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Kusumpuka kwatekkinoloji ya haayidirojeni kuli akati-kati kazyintu zitakwe busani. Mbuli chintu chiyandikana kuti kube kubamba kwa haayidirojeni, zintu zibeleka alimwi zitazungaani zyakugwisya haayidirojeni zilayandika. Kusikila lino, busena obu bwakali kweendelezyegwa akubelesya zintu ziyandisi zidula. Aawa, twasala nzila mpya iitayandiki mali manji iibelesya cobalt (Co-SAs/NPs@NC) oomo masena aajisi nsimbi yomwe aamwaigwa kapati moajatikizyidwe antoomwe ama nanoparticles mabotu kutegwa kube kugwisya maanzi munzila iili kabotu. Kubelesya zintu zibotu zya CoN2C2 zyakamwaikide aatomu antoomwe a nanoparticles zya 7-8 nm, kubelesya propylene carbonate mbuli musamu, kwakajanwa muya mubotu loko wa 1403.8 ml g-1 h-1, mpo kwakanyina kusweekelwa nokwakainda ziindi zili musanu. mulimo, ooyo uuli kabotu ziindi zili kkumi amusanu kwiinda Pd/C yamakwebo. Kusunkwa kwabusena butondezya kuti, kweezyanisya aatomu yomwe yabutale antoomwe azintu zipa kuti zintu zibe kabotu, Co-SAs/NPs@NC ilasumpula kunjila akubeleka kwa monodentate intermediate HCOO*, aboobo ilasumpula CH bond cleavage. Kubalila kwakuyeeyela kutondeezya kuti kuswaangana kwa cobalt nanoparticles kusumpula kusanduka kwa d-band center ya Co atom yomwe kuti ibe busena bubeleka, aboobo kusumpula kuswaangana aakati ka carbonyl O ya HCOO* akati-kati a Co center, aboobo kuchesya nguzu zyakukwabilila.
I-Hydrogen ilabonwa kuti nchintu chipati chitola manguzu mukucinca kwanguzu zyanyika yoonse lino mpawo ilakonzya kuba chintu chipati chikonzya kugwasya kuti kutabi carbon neutrality1. Akaambo kazyintu ziliwo zilimbuli kupya akubula bunji, kubamba kabotu akutola kabotu hydrogen nzintu zipati mukuzuzikizya buvubi bwa hydrogen2,3,4. Ma Liquid organic hydrogen carriers (LOHCs), aayo aabamba akugwisya haayidirojeni kwiinda mukusangana kwamakemikalu, akayeeyelwa kuti ngaakonzya kugwasya. Kweezyanisya a haayidirojeni, zintu ziliboobu (methanol, toluene, dibenzyltoluene, azimwi) nzyubauba alimwi zilagwasya kweendelezya5,6,7. Akati kama LOHC aasiyene-siyene, asidi yafoomu (FA) ilaa busi busyoonto (LD50: 1.8 g/kg) antoomwe a H2 capacity ya 53 g/L naa 4.4 wt%. Chazibinkene, FA nje LOHC ilikke iikonzya kubamba akugwisya haayidirojeni mubukkale buteteete kakuli zintu zigwasya, aboobo taziyandiki nguzu zyiingi zyaanze1,8,9. Mubunike, zintu zyiingi zyabutale zibotu zyakabambwa kuti zibelesyegwe kugwisya maanzi mu asidi yafoomu, mbuli chitondeezyo, zintu zibelesya palladium zilabeleka ziindi zili 50-200 kwiinda zintu zitayandiki mali manji10,11,12. Nokuba boobo, kuti wabikkila maanu kumuulo wazintu zibeleka, mbuli chitondeezyo, palladium iladula ziindi ziinda ku 1000.
Cobalt, Kuyandaula zintu zibeleka loko alimwi zitazungaani zya heterogeneous metal catalysts kuzumanana kukwela luyandisisyo lwabasikuvwuntauzya banji muziiyo zyaatala amumakwebo13,14,15.
Nikuba kuti zintu zitayandiki mali manji zibelesya Mo a Co, antoomwe azintu zipangwa kuzwa ku noble/base metal alloys,14,16 zyakabambwa kuti zibelesyegwe kugwisya maanzi mu FA, kuzima kwazyo asyoonto-asyoonto muchiindi chakusanduka takukonzyi kweelebwa akaambo kakujanika mumasena aabeleka aazibulo, CO2, antoomwe a H2O amapulotoni. naa formate anions (HCOO-), FA contamination, particle aggregation antoomwe a CO poisoning17,18. Swebo abamwi lino-lino twakatondezya kuti zintu zipa kuti kube atomu yomwe (SACs) zili amasena aa CoIINx aamwaikide kapati mbuli masena aabeleka alasumpula nguzu zyakusanduka akukazya asidi ya formic acid dehydrogenation kweelanisigwa ama nanoparticles17,19,20,21,22,23,24. Muzintu eezyi zya Co-NC, ma atomu aa N abelekela mbuli masena mapati aakusumpula FA deprotonation kumwi kasumpula kukkalikana kwabupange kwiinda mukubelekela antoomwe a atomu ya Co iili akati, kakuli ma atomu aa Co alapa masena aa H adsorption akusumpula CH22 scission, 25,26. Mupenzi, kubeleka akukkalikana kwazibelesyo eezyi zichili kule kuzwa kuzibelesyo zyamazubaano zikozyenye azintu ziindene-indene (Mufanikisyo. 1) 13 .
Nguzu zyiingi zizwa kuzintu zikonzya kubelesegwa lubo mbuli zuba naa guwo zilakonzya kuchitwa kwiinda mukubelesya magesi mumaanzi. I-hydrogen iipangwa ilakonzya kuyobolwa kubelesya LOHC, maanzi aayo aakonzya kujokoloka. Munzila yakugwisya maanzi mumubili, chintu chomwe chiliwo ni haayidirojeni, mpawo maanzi aanyamuna alajokezyegwa muchimo chakwe chakusanguna mpawo ayungizigwa alimwi. I-hydrogen ilakonzya kubelesegwa mumasena aakusambalila mafuta, mumabbattery, mumaanda aamakwebo, azimwi.
Ino-ino, kwakaambwa kuti mulimu wamukati wa SACs ulakonzya kuyungizigwa kakuli ma atomu aasiyene aabutale naakuti masena aambi aabutale aapegwa a nanoparticles (NPs) naakuti nanoclusters (NCs)27,28. Eezi zijula ​​nzila zyakuyungizya kunjila akuchita kuti zyintu zibeleke, antoomwe akucinca-cinca kwa geometry a bupange bwa electronic bwa masena aa monatomic. Munzila eyi, kunyonyoona/kusungwaazya kwa substrate kulakonzya kuchitwa kabotu, kupa kuti kube kubeleka kabotu kwa catalytic29,30. Eezi zitupa muzeezo wakupanga zintu zikonzya kugwasya kuchita zintu antoomwe amasena aabeleka. Nikuba kuti ma SAC asumpukide atondezya kuchita obotu mumilimo myiingi yakugwasya31,32,33,34,35,36, kweendelanya aluzibo lwesu, mulimo wayo mukubamba haayidirojeni tausalali pe. Muleezi, twaambilizya nzila iikonzya kubelesegwa munzila zyiingi alimwi iili kabotu yakupanga zintu zipangwa a cobalt (Co-SAs/NPs@NCs) zijisi ma nanoparticles aasalala antoomwe amasena aabutale. I Co-SAs/NPs@NC iibambidwe kabotu itondezya mulimo mubotu wakugwisya mafuta mumubili, ooyo uuli kabotu kwiinda zintu zitali kabotu zya nanostructured catalysts (mbuli CoNx, single cobalt atoms, cobalt@NC a γ-Mo2N) antoomwe a noble metal catalysts. Kuvwuntauzya kwabusena antoomwe akubala kwa DFT kwazibelesyo zibeleka zitondezya kuti masena aabutale amwi abelekela mbuli masena aabeleka, mpawo ma nanoparticles aajanika lino alasumpula akati ka d-band yama atomu aa Co, akusumpula kunjila akubeleka kwa HCOO*, aboobo akucesya nguzu zyakukwabilila. .
Zeolite imidazolate frameworks (ZIFs) nzintu zisalazyidwe kabotu zijisi zibeela zyotatwe zipa kuti kube zintu zipa kuti kube nitrogen-doped carbon materials (metal-NC catalysts) kuti zigwasye misyobo isiyene-siyene yazibulo37,38. Aboobo, Co(NO3)2 antoomwe a Zn(NO3)2 zilaswaangana a 2-methylimidazole mu methanol kuti zipange nsimbi zyeendelana mumusamu. Musule akuyuminizya, CoZn-ZIF yaka pyrolyzed atempelecha zisiyene (750-950 °C) mumulengalenga wa 6% H2 antoomwe a 94% Ar. Mbuli mbokutondezyedwe achifanikisyo chili munsi, zintu zyakajanika zili amasena aasiyene-siyene mpawo zyaambwa kuti Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750 (Chitondeezyo 2a). ) . Kulangisisya kwakusola kwa ntaamu zimwi zipati munzila yakupanga zintu kulilembedwe mufanikisyo 1 a 2. C1-C3. Kusanduka kwakupya kwa X-ray (VTXRD) kwakachitwa kuti kulangisisye kusanduka kwa catalyst. Ikuti kupya kwa pyrolysis kwasika ku 650 °C, nzila ya XRD ilachincha loko akaambo kakuwa kwabupange bwa ZIF (Fig. S4) 39 . Mbuli kupya mbokuyaabutanta, nsumbu zyobile zipati zilaboneka muma XRD aa Co-SAs/NPs@NC-850 a Co-SAs/NPs@NC-750 a 20–30° a 40–50°, ziiminina nsumbu ya amorphous carbon (Fig. C5). 40. Nchintu chibotu kuzyiba kuti buyo mitwe yotatwe yakabonwa a 44.2°, 51.5° a 75.8°, ya metallic cobalt (JCPDS #15-0806), antoomwe a 26.2°, ya graphitic carbon (JCPDS # 41-1487). I X-ray spectrum ya Co-SAs/NPs@NC-950 itondezya kubako kwa graphite-like encapsulated cobalt nanoparticles aa catalyst41,42,43,44. I Raman spectrum itondezya kuti Co-SAs/NPs@NC-950 ilibonya kuti ilijisi D a G peaks ziyumu alimwi zifwaafwi kwiinda zimwi zitondezyo, kutondezya kuti kuli graphitization mpati ( Cifwanikiso S6 ). Mukuyungizya, Co-SAs/NPs@NC-950 itondezya busena bupati bwa Brunner-Emmett-Taylor (BET) abupati bwamapopwe (1261 m2 g-1 a 0.37 cm3 g-1) kwiinda zimwi zitondezyo alimwi bunji bwa ZIFs nzintu zizwa ku NC. zintu (Mufanikisyo S7 a Table S1). Atomic absorption spectroscopy (AAS) itondezya kuti cobalt zili mu Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@ zili 2.69 wt.%, 2.74 wt.% antoomwe a 2.73 wt.%. NC-750 kweendelana (Table S2). Zn iili mu Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750 ilatanta asyoonto-asyoonto, eezi zyeendelezyegwa akuyungizya kucheya akuvwuuma kwa Zn units. Kuyungizya kwakupya kwa pyrolysis (Zn, busena bwakubila = 907 °C) 45.46. Kuvwuntauzya kwazibeela (EA) kwakatondeezya kuti mweelwe wa N ulaselemuka aawo kupya kwa pyrolysis nokwatanta, mpawo bunji bwa O bulakonzya kuba akaambo kakunjila kwa O2 kuzwa kukunjila mumuwo. (Table S3). Aawo kuli cobalt imwi, ma nanoparticles antoomwe ama coatoms aalikke alapona antoomwe, mpawo eezi zipa kuti kube kuyungizigwa kupati kwakubeleka kwa catalyst, mbuli mbokwabandikwa munsi.
Cifwanikiso chakupangwa kwa Co-SA/NPs@NC-T, aawo T nkupya (°C). b Cifwanikiso cha TEM. c Cifwanikiso cha Co-SAs/NPs@NC-950 AC-HAADF-STEM. Ma atomu aa Co alikke alilembedwe amabbanga aasalala pyu. d EDS spectrum ya Co-SA/NPs@NC-950.
Chazibinkene, transmission electron microscopy (TEM) yakatondezya kubako kwa tuniini twa cobalt (NPs) twaakati-kati twa 7.5 ± 1.7 nm mu Co-SAs/NPs@NC-950 luzutu (Zifwanikiso 2 b a S8). Aaya ma nanoparticles alivwumbidwe a graphite-like carbon iijisi nitrogen. Kusiyana kwa 0.361 a 0.201 nm kweendelana a graphitic carbon (002) antoomwe a metallic Co (111) particles, kweendelana. Mukuyungizya, high-angle aberration-corrected annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) yakatondeezya kuti Co NPs mu Co-SAs/NPs@NC-950 zyakali zingulukidwe a atomic cobalt (Fig. 2c). Nokuba boobo, buyo ma atomu aa cobalt aakamwaikide ngaakabonwa aakugwasyilizya zitondezyo zimbi zyobile (Fig. S9). Energy dispersive spectroscopy (EDS) Cifwanikiso cha HAADF-STEM chitondeezya kwaabwa kweendelana kwa C, N, Co antoomwe a Co NPs mu Co-SAs/NPs@NC-950 (Fig. 2d). Zyoonse eezyi mpindu zitondezya kuti masena aa Co aamwaikide muma atomu antoomwe ama nanoparticles aajatikizyidwe mu N-doped graphite-like carbon alazwidilila kujatikizyigwa ku NC substrates mu Co-SAs/NPs@NC-950, kakuli buyo masena aabutale aalikke.
Chiimo cha valence antoomwe a kkemikkalu yazintu zyakajanwa zyakavwuntauzyigwa a X-ray photoelectron spectroscopy (XPS). I XPS spectra yazibelesyo zyotatwe zyakatondezya kubako kwazibeela zya Co, N, C a O, asi Zn yakaliko buyo mu Co-SAs/NPs@NC-850 a Co-SAs/NPs@NC-750 (Fig. 2). ). C10). Mbuli kupya kwa pyrolysis mbokuyaabutanta, mweelwe woonse wa nitrogen ulaselemuka aawo misyobo ya nitrogen niyatazungaani mpawo yabola kuba NH3 a NOx muya aawo nokwapya kapati (Table S4) 47 . Aboobo, mweelwe woonse wa kaboni wakatanta asyoonto-asyoonto kuzwa ku Co-SAs/NPs@NC-750 kuya ku Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-950 (Mifanikisyo S11 a S12). Isampulu yakapya kapati ilijisi mweelwe musyoonto wama atomu aa nitrogen, eezi zyaamba kuti mweelwe wa NC carriers mu Co-SAs/NPs@NC-950 weelede kuba muniini kwiinda wamwi musamu. Eezi zyeetelezya kuyuma kwatuniini twa cobalt. I O 1s spectrum itondezya nsumbu zyobile C=O (531.6 eV) a C–O (533.5 eV), kweendelana (Figure S13) 48 . Mbuli mbokutondezyedwe achifanikisyo 2a, N 1s spectrum ilakonzya kubambululwa muzibeela zyone zya pyridine nitrogen N (398.4 eV), pyrrole N (401.1 eV), graphite N (402.3 eV) antoomwe a Co-N (399.2 eV). Zilongwe zya Co-N ziliwo mumasampu woonse otatwe, kutondezya kuti amwi ma atomu aa N aliswaangene kumasena aa monometallic, pesi bube bwawo buliindene kapati49. Kubelesya kupya kwa pyrolysis kulakonzya kucesya kapati bunji bwa Co-N kuzwa ku 43.7% mu Co-SA/NPs@NC-750 kusika ku 27.0% mu Co-SAs/NPs@NC-850 antoomwe a Co 17.6%@ NC-950. mu -CA/NPs, eezyo zyeendelana akuyungizya kwa C (Mufanikisyo 3a), kutondezya kuti mweelwe wabo wa Co-N ulakonzya kuchincha akunjililwa busena a C50 atoms. Zn 2p spectrum itondezya kuti eechi chintu chiliwo muchimo cha Zn2+. (Mufanikisyo S14) 51. Mumuni wa Co 2p utondezya zibeela zyobile zipati zili a 780.8 a 796.1 eV, eezyo zyeendelezyegwa a Co 2p3/2 a Co 2p1/2, kweendelana (Mufanikisyo 3b). Kweezyanisya a Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750, Co-N peak mu Co-SAs/NPs@NC-950 yasanduka kuya kulubazu lubotu, kutondezya kuti atomu ya Co yomwe atala -SAs/NPs@NC-950 ilijisi mweelwe mupati wakugwisya ma electron, eezi zipa kuti kube kupya kupati. Nchintu chibotu kuzyiba kuti Co-SAs/NPs@NC-950 luzutu yakatondeezya ntalisyo ya zero-valent cobalt (Co0) a 778.5 eV, eezi zitondezya kubako kwa nanoparticles zizwa mukubunganya kwa SA cobalt atempelecha mpati.
a N 1s a b Co 2p spectra ya Co-SA/NPs@NC-T. c XANES antoomwe a d FT-EXAFS spectra ya Co-K-edge ya Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750. e WT-EXAFS zifwanikiso zya Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850, antoomwe a Co-SAs/NPs@NC-750. f FT-EXAFS kweendelana kwa Co-SA/NPs@NC-950.
Chiindi cha X-ray absorption spectroscopy (XAS) chakabelesegwa kulanga-langa bupange bwamagesi antoomwe abusena bwakujatana bwa Co species mumusamu wakabambilwa. Chiimo cha Cobalt mu Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750 Bupange bwamumbali bwakayubununwa akujanika kwa X-ray afwaafwi a Co-K edge (XANES) spectrum. Mbuli mbokutondezyedwe muchifanikisyo 3c, kunywida afwaafwi ambali lyazitondezyo zyotatwe kuli aakati ka Co a CoO foils, kutondezya kuti chiimo cha valence cha Co chili akati ka 0 kusika ku +253. Mukuyungizya, kusanduka kuya kunguzu ziche kwakabonwa kuzwa ku Co-SAs/NPs@NC-950 kuya ku Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750, kutondezya kuti Co-SAs/NPs@NC-750 ilijisi chiimo chaansi. Kujokela musule. Kweelana akusanganya kwamulongo, chiimo cha Co-SAs/NPs@NC-950 chiyeeyelwa kuti chili +0.642, eecho chili munsi aachiimo cha Co-SAs/NPs@NC-850 (+1.376). Co-SA/NP @NC-750 (+1.402). Eezyi mpindu zitondezya kuti mweelwe waakati aakati wakusanduka kwa tuniini twa cobalt mu Co-SAs/NPs@NC-950 wacheya loko, eezi zyeendelana a XRD antoomwe a HADF-STEM zyazwa mpawo zilakonzya kupandululwa akukkala antoomwe kwa tuniini twa cobalt a cobalt yomwe. . Co atoms 41. Fourier transform X-ray absorption fine structure (FT-EXAFS) spectrum of the Co K-edge shows that main peak at 1.32 Å is of Co-N/Co-C shell, while scattering path of metallic Co -Co is at 2.18 only in Co-SAs Ås /NCs /NCs (Fig.505 3d). Kwiindawo, wavelet transform (WT) contour plot itondezya nguzu zipati zili a 6.7 Å-1 zipegwa kuli Co-N/Co-C, mpawo Co-SAs/NPs@NC-950 luzutu zitondezya nguzu zipati zipegwa kuli 8.8. Alubo bupati bupati buli a Å−1 ku Co–Co bond (Fig. 3e). Mukuyungizya, buvwuntauzi bwa EXAFS bwakachitilwa asikusambala bwakatondezya kuti kupya kwa pyrolysis kwa 750, 850 antoomwe a 950 °C, namba zya Co-N zyakali 3.8, 3.2 a 2.3, kweendelana, mpawo namba zya Co-C zyakali 0. 0.9 a 1.8 (Fig. Sf3, Sf15, S15). Mubwini, mpindu zyamazubaano zilakonzya kwaambwa kuti zyakajanika akaambo kakubako kwa CoN2C2 yama atomu aama nanoparticles mu Co-SAs/NPs@NC-950. Mukwiimpana, mu Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750, buyo CoN3C antoomwe a CoN4 ziliwo. Chilisalede kuti akuyungizya kupya kwa pyrolysis, ma atomu aa N muchibeela cha CoN4 alanjililwa busena ama atomu aa C, mpawo cobalt CA ilabungana kuchita ma nanoparticles.
Ziimo zyakusanduka zyakavwuntauzyigwa musule zyakabelesegwa kwiiya mbozigwasya ziimo zyakulibambila kuzintu ziindene-indene (Fig. S16)17,49. Mbuli mbokutondezyedwe achifanikisyo 4 a, mulimo wa Co-SAs/NPs@NC-950 ulisumpukide kwiinda wa Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750. Chazibinkene, zyoonse zyotatwe zya Co zyakabambilwa zyakatondezya kubeleka obotu loko kweelanisigwa azibelesyo zyamakwebo ziyandisi (Pd/C a Pt/C). Mukuyungizya, zikozyanyo zya Zn-ZIF-8 antoomwe a Zn-NC tiizyakali kubeleka ku formic acid dehydrogenation, kutondezya kuti zibeela zya Zn tazili busena bubeleka pe, pesi mulimo wazyo mumulimo tauli kabotu pe. Mukuyungizya, mulimu wa Co-SAs/NPs@NC-850 antoomwe a Co-SAs/NPs@NC-750 wakainda mu pyrolysis yabili a 950°C kwawoola lyomwe, asi wakali munsi a Co-SAs/NPs@NC-750 . @NC-950 (Fig. S17). Bupange bwazintu eezyi bwakatondezya kubako kwa Co nanoparticles mumasampuli aakapilusyigwa, asi busena busyoonto bwaatala akubula graphite-like carbon zyakapa kuti kube kubeleka kusyoonto kweelanisigwa a Co-SAs/NPs@NC-950 (Chitondeezyo S18–S20). Ikubeleka kwamasampu aajisi mweelwe wa Co precursor uuindene-indene akwalo kwakakozyanisyigwa, akubeleka kupati kwakatondezyegwa a 3.5 mol yakuyungizya (Table S6 a Figure S21). Chilisalede kuti kupangwa kwamasena aasiyene-siyene aabutale kulajatikizyigwa a haayidirojeni iili mumulengalenga wa pyrolysis antoomwe achiindi cha pyrolysis. Aboobo, zimwi zintu zya Co-SAs/NPs@NC-950 zyakali kulinguwe kuti zibone naa zilakonzya kugwisya maanzi mumubili. Zyoonse zibelesyo zyakatondezya kubeleka kabotu loko; nokuba boobo, taakwe akati kabo wakali kabotu kwiinda Co-SAs/NPs@NC-950 (Mifanikisyo S22 a S23). Bupange bwachintu eechi bwakatondezya kuti akuyungizya chiindi chakupya, zyintu zili mu monoatomic Co-N zilaselemuka asyoonto-asyoonto akaambo kakubungana kwama atomu aabutale kuba ma nanoparticles, eezi zipandulula kusiyana kwakubeleka aakati kazitondezyo zili achiindi cha pyrolysis cha 100-2000. musiyano. 0.5 h, 1 h, antoomwe a 2 h (Mifanikisyo S24-S28 a Table S7).
Igilafu yabunji bwamafuta kweendelanya achiindi chakajanwa muchiindi chakugwisya mafuta mumafuta kubelesya zintu zisiyene-siyene. Ziimo zyakusanduka: PC (10 mmol, 377 μl), chitondeezyo (30 mg), PC (6 ml), Tback: 110 °C, Nzila: 98 °C, 4 zibeela b Co-SAs/NPs@NC-950 ( 30 mg), zintu zisiyene-siyene. c Kweezyanisya mweelwe wakusanduka kwamuwo wazyintu zipa kuti kube zintu ziindene-indene muzintu zipona a 85–110 °C. d Co-SA/NPs@NC-950 kubelesya zintu zyakalengwa buya. Ziimo zyakusanduka: FA (10 mmol, 377 μl), Co-SAs/NPs@NC-950 (30 mg), solvent (6 ml), Tset: 110 °C, Tactual: 98 °C, kuchincha kuli koonse kutola woola lyomwe. Mibala yakulubizya yiiminina kusiyana kwakabalilwa kuzwa kumasunko otatwe aaliwo.
Muchiindi choonse, bubotu bwa FA dehydrogenation catalysts buyeeme kapati abukkale bwakusanduka, ikapati musamu uubelesyegwa8,49. Notubelesya maanzi mbuli chintu, Co-SAs/NPs@NC-950 yakatondezya mweelwe mupati wakusaanguna, asi kwakaba kuzima, ambweni akaambo kakuti ma proton naa H2O18 akakkede mumasena aabeleka. Kusunka kwa catalyst muzintu zipona zilimbuli 1,4-dioxane (DXA), n-butyl acetate (BAC), toluene (PhMe), triglyme a cyclohexanone (CYC) akwalo tiikwakatondezya kuyaambele kuli koonse, alimwi amu propylene carbonate (PC) ) (Fig. 4b a Table S8). Mbubwenya buyo, zintu ziyungizyidwe zilimbuli triethylamine (NEt3) naa sodium formate (HCCONa) tiizyakali amulimu mubotu pe mukubeleka kwa catalyst (Chitondeezyo S29). Mubukkale buli kabotu bwakusanduka, muya wakasika ku 1403.8 mL g−1 h−1 (Fig. S30), ooyo wakali mupati kwiinda zyoonse zyakaambwa musyule zya Co catalysts (kubikkilizya a SAC17, 23, 24). Mukweezeezya kusiyene, kakutabikkilizyi zyintu zyakachitika mumaanzi antoomwe azintu ziyungizyidwe, kusala kwakugwisya maanzi akugwisya maanzi kusika ku 99.96% kwakajanwa (Table S9). Nguzu zyakutalisya zyakabalilwa zili 88.4 kJ/mol, eezyo zyeelene anguzu zyakutalisya zya noble metal catalysts (Chitondeezyo S31 a Table S10).
Mukuyungizya, twakakozyanisya mweelwe wazintu zimwi zitabeleki kabotu zya formic acid dehydrogenation mubukkale bukozyenye (Fig. 4c, matebulu S11 a S12). Mbuli mbokutondezyedwe muchifanikisyo 3c, mweelwe wakupanga muya wa Co-SAs/NPs@NC-950 wiinda mweelwe wazyintu zizyibidwe zya heterogeneous base metal catalysts alimwi ulisumpukide ziindi zili 15 a 15 kwiinda wa 5% Pd/C a 5% Pd/C, kweendelana, a 10 chiindi chomwe. % Pt/C chakugwasya.
Chintu chiyandikana loko mukubelesya (de)hydrogenation catalysts nkukkalilila kwazyo. Aboobo, kwakachitwa nzila zyiingi zyakusola kubelesya Co-SAs/NPs@NC-950. Mbuli mbokutondezyedwe muchifanikisyo 4 d, mulimu wakusaanguna akusala kwazintu kwakazumanana kutachincha kwamazuba osanwe aatobelana (amubone a Table S13). Kusunkwa kwachiindi chilamfu kwakachitwa mpawo kupanga muya kwakatanta muchiindi chamawoola aali 72 (Chitondeezyo S32). Bunji bwa cobalt mu Co-SA/NPs@NC-950 yakabelesegwa bwakali 2.5 wt%, oobo bwakali afwaafwi kapati abwa catalyst mpya, kutondezya kuti kwakanyina kuzwa kwa cobalt (Table S14). Kunyina kucinca kwamubala naa kubungana kwatuniini twabutale kwakabonwa kakutanaba akumana kwakusanduka (Chitondeezyo S33). AC-HAADF-STEM antoomwe a EDS yazintu zyakabelesegwa mukusola kwachiindi chilamfu zyakatondezya kubamba akumwaika kweendelana kwamasena aakumwaika kwa atomu mpawo taakwe kucinca kupati kwabupange (Mifanikisyo S34 a S35). Zibeela zya Co0 a Co-N zichiliko mu XPS, kutondezya kujanika antoomwe kwa Co NPs amasena aabutale, mpawo akusinizya kukkalikana kwa Co-SAs/NPs@NC-950 catalyst (Chitondeezyo S36).
Kuziba masena aabeleka kapati aajisi mukuli wakugwisya maanzi mumubili, zintu zyakasalwa zijisi buyo busena bomwe bwachibulo (CoN2C2) naa Co NP zyakabambilwa kweendelanya aziiyo zyakachitika musule17. Bweendelezi bwakugwisigwa kwa asidi ya foomu bwakabonwa mubukkale bukozyenye mbubwakuti Co-SAs/NPs@NC-950 > Co SA > Co NP (Table S15), kutondezya kuti masena aa CoN2C2 aamwaikide aatomu alabeleka kwiinda NPs. Ikusanduka kwa hydrogen kutondezya kuti kusanduka kwa haayidirojeni kutobela nzila yakusaanguna yakusanduka, pesi kuseluka kwama curve manji aali mu cobalt yiindene-indene takukozyenye pe, kutondezya kuti kweenda takuyeeme buyo a formic acid, pesi abusena bubeleka (Fig. 2). C37). Buvwuntauzi bumbi bwakuvwuntauzya bwakatondezya kuti, akaambo kakubula nkomo zya cobalt metal mu X-ray diffraction analysis, nzila ya kinetic ya reaction mumakani aa cobalt yakajanwa kuti 1.02 kumasena aali munsi (munsi aa 2.5%), kutondezya kwaabwa kwa monoatomic cobalt centers. chili nchicho. busena bubeleka (mifanikisyo S38 a S39). Eelyo zibeela zya Co nozisika ku 2.7%, r ilatanta mpawo, kutondezya kuti zibeela zya nano zilaswaangana obotu ama atomu alikke kuti zibe amulimu mupati. Mbuli zibeela zya Co mboziyaabukomena, chikozyano chiba chitali chamulongo, eecho chiswaangene akuyungizya mweelwe wama nanoparticles akucheya kwazibeela zya monatomic. Aboobo, kusumpuka kwa LC dehydrogenation kwa Co-SA/NPs@NC-950 kuzwa kukubelekela antoomwe kwamasena aabutale a nanoparticles.
Chiiyo chiyumu chakachitwa kubelesya in situ diffuse reflectance Fourier transform (in situ DRIFT) kuchitila kuzyiba zintu zili akati-akati zyakuchita. Nikwakamana kupya zitondezyo kusikila kuma temperature aasiyene-siyene nikwakamana kuyungizya asidi yafoomu, kwakabonwa zibeela zyobile zyama frequency (Fig. 5a). Zibeela zyotatwe zya HCOOH* zilibonya a 1089, 1217 antoomwe a 1790 cm-1, eezyo zyeendelana akuzungaana kwa CH π (CH), CO ν (CO) kuzungaana a C=O ν (C=O) kuzungaana, kweendelana. Imwi ntalisyo ya 1363 a 1592 cm-1 yeendelana akuzungaana kwa OCO νs(OCO) akuzungaana kwa OCO kutali kabotu νas(OCO)33.56 HCOO*, kweendelana. Mbuli kusanduka mbokuyaabuzumanana, nsumbu zya HCOOH* antoomwe a HCOO* zilamana asyoonto-asyoonto. Mukwaamba biyo, kubola kwa asidi ya foomu kulabikkilizya ntaamu zyotatwe zipati: (I) kunyonyooka kwa asidi ya foomu mumasena aabeleka, (II) kugwisya H kwiinda munzila ya formate naa carboxylate, antoomwe a (III) kusanganya H yobile yakanjila mukupanga haayidirojeni. HCOO* a COOH* nzintu zipati zili akati-akati mukuziba nzila zya formate naa carboxylate, kweendelana57. Kubelesya nzila yesu yakugwasya, buyo HCOO* peak yakaboneka, kutondezya kuti kubola kwa formic acid kulachitika biyo kwiinda munzila ya formic acid58. Zyakabonwa zikozyania zyakachitilwa aawo mpaakali kupya kapati a 78 °C a 88 °C (fig. S40).
In situ DRIFT spectra ya HCOOH dehydrogenation a Co-SAs/NPs@NC-950 antoomwe a b Co SAs. Makani aakaindi atondezya chiindi chakusandula aawo. c Kusiyana kwabunji bwamuya uuzwa kubelesya misamu iindene-indene yakulemba ma isotope muchindi. d Data ya isotope iibeleka.
Kusola kukozyenye kwa DRIFT kwakachitwa kuzintu zijatikizyidwe Co NP a Co SA kuti kuvwuntauzyigwe mulimo wakubelekela antoomwe mu Co-SA/NPs@NC-950 (Zifwanikiso 5 b a S41). Zintu zyoonse zyobile zitondezya nzila zikozyania, pesi zibeela zya HCOOH* a HCOO* zyasanduka mbichani, kutondezya kuti kunjila kwa Co NPs kuchincha bupange bwamagesi bwa monoatomic center. Chitondeezyo cha νas(OCO) chilibonya mu Co-SAs/NPs@NC-950 a Co SA pesi kutali mu Co NPs, mpawo kutondeezya kuti aakati-akati kazwa mukuyungizya asidi yafoomu ni asidi yafoomu iigaminide aawo mwinyo. mpawo ilanjila mu SA mbuli busena bubeleka 59 . Nchintu chibotu kuzyiba kuti kuyungizigwa kupati kwakuzungaana kwazibeela zya π(CH) antoomwe a ν(C = O) kwakabonwa, ooko kwakasololela kukunyongana kwa HCOOH* mpawo kwakapa kuti kube kusanduka. Mukujana mpindu, zibeela zya HCOOH* a HCOO* mu Co-SAs/NPs@NC zyakamana musule lyamaminiti obile aakusanduka, eezi zifwambaana kwiinda zya monometallic (6 min) antoomwe a nanoparticle-based catalysts (12 min). . Zyoonse eezyi zyazwa zisinizya kuti nanoparticle doping ilasumpula kunjila akubeleka kwazintu zili akati-akati, aboobo akufwambaanya nsandulo zyaambwa atala aawa.
Kuyungizya kulanga-langa nzila yakusanduka akuzyiba ntaamu yakusala mweelwe (RDS), KIE yakachitwa kakuli Co-SAs/NPs@NC-950. Aawa, zibeela zya asidi zya formic zisiyene zilimbuli HCOOH, HCOOD, DCOOH antoomwe a DCOOD zilabelesyegwa muziiyo zya KIE. Mbuli mbokutondezyedwe achifanikisyo 5c, mweelwe wakugwisigwa kwamaanzi ulaselemuka munzila itobela: HCOOH > HCOOD > DCOOH > DCOOD. Mukuyungizya, mpindu zya KHCOOH/KHCOOD, KHCOOH/KDCOOH, KHCOOD/KDCOOD antoomwe a KDCOOH/KDCOOD zyakabalilwa kuti 1.14, 1.71, 2.16 antoomwe a 1.44, kweendelana (Fig. 5d). Aboobo, CH bond cleavage mu HCOO* itondezya kH/kD values ​​>1.5, kutondezya mulimo mupati60,61, mpawo ilibonya kuti yiiminina RDS ya HCOOH dehydrogenation a Co-SAs/NPs@NC-950.
Mukuyungizya, kubala kwa DFT kwakachitwa kuti kumvwisisisye mpindu ya nanoparticles yakabikkidwe mumulimo wa Co-SA. Inzila zya Co-SAs/NPs@NC antoomwe a Co-SA zyakabambwa kweendelanya akusola kwakatondezyegwa amilimo yakachitika musule (Mifanikisyo 6a a S42)52,62. Musule akubamba kabotu, tuniini twa Co6 (CoN2C2) tupona antoomwe atuniti twa monotomu twakajanwa, mpawo bulamfu bwa Co-C antoomwe a Co-N mu Co-SA/NPs@NC bwakajanwa kuti buli 1.87 Å a 1.90 Å, kweendelana. , eezyo zyeendelana azyazwa mu XAFS. Ikubalwa kwabunji bwaziimo (PDOS) kutondeezya kuti atomu yomwe ya Co a nanoparticle composite (Co-SAs/NPs@NC) zitondezya kusanganya kupati afwaafwi a Fermi level kweelanisigwa a CoN2C2, eezi zipa kuti kube HCOOH. Kusanduka kwama electron aabola kulagwasya kapati (Zifwanikiso 6b a S43). Maanda aa d-band aa Co-SAs/NPs@NC antoomwe a Co-SA akabalilwa kuti nga -0.67 eV antoomwe a -0.80 eV, kweendelana, aakati kazyeezyo kuyungizigwa kwa Co-SAs/NPs@NC kwakali 0.13 eV, ooko kwakapa kuti nikwakabikkwa NP, kunjila kwa HCOO* aama electronic particles kwakachitika mubupange bwa Co-2C2. Kwiimpana kwabunji bwamagesi kutondeezya kkumbi pati lyamagesi lizingulukide bbuloki lya CoN2C2 a nanoparticle, kutondezya kuswaangana kupati aakati kabo akaambo kakucincanya magesi. Kusanganya akuvwuntauzya kwa Bader, kwakajanwa kuti Co yakamwaikide mu atomu yakasweekelwa 1.064e mu Co-SA/NPs@NC antoomwe a 0.796e mu Co SA (Chitondeezyo S44). Eezyi mpindu zitondezya kuti kuswaangana kwa nanoparticles kuletela kumana kwama electron mumasena aa Co, eezi zipa kuti kube kuyungizigwa kwa Co valence, eezi zyeendelana azyazwa mu XPS (Fig. 6c). Ikujatana kwa Co-O kwa HCOO kunjila mu Co-SAs/NPs@NC antoomwe a Co SA kwakavwuntauzyigwa kwiinda mukubala kabunga ka Hamiltonian (COHP)63. Mbuli mbokutondezyedwe muchifanikisyo 6 d, mpindu zitali kabotu azibotu zya -COHP zyeendelana abukkale bwakulwana abukkale bwakujata, kweendelana. Nguzu zyakujatana zya Co-O zyakajatwa a HCOO (Co-carbonyl O HCOO*) zyakali kulinguwe kwiinda mukuswaanganya -COHP, eezyo zyakali 3.51 a 3.38 zya Co-SAs/NPs@NC antoomwe a Co-SA, kweendelana. Kunjila kwa HCOOH akwalo kwakatondezya mpindu zikozyenye: kuyungizigwa kwa -COHP nikwakamana kubikkwa nanoparticle kutondeezya kuyungizigwa kwa Co-O bonding, aboobo kwasumpula kubeleka kwa HCOO a HCOOH (Chitondeezyo S45).
Co-SA/NPs@NC-950 nzila yakubamba. b PDOS Co-SA/NP@NC-950 antoomwe a Co SA. c 3D isosurface yakwiimpana kwanguzu zya HCOOH adsorption a Co-SA/NPs@NC-950 a Co-SA. (d) pCOHP ya Co-O bonds yakabikkwa a HCOO a Co-SA/NPs@NC-950 (kulumwensyi) antoomwe a Co-SA (kululyo). e Nzila yakusanduka ya HCOOH dehydrogenation a Co-SA/NPs@NC-950 antoomwe a Co-SA.
Kuti tumvwisisisye kabotu mulimo wakugwisya maanzi mu Co-SA/NPs@NC, nzila yakuchita anguzu zyakajanwa. Mubwini, FA dehydrogenation ilabikkilizya ntaamu zyosanwe, kubikkilizya akusanduka kwa HCOOH kuba HCOOH*, HCOOH* kuba HCOO* + H*, HCOO* + H* kuba 2H* + CO2*, 2H* + CO2* kuba 2H* + CO2, antoomwe a 2H* mu H2 (Fig. 6e). Nguzu zyakunjilila zyama molecule aa asidi aafoomu aali atalaa chitondeezyo kwiinda mu carboxylic oxygen zili munsi kwiinda kwiinda mu hydroxyl oxygen (Mifanikisyo S46 a S47). Kuzwa waawo, akaambo kakuti manguzu masyoonto, adsorbate ilainda mu OH bond cleavage kuti ipange HCOO* kutali CH bond cleavage kuti ipange COOH*. Aawo awo, HCOO* ibelesya monodentate adsorption, eeyo isumpula kutyoka kwama bond akupanga CO2 a H2. Eezyi mpindu zileendelana akubako kwa νas(OCO) peak in situ DRIFT, mpawo zitondezya kuti kubola kwa FA kulachitika kwiinda munzila ya formate mukwiiya kwesu. Nchintu chipati kuzyiba kuti kweendelanya akupima kwa KIE, CH dissociation ilijisi nguzu zyakusanduka zisumpukide kwiinda ntaamu zimwi zyakusandula alimwi yiiminina RDS. Chikwabilizyo changuzu cha Co-SAs/NPs@NC catalyst system chili munsi a 0.86 eV kwiinda Co-SA (1.2 eV), eecho chisumpula loko kugwisya maanzi. Chazibinkene, kujanika kwama nanoparticles kweendelezya bupange bwamagesi bwama atomically dispersed coactive sites, eezyo ziyungizya kunjila akubeleka kwa intermediates, aboobo kuchesya chisinkilizyo cha reaction akusumpula kupanga hydrogen.
Muchi chifwiifwi, twatondezya mchiindi chakusanguna kuti kubeleka kwa hydrogen kulakonzya kusumpulwa kwiinda mukubelesya zintu zijisi busena bupati bwa monometallic antoomwe atuniini tuniini. Muzeezo ooyu wakasinizyigwa akupangwa kwa cobalt-based single-metal catalysts yakacincwa a nanoparticles (Co-SAs/NPs@NC), antoomwe azintu zimwi zijisi buyo single-metal centers (CoN2C2) naa Co NPs. Zintu zyoonse zyakabambwa anzila nguba ya pyrolysis. Kuvwuntauzya kwabupange kutondeezya kuti chintu chiinda kubota (Co-SAs/NPs@NC-950) chili amayuniti aa CoN2C2 aamwaikide aatomu antoomwe atuniini (7-8 nm) tujisi nitrogen a graphite-like carbon. Ilijisi muya mubotu loko kusika ku 1403.8 ml g-1 h-1 (H2:CO2 = 1.01:1), H2 antoomwe a CO selectivity ya 99.96% mpawo ilakonzya kuzumanana kubeleka kwamazuba manji. Ikubeleka kwachintu eechi chiinda kubeleka kwa Co SA antoomwe a Pd/C ziindi zili 4 a 15, kweendelana. Kusunkwa kwa DRIFT mubusena ooko kutondezya kuti kweelanisigwa a Co-SA, Co-SAs/NPs@NC-950 itondezya nguzu zya HCOO*, eezyo ziyandikana munzila ya formate, mpawo ma nanoparticles alakonzya kusumpula HCOO* activation a C–H acceleration. Kutyompokelwa kwachilongwe kwakazyibwa kuti RDS. Kubalila kwakuyeeyela kutondezya kuti Co NP doping ilayungizya d-band center ya Co atoms yomwe a 0.13 eV kwiinda mukuswaangana, ikuyungizya kunjila kwa HCOOH* a HCOO* zili akati-akati, aboobo kuchesya chisinkilizyo kuzwa ku 1.20 eV ya Co SA kusika ku 0 .86 eV. Nguujisi mukuli wakuchita obotu.
Mubufwaafwi, buvwuntauzi oobu bupa mizeezo yakubamba zintu zipya zyabutale bujisi atomu yomwe akusumpula kumvwisisisya mbokukonzya kusumpula kubeleka kwabutale kwiinda mukubelekela antoomwe kwamasena aabutale aamasaizi aasiyene. Tusyoma kuti eeyi nzila ilakonzya kubelesegwa kulizimwi nzila zyiingi zyakugwasya.
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%) yakaulwa kuzwa ku McLean, China. Asidi yafoomu (HCOOH, 98%) yakaulwa kuzwa ku Rhawn, China. Zibelesyo zyoonse zyakabelesegwa biyo kakunyina kusalazya, mpawo maanzi aasalala loko akabambwa kubelesya nzila yakusalazya. Pt/C (5% mass loading) antoomwe a Pd/C (5% mass loading) zyakaulwa kuzwa ku Sigma-Aldrich.
Kupangwa kwa CoZn-ZIF nanocrystals kwakachitwa kweendelana anzila zyakainda antoomwe akucinca kumwi23,64. Chakusanguna, 30 mmol Zn(NO3)2·6H2O (8.925 g) antoomwe a 3.5 mmol Co(NO3)2·6H2O (1.014 g) zyakasanganyigwa mpawo zyakanyonyooka mu 300 ml ya methanol. Mpawo, 120 mmol ya 2-methylimidazole (9.853 g) yakanyonyoonwa mu 100 ml ya methanol mpawo yakabikkwa kumusamu ooyu. Musanganisyo wakazungaanisigwa muchiimo chakupya kwachiindi chamawoola aali makumi obilwe atune. Kumamanino, chipangwa chakaandaanizyigwa a 6429 g kwamaminiti aali kkumi mpawo chakasanzyigwa a methanol ziindi zyotatwe. Busi bwakazwa bwakayuminizyigwa mumulengalenga a 60°C masiku woonse katanabelesyegwa.
Kupanga Co-SAs/NPs@NC-950, busi bwa CoZn-ZIF bwakayuminizyigwa a 950 °C kwa 1 h mumuwo uuzwa mu 6% H2 + 94% Ar, akupya kwa 5 °C/min. Isampulu mpawo yakatontozyegwa kusikila kutempelecha yamukati kuti ijane Co-SA/NPs@NC-950. Kuli Co-SAs/NPs@NC-850 naa Co-SAs/NPs@NC-750, kupya kwakutontola kwakachincha kusika ku 850 a 750 °C, kweendelana. Zitondezyo zyakabambilwa zilakonzya kubelesegwa kakunyina kuchita zimwi zintu, mbuli kubelesya asidi.
Kupima kwa TEM (transmission electron microscopy) kwakachitwa a Thermo Fisher Titan Themis 60-300 "cube" microscope iijisi chintu chakululamika zifwanikiso antoomwe a 300 kV probe shaping lens. Kusunka kwa HAADF-STEM kwakachitwa kubelesya FEI Titan G2 antoomwe a FEI Titan Themis Z ma microscopes aajisi zibelesyo zyakuvwuntauzya azibelesyo zyakululamika zifwanikiso, antoomwe a DF4 zibelesyo zyakuzyiba zibeela zyone. Zifwanikiso zya EDS zyakajanwa a FEI Titan Themis Z microscope. Kuvwuntauzya kwa XPS kwakachitwa a X-ray photoelectron spectrometer (Thermo Fisher model ESCALAB 250Xi). XANES antoomwe a EXAFS Co K-edge spectra zyakayobolwa kubelesya XAFS-500 tebulu (China Spectral Instruments Co., Ltd.). Co yakajanwa kwiinda mukubelesya nzila ya atomic absorption spectroscopy (AAS) (PinAAcle900T). X-ray diffraction (XRD) spectra zyakalembwa a X-ray diffractometer (Bruker, Bruker D8 Advance, Germany). Isotherms yakunjilila kwa nitrogen yakajanwa kubelesya chibelesyo chakuyobola (Micromeritics, ASAP2020, USA).
Ikusanduka kwakugwisya maanzi kwakachitwa mumulengalenga wa argon mpawo muuya wakagwisigwa kweendelanya anzila ya Schlenk. Chibiya chakusanduka chakagwisigwa mpawo chakazuzyigwa a argon ziindi zili musanu ayimwi. Jula maanzi aakutontozya mpawo ubike chitondeezyo (30 mg) antoomwe asolvent (6 ml). Pya chibiya kusikila aawo mpoyanda kubelesya chitondeezyo chakutontola mpawo uchileke kuti chikkale kabotu kwamaminiti aali 30. Asidi yafoomu (10 mmol, 377 μL) mpawo yakabikkwa mumupika wakuchita zintu munsi lya argon. Sandula vvalavu ya burette iijisi nzila zyotatwe kuti igwisye muya mu reactor, ujale alimwi, mpawo utalike kupima mweelwe wa gasi uuzwa kubelesya burette iibelesyegwa amaanza (Chitondeezyo S16). Nikwakainda chiindi chakuti zyintu zimane, musamu wamuwo wakabwezegwa kuti uchitilwe GC kulanga-langa kubelesya syringe iitakwe muya yakasanzyigwa a argon.
Kusola kwa DRIFT kwakachitwa a Fourier transform infrared (FTIR) spectrometer (Thermo Fisher Scientific, Nicolet iS50) yakajisi mercury cadmium telluride (MCT) detector. Ibbwe lyakugwasya lyakabikkwa muchibaka chakusanduka (Harrick Scientific Products, Praying Mantis). Nikwakamana kubamba chintu eechi amulonga wa Ar (50 ml/min) aawo mpaakali kupya, musamu wakapya kusika aawo mpaakali kupya, mpawo wakabikkwa Ar (50 ml/min) mumusamu wa HCOOH mpawo wakatilwa muchibaka chakuchita zintu. kuti ubweze ntaamu. Chitondeezyo cha nzila zyakuchita zintu ziindene-indene. Infrared spectra zyakalembwa muchiindi chitalikila kuzwa ku 3.0 masekondi kusikila kuwoola lyomwe.
HCOOH, DCOOH, HCOOD antoomwe a DCOOD zibelesyegwa mbuli zintu zyaansi mu propylene carbonate. Ziimo zyakasyaala zyeendelana anzila ya HCOOH dehydrogenation.
Kubala kwakusaanguna kwakachitwa kubelesya nzila ya density functional theory mukati ka Vienna Ab initio modeling package (VASP 5.4.4) 65,66. Kabeela ka superunit kajisi busena bwa graphene (5 × 5) kajisi bupati bwa 12.5 Å bwakabelesegwa mbuli busena bwa CoN2C2 antoomwe a CoN2C2-Co6. Musinzo wa vacuum wiinda ku 15 Å wakayungizigwa kuchitila kutabilila kuswaangana aakati kazyintu zili afwaafwi. Kuswaangana aakati kama ion ama electron kwapandululwa anzila ya projected amplified wave (PAW)65,67. I Perdue-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) function antoomwe a van der Waals correction yakaambwa a Grimm68,69 yakabelesegwa. Izyeelelo zyakujatana kwanguzu zyoonse antoomwe anguzu zili 10−6 eV/atomu antoomwe a 0.01 eV/Å. Ikugwisigwa kwanguzu kwakabikkwa a 600 eV kubelesya Monkhorst-Pack 2 × 2 × 1 K-point grid. Inguzu zyakubeja zyakabelesegwa muchikozyano eechi zyakabambwa kuzwa kukubamba kwamagesi kuya muchiimo cha C 2s22p2, chiimo cha N 2s22p3, chiimo cha Co 3d74s2, chiimo cha H 1 s1, antoomwe achiimo cha O 2s22p4. Nguzu zyakunjilila akusiyana kwabunji bwama electron zilabalilwa akugwisya nguzu zyamuwo wamuwo amusyobo wazyintu zili atala kuzwa kunguzu zyabweende bwazintu kweendelanya anzila zyakunjilila naakuti zyakujatana70,71,72,73,74. Kululamika kwanguzu zya Gibbs kwabelesyegwa kusandula nguzu zya DFT kuba nguzu zya Gibbs zyaangulukide mpawo kulabikkila maanu kukugwasya kwakuzungaana ku entropy anguzu zya zero point75. Nzila yakutanta kwachifanikisyo-kusungilizya bbanti (CI-NEB) yakabelesegwa kuyandaula chiimo chakusanduka kwachiimo76.
Data yoonse yakajanwa akuvwuntauzyigwa muchiiyo eechi ilibikkilizyidwe muchibalo amuzibelesyo zyakuyungizya naakuti ilajanwa kuzwa kuli sikulemba kuti walomba. Data yakusaanguna ilapegwa muchibalo eechi.
Ma kkoodi woonse akabelesegwa mukweezyanisya kweendelana achibalo eechi alajanwa kuzwa kuli balembi kuti walomba.
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