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Mmeghachi omume mbelata ikuku oxygen (ORR) dị mma, dị ọnụ ala na inogide dị oke mkpa maka batrị Zn-ikuku nke abụọ.A nyochara ọrụ ORR nke otu oxides metal na agwakọta na carbon electrocatalysts site na iji nha diski eletrọd (RDE), mkpọda Tafel, na atụmatụ Kutetsky-Levich.Achọpụtara na nchikota MnOx na XC-72R na-egosipụta ọrụ PBP dị elu na nkwụsi ike dị mma, ruo 100 mA cm-2.A na-anwale arụmọrụ nke electrodes ORR ahọpụtara na mmeghachi omume oxygen evolushọn nke mbụ (OER) na batrị zinc-ikuku nke abụọ wuru nke ọma na nhazi electrode atọ, yana njupụta ugbu a, molarity electrolyte, okpomọkụ, ịdị ọcha oxygen bụ. nwalekwara.Njirimara ORR na OERelectrodes.N'ikpeazụ, a tụlere ịdịte aka nke usoro zinc-ikuku nke abụọ, na-egosipụta ike ike nke 58-61% na 20 mA cm-2 na 4 M NaOH + 0.3 M ZnO na 333 K maka awa 40.
A na-ewere batrị metal-ikuku nwere electrodes oxygen dị ka usoro mara mma nke ukwuu n'ihi na ihe electroactive maka electrodes oxygen nwere ike ịnweta ngwa ngwa site na ikuku gbara ya gburugburu ma ọ dịghị achọ nchekwa1.Nke a na-eme ka nhazi usoro ahụ dị mfe site n'ikwe ka ikuku oxygen nwee ikike na-akparaghị ókè, si otú a na-amụba njupụta ike nke usoro ahụ.Ya mere, batrị ígwè-ikuku na-eji ihe anode dị ka lithium, aluminum, iron, zinc, na magnesium apụtawo n'ihi ikike ha dị oke mma.N'ime ha, batrị ikuku zinc nwere ike imezu oke ahịa maka ọnụ ahịa, nchekwa, na enyi na gburugburu ebe obibi, ebe ọ bụ na zinc nwere ọtụtụ njirimara a na-achọsi ike dị ka ihe anode, dị ka nkwụsi ike dị mma na electrolytes aqueous, njupụta ike dị elu, na nha dị ala.ike., electrochemical reversibility, ezigbo ọkụ eletrik, ụba na mfe njikwa4,5.Ugbu a, ọ bụ ezie na a na-eji batrị ikuku zinc bụ isi na ngwa azụmahịa dị ka ihe na-anụ ihe, akara ụgbọ okporo ígwè na ọkụ ịnyagharị, batrị zinc nke abụọ nwere ikike nke njupụta ume dị elu tụnyere batrị lithium.Nke a na-eme ka ọ dị mma ịga n'ihu na nyocha na batrị ikuku zinc maka ngwa na ngwa eletrọnịkị, ụgbọ ala eletrik, nchekwa ike grid na ịkwado mmepụta ume ọhụrụ6,7.
Otu n'ime ebumnuche ndị bụ isi bụ imeziwanye arụmọrụ nke mmeghachi omume oxygen na ikuku electrode, ya bụ mmeghachi omume mbelata oxygen (ORR) na mmeghachi omume evolushọn oxygen (OER), iji kwalite azụmaahịa nke batrị Zn-ikuku nke abụọ.Iji mezuo nke a, enwere ike iji electrocatalysts na-arụ ọrụ nke ọma mee ka ọnụ ọgụgụ mmeghachi omume dịkwuo elu ma si otú a na-abawanye arụmọrụ.Ka ọ dị ugbu a, a na-akọwapụta electrodes oxygen nwere ihe na-akpata bifunctional nke ọma na akwụkwọ 8,9,10.Ọ bụ ezie na bifunctional catalysts nwere ike ime ka nhazi nke electrodes dị mfe ma belata nkwụsị nke mbufe oke, nke nwere ike inye aka belata ụgwọ ọrụ mmepụta ihe, na omume, ihe ndị na-eme ka ọ dị mma maka ORR anaghị adịkarị mma maka OER, na vice versa11.Ọdịiche a na ikike ịrụ ọrụ na-eme ka onye na-eme ihe na-eme ka ọ pụta ìhè n'ọtụtụ ohere dị iche iche, nke nwere ike ịgbanwe nhazi elu ya ka oge na-aga.Tụkwasị na nke ahụ, ntinye aka nke ike na-ejikọta ike na-arụ ọrụ na-egosi na saịtị ndị na-arụ ọrụ na ihe na-eme ka ọ dị iche iche nwere ike ịdị iche maka mmeghachi omume ọ bụla, nke nwere ike ime ka njikarịcha.
Nsogbu ọzọ dị ukwuu maka batrị Zn-ikuku nke abụọ bụ nhazi nke ikuku oxygenelectrode, tumadi n'ihi na monofunctional catalysts maka ORR na OER na-arụ ọrụ na mgbasa ozi mmeghachi omume dị iche iche.Igwe mgbasa ozi gas nke ORR ga-abụrịrị hydrophobic iji mee ka ikuku oxygen banye na saịtị ndị na-akpata catalytic, ebe maka OER, elu electrode ga-abụrịrị hydrophilic iji kwado mwepụ nke ikuku oxygen.Na fig.1 na-egosi atụmatụ atọ nke ikuku oxygen nke abụọ e nwetara site na nyocha nke Jorissen12, ya bụ (i) ihe na-eme ka monolayer bifunctional, (ii) okpukpu abụọ ma ọ bụ multilayer catalysts, na (iii) nhazi electrode atọ.
N'ihi na nke mbụ electrode imewe, nke na-agụnye nanị otu oyi akwa bifunctional catalyst na n'out oge catalyzes ORR na OER, ma ọ bụrụ na a akpụkpọ ahụ agụnyere na nke a imewe, mgbe a membrane-electrode mgbakọ (MEA) na-guzobere dị ka egosiri.Ụdị nke abụọ na-agụnye akwa abụọ (ma ọ bụ karịa) na-emepụta ihe na-emepụta ihe dị iche iche na porosity dị iche iche na hydrophobicity iji kọwaa ọdịiche dị na mpaghara mmeghachi omume13,14,15.N'ọnọdụ ụfọdụ, a na-ekewa akwa abụọ catalytic, na akụkụ hydrophilic nke OER chere ihu na electrolyte na akụkụ nke ọkara-hydrophobic nke ORR chere ihu na nsọtụ oghere nke electrodes 16, 17, 18. cell nwere mmeghachi omume abụọ- kpọmkwem oxygen electrodes na a zinc electrode19,20.Tebụl S1 depụtara uru na ọghọm dị n'ichepụta ọ bụla.
Mmejuputa nhazi nke elektrọd na-ekewa mmeghachi omume ORR na OER egosila nkwụsi ike ịgba ígwè19 ka mma.Nke a bụ eziokwu karịsịa maka nhazi electrode atọ, ebe a na-ebelata mmebi nke ihe ndị na-emepụta ihe na-adịghị akwụsi ike na ihe mgbakwunye na mpụ ga-enwe ike ịchịkwa ya n'ogo niile.N'ihi ihe ndị a, anyị na-eji atọ-electrode Zn-ikuku nhazi na ọrụ a.
N'ime edemede a, anyị na-ebu ụzọ họrọ ihe nrụpụta ORR dị elu site n'ịtụle ụdị oxides mgbanwe dị iche iche, ihe carbonaceous, na ihe ntụnye aka na nnwale diski eletrọd (RDE).Ntugharị metal oxides na-abụkarị ezigbo electrocatalysts n'ihi na ha dị iche iche oxidation na-ekwu;mmeghachi omume na-adị mfe catalyzed na ọnụnọ nke ogige ndị a21.Dị ka ihe atụ, manganese oxides, cobalt oxides, na cobalt dabeere ngwakọta oxides (dị ka NiCo2O4 na MnCo2O4) 22,23,24 na-egosi ezi ORR na alkaline ọnọdụ n'ihi na ha ọkara jupụtara d-orbitals, electron ike ọkwa nke na-enye ohere maka electron. na-arụ ọrụ na mma ịcha nkasi obi.Tụkwasị na nke ahụ, ha na-aba ụba na gburugburu ebe obibi ma na-enwe mmetụta eletrik a na-anabata, mmeghachi omume dị elu na nkwụsi ike dị mma.N'otu aka ahụ, a na-eji ihe carbonaceous eme ihe n'ọtụtụ ebe, na-enwe uru nke eletriki eletrik dị elu na nnukwu elu.N'ọnọdụ ụfọdụ, heteroatoms dị ka nitrogen, boron, phosphorus, na sọlfọ abanyela n'ime carbon iji gbanwee nhazi ya, na-emewanyewanye njirimara ORR nke ihe ndị a.
Dabere na nsonaazụ nnwale ahụ, anyị gụnyere ihe ndị na-akpata OVR ahọpụtara na electrodes mgbasa gas (GDE) wee nwalee ha na njupụta dị ugbu a.A na-achịkọta ihe kacha arụ ọrụ nke ORR GDE n'ime batrị Zn-ikuku nke atọ na-arụ ọrụ nke ọma yana electrodes OER nke mmeghachi omume akọwapụtara na ọrụ anyị gara aga26,27.A na-enyocha ikike nke electrodes oxygen n'otu n'otu n'oge mwepu na-aga n'ihu ma na-ana nnwale ịgba ígwè iji mụọ mmetụta nke ọnọdụ ọrụ dị ka njupụta ugbu a, molarity electrolyte, okpomọkụ na-arụ ọrụ cell, na ịdị ọcha oxygen.N'ikpeazụ, a tụlere nkwụsi ike nke batrị abụọ nke Zn-air n'okpuru ịgba ígwè na-aga n'ihu n'okpuru ọnọdụ ọrụ kacha mma.
A kwadebere MnOx28 site na usoro redox nke kemịkalụ: 50 ml nke 0.04 M KMnO4 ngwọta (Fisher Scientific, 99%) ka agbakwunyere na 100 ml nke 0.03 M Mn (CH3COO) 2 (Fisher Scientific, 98%) ka ọ bụrụ mmiri ozuzo.A na-emezi ngwakọta ahụ ka ọ bụrụ pH 12 na sodium hydroxide na-agbaze, wee kechie ya ugboro 3-5 na 2500 rpm iji kpokọta ihe na-asọpụta.A na-ejikwa mmiri deionized sachaa ihe na-asọpụta ruo mgbe agba odo odo nke ion permanganate kwụsịrị.N'ikpeazụ, a na-ekpochapụ ihe nkwụnye ego ahụ na 333 K n'otu ntabi anya wee kpoo ya.
Spinel oxides Co3O4, NiCo2O4, na MnCo2O4 bụ site na ire ere ọkụ.A kwadebere NiCo2O4 na MnCo2O4 site na ịgbakwunye 0.5 M (14.5 g) nickel (II) nitrate hexahydrate, Ni (NO3) 2⋅6H2O (Fisher Scientific, 99.9%) ma ọ bụ 0.5 M (12.6 g) tetrahydrate manganese (II) nitrate min ).)2 4H2O (Sigma Aldrich, ≥ 97%) na 1 M (29.1 g) cobalt (II) nitrate hexahydrate, Co (NO3) 2 6H2O (Fisher Scientific, 98+%, ACS reagents) na methanol (Fisher Scientific, 99.9% ) na 100 ml nke dilution vials.A na-agbakwunye methanol n'obere akụkụ na nitrate metal mgbanwe na-akpali akpali na-aga n'ihu ruo mgbe a na-enweta ihe ngwọta otu.Mgbe ahụ, a na-ebufe ihe ngwọta ahụ na crocible ma kpoo ọkụ na efere ọkụ, na-ahapụ ọchịchịrị gbara ọchịchịrị.Emebere ihe siri ike na 648 K maka awa 20 n'ikuku.A na-akụsị ihe siri ike nke rụpụtara na ntụ ntụ dị mma.Ọ dịghị Ni(NO3)2 6H2O ma ọ bụ Mn(NO3)2 4H2O ka agbakwunyere n'oge njikọ nke Co3O4.
Graphene nanosheets na elu nke 300 m2 / g (Sigma Aldrich), graphene doped na nitrogen (Sigma Aldrich), carbon ojii ntụ ntụ (Vulcan XC-72R, Cabot Corp., 100%), MnO2 (Sigma Aldrich) na 5 wt.% Pt/C (Acros Organics) ka ejiri mee ya.
A na-eji nha RDE (Pine Research Instrumentation) iji nyochaa ọrụ nke ihe mkpali ORR dị iche iche na 1 M NaOH.A na-eji ink catalytic nke nwere 1 mg ihe na-eme ihe + 1 ml deionized (DI) H2O + 0.5 ml isopropanol (IPA) + 5 μl 5 wt% Nafion 117 (Sigma-Aldrich) dị ka ọ dị.Mgbe agbakwunyere Vulcan XC-72R, agba catalytic nwere 0.5 mg catalyst + 0.5 mg Vulcan XC-72R + 1 ml DI HO + 0.5 ml IPA + 5 µl 5 wt% Nafion 117 iji hụ na a na-ebugharị ihe na-agbanwe agbanwe.The ngwakọta e sonicated maka 20 nkeji na homogenized iji a Cole-Parmer LabGen 7 Series homogenizer na 28,000 rpm maka 4 nkeji.A na-etinye ink ahụ na atọ aliquots nke 8 μl n'elu otu iko carbon electrode (Pine Instrument Company) na dayameta nke 4 mm (ebe ọrụ ≈ 0.126 cm2) na akpọnwụwo n'etiti n'ígwé iji nye ibu nke ≈120 μg cm. -2.N'etiti ngwa, enyo carbon electrode elu bụ successively mmiri polished na MicroCloth (Buehler) na 1.0 mm na 0.5 mm alumina ntụ ntụ (MicroPolish, Buehler) sonication sonication na deionized H2O.
Emebere ihe nlele elektrọd mgbasa ozi ORR dị ka protocol anyị akọwara na mbụ28.Nke mbụ, a na-agwakọta ntụ ntụ ntụ ntụ na Vulcan XC-72R na nha 1: 1 dị arọ.Mgbe ahụ, ngwakọta nke ngwọta nke polytetrafluoroethylene (PTFE) (60 wt.% na H2O) na ihe mgbaze nwere oke nke IPA / H2O nke 1: 1 ka agbakwunyere na ngwakọta ntụ ntụ.Sonicate na catalytic agba maka ihe dị ka nkeji iri abụọ na homogenize maka ihe dị ka nkeji 4 na 28,000 rpm.A na-etinye ink ahụ nke ọma na spatula n'elu mpempe akwụkwọ carbon 13 mm na dayameta (AvCarb GDS 1120) wee kpoo ruo mgbe enwere ihe na-akpali akpali nke 2 mg cm2.
Emebere OER electrodes site na kathodic electrodeposition nke Ni-Fe hydroxide catalysts na igwe anaghị agba nchara 15 mm x 15 mm.ntupu(DeXmet Corp, 4SS 5-050) ka akọwara 26,27.Emere electrodeposition na ọkọlọtọ atọ-electrode ọkara cell (ihe mkpuchi mkpuchi polymer nke ihe dịka 20 cm3) na grid Pt dị ka electrode counter na Hg/HgO na 1 M NaOH dị ka electrode ntụaka.Kwe ka ihe mkpuchi igwe anaghị agba nchara ka ọ kpọọ nkụ tupu ya ebipụ ebe ihe dịka 0.8 cm2 nwere ntụ ntụ carbon siri ike 10 mm.
Maka ntụnyere, a na-eji ORR azụmahịa na OER electrodes mee ihe dịka anatara na nwalere n'okpuru otu ọnọdụ ahụ.Electrode ORR nke azụmahịa (QSI Nano Gas Diffusion Electrode, Quantum Sphere, 0.35 mm thick) mejupụtara manganese na carbon oxide nke ejiri nickel mesh na-anakọta ugbu a, ebe electrode OER azụmahịa (ụdị 1.7, Magneto anode pụrụ iche, BV) nwere ọkpụrụkpụ 1.3. mm.ruo 1.6 mm gbasaa titanium ntupu nke ru-Ir agwakọta metal oxide.
E ji FEI Quanta 650 FEG scanning eletrọn microscope (SEM) na-arụ ọrụ n'okpuru oghere dị elu yana voltaji na-agba ọsọ nke 5 kV.A nakọtara data X-ray ntụ ntụ (XRD) na Bruker D8 Advance X-ray diffractometer nwere isi iyi tube ọla kọpa (λ = 1.5418 Å) wee nyochaa site na iji ngwanrọ Bruker Diffraction Suite EVA.
Emere nha electrochemical niile site na iji Biologic SP-150 potentiostat na EC-lab software.A nwalere ihe atụ nke RDE na GDE na ọkọlọtọ atọ-electrode ntọlite ​​nke nwere cell jakị 200 cm3 na Laggin capillary dị ka electrode ntụaka.A na-eji Pt mesh na Hg/HgO na 1 M NaOH mee ihe dị ka igwe eletrik na ntụnye aka, n'otu n'otu.
Maka nha RDE na nnwale ọ bụla, a na-eji 1 M NaOH electrolyte ọhụrụ, nke a na-edebe okpomọkụ ya na 298 K na-eji mmiri na-ekesa mmiri (TC120, Grant).Oxygen gaseous (BOC) nọ na-abata n'ime electrolyte site na frit iko nwere porosity nke 25–50 µm ma ọ dịkarịa ala 30 min tupu nnwale ọ bụla.Iji nweta nkwubi okwu polarization ORR, a na-enyocha ike ya site na 0.1 ruo -0.5 V (n'ihe metụtara Hg/HgO) na ọnụ ọgụgụ nyocha nke 5 mV s -1 na 400 rpm.Enwetara voltammogram nke cyclic site n'ịzacha ikike dị n'etiti 0 na -1.0 V na Hg/HgO n'ọkwa nke 50 mV s-1.
Maka nha HDE, edobere 1 M NaOH electrolyte na 333 K jiri mmiri ịsa mmiri na-ekesa.Ebe na-arụ ọrụ nke 0.8 cm2 ka ekpughere na electrolyte na-enye oxygen na-aga n'ihu n'akụkụ azụ nke electrode na ọnụego 200 cm3 / min.Ebe dị anya n'etiti electrode na-arụ ọrụ na electrode ntụaka bụ 10 mm, na anya n'etiti electrode na-arụ ọrụ na electrode counter bụ 13-15 mm.Waya nickel na ntupu na-enye kọntaktị eletrik n'akụkụ gas.Ewere nha Chronopotentiometric na 10, 20, 50 na 100 mA cm-2 iji nyochaa nkwụsi ike na arụmọrụ nke electrode.
A tụlere njirimara nke electrodes ORR na OER n'ime cell iko nwere jaketị 200 cm3 nwere ntinye PTFE29.E gosipụtara eserese schematic nke sistemu na foto S1.A na-ejikọta electrodes na batrị ahụ na usoro electrode atọ.Eletrọd na-arụ ọrụ nwere mmeghachi omume dị iche iche-kpọmkwem ORR na OER electrodes ejikọrọ na modul ọsọ agba anọ (Songle, SRD-05VDC-SL-C) na microcontroller (Raspberry Pi 2014© model B+V1.2) nwere zinc anode.dị ka ụzọ abụọ Eletrọd na electrode ntụaka Hg/HgO dị na 4 M NaOH nọ n'ebe dị anya nke 3 mm site na zinc anode.Edeela script Python iji rụọ ọrụ na jikwaa Raspberry Pi na Module Relay.
Emeziri cell ahụ ka ọ nabata zinc foil anode (Goodfellow, 1 mm thick, 99.95%) na mkpuchi polymer kwere ka etinye electrodes n'ebe dị anya nke ihe dịka 10 m.4 mm iche.Nitrile rọba plọg na-edozi electrodes na mkpuchi, na nickel wires (Alfa Aesar, 0.5 mm dayameta, annealed, 99.5% Ni) na-eji maka eletriki kọntaktị nke electrodes.Ejiri isopropanol hichaa zinc foil anode nke mbụ wee jiri mmiri deionized, kpuchie elu ya na teepu polypropylene (Avon, AVN9811060K, 25 µm gbara ọkpụrụkpụ) iji kpughee mpaghara na-arụ ọrụ nke ihe dịka 0.8 cm2.
Emere nnwale ịgba ígwè niile na 4 M NaOH + 0.3 M ZnO electrolyte na 333 K ọ gwụla ma amataghị ya.Na ọnụ ọgụgụ, Ewe n'ihe gbasara Hg/HgO na-ezo aka n'ikike nke oxygen electrode (ORR na OER), Ece n'ihe gbasara Hg/HgO na-anọchi anya ikike nke zinc electrode, Ecell n'ihe gbasara Hg/HgO na-anọchi anya zuru oke. cell ikike ma ọ bụ nwere ike iche.n'etiti ike batrị abụọ.A na-enye oxygen ma ọ bụ ikuku abịakọrọ n'azụ nke electrode OPP na ọsọ ọsọ nke 200 cm3 / min.A mụrụ nkwụsi ike ịgba ígwè na arụmọrụ nke electrodes na njupụta dị ugbu a nke 20 mA cm-2, oge okirikiri nke 30 min, na oge ezumike OCV nke 1 min n'etiti ọkara okirikiri ọ bụla.A na-eme opekempe nke cycles 10 maka ule ọ bụla, wee wepụta data site na okirikiri 1, 5, na 10 iji chọpụta ọnọdụ electrodes ka oge na-aga.
Ihe omuma nke ihe omuma nke ORR bu SEM (Fig 2), na ntụ ntụ nke X-ray diffraction kwadoro usoro kristal nke ihe atụ (Fig 3).A na-enye usoro nhazi nke ihe atụ nke ihe na-eme ka ọ dị na Tebụl 1. 1. Mgbe ị na-atụnyere manganese oxides, azụmahịa MnO2 na fig.2a nwere nnukwu akụkụ, na usoro ntụgharị dị na Fig. 3a kwekọrọ na JCPDS 24-0735 maka tetragonal β-MnO2.N'ụzọ megidere nke ahụ, n'elu MnOx dị na Fig. 2b na-egosi ihe ndị dị mma na nke dị mma, nke kwekọrọ na usoro mgbagwoju anya na Fig. 66 ° kwekọrọ na ọnụ ọgụgụ kasị elu (110), (220), (310), (211), na (541) nke α-MnO2 hydrate tetrahedrally gbadoro ụkwụ, JCPDS 44-014028.
(a) MnO2, (b) MnOx, (c) Co3O4, (d) NiCo2O4, (e) MnCo2O4, (f) Vulcan XC-72R, (g) graphene, (h) nitrogen doped graphene, (na) 5 wt .% Pt/C.
Usoro X-ray nke (a) MnO2, (b) MnOx, (c) Co3O4, (d) NiCo2O4, (e) MnCo2O4, (f) Vulcan XC-72R, graphene-doped nitrogen na graphene, na (g) 5 % platinum/carbon.
Na fig.2c-e, ọdịdị elu nke oxides dabere na cobalt Co3O4, NiCo2O4, na MnCo2O4 nwere ụyọkọ nke ụmụ irighiri ihe na-adịghị agbanwe agbanwe.Na fig.3c–e gosiri na mgbanwe ndị a niileigweoxides nwere usoro spinel na sistemu cubic crystal (JCPDS 01-1152, JCPDS 20-0781, na JCPDS 23-1237, n'otu n'otu).Nke a na-egosi na usoro ire ere ọkụ na-enwe ike imepụta oxides metal kristal nke ukwuu, dịka ọ na-egosi site na ọnụ ọgụgụ siri ike akọwapụtara nke ọma na usoro ntụgharị.
Ihe onyonyo SEM nke ihe carbon na-egosi nnukwu mgbanwe.Na fig.2f Vulcan XC-72R carbon ojii mejupụtara nanoparticles juru n'ọnụ.N'ụzọ megidere nke ahụ, ọdịdị nke graphene na Fig. 2g bụ efere nwere nsogbu nke ukwuu na ụfọdụ agglomerations.Otú ọ dị, N-doped graphene (Fig. 2h) na-egosi na ọ nwere akwa akwa.Usoro mgbasa X-ray kwekọrọ nke Vulcan XC-72R, graphene nanosheets azụmahịa, na graphene N-doped na fig.3f gosipụtara obere mgbanwe na ụkpụrụ 2θ nke (002) na (100) ọnụ ọgụgụ carbon.Achọpụtara Vulcan XC-72R dị ka graphite hexagonal na JCPDS 41-1487 nwere ọnụ ọgụgụ kacha elu (002) na (100) pụtara na 24.5° na 43.2° n'otu n'otu.N'otu aka ahụ, ọnụ ọgụgụ (002) na (100) nke N-doped graphene pụtara na 26.7° na 43.3°, n'otu n'otu.Ike ndabere a na-ahụ na usoro mgbasa X-ray nke Vulcan XC-72R na nitrogen-doped graphene bụ n'ihi oke mgbagwoju anya nke ihe ndị a na ọdịdị elu ha.N'ụzọ dị iche, usoro dị iche iche nke graphene nanosheets na-egosi ọnụ ọgụgụ dị nkọ, nke siri ike (002) na 26.5 ° na obere ọnụ ọgụgụ buru ibu (100) na 44 °, na-egosi ọdịdị kristal karịa nke nlele a.
N'ikpeazụ, na fig.2i SEM oyiyi nke 5 wt.% Pt/C na-egosi mkpara ekara carbon iberibe na gburugburu voids.A na-ekpebi Cubic Pt site na ọtụtụ n'ime ọnụ ọgụgụ kachasị elu na 5 wt% Pt/C ụkpụrụ dị na Fig. 3g, na ọnụ ọgụgụ kasị elu na 23° kwekọrọ na (002) ọnụ ọgụgụ kasị elu nke carbon dị ugbu a.
Edekọkwara voltammogram nke na-ekpochapụ ORR n'ahịrị n'ọ̀tụ̀tụ̀ sweep nke 5 mV s-1.N'ihi oke mbufe oke, maapụ anakọtara (Fig 4a) na-enwekarị ụdị S na-agbatị ruo ala dị larịị nwere ikike na-adịghị mma.Mbelata njupụta dị ugbu a, jL, nwere ike E1 / 2 (ebe j / jL = ½) na ikike mmalite na -0.1 mA cm-2 bụ nke e wepụtara na atụmatụ ndị a ma depụta ya na Tebụl 2. Ọ dị mma ịmara na na fig.4a, a na-ekewa ndị na-emepụta ihe dị ka ikike E1 / 2 ha si dị n'ime: (I) metal oxides, (II) carbonaceous material, na (III) ọla ndị mara mma.
Voltammogram nke na-ekpochapụ Linear nke (a) onye na-enye ike na (b) ihe nkiri dị mkpa nke onye na-emepụta ihe na XC-72R, nke a tụrụ na nyocha carbon nke enyo RDE na 400 rpm na ọnụego nyocha nke 5 mV s-1 na O2 saturation na 298 K na 1 M NaOH cf.
N'otu n'otu metal oxides nke Mn na Co na otu m na-egosi mmalite ikike nke -0.17 V na -0.19 V n'otu n'otu, na E1 / 2 ụkpụrụ dị n'etiti -0.24 na -0.26 V. Mbelata mmeghachi omume nke metal oxides ndị a na-egosi na nhata. .(1) na (2), nke pụtara na-esote ike mmalite na fig.4a dakọtara na ikike ọkọlọtọ nke nzọụkwụ mbụ 2e nke ụzọ na-apụtaghị ìhè nke ORR na nha anya.(3).
Ngwakọta ọla oxides MnCo2O4 na NiCo2O4 n'otu otu ahụ na-egosi ntakịrị ike izizi agbaziri na -0.10 na -0.12 V n'otu n'otu, mana jigide ụkpụrụ E1/2 nke ihe dịka 10.-0.23 volts.
Ngwa carbon nke Group II na-egosi ụkpụrụ E1/2 dị mma karịa otu m metal oxides.Ihe graphene nwere ikike izizi nke -0.07 V na uru E1 / 2 nke -0.11 V, ebe ikike izizi na E1 / 2 nke 72R Vulcan XC bụ -0.12V na -0.17V n'otu n'otu.Na otu III, 5 wt% Pt / C gosipụtara ikike mmalite kachasị mma na 0.02 V, E1 / 2 nke -0.055 V, na njedebe kachasị na -0.4 V, ebe ọ bụ na mbelata oxygen mere site na njupụta ugbu a nke ụzọ 4e. .Ọ nwekwara E1 / 2 kasị ala n'ihi na elu conductivity nke Pt / C na reversible kinetics nke ORR mmeghachi omume.
Ọgụgụ S2a na-enye nyocha mkpọda Tafel maka ihe dị iche iche.Mpaghara a na-achịkwa kinetically nke 5 wt.% Pt / C na-amalite na 0.02 V n'ihe gbasara Hg / HgO, ebe mpaghara nke metal oxides na carbon carbon dị n'ókè nke ikike na-adịghị mma site na -0.03 ruo -0.1 V. Mkpọda uru. maka Tafel Pt / C bụ -63.5 mV ss-1, nke a na-ahụkarị maka Pt na densities dị ugbu a deE / d log i = -2.3 RT / F31.32 nke usoro nke na-achọpụta ọnụego gụnyere mgbanwe nke oxygen si physisorption gaa chemissorption33,34.Ụkpụrụ mkpọda Tafel maka ihe carbon dị n'otu mpaghara dị ka Pt / C (-60 ruo -70 mV div-1), na-atụ aro na ihe ndị a nwere ụzọ ORR yiri ya.Onye ọ bụla metal oxides nke Co na Mn na-akọ Tafel mkpọda sitere na -110 ruo -120 mV dec-1, nke bụ dE/d log i = -2.3 2RT/F, ebe ọnụego-ekpebi nzọụkwụ bụ mbụ eletrọn.nyefe nzọụkwụ 35, 36. Ubé elu mkpọda ụkpụrụ ndekọ maka agwakọta metal oxides NiCo2O4 na MnCo2O4, banyere -170 mV dec-1, na-egosi ọnụnọ nke OH- na H2O ions n'elu nke oxide, nke na-egbochi oxygen adsorption na nnyefe elektrọn, si otú ahụ na-emetụta oxygen.ụzọ mbelata 35.
A na-eji nha Kutetsky-Levich (KL) chọpụta usoro mmeghachi omume nke kinetic maka ihe nlele dị iche iche na-enweghị mbufe oke.na nha nha.(4) ngụkọta atụnyere njupụta ugbu a j bụ nchikota nke njupụta dị ugbu a nke nnyefe eletrọn na mbufe oke.
site na nha anya.(5) Mbelata njupụta jL dị ugbu a dabara na mgbọrọgwụ square nke ọsọ ntụgharị.Ya mere, KL nha nha.(6) na-akọwa eserese ahịrị j-1 na ω−1//2, ebe ebe nrutu aka bụ jk na mkpọda eserese ahụ bụ K.
ebe ν bụ viscosity kinematic nke electrolyte 1 M NaOH (1.1 × 10-2 cm2 s-1) 37, D bụ ọnụọgụ mgbasa ozi nke O2 na 1 M NaOH (1.89 × 10-5 cm2 s-1) 38, ω bụ rpm bụ ntụgharị ntụgharị, C bụ ikuku oxygen na nnukwu ngwọta (8.4 × 10-7 mol cm-3) 38.
Chịkọta voltammogram ndị a na-ekpochapụ n'ahịrị na-eji RDE na 100, 400, 900, 1600, na 2500 rpm.E wepụrụ ụkpụrụ site na -0.4 V na mpaghara mbufe oke oke iji kpapụta eserese KL, ntụgharị -j-1 na ω-1//2 maka onye na-eme ihe (Fig. S3a).Jiri nha nhata.Na nha nha (6) na (7), ndị na-egosi arụmọrụ nke onye na-emepụta ihe, dị ka njupụta nke ugbu a nke kinetic n'ebughị n'uche mmetụta nke oke nnyefe jk, kpebisiri ike site na njedebe nke nkwụsịtụ na axis y, na ọnụ ọgụgụ nke A na-ekpebi nnyefe elektrọn site na gradient K nke usoro.E depụtara ha na tebụl 2.
5 wt% Pt/C na XC-72R nwere ụkpụrụ jk kacha dị ala, na-egosi kinetics ngwa ngwa maka ihe ndị a.Otú ọ dị, mkpọda nke eriri XC-72R fọrọ nke nta ka ọ bụrụ okpukpu abụọ maka 5 wt% Pt/C, nke a na-atụ anya ebe ọ bụ na K bụ ihe ngosi nke ọnụọgụ electrons na-ebufe n'oge mmeghachi omume mbelata oxygen.N'ụzọ doro anya, atụmatụ KL maka 5 wt% Pt / C kwesịrị ịgafe na mmalite 39 n'okpuru ọnọdụ nnyefe oke oke, agbanyeghị nke a anaghị ahụ ya na Figure S3a, na-atụ aro njedebe kinetic ma ọ bụ mgbasa ozi na-emetụta nsonaazụ ya.Nke a nwere ike ịbụ n'ihi na Garsani et al.40 egosila na obere nkwekọrịta na topology na morphology nke ihe nkiri Pt / C catalytic nwere ike imetụta izi ezi nke ụkpụrụ ọrụ ORR.Otú ọ dị, ebe ọ bụ na a kwadebere ihe nkiri niile na-akpali akpali n'otu ụzọ ahụ, mmetụta ọ bụla na nsonaazụ kwesịrị ịbụ otu maka ihe nlele niile.The graphene KL cross point of ≈ -0.13 mA-1 cm2 dị ka nke XC-72R, ma -0.20 mA-1 cm2 cross point maka N-doped graphene KL graph na-egosi na njupụta ugbu a dị ukwuu dabere na. voltaji na catalytic Ntụgharị.Nke a nwere ike ịbụ n'ihi na nitrogen doping nke graphene na-ebelata mkpokọta ọkụ eletrik, na-ebute kinetics nnyefe eletrọn nwayọọ nwayọọ.N'ụzọ dị iche, uru K zuru oke nke nitrogen-doped graphene dị ntakịrị karịa nke graphene n'ihi na ọnụnọ nitrogen na-enyere aka ịmepụta saịtị na-arụ ọrụ maka ORR41,42.
Maka oxides nke dabeere na manganese, a na-ahụ ebe nkwụsị nke uru zuru oke - 0.57 mA-1 cm2.Ka o sina dị, uru K zuru oke nke MnOx dị ala karịa nke MnO2 ma dị nso 5 wt %.%Pt/C.Achọpụtara ọnụọgụ mbufe eletrọn ka ihe ruru.MnOx bụ 4 na MnO2 dị nso na 2. Nke a kwekọrọ na nsonaazụ ndị e bipụtara na akwụkwọ akụkọ, nke na-akọ na ọnụọgụ electron na-enyefe na ụzọ α-MnO2 ORR bụ 4, ebe β-MnO243 na-adịkarị ala karịa 4. Ya mere, , Ụzọ ORR dị iche iche maka ụdị polymorphic dị iche iche nke ndị na-emepụta ihe na-adabere na manganese oxide, ọ bụ ezie na ọnụego nke usoro kemịkal na-anọgide na-adị ka otu.Karịsịa, MnOx na MnCo2O4 catalysts nwere ọnụọgụ eletrọn dị elu karịa 4 n'ihi na mbelata nke manganese oxides dị na ihe ndị a na-eme n'otu oge na mbelata oxygen.N'ime ọrụ gara aga, anyị chọpụtara na mbelata electrochemical nke manganese oxide na-eme n'otu ụzọ ahụ dị ka mbelata oxygen na ngwọta jupụtara na nitrogen28.Ntinye aka nke mmeghachi omume akụkụ na-eduga na ọnụọgụ eletrọn gbakọrọ ntakịrị karịa 4.
Njikọ nke Co3O4 bụ ≈ -0.48 mA-1 cm2, nke na-adịchaghị njọ karịa ụdị abụọ nke manganese oxide, na ọnụ ọgụgụ mbufe eletrọn pụtara na-ekpebi uru nke K nha 2. Dochie Ni na NiCo2O4 na Mn na MnCo2O4. site Co na-eduga na mbelata na ụkpụrụ zuru oke K, nke na-egosi mmụba nke elektrọn nnyefe kinetics na ngwakọta metal oxides.
A na-agbakwunye ihe ndị na-emepụta carbon na ink mkpata ORR iji mee ka ọkụ eletrik dịkwuo elu ma mee ka nhazi nke usoro atọ kwesịrị ekwesị na electrodes mgbasa ozi gas.A họọrọ Vulcan-XC-72R n'ihi ọnụ ahịa ya dị ala, nnukwu akụkụ elu nke 250 m2 · g-1, yana obere resistivity nke 0.08 ruo 1 Ω · cm44.45.E gosipụtara atụmatụ LSV nke ihe nleba anya nke agwakọta ya na Vulcan XC-72R na 400 rpm na eserese 1. 4b.Mmetụta pụtara ìhè nke ịgbakwunye Vulcan XC-72R bụ ịbawanye njupụta kachasị ugbu a.Rịba ama na nke a bụ ihe a na-ahụ anya maka ígwè oxides, yana 0.60 mA cm-2 ọzọ maka otu metal oxides, 0.40 mA cm-2 maka ngwakọta metal oxides, na 0.28 mA cm-2 maka graphene na doped graphene.N. Tinye 0.05 mA cm-2.-2.Mgbakwunye nke Vulcan XC-72R na ink nke na-eme ka ọ bụrụ ihe na-eme ka ọ bụrụ mgbanwe dị mma na mmalite mmalite yana ikike E1 / 2 nke ọkara-ebili mmiri maka ihe niile na-eme ka ọ bụrụ graphene.Mgbanwe ndị a nwere ike ịbụ nsonaazụ n'ịbawanye mpaghara eletrọkị kemịkalụ46 yana mma kọntaktị47 n'etiti ụmụ irighiri ihe na-eme ka ihe na-akwado Vulcan XC-72R.
E gosipụtara atụmatụ Tafel kwekọrọ na paramita kinetic maka ngwakọta ndị a na-akpali akpali na Figure S2b na Tebụl 3, n'otu n'otu.Ụkpụrụ mkpọda Tafel bụ otu maka ihe MnOx na graphene nwere na enweghị XC-72R, na-egosi na emetụtaghị ụzọ ORR ha.Agbanyeghị, oxides cobalt Co3O4, NiCo2O4 na MnCo2O4 nyere ụkpụrụ mkpọda Tafel na-adịghị mma n'etiti -68 na -80 mV dec-1 yana XC-72R na-egosi mgbanwe n'ụzọ ORR.Ọgụgụ S3b na-egosi atụmatụ KL maka ihe nlere anya nke jikọtara ya na Vulcan XC-72R.N'ozuzu, a hụrụ mbelata na ụkpụrụ zuru oke nke jk maka ihe niile na-eme ka ọ bụrụ XC-72R.MnOx gosipụtara mbelata kachasị na uru zuru oke nke jk site na 55 mA-1 cm2, ebe NiCo2O4 dekọrọ mbelata site na 32 mA-1 cm-2, na graphene gosipụtara mbelata kacha nta site na 5 mA-1 cm2.Enwere ike ikwubi na mmetụta nke Vulcan XC-72R na arụmọrụ nke onye na-eme ihe na-ejedebe na-ejedebe site na ọrụ mbụ nke ihe na-eme ka ọ bụrụ ihe gbasara OVR.
Vulcan XC-72R anaghị emetụta ụkpụrụ K nke NiCo2O4, MnCo2O4, graphene, na nitrogen-doped graphene.Agbanyeghị, uru K nke Co3O4 belatara nke ukwuu yana mgbakwunye Vulcan XC-72R, na-egosi mmụba nke ọnụọgụ elektrọn nke ORR bufere.Njikọ dị otú ahụ nke Co3O4 na ihe carbon ka akọpụtala na refs.48, 49. Na enweghị nkwado carbon, a na-eche na Co3O4 na-akwalite disproportionation nke HO2- ka O2 na OH-50.51, nke dị na nkwekọrịta dị mma na Co3O4's electron transfer number of about 2 in Table 2. A na-atụ anya mgbasa ozi anụ ahụ nke Co3O4 na mkpụrụ carbon ga-emepụta ụzọ 2 + 2 anọ-electron ORR ụzọ52 nke mbụ electroreduces O2 ka HO2- na interface nke Co3O4 catalyst na Vulcan XC-72R (equation 1) na mgbe ahụ HO2 - The ngwa ngwa disproportionated. A na-atụgharị elu igwe oxide ka ọ bụrụ O2 na-esote electroreduction.
N'ụzọ dị iche, uru zuru oke nke K MnOx mụbara na mgbakwunye nke Vulcan XC-72R, nke na-anọchite anya mbelata na nọmba nnyefe eletrọn site na 4.6 ruo 3.3 (Table 3).Nke a bụ n'ihi ọnụnọ nke saịtị abụọ na carbon catalyst composite maka ụzọ eletrọn ụzọ abụọ.Mbelata mbụ nke O2 ruo HO2- na-eme ngwa ngwa na nkwado carbon, na-ebute mmasị dị ntakịrị maka ụzọ elektrọn abụọ nke ORR53.
A tụlere nkwụsi ike nke ihe na-eme ka ọ dị na GDE ọkara cell n'ogo nke njupụta dị ugbu a.Na fig.5 na-egosi atụmatụ nke nwere ike karịa oge maka GDE MnOx, MnCo2O4, NiCo2O4, graphene, na nitrogen-doped graphene.MnOx na-egosi nkwụsi ike zuru oke na arụmọrụ ORR na njupụta dị ala na nke dị ugbu a, na-atụ aro na ọ dabara maka nkwalite ọzọ.
Chronopotentiometry nke ihe atụ HDE dị ugbu a site na 10 ruo 100 mA/cm2 na 1 M NaOH, 333 K, O2 eruba 200 cm3/min.
MnCo2O4 na-egosikwa na ọ na-ejigide nkwụsi ike ORR dị mma n'ofe njupụta dị ugbu a, mana na njupụta dị elu ugbu a nke 50 na 100 mA cm-2 nnukwu overvoltages na-egosi na MnCo2O4 adịghị arụ ọrụ yana MnOx.Graphene GDE na-egosipụta arụmọrụ ORR kachasị dị ala karịa ogo njupụta dị ugbu a a nwalere, na-egosi mbelata arụmọrụ ngwa ngwa na 100 mA cm-2.Ya mere, n'okpuru ọnọdụ nnwale ahọpụtara, a họọrọ MnOx GDE maka ule ndị ọzọ na usoro nke abụọ nke Zn-air.