o nā ʻano ʻelua o ka manganese oxide, a ʻo ka helu hoʻololi electron ʻike ʻia e hoʻoholo ʻia e ka waiwai o K like me 2. Hoʻololi iā Ni i NiCo2O4 a me Mn i MnCo2O4. e Co ke alakaʻi i ka emi ʻana o nā waiwai kūʻokoʻa K, e hōʻike ana i ka hoʻomaikaʻi ʻana i nā kinetics hoʻoili electron i loko o nā oxide metala hui ʻia.
Hoʻohui ʻia nā substrate kalapona i ka ʻīnika catalyst ORR e hoʻonui i ka conductivity uila a hoʻomaʻamaʻa i ka hoʻokumu ʻana i nā palena ʻekolu-phase kūpono i nā electrodes diffusion gas.Ua koho ʻia ʻo Vulcan-XC-72R ma muli o ke kumu kūʻai haʻahaʻa, ka ʻili nui o 250 m2·g-1, a me ka resistivity haʻahaʻa o 0.08 a 1 Ω·cm44.45.Hōʻike ʻia kahi ʻāpana LSV o kahi laʻana catalyst i hui pū ʻia me Vulcan XC-72R ma 400 rpm ma ke Kiʻi 1. 4b.ʻO ka hopena maopopo loa o ka hoʻohui ʻana i ka Vulcan XC-72R ʻo ia ka hoʻonui ʻana i ka nui o kēia manawa.E hoʻomaopopo he ʻoi aku ka ʻike ʻia o kēia no nā ʻokikene metala, me kahi 0.60 mA cm-2 hou no nā ʻokikene metala hoʻokahi, 0.40 mA cm-2 no nā ʻokikene metala hui ʻia, a me 0.28 mA cm-2 no ka graphene a me ka graphene doped.N. Hoʻohui 0.05 mA cm-2.−2.ʻO ka hoʻohui ʻana o Vulcan XC-72R i ka ʻīnika catalyst ua hopena hoʻi i ka hoʻololi maikaʻi ʻana i ka hiki ke hoʻomaka a me ka hiki ʻana o ka hapalua hawewe E1/2 no nā catalysts a pau koe ka graphene.He hopena paha kēia o ka hoʻonui ʻia ʻana o ka hoʻohana ʻana i ka ʻāina electrochemical46 a me ka hoʻomaikaʻi ʻana i ka hoʻopili ʻana47 ma waena o nā ʻāpana catalyst ma ka Vulcan XC-72R catalyst i kākoʻo ʻia.
Hōʻike ʻia nā ʻāpana Tafel a me nā ʻāpana kinetic no kēia mau hui ʻana o ka catalyst ma ke Kiʻi S2b a me ka Papa 3.Ua like nā koina slope ʻo Tafel no nā MnOx a me nā mea graphene me XC-72R a me ka ʻole o ka XC-72R, e hōʻike ana ʻaʻole i hoʻopilikia ʻia ko lākou ala ORR.Eia nō naʻe, hāʻawi nā kobalt-based oxides Co3O4, NiCo2O4 a me MnCo2O4 i nā koina liʻiliʻi liʻiliʻi Tafel ma waena o -68 a me -80 mV dec-1 i hui pū ʻia me XC-72R e hōʻike ana i kahi hoʻololi i ke ala ORR.Hōʻike ke Kiʻi S3b i kahi ʻāpana KL no kahi laʻana catalyst i hui pū ʻia me kahi Vulcan XC-72R.Ma keʻano laulā, ua ʻike ʻia ka emi ʻana o nā waiwai kūʻokoʻa o jk no nā catalysts āpau i hui pū ʻia me XC-72R.MnOx hōʻike i ka nui loa emi i loko o ka waiwai kūʻai o jk e 55 mA-1 cm2, oiai NiCo2O4 i kakau i ka emi ma 32 mA-1 knm-2, a graphene hōʻike i ka liʻiliʻi loa emi e 5 mA-1 cm2.Hiki ke hoʻoholo i ka hopena o ka Vulcan XC-72R i ka hana o ka mea hoʻoheheʻe i kaupalenaʻia e ka hana mua o ka mea hōʻailona ma keʻano o OVR.
ʻAʻole pili ʻo Vulcan XC-72R i nā waiwai K o NiCo2O4, MnCo2O4, graphene, a me ka graphene-doped nitrogen.Eia naʻe, ua emi nui ka helu K o Co3O4 me ka hoʻohui ʻana o Vulcan XC-72R, e hōʻike ana i ka piʻi ʻana o ka helu o nā electrons i hoʻoili ʻia e ka ORR.Ua hōʻike ʻia ka hui like ʻana o Co3O4 me nā ʻāpana kalapona i nā refs.48, 49. No ka loaa ole o ke kokua kalapona, ua manaoia Co3O4 e paipai i ka like ole o HO2- i O2 a me OH-50.51, i kulike pono me ka helu hoololi electron o Co3O4 ma kahi o 2 ma ka Papa 2. ʻO ka adsorption kino o Co3O4 ma nā substrates kalapona e manaʻo ʻia e hana i kahi ala 2 + 2 ʻehā-electron ORR ala52 e hoʻoemi mua i ka O2 i HO2- ma ke kikowaena o ka catalyst Co3O4 a me Vulcan XC-72R (equation 1) a laila HO2 - The rapidly disproportionated Hoʻololi ʻia ka ʻili o ka metala i O2 a ukali ʻia e ka electroreduction.
I ka hoʻokaʻawale ʻana, ua hoʻonui ʻia ka waiwai paʻa o K MnOx me ka hoʻohui ʻana o Vulcan XC-72R, e hōʻike ana i ka emi ʻana o ka helu hoʻoili electron mai 4.6 a i 3.3 (Table 3).Loaʻa kēia ma muli o ka loaʻa ʻana o nā pūnaewele ʻelua ma ka carbon catalyst composite no ke ala electron ʻelua pae.ʻOi aku ka maʻalahi o ka hoʻemi mua ʻana o O2 a i HO2- ma nā kākoʻo kalapona, e hoʻonui iki i ka makemake no ke ala uila ʻelua o ORR53.
Ua loiloi ʻia ke kūpaʻa o ka catalyst ma ka GDE half-cell i ka laulā o nā density o kēia manawa.Ma ka fig.Hōʻike ka 5 i nā ʻāpana o ka hiki ke kūʻē i ka manawa no GDE MnOx, MnCo2O4, NiCo2O4, graphene, a me ka graphene-doped nitrogen.Hōʻike ʻo MnOx i ka paʻa holoʻokoʻa maikaʻi a me ka hana ORR ma nā haʻahaʻa haʻahaʻa a kiʻekiʻe o kēia manawa, e hōʻike ana he kūpono ia no ka hoʻonui hou ʻana.
Chronopotentiometry o HDE laʻana i kēia manawa mai 10 a hiki i 100 mA/cm2 ma 1 M NaOH, 333 K, O2 kahe kahe 200 cm3/min.
ʻIke ʻia hoʻi e mālama ʻo MnCo2O4 i ka paʻa ORR maikaʻi ma waena o ka laulā o kēia manawa, akā ma nā densities kiʻekiʻe o kēia manawa o 50 a me 100 mA cm-2 mau overvoltages nui e ʻike ʻia e hōʻike ana ʻaʻole hana ʻo MnCo2O4 e like me MnOx.Hōʻike ʻo Graphene GDE i ka hana ORR haʻahaʻa loa ma luna o ka laulā density o kēia manawa i hoʻāʻo ʻia, e hōʻike ana i ka hāʻule wikiwiki o ka hana ma 100 mA cm-2.No laila, ma lalo o nā kūlana hoʻokolohua i koho ʻia, ua koho ʻia ʻo MnOx GDE no nā hoʻokolohua hou aku ma ka ʻōnaehana Zn-air.