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Entunguuka ya tekinologiya ya haidrojeni eri aha mutima gw’eby’entaasya y’ebishaka. Nk‘ekiragiro ky‘okubanza eky‘okuhikiiriza okubiika kwa haidrojeni, ebikwato ebirikukora kandi ebigumire eby‘okugarukamu kwa haidrojeni (de)haidrojeni nibyetengyesa. Okuhitsya hati, omwanya ogu gukaba nigukoresibwa munonga ebyoma by’omuhendo. Aha, nituteekateeka aha nkora ensya ey’omuhendo mukye erikwegamira aha cobalt (Co-SAs/NPs@NC) omu myanya y’ekyoma kimwe erikugabwa munonga erikugambwaho omu muringo gw’okukoragana n’ebicweka bikye ebikye (nanoparticles) kubaasa kutunga okukyendeeza kw’amaizi g’omubiri (formic acid) okuhikire. Okukozesa ebintu ebirungi munonga eby’ebicweka bya CoN2C2 ebijanjaire omu atomu n’ebicweka bya nano ebikingirwe eby’obuhango bwa 7-8 nm, okukozesa propylene carbonate nk’ekirungo, okutunga gaasi nungi munonga eya 1403.8 ml g-1 h-1 kukatunga, kandi tihaine okufeerwa bwanyima y’enzindo 5. omurimo, ogurikukira Pd/C y‘obushuubuzi emirundi 15. Okucondooza okwakozirwe omu mwanya nikworeka ngu, waagyeragyeranisa n’ebintu ebiine akakwate n’ekyoma kimwe n’ebintu ebikye, Co-SAs/NPs@NC neeyongyera aha kunywanisa n’okukora kw’ekikuru ky’omugati HCOO*, obwo neetunguura okucwanyagura kw’omukago gwa CH okurikukuratiraho. Okubara kw’ebiteekateeko nikworeka ngu okuteerana kwa nanoparticles za cobalt nikutunguura okuhindura kwa d-band center ya atomu emwe eya Co kuba omwanya ogurikukoreramu, obwo nikwo kwongyera aha kugaita ahagati ya carbonyl O eya HCOO* intermediate na Co center, obwo nikwo kukyendeeza aha nkora y’amaani.
Hydrogen neetwarwa nk’ekintu kikuru ekirikutwara amaani g’okuhindura amaani g’ensi yoona hati kandi neebaasa kuba omuvugi mukuru w’okuhikiiriza obutagira kaboni1. Ahabw’emitwarize yaayo ey’omubiri nk’okubaasa kukwatwa omuriro n’okugira oburemeezi bukye, okubiika n’okutwara amaizi g’omubiri omu muringo oguhikire kandi oguhikire n’enshonga nkuru omu kuhikiiriza eby’entaasya y’amaizi2,3,4. Ebikwato ebirikutwara amaizi g’omubiri (LOHCs), ebirikubiika n’okurekura amaizi g’omubiri kurabira omu nkora y’eby’obuhangwa, biteekateekirweho nk’omubazi gw’okushoboorora enshonga. Wagyeragyeranisa n’amaizi g’omubiri, ebintu nk’ebyo (methanol, toluene, dibenzyltoluene, n’ebindi) nibyanguhi kandi nibikora gye5,6,7. Omuri LOHC z‘obuhangwa zitari zimwe na zimwe, formic acid (FA) eine obutwa bukye (LD50: 1.8 g/kg) n‘obushoboorozi bwa H2 bwa 53 g/L nari 4.4 wt%. Ekikuru, FA niyo LOHC yonka erikubaasa kubiika n’okurekura haidrojeni omu mbeera ezitari nkuru omu kubaho kw’ebintu ebihikire, n’ahabw’ekyo terikwetaaga amaani maingi kuruga aheeru1,8,9. Omu mazima, eby’ekyoma bingi eby’omuhendo bikozirwe ahabw’okukyendeeza amaizi omu formic acid, eky’okureeberaho, eby’okukoresa ebirikwegamira ahari palladium nibikora emirundi 50-200 kukira eby’ekyoma ebitari by’obuguzi bwingi10,11,12. Kwonka waateekateeka aha sente z’ebyoma ebirikukora nk’eky’okureeberaho, palladium neegura emirundi erikurenga 1000.
Cobalt, Okusherura eby’okukoresa eby’ekyoma ebitarikushushana ebirikukora munonga kandi ebigumire nibigumizamu kureetaho okukunda kw’abacondoozi baingi omu by’obwegyese n’omu by’amakorero13,14,15.
N’obu ebikwato by’obuguzi bukye ebirikwegamira ahari Mo na Co, hamwe n’ebikwato bya nanocatalysts ebikozirwe kuruga omu byoma by’ekitiinisa/eby’omutaano,14,16 bikozirwe ahabw’okukyendeeza amaizi ga FA, okuzibira kwabyo mporampora omu bwire bw’okugarukamu tikurikwetantarwa ahabw’okutwarwa kw’emyanya erikukora ey’ebyoma, CO2, na H2. nari formate anions (HCOO-), okushiisha kwa FA, okuteerana kw‘ebicweka n‘okubaasa kutunga obutwa bwa CO17,18. Itwe n’abandi tuherize kworeka ngu ebikwato ebirikureetaho atomu emwe (SACs) ebiine emyanya ya CoIINx ejanjaire munonga nk’emyanya erikukora nibitunguura okugarukamu n’okuzibira asidi y’okusheeshasheesha kwa asidi ya formic kugyeragyeranisa na nanoparticles17,19,20,21,22,23,24. Omu bintu ebi ebya Co-NC, atomu za N nizikora nk’emyanya mikuru y’okutunguura FA deprotonation obwo zirikwongyera aha kuhama kw’enkora kurabira omu kukwatanisa n’atomu ya Co eyagati, obwo atomu za Co zirikuha emyanya y’okutwara H kandi zirikutunguura CH22 scission, 25,26. Ekibi munonga, emirimo n’okuhama kw’ebintu ebi nibikiri hare n’ebintu by’obunaku obu ebirikushushana n’ebitarikushushana (Fig. 1) 13 .
Amaani agarengire kuruga omu bintu ebirikugarukaho nk’eizooba nari omuyaga nigabaasa kuruga omu kuhindura amaizi g’amashanyarazi. Haidrojeni erikurugamu neebaasa kubiikwa orikukoresa LOHC, amaizi agarimu okuhinduka kwago n’okuhinduka kwago okurikugaruka enyima. Omu nkora y’okukyendeeza amaizi, ekirugiremu kyonka n’amaizi, kandi amaizi agarikutwara nigagaruka omu mbeera yaago ey’okubanza kandi gagaruka gahindurwa amaizi. Haidrojeni ekaba neebaasa kuhika aha kukoresibwa omu maduuka g’amajuta, omu bateri, omu byombeko by’amakorero n’ebindi.
Enyimaho, kikagambwa ngu emirimo y’omunda ya SACs ezitari zimwe na zimwe neebaasa kwongyerwamu amaani omu kubaho kw’atomu z’ebyoma zitari zimwe na zimwe nari emyanya y’ebyoma eyongyeirweho erikuheebwa nanoparticles (NPs) nari nanoclusters (NCs)27,28. Eki nikiiguraho okubaasa kw’okwongera kunywanisa n’okukora kw’ekicweka ky’ahansi, hamwe n’okuhindura omu nkora ya geometry n’eby’amashanyarazi eby’emyanya ya monatomic. Omu muringo ogu, okushohoza/okukora kw’ebintu ebiri ahansi y’eitaka nikubaasa kubonezibwa, kuha oburungi bw’okukora gye omu bwijwire29,30. Eki nikituha ekiteekateeko ky’okukora ebintu ebihikire eby’okureetaho okutunguuka n’ebicweka ebirikukora eby’omutaano. N‘obu SACs ezitunguukire ziraabe zoorekire obushoboorozi bwingi omu miringo mingi y‘okukoresa eby‘okureeberaho31,32,33,34,35,36, nk‘oku turikumanya, omurimo gwazo omu kubiika haidrojeni tigurikwetegyerezibwa gye. Omu nshonga egi, nituha ripooti y’enkora y’emiringo mingi kandi ey’amaani ey’okuteerana eby’okuteerana ebirikwegamira aha cobalt (Co-SAs/NPs@NCs) ebirimu nanoparticles ezishobooroirwe n’ebicweka by’ebyoma eby’omuntu omwe. Co-SAs/NPs@NC ezitebeekanisiibwe gye nizooreka okukora kurungi kw’okukyendeeza amaizi g’omu itaka, okukira ebikwato ebitari by’ekitiinisa (nka CoNx, atomu za cobalt emwe, cobalt@NC na γ-Mo2N) nangwa n’ebikwato by’ekyoma eby’ekitiinisa. Okucondooza omu mwanya n’okubara kwa DFT kw’ebintu ebirikukora nibyoreka ngu emyanya y’ebyoma buri omwe neekora nk’emyanya erikukora, kandi nanoparticles z’okucondooza oku nizitunguura d-band center ya Co atoms, nizitunguura okushohoza n’okukora kwa HCOO*, obwo nizikyendeeza aha nkora y’amaani g’okugarukamu. .
Zeolite imidazolate frameworks (ZIFs) nizo zishobooroirwe gye ezirikubanza omu miringo eshatu ezirikuha ebikwato by‘okureetaho ebintu bya kaboni ebirimu nitrogen (ebikwato by‘ekyoma-NC) kushagika emiringo y‘ebyoma etari emwe n‘emwe37,38. Nahabwekyo, Co(NO3)2 na Zn(NO3)2 nizikwatanisa na 2-methylimidazole omu methanol kuhanga ebyoma ebirikuhikaana omu nshonga. Bwanyima y’okukyebera n’okuyomesa, CoZn-ZIF ekakyeberwa aha bwire bw’obwire obutari bumwe na bumwe (750–950 °C) omu mwanya ogurimu 6% H2 na 94% Ar. Nkoku kirikworekwa omu kishushani ahaifo, ebintu ebirugiremu biine emitwarize y‘ebicweka ebirikukora etari emwe n‘emwe kandi nibyetwa Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-750 na Co-SAs/NPs@NC-750 (ekishushani 2a). ) . Ebigyezo by‘okureeberaho eby‘omutaano eby‘amatembezo agamwe makuru omu nkora y‘okucondooza nibishoboororwa omu bwijwire omu bishushani 1 na 2. C1-C3. Okukyebera okurikuhinduka kw’obutagatsi (VTXRD) kukakorwa kureeba oku ekirungo ky’omubiri kirikuhinduka. Ebiriisa bya pyrolysis byahika ahari 650 °C, omuringo gwa XRD niguhinduka munonga ahabw’okugwa kw’omutindo gw’ekibiriiti ogutebeekanisiibwe ogwa ZIF (Fig. S4) 39 . Obutagatsi ku burikweyongyera, enshonga ibiri z’amaani nizireebeka omu nkora za XRD eza Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750 ahari 20–30° na 40–50°, ezirikworeka enshonga ya kaboni etaine mubiri (ekishushani C5). 40. Nikirungi kumanya ngu enshonga ishatu zonka ez’obumanyiso zikareebeka ahari 44.2°, 51.5° na 75.8°, ez’ekyoma kya cobalt (JCPDS #15-0806), na 26.2°, ez’ekyoma kya kaboni (JCPDS # 41-1487). Eby’okureeberaho bya X-ray ebya Co-SAs/NPs@NC-950 nibyoreka okubaho kw’ebicweka bya cobalt ebirikushushana n’eby’omu itaka aha kikwato ky’okuteera ebishushani41,42,43,44. Ekishushani kya Raman nikyoreka ngu Co-SAs/NPs@NC-950 neereebeka nk’eine enshonga z’amaani kandi ezikye eza D na G kukira ebindi bishushani, ekirikworeka omutindo gw’ahaiguru gw’okuteera ebishushani ( Ekishushani S6 ). Okwongyera ahari ekyo, Co-SAs/NPs@NC-950 neeyoreka omwanya gw‘ahaiguru gw‘ahaiguru n‘obuhango bw‘ebizimba (1261 m2 g-1 na 0.37 cm3 g-1) kukira ebindi bishushani kandi ZIFs nyingi niziruga omu NC. ebikwato (ekishushani S7 n‘ekipande S1). Okucondooza okurikukwata aha nkora y’okukyebera ebiriisa (AAS) nikworeka ngu ebiri omu cobalt ebiri omu Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 na Co-SAs/NPs@ ni 2.69 wt.%, 2.74 wt.% na 2.73 wt.%. NC-750 nk’oku biri (Ekipande S2). Ebirimu Zn omu Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750 nibyeyongyera mporampora, ekirikureetwaho okweyongyera kw’okukyendeeza n’okuhinduka kw’ebicweka bya Zn. Okwongyera aha bwire bw’okufuka (Zn, obutagatsi bw’okufuka = ​​907 °C) 45.46. Okushwijuma eby’obuhangwa (EA) kukooreka ngu ebicweka 10 ahari 100 bya N nibikyendeera n’okweyongyera kw’obutagatsi bwa pyrolysis, kandi O eri ahaiguru neebaasa kuba neereetwa okushohoza molecular O2 kuruga omu kukwatwa omuyaga. (Ekipande S3). Aha nkora ya cobalt emwe, nanoparticles na coatoms ezitaine rubaju nizituura hamwe, ekirikureetaho okweyongyera kw’amaani omu mirimo y’okureetaho, nk’oku kirikugambwaho ahaifo.
Ekishushani ky‘okuteerana kw‘okuteerana kwa Co-SA/NPs@NC-T, ahu T eri obutagatsi bw‘okusheeshasheesha (°C). b Ekishushani kya TEM. c Ekishushani kya Co-SAs/NPs@NC-950 AC-HAADF-EKITEBE. Atoms za Co ezimwe ziine akamanyiso k’enziga ezirikwiragura. d EDS ebiri omu nkora ya Co-SA/NPs@NC-950.
Ekikuru, okucondooza okurikurabira omu nkora y’okujanjaaza (TEM) kukooreka okubaho kw’ebicweka by’omubiri ebitari bimwe na bimwe (NPs) ebiine obuhango bwa 7.5 ± 1.7 nm omu Co-SAs/NPs@NC-950 zonka ( Ebishushani 2 b na S8). Obucweka obu obukye munonga nibukingwaho kaboni eri nk’eya graphite erimu nitrogen. Omubaro gw’ebicweka by’omubiri ebiri ahagati y’ebicweka bya lattice ogwa 0.361 na 0.201 nm niguhikaana n’ebicweka bya graphitic carbon (002) n’eby’ekyoma Co (111), nk’oku biri. Okwongyera ahari ekyo, okukyebera okurikukoresibwa omu mwanya gw’omwirima (AC-HAADF-STEM) kukashohoza ngu Co NPs omu Co-SAs/NPs@NC-950 zikaba zeehinguririziibwe obutafaari bw’omubiri bwingi (Fig. 2c). Kwonka, atomu za cobalt ezijanjaire omu atomu zonka nizo zaareebekire aha bushagiki bw’ebindi bishushani bibiri (Fig. S9). Ekishushani kya HAADF-STEM eky‘okujanjaaza amaani (EDS) nikyoreka okujanjaara kw‘amaani kwa C, N, Co na Co NPs ezitaanisiibwe omu Co-SAs/NPs@NC-950 (ekishushani 2d). Ebirugiremu ebi byona nibyoreka ngu emyanya ya Co ejanjaire omu atomu n’ebicweka bya nano ebikingirwe omu kaboni eri nk’eya graphite erimu N nibibaasa kukwatiraine gye n’ebicweka bya NC omu Co-SAs/NPs@NC-950, obwo emyanya y’ebyoma yonka erikwetaanisa.
Embeera ya valence n’eby’obuhangwa by’ebintu ebyatungirwe bikakyeberwa omu nkora ya X-ray photoelectron spectroscopy (XPS). Ebishushani bya XPS eby’ebintu bishatu ebirikureetaho okuhinduka kw’ebintu bikooreka okubaho kw’ebintu Co, N, C na O, kwonka Zn ekaba eriho omu Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750 zonka (ekishushani 2). ). C10). Ebiriisa bya pyrolysis byayeyongyera, ebiri omu nitrogen byona nibikyendeera nk’oku ebika bya nitrogen birikuguma bitagumire kandi bikavunda bikahinduka NH3 na NOx gases aha biriisa by’ahaiguru (Ekipande S4) 47 . Nahabwekyo, omubaro gwona ogwa kaboni gukeeyongyera mpora mpora kuruga ahari Co-SAs/NPs@NC-750 kuhika ahari Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-950 (ebishushani S11 na S12). Sampuli erikufukiirwa aha bwire bw’obwire bw’obwire bw’obwire bw’obwire bw’obwire bw’obwire bw’obwire bw’obwire bw’obwire bw’obwire bw’obwire, eine ekicweka kikye ky’atomu za nitrogen, ekirikumanyisa ngu omubaro gw’ebintu ebirikutwara NC omu Co-SAs/NPs@NC-950 gushemerire kuba mukye kukira ogw’omu sampuli ezindi. Eki nikireetaho okuteerana kw’amaani kw’ebicweka bya cobalt. Ekishushani kya O 1s nikyoreka enshonga ibiri C=O (531.6 eV) na C–O (533.5 eV), nk‘oku biri (Ekishushani S13) 48 . Nkoku kirikworekwa omu kishushani 2a, omubaro gwa N 1s nigubaasa kushoboororwa omu nshonga ina z‘obumanyiso bwa piridiini nitrojeni N (398.4 eV), pirolo N (401.1 eV), giraafaiti N (402.3 eV) na Co-N (399.2 eV). Co-N bonds ziriho omu sampo zoona ishatu, ekirikworeka ngu atomu ezimwe eza N nizikwatanisa n’emyanya y’ekyoma kimwe, kwonka emitwarize neetaanira kimwe49. Okukozesa ebiriisa by’okwotsya ebiri ahaiguru nikibaasa kukyendeeza munonga aha biri omu miringo ya Co-N kuruga ahari 43.7% omu Co-SA/NPs@NC-750 kuhika ahari 27.0% omu Co-SAs/NPs@NC-850 na Co 17.6%@NC-950. omu -CA/NPs, ekirikuhikaana n’okwongyera aha biri omu C (Fig. 3a), ekirikworeka ngu omubaro gwabo gw’okuteerana Co-N nigubaasa kuhinduka kandi guhindurwe ekicweka kya atomu za C50. Ekishushani kya Zn 2p nikyoreka ngu ekintu eki kiriho munonga omu muringo gwa Zn2+. (Ekishushani S14) 51. Ekishushani kya Co 2p nikyoreka enshonga ibiri ezirikumanywa munonga ahari 780.8 na 796.1 eV, ezirikuteebwa ahari Co 2p3/2 na Co 2p1/2, nk’oku biri (Ekishushani 3b). Okwegyeragyeranisa na Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750, enshonga ya Co-N omu Co-SAs/NPs@NC-950 neehindurwa ekaza aha rubaju orurungi, ekirikworeka ngu atomu emwe eya Co aha mutwe -SAs/NPs@NC-950 eine diguri y‘ahaiguru y‘okukyendeeza aha nkora y‘okukyendeeza aha nkora y‘okukyendeeza aha nkora y‘okukyendeeza aha nkora y‘okukyendeeza aha nkora y‘okukyendeeza aha nkora y‘okukyendeeza aha nkora y‘okushohoza. Nikirungi kumanya ngu Co-SAs/NPs@NC-950 yonka niyo yaayorekire enshonga y’amaani eya zero-valent cobalt (Co0) ahari 778.5 eV, ekirikuhamya okubaho kwa nanoparticles ezirikuruga omu kuteerana kwa SA cobalt aha bwire bw’obwire bw’obwire bw’obwire.
a N 1s na b Co 2p ebiri omu nkora ya Co-SA/NPs@NC-T. c XANES na d FT-EXAFS ebiri omu nkora ya Co-K-edge y‘ebicweka by‘omubiri ebirikwetwa Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750. e Ebishushani bya kontura bya WT-EXAFS eby‘ebicweka bya Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850, na Co-SAs/NPs@NC-750. f FT-EXAFS okuhikaana n‘omutindo gw‘okukoresa Co-SA/NPs@NC-950.
Obwire obukingirwe X-ray absorption spectroscopy (XAS) bwanyima bukakoresibwa kucondooza aha nkora y’ebyoma n’embeera y’okukwatanisa ey’ebika bya Co omu sampo eyatebeekanisiibwe. Cobalt valence neegira omu Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750 Enkora y‘omukono erikworekwa okunywanisa kwa X-ray okuri haihi n‘omusiri okwa buriijo aha rubaju rwa Co-K (XANES). Nkoku kirikworekwa omu kishushani 3c, okunywanisa haihi n’omuheru gw’eby’okureeberaho bishatu kuri ahagati y’ebipande bya Co na CoO, ekirikworeka ngu embeera ya valence y’ebika bya Co neeruga ahari 0 kuhika ahari +253. Okwongyera ahari ekyo, okuhinduka kw’amaani g’ahansi kukareebeka kuruga ahari Co-SAs/NPs@NC-950 kuza ahari Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750, ekirikworeka ngu Co-SAs/NPs@NC-750 eine embeera y’okwotsya eri ahansi. Okugaruka enyima omu nkora. Okurugirira aha byarugamu eby‘okuteerana kw‘omutindo, embeera ya Co valence ya Co-SAs/NPs@NC-950 neeteekateekwaho kuba +0.642, eri ahansi y‘embeera ya Co valence ya Co-SAs/NPs@NC-850 (+1.376). 750 (+1.402). Ebirugiremu ebi nibyoreka ngu embeera y’okuhindura ebiriisa bya cobalt omu Co-SAs/NPs@NC-950 neekyendeera munonga, ekirikuhikaana n’ebyarugamu bya XRD na HADF-STEM kandi nikibaasa kushoboororwa okutuura hamwe kw’ebicweka bya cobalt nanoparticles na cobalt emwe. . Co atoms 41. Fourier okuhindura X-ray okunywanisa omu nkora nungi (FT-EXAFS) ekishushani kya Co K-edge nikyoreka ngu enshonga nkuru eri aha 1.32 Å n’ey’ekigogo kya Co-N/Co-C, obwo omuhanda gw’okujanjaara kw’ekyoma Co -Co guri ahari 2.18 gwonka ogurikushangwa omu Co-SAs /Fig.NP3d Å). Ekindi, puroguraamu y‘okuhindura kw‘omuyaga (WT) neeyoreka amaani maingi ahari 6.7 Å-1 agarikuteebwa ahari Co-N/Co-C, obwo Co-SAs/NPs@NC-950 yonka erikworeka amaani maingi agarikuteebwa ahari 8.8. Ekindi ekirikukizayo amaani kiri ahari Å−1 kuhika aha nkoragana ya Co–Co (Fig. 3e). Okwongyera ahari ekyo, okucondooza kwa EXAFS okwakozirwe omupangisa kukooreka ngu aha bwire bw‘obwire bw‘okukyebera (pyrolysis) bwa 750, 850 na 950 °C, enamba z‘okuteerana za Co-N zikaba ziri 3.8, 3.2 na 2.3, buri kimwe, kandi enamba z‘okuteerana za Co-C zikaba ziri 0. 0.1, S.5 (Fig1.1, S.5). Ekikuru munonga, ebyarugamu ebihererukireyo nibibaasa kugambwaho ahabw’okugira ngu hariho ebicweka bya CoN2C2 ebijanjaire omu nkora ya atomu n’ebicweka bya nano omu Co-SAs/NPs@NC-950. Okutaana n‘ekyo, omu Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750, ebicweka bya CoN3C na CoN4 byonka nibyo birimu. Nikireebeka gye ngu n’okweyongyera kw’obutagatsi bwa pyrolysis, atomu za N omu kicweka kya CoN4 nizihindurwa mpora mpora atomu za C, kandi cobalt CA neeteerana kukora nanoparticles.
Embeera z‘okugarukamu ezaabaire zikyeberwa enyima zikakoresibwa kwega aha nkora y‘embeera z‘okutebeekanisa aha mitwarize y‘ebintu bitari bimwe na bimwe (Fig. S16)17,49. Nkoku kirikworekwa omu kishushani 4 a, emirimo ya Co-SAs/NPs@NC-950 eri ahaiguru munonga kukira ey‘abakozi ba Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750. Ekikuru, eshampu za Co zoona ishatu ezatebeekanisiibwe zikooreka okukora kurungi waagyeragyeranisa n’eby’obushuubuzi eby’omutindo gw’ebyoma by’omuhendo (Pd/C na Pt/C). Okwongyera ahari ekyo, eshampu za Zn-ZIF-8 na Zn-NC zikaba zitarikukora aha kusheeshasheesha kwa formic acid, ekirikworeka ngu obucweka bwa Zn tiburi myanya erikukora, kwonka ebirikurugamu aha mirimo nibikye. Okwongyera ahari ekyo, emirimo ya Co-SAs/NPs@NC-850 na Co-SAs/NPs@NC-750 ekakora okukyeberwa kwa kabiri aha 950°C kumara eshaaha 1, kwonka ekaba eri ahansi y’eya Co-SAs/NPs@NC-750 . @NC-950 (Ekishushani S17). Okucondooza aha nkora y’ebintu ebi kukooreka okubaho kwa Co nanoparticles omu sampo ezaagarukiremu kukyeberwa, kwonka omwanya mukye gw’ahaiguru ogw’omutaano n’okuburaho kwa carbon eri nk’eya graphite bikarugamu emirimo y’ahansi waagyeragyeranisa na Co-SAs/NPs@NC-950 (Ekishushani S18–S20). Omurimo gw‘eby‘okureeberaho ebiine emihendo etari emwe n‘emwe ya Co precursor nagwo gukagyeragyeranisibwa, n‘omurimo gw‘ahaiguru gworekwa aha kwongyeraho 3.5 mol (Ekipande S6 n‘ekishushani S21). Nikireebeka gye ngu okuhangwa kw’emyanya y’ebyoma etari emwe n’emwe nikukwatwaho ebiri omu mwanya gw’okusheeshasheesha n’obwire bw’okusheeshasheesha. Nahabwekyo, ebindi bikoreso bya Co-SAs/NPs@NC-950 bikakyeberwa ahabw‘emirimo y‘okukyendeeza amaizi g‘omubiri. Ebintu byona byorekire okukora gye munonga; kwonka tihaine n‘emwe aharizo eyaabaire eri nungi kukira Co-SAs/NPs@NC-950 (ebishushani S22 na S23). Okucondooza aha nkora y’ebintu kukareebeka ngu obwire bw’okusheenya burikweyongyera, ebiri omu myanya ya monoatomic Co-N nibikyendeera mpora mpora ahabw’okuteerana kw’atomu z’ekyoma omu nanoparticles, ekirikushoboorora entaaniso eri omu mirimo ahagati y’eby’okureeberaho ebiine obwire bw’okusheenya bwa 100-2000. enyahukana. 0.5 h, 1 shaaha, na 2 shaaha (ebishushani S24–S28 n‘ekipande S7).
Giraafu y‘omubaro gwa gaasi n‘obwire obutungirwe omu bwire bw‘okukyendeeza amaizi omu nteerane z‘amajuta barikukoresa ebikwato bitari bimwe na bimwe ebirikureetaho okusheeshasheesha. Embeera z‘okugarukamu: PC (10 mmol, 377 μl), ekirikureetaho (30 mg), PC (6 ml), Tback: 110 °C, Obukodyo: 98 °C, ebicweka 4 b Co-SAs/NPs@NC-950 ( 30 mg), ebirungo bitari bimwe na bimwe. c Okugyeragyeranisa emihendo y’okuhinduka kwa gaasi y’ebintu ebitarikushushana omu bihingwa ebirikukora aha 85–110 °C. d Okugyezesa okugaruzaho eby‘okukoresa omu nkora ya Co-SA/NPs@NC-950. Embeera z‘okugarukamu: FA (10 mmol, 377 μl), Co-SAs/NPs@NC-950 (30 mg), ekirungo (6 ml), Tset: 110 °C, Okukwata: 98 °C, buri nkora y‘okugarukamu neemara eshaaha emwe . Enshobi z‘emibaro nizijwekyera okutaana kw‘omutindo okubariirwe kuruga omu bigyezo bishatu ebirikukora.
Omu kutwariza hamwe, oburungi bwa FA dehydrogenation catalysts niburugiirira munonga aha mbeera z’okugarukamu, namunonga ekirungo ekirikukoresibwa8,49. Ku baakozeise amaizi nk’ekirungo, Co-SAs/NPs@NC-950 ekooreka omubaro gw’okubanza gw’okugarukamu ogurikukirayo, kwonka okuremwa kukora kukabaho, nikibaasa kuba kyarugire ahari purotoni nari H2O18 kutwara emyanya erikukora. Okugyezesa ekirungo ky’okureetaho okutunguuka omu bihingwa ebirimu ebiriisa nk’ebirungo bya 1,4-dioxane (DXA), n-butyl asetate (BAC), toluene (PhMe), triglyme na cyclohexanone (CYC) nabyo tibikaayorekire okutunguuka kwona, kandi omu birungo bya propylene carbonate (PC) ) (Ekishushani 4b n’Ekipande S8). Nikyo kimwe, eby‘okwongyeramu nk‘ebiriisa bya triethylamine (NEt3) nari sodium formate (HCCONa) tibiine ekindi kirungi aha kukora kw‘ekiriisa ky‘okureetaho (ekishushani S29). Omu mbeera nungi z‘okugarukamu, okuruga omu gaasi kukahika ahari 1403.8 mL g−1 h−1 (Fig. S30), ekyabaire kiri ahaiguru munonga kukira byona ebyabaire nibigambwaho enyima ebyabaire nibireetaho Co (obariiremu SAC17, 23, 24). Omu kucondooza okutarikushushana, otabariiremu ebikorwa omu maizi n’ebintu ebirikwongera aha formate, okutoorana kw’okukyendeeza amaizi n’okukyendeeza amaizi kuhika ahari 99.96% kukatunga (Ekipande S9). Amaani g‘okukora agabariirwe ni 88.4 kJ/mol, agarikugyeragyeranisibwa n‘amaani g‘okukora g‘ebyoma by‘ekitiinisa (ekishushani S31 n‘ekipande S10).
Okwongyera ahari ekyo, tukagyeragyeranisa omubaro gw’ebindi bihingwa ebitarikushushana ebirikureetaho okukyendeeza aha maizi g’omubazi gwa formic acid omu mbeera zirikushushana (Fig. 4c, tables S11 na S12). Nkoku kirikworekwa omu kishushani 3c, omubaro gw’okukora gaasi gwa Co-SAs/NPs@NC-950 nigukira ogw’ebintu ebitari bimwe na bimwe ebirikumanywa munonga kandi nigukira ogw’eby’obushuubuzi 5% Pd/C na 5% Pd/C, nk’oku biri, n’emirundi 10 omurundi gumwe. % Pt/C ekirikureetaho okuhinduka.
Ekikuru omu kukozesa kwona okw’omugasho kw’ebintu ebirikureetaho (de)hydrogenation n’okugumaho kwabyo. Nahabwekyo, okugyezesa okurikukuratana okw’okugaruza ebintu omu nkora barikukoresa Co-SAs/NPs@NC-950 kukakorwa. Nkoku kirikworekwa omu kishushani 4 d, omurimo gw‘okubanza n‘okutoorana eby‘okukoresa bikaguma bitahindukire omu mivuyo etaano erikukuratana (reeba n‘ekipande S13). Okukyebera kw‘obwire buraingwa kukakorwa kandi okukora gaasi kukeeyongyera omu murongooti aha shaaha 72 (ekishushani S32). Ebirimu cobalt omu Co-SA/NPs@NC-950 eyakozesiibwe bikaba biri 2.5 wt%, ebyabaire biri haihi munonga n’eby’omubazi musya, ekirikworeka ngu hakaba hatariho kusheeshasheesha okurikureebwa okwa cobalt (Ekipande S14). Tihariho mpindahinduka y‘erangi erikureebwa nari okuteerana kw‘ebicweka by‘ekyoma okwareebirwe hatakabaireho n‘enyima y‘okugarukamu ( Ekishushani S33 ). AC-HAADF-STEM na EDS y‘ebintu ebyakozesiibwe omu kucondooza kw‘obwire buraingwa bikooreka okugumaho n‘okujanjaara okurikushushana kw‘emyanya y‘okujanjaara kw‘atomu kandi hatariho mpindahinduka z‘amaani omu nkora (ebishushani S34 na S35). Enshonga z‘obumanyiso bwa Co0 na Co-N zikyabaho omu XPS, nizihamya okutuura hamwe kwa Co NPs n‘emyanya y‘ebyoma buri omwe, eki nakyo nikihamya okuhama kw‘ekirungo kya Co-SAs/NPs@NC-950 (ekishushani S36).
Kubaasa kumanya emyanya erikukirayo kukora erikujunanizibwa aha kusheeshasheesha kwa formic acid, ebintu ebitoorainwe ebiine omwanya gumwe gwonka ogw’ekyoma (CoN2C2) nari Co NP bikatebeekanisibwa kurugiirira aha kucondooza okwabandize17. Omuringo gw’emirimo y’okusheeshasheesha kwa asidi ya formik erikureebeka omu mbeera niyo emwe ni Co-SAs/NPs@NC-950 > Co SA > Co NP (Ekipande S15), ekirikworeka ngu emyanya ya CoN2C2 ejanjaire omu atomu neekora munonga kukira NPs . Enkora y’okugarukamu neeyoreka ngu okuhinduka kwa haidrojeni nikukuratira enkora y’okugarukamu ey’omutindo gw’okubanza, kwonka okushenda kw’ebifunjo bitari bimwe na bimwe aha bintu bya cobalt ebitarikushushana tibirikushushana, ekirikworeka ngu enkora y’okugarukamu terikurugiirira ahari formic acid yonka, kureka n’aha mwanya ogurikukora (Fig. 2). C37). Okucondooza okundi okwa kinetic kukooreka ngu, ahabw’okubura enshonga z’ebyoma bya cobalt omu kucondooza kwa X-ray diffraction, omubaro gw’enkora y’okugarukamu omu kureeba ebiri omu cobalt gukashangwa guri 1.02 aha rurengo rwa hansi (ahansi ya 2.5%), ekirikworeka okugabwa haihi okurikushushana kw’emyanya ya cobalt ey’atomu emwe. ekikuru. omwanya ogurikukora (ebishushani S38 na S39). Ebirimu obucweka bwa Co ku birikuhika ahari 2.7%, r neeyongyera ahonaaho, ekirikworeka ngu obucweka bwa nano nibukwatagana gye n’atomu z’omuntu ahabwe kutunga emirimo y’ahaiguru. Ebirimu omu bicweka bya Co ku birikweyongyera, omugoye niguhinduka ogutari gw’omutindo, ekirikukwatagana n’okwongyera aha mubaro gw’ebicweka bya nano n’okukyendeera omu myanya ya monatomic. Nahabwekyo, okutunguuka omu kukora kwa LC okukyendeeza amaizi omu Co-SA/NPs@NC-950 nikuruga omu mitwarize y’obumwe ey’emyanya y’ebyoma n’ebicweka bya nano.
Okwega okuri omu bwijwire kukakorwa barikukoresa okuhindura kwa Fourier okurikujanjaara omu mwanya (in situ DRIFT) kubaasa kumanya ebiri ahagati y‘okugarukamu omu nkora. Bwanyima y‘okuhingisa eby‘okureeberaho aha bwire bw‘okugarukamu obutarikushushana bwanyima y‘okutaho formic acid, ebicweka bibiri by‘emirundi bikakyeberwa (Fig. 5a). Enshonga ishatu z‘obumanyiso bwa HCOOH* nizireebeka ahari 1089, 1217 na 1790 cm-1, ezirikuteebwaho okutengeeta kw‘okutambatambura CH π (CH) okuri aheeru y‘enyonyoozi, okutengeeta kw‘okutambatambura kwa CO ν (CO) n‘okutengeeta kw‘okutambatambura kwa C=O ν (C=O) respectly,55. Ekindi kicweka ky‘enshonga aha 1363 na 1592 cm-1 nikihikaana n‘okutengeeta kwa OCO okurikushushana νs(OCO) n‘okutengeeta kw‘okutambatambura kwa OCO okutarikushushana νas(OCO)33.56 HCOO*, nk‘oku biri. Okugarukamu kwaba nikugyenda omu maisho, enshonga z‘okugyeragyeranisa ez‘ebika bya HCOOH* na HCOO* nizihwaho mporampora. Okutwarira hamwe, okuvunda kwa formic acid nikutwariramu emiringo eshatu mikuru: (I) okushohoza formic acid omu myanya erikukora, (II) okuihaho H kurabira omu muhanda gwa formate nari carboxylate, na (III) okuteerana H ibiri ezikwatsirwe kubaasa kureetaho haidrojeni. HCOO* na COOH* nizo nshonga nkuru eziri ahagati y‘okumanyisa emihanda ya formate nari carboxylate, nk‘oku biri57. Okukozesa enkora yaitu ey’okureetaho okuhinduka, enshonga ya HCOO* ey’obumanyiso yonka ekareebeka, ekirikworeka ngu okuvunda kwa formic acid nikubaho kurabira omu muhanda gwa formic acid gwonka58. Ebishushani nk’ebyo bikakorwa aha bwire bw’obwire obukye bwa 78 °C na 88 °C (ekishushani S40).
Omu mwanya gw‘okusheeshasheesha kw‘okusheeshasheesha kwa HCOOH aha Co-SAs/NPs@NC-950 na b Co SAs. Enfumu neeyoreka obwire bw‘okugarukamu aha mwanya. c Okuhinduka kw‘omubaro gwa gaasi ogurikukorwaho barikukoresa ebikwato by‘okuhandiika isotope ebitarikushushana omu bwire. d Ebihandiiko by‘ebirikuruga omu isotopu y‘omubiri.
Okucondooza okurikushushana okwa in situ DRIFT kukakorwa aha bintu ebiine akakwate Co NP na Co SA kwega aha nkora y‘okukoragana omu Co-SA/NPs@NC-950 ( Ebishushani 5 b na S41). Ebintu byombi nibyoreka emitwarize erikushushana, kwonka enshonga z’obumanyiso bwa HCOOH* na HCOO* nizihindurwa kakye, ekirikworeka ngu okutaho Co NPs nikuhindura omu nkora y’eby’amashanyarazi ey’omugati gw’atomu emwe. Enshonga y’obumanyiso νas(OCO) neereebeka omu Co-SAs/NPs@NC-950 na Co SA kwonka tihariho omu Co NPs, ekirikwongyera kworeka ngu ekicweka ky’ahagati ekirikubaho aha kwongyeraho asidi ya formik ni monodentate formic acid erikuhikaana n’ahaiguru y’omunyugunyu gw’enyonyoozi. kandi neekwatanisa na SA nk‘omwanya ogurikukora 59 . Nikirungi kumanya ngu okweyongyera kw’amaani omu kutengeeta kw’enshonga z’obumanyiso π(CH) na ν(C = O) kukareebeka, ekirikureebeka ngu kikareetera HCOOH* kuhinduka kandi kyanguhiza okugarukamu. Ekirugiremu, enshonga z’obumanyiso bwa HCOOH* na HCOO* omu Co-SAs/NPs@NC zikaba ziri haihi kubura bwanyima y’edakiika 2 z’okugarukamu, ekirikurahuka kukira eky’ekyoma kimwe (edakiika 6) n’ebirikwegamira aha nanoparticles (edakiika 12). . Ebirugire omu kucondooza oku byona nibihamya ngu okutaho nanoparticle doping nikutunguura okushohoza n’okukora kw’ebintu ebiri ahagati, obwo nikutunguura okugarukamu okuteirweho ahaiguru.
Okwongyera kweshwijuma omuhanda gw‘okugarukamu n‘okumanyisa eitembezo ry‘okumanyisa omubaro (RDS), ekirugire omu KIE kikakorwa omu kubaho kwa Co-SAs/NPs@NC-950. Aha, ebiriisa by‘omubiri ebitarikushushana nka HCOOH, HCOOD, DCOOH na DCOOD nibikoresibwa omu kucondooza kwa KIE. Nkoku kirikworekwa omu kishushani 5c, omubaro gw’okusheeshasheesha nigukyendeera omu mubaro ogu: HCOOH > HCOOD > DCOOH > DCOOD. Okwongyera ahari ekyo, emihendo ya KHCOOH/KHCOOD, KHCOOH/KDCOOH, KHCOOH/KDCOOD na KDCOOH/KDCOOD ekabarwa nka 1.14, 1.71, 2.16 na 1.44, nk’oku biri (ekishushani 5d). Nahabwekyo, okucwanyagura kwa CH bond omu HCOO* nikworeka emihendo ya kH/kD >1.5, ekirikworeka ekikuru ekirikureetaho okutambura60,61, kandi nikireebeka ngu nikijwekyera RDS y‘okukyendeeza aha maizi ga HCOOH aha Co-SAs/NPs@NC-950.
Okwongyera ahari ekyo, okubara kwa DFT kukakorwa kwetegyereza oku nanoparticles ezirimu ebiriisa zirikukora aha mirimo y’omunda ya Co-SA. Eby‘okureeberaho bya Co-SAs/NPs@NC na Co-SA bikakorwa kurugiirira aha kucondooza okwayorekwa n‘emirimo eyabandize (ebishushani 6a na S42)52,62. Bwanyima y’okutunguura eby’obuhangwa, obucweka bukye bwa Co6 (CoN2C2) oburikutuura hamwe n’ebicweka bya monoatomic bukamanyirwa, kandi oburaingwa bw’enkoragana ya Co-C na Co-N omu Co-SA/NPs@NC bukamanyirwa kuba 1.87 Å na 1.90 Å, buri kimwe. , ekirikuhikaana n’ebyarugamu bya XAFS. Ekicweka ky’obuhango bw’amahanga ekibariirwe (PDOS) nikyoreka ngu atomu y’ekyoma kya Co emwe n’ekicweka kya nanoparticle (Co-SAs/NPs@NC) nibyoreka okuteerana kw’ahaiguru haihi n’omutindo gwa Fermi kugyeragyeranisa na CoN2C2, ekirikureetaho HCOOH. Okuhingisa kwa electron okuvunda nikukirayo kukora gye ( Ebishushani 6b na S43). Ebicweka bya d-band ebirikuhikaana ebya Co-SAs/NPs@NC na Co-SA bikabarwa kuba -0.67 eV na -0.80 eV, buri kimwe, omuri ebyo okweyongyera kwa Co-SAs/NPs@NC kukaba kuri 0.13 eV, ekyareeteire ngu bwanyima y’okutaho NP, okushohoza kwa electronic kwa HCOO*N okwa adapts2 kukabaho. Entaaniso omu charge density neeyoreka ekicu kihango kya electron okwehinguririize CoN2C2 block na nanoparticle, ekirikworeka okukwatanisa kw’amaani ahagati yaabyo ahabw’okuhindura kwa electron. Ku twagaita n’okucondooza kwa Bader charge, kikashangwa ngu Co ejanjaire omu atomu ekafeerwa 1.064e omu Co-SA/NPs@NC na 0.796e omu Co SA ( Ekishushani S44 ). Ebirugiremu ebi nibyoreka ngu okuteerana kwa nanoparticles nikureetaho okukyendeeza kwa electron omu myanya ya Co, ekirikureetaho okweyongyera kwa Co valence, ekirikuhikaana n’ebirugire omu XPS (Fig. 6c). Emitwarize y‘okukoragana kwa Co-O ey‘okushohoza HCOO aha Co-SAs/NPs@NC na Co SA ekakyeberwa barikubara ekibiina kya Hamiltonian eky‘enzindo y‘ekibiriiti (COHP)63. Nk‘oku kirikworekwa omu kishushani 6 d, emihendo mibi n‘emirungi ya -COHP neehikaana n‘embeera y‘okurwanisa n‘embeera y‘okukwatira, nk‘oku biri. Amaani g’okuteerana kwa Co-O agakwatsirwe HCOO (Co-carbonyl O HCOO*) gakakyeberwa barikuteerana emihendo ya -COHP, eyabaire eri 3.51 na 3.38 ahari Co-SAs/NPs@NC na Co-SA, nk’oku biri. HCOOH adsorption nayo ekooreka ebirugiremu nk’ebyo: okweyongyera kw’omuhendo gw’omutaano gwa -COHP bwanyima y’okutaho nanoparticle doping nikworeka okweyongyera kw’okuteerana kwa Co-O, obwo nikwo kutunguura okukora kwa HCOO na HCOOH ( Ekishushani S45 ).
950 omubumbi w’ekibumbe ky’omubiri. b PDOS Co-SA/NP@NC-950 hamwe na Co-SA. c 3D isosurface y‘entaaniso omu nkora y‘okushohoza HCOOH aha Co-SA/NPs@NC-950 na Co-SA. (d) pCOHP y‘enkoragana za Co-O ezirikukwatwaho HCOO aha Co-SA/NPs@NC-950 (aha rubaju rwa bumosho) na Co-SA (aha rubaju rwa buryo). e Omuhanda gw‘okugarukamu gw‘okukyendeeza aha maizi ga HCOOH aha Co-SA/NPs@NC-950 na Co-SA.
Kubaasa kwetegyereza gye okukora kw’okukyendeeza amaizi g’omubiri okwa Co-SA/NPs@NC okurikukirayo, omuhanda gw’okugarukamu n’amaani bikamanyirwa. Buzima, okukyendeeza amaizi omu FA nikutwariramu amatembezo ataano, harimu okuhindura HCOOH kuba HCOOH*, HCOOH* kuba HCOO* + H*, HCOO* + H* kuba 2H* + CO2*, 2H* + CO2* kuba 2H* + CO2, na 2H* omu H2 (ekishushani 6e). Amaani g’okushohoza molekyu za formic acid aha rubaju rw’ekirungo kurabira omu oxygen ya carboxylic nigakira kurabira omu oxygen ya hydroxyl (ebishushani S46 na S47). Okurugirira ahari ekyo, ahabw’amaani makye, ekirikunywanisa nikikunda kuraba omu kucwanyagura kwa OH bond kubaasa kukora HCOO* okukira okucwanyagura kwa CH bond kubaasa kukora COOH*. Omu bwire nibwo bumwe, HCOO* neekozesa okushohoza kwa monodentate, ekirikureetaho okuhendagura enkoragana n’okukora CO2 na H2. Ebirugiremu ebi nibikwatagana n‘okugira ngu hariho enshonga ya νas(OCO) omu in situ DRIFT, ekirikwongyera kworeka ngu okusheenyagura kwa FA nikubaho kurabira omu muhanda gwa formate omu kucondooza kwaitu. Ni kikuru kumanya ngu kurugiirira aha bipimo bya KIE, CH dissociation eine ekizibu ky‘amaani g‘okugarukamu ky‘ahaiguru munonga kukira amatembezo agandi g‘okugarukamu kandi nikijwekyera RDS. Ekizibu ky‘amaani ky‘enkora y‘okureetaho okutunguuka erikukirayo oburungi eya Co-SAs/NPs@NC kiri ahansi ya 0.86 eV kukira eya Co-SA (1.2 eV), ekirikutunguura munonga obushoboorozi bw‘okukyendeeza amaizi omu nkora yoona. Ekikuru, okubaho kwa nanoparticles nikutegyeka omutindo gw’ebyoma by’ebicweka by’omubiri ebijanjaire omu atomu, ekirikwongyera kwongyera aha kunywanisa n’okukora kw’ebintu ebiri ahagati, obwo nikikyendeeza aha nkora y’okugarukamu n’okutunguura okukora kwa haidrojeni.
Omu bugufu, nitworeka omurundi gw’okubanza ngu okukora kw’ebintu ebirikureetaho amaizi g’omubiri nikubaasa kutunguuka munonga turikukoresa ebintu ebiine emyanya y’ekyoma kimwe erikugabwa munonga n’obucweka bukye bw’ebyoma. Ekiteekateeko eki kihamibwe ahabw’okuteerana eby’okukoresa eby’ekyoma kimwe ebirikwegamira ahari cobalt ebihindwirwemu nanoparticles (Co-SAs/NPs@NC), hamwe n’ebintu ebiine akakwate nabyo ebiine emyanya y’ekyoma kimwe yonka (CoN2C2) nari Co NPs. Ebintu byona bikatebeekanisibwa omu muringo gworobi ogw’okukyebera (pyrolysis) ogw’eidaara rimwe. Okushwijuma eby’obuhangwa nikworeka ngu ekikwato ekirungi munonga (Co-SAs/NPs@NC-950) kirimu ebicweka bya CoN2C2 ebijanjaire omu atomu n’obucweka bukye (7-8 nm) oburimu nitrogen na kaboni eri nk’eya graphite. Eine obushoboorozi burungi bw’okukora gaasi kuhika ahari 1403.8 ml g-1 h-1 (H2:CO2 = 1.01:1), H2 na CO okutoorana 99.96% kandi neebaasa kuguma neekora obutoosha kumara ebiro bingi. Omurimo gw’ekirungo eki nigukira emirimo y’ekirungo ekimwe ekya Co SA na Pd/C emirundi 4 na 15, nk’oku biri. Okucondooza kwa DRIFT omu mwanya nikworeka ngu waagyeragyeranisa na Co-SA, Co-SAs/NPs@NC-950 neeyoreka okushohoza kw’amaani okwa HCOO*, ekikuru aha muhanda gwa formate, kandi nanoparticles ezirimu ebiriisa nizibaasa kutunguura okukora kwa HCOO* n’okutunguuka kwa C–H . Okusharaho kw’omukago kukamanyirwa nka RDS. Okubara kw’ebiteekateeko nikworeka ngu okutaho Co NP nikwongera aha d-band center ya atomu za Co emwe na 0.13 eV kurabira omu kukwatagana, kwongyera aha kunywanisa kwa HCOOH* na HCOO* ebiri ahagati, obwo nikukyendeeza aha nkora y’okugarukamu kuruga ahari 1.20 eV ahabwa Co SA kuhika ahari 0 .86 eV. Niwe aine obujunaanizibwa bw’okukora gye munonga.
Omu bwijwire, okucondooza oku nikuha ebiteekateeko by’okukora eby’okukoresa bisya eby’ekyoma ebiine atomu emwe kandi nikutunguura okwetegyereza oku orikubaasa kutunguura okukora kw’ebyoma kurabira omu nkora y’okukoragana kw’ebicweka by’ekyoma eby’obuhango butarikushushana. Nitwikiriza ngu enkora egi neebaasa kujanjaara omu miringo endiijo mingi ey’okureetaho okuhinduka.
Co(NO3)2 6H2O (AP, 99%), Zn(NO3)2 6H2O (AP, 99%), 2-methylimidazole (98%), methanol (99.5%), propylene carbonate (PC, 99% ) ethanol (AR, 99.7%) bikagurwa kuruga omu McLean, China. Asidi y’omubiri (HCOOH, 98%) ekagurwa kuruga Rhawn, China. Ebirikukoresibwa byona bikakoresibwa butunu hatariho kwongyera aha kushemezibwa, kandi amaizi aga ultrapure gakatebeekanisibwa barikukoresa enkora y’okushemeza ultrapure. Pt/C (5% y’okutaho oburemeezi) na Pd/C (5% y’okutaho oburemeezi) bikagurwa kuruga omu kampuni ya Sigma-Aldrich.
Okuteerana kwa CoZn-ZIF nanocrystals kukakorwa kurugiirira aha miringo eyabandize n’okuhindura okumwe23,64. Eky’okubanza, mmol 30 za Zn(NO3)2·6H2O (8.925 g) na mmol 3.5 za Co(NO3)2·6H2O (1.014 g) zikatabura kandi zishukwa omu miriyoni 300 z’omubazi gwa methanol. Bwanyima, mmol 120 za 2-methylimidazole (9.853 g) zikashohozibwa omu miriyoni 100 z’omubazi gwa methanol kandi ziyongyerwa omu nkora eri aharuguru. Omutaano gukaba guteebwa omu bwire bw’obutagatsi bw’omu kishengye kumara eshaaha 24. Eky’aha muheru, ekirugiremu kikataanisibwa omu kukyebera aha 6429 g kumara edakiika 10 kandi kyayozibwa gye na methanol emirundi eshatu. Empunu eyarugiremu ekayomezibwa omu mwanya ogutarimu kintu kyona aha 60°C ekiro kyona etakakoresiibwe.
Okubaasa kukora Co-SAs/NPs@NC-950, empunu ya CoZn-ZIF eyomire ekakyeberwa aha 950 °C kumara eshaaha 1 omu nkora ya gaasi eya 6% H2 + 94% Ar, n’omubaro gw’okwotsya 5 °C/edakiika. Sampuli bwanyima ekakyeberwa kuhika aha butagasi bw’omu kishengye kutunga Co-SA/NPs@NC-950. Aha Co-SAs/NPs@NC-850 nari Co-SAs/NPs@NC-750, ebiriisa by’okukyebera eby’okurya bikahinduka kuhika ahari 850 na 750 °C, nk’oku biri. Sampuli ezitebeekanisiibwe nizibaasa kukoresibwa hatariho kugaruka kuzikoraho, nk’okuziteeraho asidi.
Okupima kwa TEM (okujanjaaza ebiri omu nkora) kukakorwa aha kipimo kya Thermo Fisher Titan Themis 60-300 “cube” ekiine ekikwato ky’okutereeza okutambura kw’ebishushani n’ekikwato ky’okucondooza ekya 300 kV. Okucondooza kwa HAADF-STEM kukakorwa barikukoresa ebikwato bya FEI Titan G2 na FEI Titan Themis Z ebiine ebikwato by’okucondooza n’okutereeza ebishushani, n’ebikwato bya DF4 eby’okucondooza eby’ebicweka bina. Ebishushani bya maapu y‘ebintu bya EDS nabyo bikatunga aha nkora ya FEI Titan Themis Z. Okushwijuma kwa XPS kukakorwa aha kikwato ky‘okupima ebiri omu mubiri (eky‘okureeberaho kya Thermo Fisher ESCALAB 250Xi). Ebishushani bya XANES na EXAFS Co K-edge bikatorotoorwaho barikukoresa emeeza ya XAFS-500 (Ebikwato by‘okucondooza eby‘omu China). Ebirimu Co bikamanyirwa aha nkora y’okukyebera ebiri omu nkora (AAS) (PinAAcle900T). Ebishushani by’okureeba ebiri omu itaka (XRD) bikahandiikwa aha kikwato ky’okupima ebiri omu itaka (Bruker, Bruker D8 Advance, Bugirimaani). Ebishushani by’okushohoza ebiriisa bya nitrogen bikatunga okukozesa eby’okushohoza eby’omubiri (Micromeritics, ASAP2020, USA).
Okukora kwa dehydrogenation kukakorwa omu mwanya gwa argon n’omuyaga gukaihwaho kurugiirira aha nkora ya Schlenk ey’omutindo. Ekintu ky’okugarukamu kikaihwaho kandi kyagaruka kyaijuzibwa argon emirundi 6. Taho amaizi g‘okuteeka omu kondensa kandi otemu ekirungo (30 mg) n‘ekirungo (6 ml). Okwotsya ekikopo kuhika aha bwire obu orikwenda orikukoresa ekikwato ky’okukyebera obutagatsi kandi okireke kigyeragyeranisibwe kumara edakiika 30. Bwanyima, asidi ya formiki (10 mmol, 377 μL) ekateebwa omu nkora y’okugarukamu ahansi ya argon. Hindura valve ya burette ey’emiringo eshatu kukyendeeza aha nkora y’okuteera, ogarukye okikingire, kandi otandikye kupima obuhango bwa gaasi erikuruga omu nkora orikukoresa burette y’omu ngaro (Ekishushani S16). Bwanyima y‘obwire oburikwetengwa ngu okugarukamu kuhwe, sampo ya gaasi ekatorotoorwamu ahabw‘okukyebera GC barikukoresa empiira etarikutaaha omu gaasi eshemeziibwe na argon.
Okucondooza kwa DRIFT omu mwanya kukakorwa aha kikwato ky’okupima ebiri omu itaka (FTIR) ekiine ekikwato ky’okupima ebiri omu itaka (MCT). Empunu y’okureetaho okuhinduka ekateebwa omu kacupa k’okugarukamu (ebintu bya sayansi ebya Harrick, Praying Mantis). Bwanyima y’okujanjaba ekikwato ky’okureetaho okuhinduka n’omugyera gwa Ar (50 ml/min) aha butagasi bw’omu kishengye, sampo ekaheebwa omuriro kuhika aha butagasi obuhairwe, bwanyima yaafumbirwa Ar (50 ml/min) omu nshonga ya HCOOH kandi yaashukwa omu nkora y’okugarukamu ey’omu mwanya. ahabw’okugarukamu. Eky‘okureeberaho ky‘emiringo y‘okureetaho ebintu etari emwe n‘emwe. Infrared spectra zikahandiikwa omu bwire kuruga ahari sekondi 3.0 kuhika aha shaaha 1.
HCOOH, DCOOH, HCOOD na DCOOD nizikoresibwa nk’ebintu ebiri ahansi y’omubazi gw’okukyebera. Embeera ezisigaireho nizihikaana n‘omuringo gw‘okukyendeeza amaizi omu HCOOH.
Okubara kw‘emisingye y‘okubanza kukakorwa barikukoresa enkora y‘okuteekateeka aha nkora y‘obuhango bw‘abantu omu nkora ya Vienna Ab initio (VASP 5.4.4) 65,66. Obutafaari bwa superunit oburimu aha mutwe gwa graphene (5 × 5) oburimu obuhango bw’okuraba burikwingana 12.5 Å bukakoresibwa nk’ekicweka ky’ahansi kya CoN2C2 na CoN2C2-Co6. Ekicweka ky’omuyaga ekirikurenga 15 Å kikongyerwaho okwetantara okukoragana ahagati y’ebicweka by’ahansi ebiri haihi. Enkoragana ahagati ya ions na electrons neeshoboororwa omu muringo gw’okuteekateeka (PAW)65,67. Omurimo gwa Perdue-Burke-Ernzerhof (PBE) ogw‘okugyeragyeranisa (GGA) n‘okutereeza kwa van der Waals ogwateirweho Grimm68,69 gukakoresibwa. Enkora y’okuteerana kw’amaani goona n’amaani ni 10−6 eV/atom na 0.01 eV/Å. Okusharaho kw’amaani kukateebwa ahari 600 eV barikukoresa enkora ya Monkhorst-Pack 2 × 2 × 1 ey’obubonero bwa K. Obushoboorozi bw’ebishuba oburikukoresibwa omu muringo ogu nibwombekwa kuruga omu ntebeekanisa y’ebyoma kuza omu mbeera ya C 2s22p2, N 2s22p3, Co 3d74s2, H 1 s1, n’O 2s22p4. Amaani g’okushohoza n’entaaniso y’obuhango bw’ebiriisa nibibarwa barikuihaho amaani g’omutindo gwa gaasi n’ebika by’ahaiguru kuruga aha maani g’enkora y’okushohoza kurugiirira aha nkora y’okushohoza nari ey’okutaaha omu nkora70,71,72,73,74. Okutereeza kw‘amaani ga Gibbs ag‘obuntu nikukoresibwa kuhindura amaani ga DFT kuba amaani ga Gibbs ag‘obuntu kandi nikutwara omu nkora ebiconco by‘okutengeeta aha entropy n‘amaani g‘enshonga ya zero75. Enkora y‘okutunguuka kw‘ekishushani-okuteera elastic band (CI-NEB) ekakoresibwa kusherura embeera y‘okuhinduka kw‘okugarukamu76.
Ebihandiiko byona ebyatungirwe kandi byashwijumwa omu kucondooza oku biri omu kihandiiko n‘ebihandiiko by‘okwongyeraho nari nibibaasa kutunga kuruga aha muhandiiki orikukora aha nshonga egi waashaba omu muringo oguhikire. Ebihandiiko ebirikuruga omu kihandiiko eki nibiheebwayo.
Koodi zoona ezirikukoresibwa omu kugyeragyeranisa okurikuhererukayo n’ekicweka eki nizitunga abahandiiki abarikugikwataho waashaba.
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