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Haidrodzin mɔ̃ɖaŋununyawo ƒe ŋgɔyiyie nye ganya si me womezãa nu gbegblẽwo le o ƒe taɖodzinu. Abe nɔnɔme si woatsɔ akpɔ haidrodzin dzadzraɖo adze sii ene la, wohiã na nusiwo naa haidrodzin (de)hydrogenation ƒe dɔwɔwɔ si wɔa dɔ eye woli ke. Vaseɖe fifia la, ga xɔasi xɔasiwo zazãe xɔ aƒe ɖe nuto sia me. Le afisia la, míedo susua ɖa be woawɔ nu yeye aɖe si mexɔ asi boo o si wotu ɖe cobalt dzi (Co-SAs/NPs@NC) si me wotsɔ ga ɖeka ƒe teƒe siwo woma ŋutɔ la kpe ɖe nanoparticles nyuiwo ŋu le nuwɔwɔ aduadu me be woakpɔ formic acid dehydrogenation si wɔa dɔ nyuie gbɔ. Esi wozã nu nyuitɔ kekeake si nye atɔm me kaka CoN2C2 units kple encapsulated nanoparticles ƒe lolome 7-8 nm, zã propylene carbonate abe solvent, wokpɔ gas ƒe wɔwɔme nyuitɔ kekeake si nye 1403.8 ml g-1 h-1, eye womebu le tsatsam 5 megbe o. dɔwɔna, si nyo wu asitsatsa ƒe Pd/C zi gbɔ zi 15. Dodokpɔ siwo wowɔ le teƒea ɖee fia be, ne wotsɔe sɔ kple ga atɔm ɖeka kple nanoparticle catalysts siwo do ƒome kplii la, Co-SAs/NPs@NC doa ŋusẽ monodentate domedome HCOO * vevitɔ ƒe adsorption kple dɔwɔwɔ, si wɔnɛ be wòdoa CH ƒe kadodo ƒe mama si kplɔe ɖo ɖe ŋgɔ. Nukpɔsusu ƒe akɔntabubuwo ɖee fia be cobalt nanoparticles ƒe ƒoƒo ɖekae doa Co atɔm ɖeka ƒe d-band titina ƒe tɔtrɔ ɖe ŋgɔ wòzua teƒe si le dɔ wɔm, si wɔnɛ be kadodo si le HCOO * domedometɔ ƒe carbonyl O kple Co titina dome la nyona ɖe edzi, si wɔnɛ be ŋusẽ ƒe mɔxenu la dzi ɖena kpɔtɔna.
Wobua haidrodzin be enye ŋusẽtsɔla vevi aɖe na xexeame katã ƒe ŋusẽ ƒe tɔtrɔ si li fifia eye ateŋu anye nu vevi aɖe si ana woakpɔ carbon ƒe akpaɖekedzimademade1. Le eƒe dzɔdzɔmenunɔamesiwo abe dzobibi kple eƒe ʋeʋẽ si mebɔ o ta la, haidrodzin dzadzraɖo kple etsɔtsɔ yi teƒe bubu dedie eye wòwɔa dɔ nyuie nye nya veviwo le haidrodzin ƒe gazazã ƒe nyateƒenyenye me2,3,4. Wodo liquid organic hydrogen carriers (LOHCs), siwo dzraa hydrogen ɖo heɖea asi le eŋu to atikewo ƒe dɔwɔwɔ me, ɖa be woatsɔ akpɔ egbɔe. Ne wotsɔe sɔ kple molecule hydrogen la, nu mawo tɔgbe (methanol, toluene, dibenzyltoluene, kple bubuawo) zazã le bɔbɔe eye wosɔna5,6,7. Le LOHC vovovo siwo wozãna tsã dome la, aɖi si le formic acid (FA) me le sue ŋutɔ (LD50: 1.8 g/kg) eye H2 ƒe ŋutete nye 53 g/L alo 4.4 wt%. Eɖe dzesi be FA koe nye LOHC si ateŋu adzra haidrodzin ɖo ahaɖe asi le eŋu le nɔnɔme fafɛwo me le nusiwo naa nu ʋãna siwo sɔ ƒe anyinɔnɔ me, eyata mehiã be woatsɔ gotagome ŋusẽ gãwo ade eme o1,8,9. Le nyateƒe me la, woto ga bubume geɖewo vɛ na formic acid ƒe hydrogenation ɖeɖeɖa, le kpɔɖeŋu me, palladium-based catalysts wɔa dɔ wu ga si mexɔ asi o zi gbɔ zi 50-20010,11,12. Gake ne èbu ga si wozãna ɖe ga siwo le dɔ wɔm ŋu ŋu, le kpɔɖeŋu me, palladium xɔ asi wu zi gbɔ zi 1000.
Cobalt, Didi be yeakpɔ heterogeneous base metal catalysts siwo wɔa dɔ ŋutɔ eye woli ke la yi edzi le numekula geɖewo ƒe ɖetsɔleme hem le agbalẽnyalawo kple dɔwɔƒewo me13,14,15.
Togbɔ be woto nusiwo wotsɔna ʋãa nu siwo mexɔ asi o siwo wotu ɖe Mo kple Co dzi, kpakple nanocatalyst siwo wowɔ tso noble/base metal alloys,14,16 vɛ na FA dehydrogenation hã la, woƒe dɔmawɔmawɔ vivivi le nuwɔna la me nye nusi womate ŋu aƒo asa na o le esi protonwo xɔ ga, CO2, kple H2O ƒe teƒe siwo le dɔ wɔm ta. alo formate anions (HCOO-), FA ƒe ɖiƒoƒo, nusuewo ƒe ƒuƒoƒo kple CO ƒe aɖi si ate ŋu adzɔ17,18. Mí kple ame bubuwo míeɖee fia nyitsɔ laa be atɔm ɖeka ƒe ʋuʋudedi (SACs) siwo si CoIINx teƒe siwo kaka ŋutɔ abe teƒe siwo le dɔ wɔm ene na formic acid dehydrogenation ƒe dɔwɔwɔ kple acid ƒe tsitretsitsi nyona ɖe edzi ne wotsɔe sɔ kple nanoparticles17,19,20,21,22,23,24. Le Co-NC nu siawo me la, N atɔmwo wɔa dɔ abe teƒe veviwo ene tsɔ doa FA deprotonation ɖe ŋgɔ esime wodoa xɔtuɖoɖo ƒe liƒo ɖe ŋgɔ to ɖoɖowɔwɔ kple titina Co atɔm me, esime Co atɔmwo naa H adsorption teƒewo eye wodoa CH22 ƒe scission ɖe ŋgɔ, 25,26. Nublanuitɔe la, nusiwo naa nu ʋãna siawo ƒe dɔwɔwɔ kple woƒe liƒo gakpɔtɔ didi tso egbegbe ga bubume nusiwo wɔa dɔ ɖekae kple esiwo meto vovo o gbɔ (Fig. 1) 13 .
Woate ŋu akpɔ ŋusẽ si sɔ gbɔ tso nusiwo woate ŋu awɔ yeyee abe ɣe alo ya ene me to tsi ƒe elektrikŋusẽ me. Woate ŋu azã LOHC, si nye tsi si ƒe haidrodzin kple haidrodzin ɖeɖeɖa te ŋu trɔna la atsɔ adzra haidrodzin si wowɔ la ɖo. Le haidrodzin ɖeɖeɖa ƒe afɔɖeɖea me la, nusi ko donae nye haidrodzin, eye wogbugbɔa tsi si tsɔa tsi la yia eƒe nɔnɔme gbãtɔ me eye wogawɔa haidrodzin ake. Woate ŋu azã haidrodzin mlɔeba le mɔ̃memidzraƒewo, batriwo, dɔwɔƒewo, kple bubuwo me.
Nyitsɔ laa la, woka nya ta be woate ŋu ado SAC tɔxɛwo ƒe dɔwɔwɔ ŋutɔŋutɔ ɖe ŋgɔ ne ga atɔm vovovowo alo ga teƒe bubu siwo nanoparticles (NPs) alo nanoclusters (NCs) na27,28. Esia ʋua mɔnukpɔkpɔwo ɖi na substrate la ƒe adsorption kple dɔwɔwɔ geɖe wu, kpakple be woatrɔ asi le geometry kple elektrɔnik wɔwɔme si le monatomic teƒewo ŋu. To mɔ sia dzi la, woate ŋu awɔ substrate adsorption/activation wòanyo wu, si ana catalytic efficiency bliboa nanyo wu29,30. Esia na míesusu be míawɔ nusiwo sɔ siwo naa nu ʋãna kple teƒe siwo wowɔa dɔ le siwo wotsɔ tsaka. Togbɔ be SAC siwo nyo wu ɖe ŋutete gã aɖe fia le nusiwo naa nu ʋãna ƒe dɔwɔwɔ vovovowo me31,32,33,34,35,36 hã la, le míaƒe sidzedze nu la, akpa si wowɔna le haidrodzin dzadzraɖo me me mekɔ o. Le go sia me la, míegblɔ aɖaŋu si woate ŋu azã le mɔ vovovowo nu eye wòsẽ ŋu na cobalt-si wotu ɖe hybrid catalysts (Co-SAs/NPs@NCs) siwo me nanoparticles siwo woɖe fia kple ga titina ɖekaɖekawo ƒe wɔwɔme. Co-SAs/NPs@NC siwo wowɔ nyuie wu la ɖea formic acid dehydrogenation dɔwɔwɔ nyuie ŋutɔ fiana, si nyo wu non-noble nanostructured catalysts (abe CoNx, single cobalt atoms, cobalt@NC kple γ-Mo2N) kple noble metal catalysts gɔ̃ hã. In-situ characterization kple DFT akɔntabubuwo le active catalysts ɖee fia be ɖekaɖeka ga teƒewo subɔna abe active teƒewo, eye nanoparticles si woto vɛ fifia doa d-band titina Co atɔmwo, doa adsorption kple dɔwɔwɔ HCOO * ɖe ŋgɔ, to esia me ɖea ŋusẽ mɔxenu si le nuwɔna la dzi kpɔtɔna. .
Zeolite imidazolate frameworks (ZIFs) nye akpa etɔ̃ ƒe ŋgɔdonya siwo woɖe nyuie siwo naa nusiwo naa nitrogen-doped carbon materials (metal-NC catalysts) be woado alɔ ga ƒomevi vovovowo37,38. Eyata Co(NO3)2 kple Zn(NO3)2 ƒoa ƒu kple 2-methylimidazole le methanol me tsɔ wɔa ga ƒe ƒuƒoƒo siwo sɔ ɖe enu le tsi me. Le centrifugation kple drying megbe la, wotsɔ pyrolyzed CoZn-ZIF le dzoxɔxɔ vovovowo me (750–950 °C) le yame si me 6% H2 kple 94% Ar le me. Abe alesi woɖee fia le nɔnɔmetata si le ete me ene la, nusiwo do tso eme la ƒe teƒe si le dɔ wɔm ƒe nɔnɔmewo to vovo eye wotsɔ ŋkɔ na wo be Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 (Nɔnɔmetata 2a). ) . Wogblɔ dodokpɔ me ŋkuléle ɖe afɔɖeɖe vevi aɖewo ŋu le nuƒoƒoƒu ƒe ɖoɖoa me tsitotsito le Nɔnɔmetata 1 kple 2. C1-C3. Wowɔ dzoxɔxɔ si trɔna ƒe X-ray diffraction (VTXRD) tsɔ lé ŋku ɖe nusi naa nu ʋãna ƒe nɔnɔmetɔtrɔ ŋu. Ne dzoxɔxɔ si me dzoxɔxɔ le ɖo 650 °C ko la, XRD ƒe nɔnɔme trɔna ŋutɔ le ZIF ƒe kristalo ƒe wɔwɔme si woɖo ɖe ɖoɖo nu ƒe mumu ta (Fig. S4) 39 . Esi dzoxɔxɔa le dzidzim ɖe edzi la, ta gbadza eve dzena le Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 ƒe XRD ƒe nɔnɔmewo me le 20–30° kple 40–50°, si tsi tre ɖi na amorphous carbon ƒe taƒoƒo (Fig. C5). 40. Edze be míade dzesii be dzesi ƒe ta etɔ̃ koe wokpɔ le 44.2°, 51.5° kple 75.8°, si nye ga cobalt tɔ (JCPDS #15-0806), kple 26.2°, si nye graphitic carbon tɔ (JCPDS # 41-1487). X-ray spectrum si le Co-SAs/NPs@NC-950 ɖee fia be graphite-like encapsulated cobalt nanoparticles le catalyst la dzi41,42,43,44. Raman spectrum ɖee fia be edze abe Co-SAs/NPs@NC-950 ƒe D kple G ƒe taƒoƒo sesẽ eye wòle kpuie wu kpɔɖeŋu bubuawo ene, si fia be graphitization ƒe seƒe kɔkɔ wu ( Nɔnɔmetata S6 ). Gakpe ɖe eŋu la, Co-SAs/NPs@NC-950 ɖea Brunner-Emmett-Taylor (BET) ƒe anyigba ƒe lolome kple ʋuʋudedi ƒe lolome (1261 m2 g-1 kple 0.37 cm3 g-1) fiana wu kpɔɖeŋu bubuwo eye ZIF akpa gãtɔ nye NC ƒe dzɔdzɔmenuwo. nuwo (Nɔnɔmetata S7 kple Tabla S1). Atomic absorption spectroscopy (AAS) ɖee fia be cobalt si le Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 kple Co-SAs/NPs@ me nye 2.69 wt.%, 2.74 wt.% kple 2.73 wt.%. NC-750 le wo nɔewo yome (Tabla S2). Zn ƒe agbɔsɔsɔ si le Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 me dzina ɖe edzi vivivi, si wogblɔ be etso Zn ƒe akpawo dzi ɖeɖe kpɔtɔ kple woƒe ʋuʋu ƒe dzidziɖedzi gbɔ. Dzoxɔxɔ ƒe dzidziɖedzi (Zn, dzoxɔxɔ = 907 °C) 45.46. Elemental analysis (EA) ɖee fia be N ƒe alafa memamã dzi ɖena kpɔtɔna ne pyrolysis ƒe dzoxɔxɔ le dzidzim ɖe edzi, eye O ƒe agbɔsɔsɔ si sɔ gbɔ ate ŋu atso molecule O2 ƒe xɔxlɔ̃ tso ya me gbɔ. (Tabla S3) (Tabla S3). Le cobalt ƒe agbɔsɔsɔ aɖe me la, nanoparticles kple coatoms siwo woɖe ɖe aga nɔa anyi ɖekae, si wɔnɛ be nusiwo naa nu ʋãna ƒe dɔwɔwɔ dzina ɖe edzi ŋutɔ, abe alesi míeƒo nu tso eŋu le ete ene.
Co-SA/NPs@NC-T ƒe wɔwɔme ƒe nɔnɔmetata si wowɔ, afisi T nye dzoxɔxɔ si wotsɔna ƒoa dzoe (°C). b TEM ƒe nɔnɔmetata. c Co-SAs/NPs@NC-950 ƒe nɔnɔmetata AC-HAADF-STEM. Wotsɔa gotagome dzĩwo dea dzesi Co atɔm ɖeka. d EDS ƒe ɣeyiɣi ƒe didime si nye Co-SA/NPs@NC-950.
Eɖe dzesi be, elektrɔnik nusuekpɔmɔ̃ (TEM) ɖee fia be cobalt nanoparticles (NPs) vovovo siwo ƒe lolome le mama dedie nu nye 7.5 ± 1.7 nm le Co-SAs/NPs@NC-950 me ko ( Nɔnɔmetata 2 b kple S8). Wotsɔa carbon si le abe graphite ene si wotsɔ nitrogen de eme la dea nanoparticle siawo me. Lattice fringe dometsotso si nye 0.361 kple 0.201 nm sɔ kple graphitic carbon (002) kple metallic Co (111) ƒe akpa suewo. Tsɔ kpe ɖe eŋu la, dzogoe gã ƒe aberration-corrected annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) ɖee fia be Co NP siwo le Co-SAs/NPs@NC-950 me la ƒo xlã atɔmik cobalt gbogbo aɖe (Fig. 2c). Gake cobalt atɔm siwo kaka ɖe atɔm me koe wokpɔ le kpɔɖeŋu eve bubuawo ƒe kpeɖeŋutɔ dzi (Fig. S9). Ŋusẽ kaka ƒe spektroskopi (EDS) HAADF-STEM nɔnɔmetata ɖe C, N, Co kple Co NP siwo woɖe ɖe vovo ƒe mama ɖekae fia le Co-SAs/NPs@NC-950 (Fig. 2d). Nusiwo katã do tso eme siawo ɖee fia be Co titina siwo kaka ɖe atɔm me kple nanoparticles siwo wotsɔ N-doped graphite-like carbon me la léna ɖe NC substrates ŋu dzidzedzetɔe le Co-SAs/NPs@NC-950 me, evɔ ga titina siwo woɖe ɖe aga koe.
Wotsɔ X-ray photoelectron spectroscopy (XPS) srɔ̃ nu tso nusiwo wokpɔ ƒe valence nɔnɔme kple atikewo ƒe wɔwɔme ŋu. XPS spectra siwo le nusiwo naa nu ʋãna etɔ̃awo me ɖe nusiwo nye Co, N, C kple O ƒe anyinɔnɔ fia, gake Zn nɔ Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 me ko (Fig. 2). ). C10). Ne dzoxɔxɔ si wotsɔna ƒoa dzoe le dzidzim ɖe edzi la, nitrogen ƒe agbɔsɔsɔ bliboa dzi ɖena kpɔtɔna ne nitrogen ƒomeviwo meganɔa te o eye wogblẽna zua NH3 kple NOx ya le dzoxɔxɔ si lolo wu me (Tabla S4) 47 . Eyata carbon ƒe agbɔsɔsɔ bliboa dzi ɖe edzi vivivi tso Co-SAs/NPs@NC-750 va ɖo Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-950 (Nɔnɔmetata S11 kple S12). Kpɔɖeŋu si wotsɔ dzo wɔe le dzoxɔxɔ si kɔkɔ wu me la ƒe nitrogen atɔm ƒe agbɔsɔsɔme le ʋɛ wu, si fia be ele be NC tsɔlawo ƒe agbɔsɔsɔ le Co-SAs/NPs@NC-950 me naɖiɖi wu esi le kpɔɖeŋu bubuwo me. Esia wɔnɛ be cobalt-nu suesuesuewo ƒe dzoxɔxɔ sesẽna ɖe edzi. O 1s ƒe ɣeyiɣi ƒe didime fia ta eve C=O (531.6 eV) kple C–O (533.5 eV), le wo nɔewo yome (Nɔnɔmetata S13) 48 . Abe alesi woɖee fia le nɔnɔmetata 2a me ene la, woate ŋu akpɔ N 1s ƒe ɣeyiɣi ƒe didime gbɔ wòazu pyridine nitrogen N (398.4 eV), pyrrole N (401.1 eV), graphite N (402.3 eV) kple Co-N (399.2 eV) ƒe taƒoƒo ene siwo ɖe dzesi. Co-N kadodowo le kpɔɖeŋu etɔ̃awo katã me, si fia be N atɔm aɖewo wɔ ɖeka kple ga ɖeka ƒe teƒewo, gake nɔnɔmeawo to vovo ŋutɔ49. Dzoxɔxɔ si lolo wu zazã ateŋu aɖe Co-N ƒomeviwo ƒe agbɔsɔsɔ dzi akpɔtɔ ŋutɔ tso 43.7% le Co-SA/NPs@NC-750 va ɖo 27.0% le Co-SAs/NPs@NC-850 kple Co 17.6%@ NC-950 me. le -CA/NPs me, si sɔ kple C ƒe dzidziɖedzi (Fig. 3a), si fia be woƒe Co-N ƒe ɖoɖowɔwɔ ƒe xexlẽme ate ŋu atrɔ eye C50 atɔmwo axɔ ɖe eteƒe ƒe akpa aɖe. Zn 2p ƒe ɣeyiɣi ƒe didime ɖee fia be nu sia li koŋ le nɔnɔme si nye Zn2+ me. (Nɔnɔmetata S14) 51. Co 2p ƒe ɣeyiɣi ƒe didime ɖea ta eve siwo ɖe dzesi le 780.8 kple 796.1 eV, siwo wogblɔ be Co 2p3/2 kple Co 2p1/2 gbɔe wòtso (Nɔnɔmetata 3b). Ne wotsɔe sɔ kple Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 la, Co-N ƒe taƒoƒo si le Co-SAs/NPs@NC-950 me la trɔna yia akpa nyuitɔ dzi, si fia be Co atɔm ɖeka si le anyigba dzi -SAs/NPs@NC-950 la ƒe elektrɔnikwo ƒe vɔvɔ le dzidzim ɖe edzi, si wɔnɛ be oxidation ƒe nɔnɔme si lolo wu. Edze be míade dzesii be Co-SAs/NPs@NC-950 koe ɖe zero-valent cobalt (Co0) ƒe taƒoƒo si gbɔdzɔ fia le 778.5 eV, si ɖo kpe nanoparticles siwo dona tso SA cobalt ƒe ƒuƒoƒo me le dzoxɔxɔ gã me ƒe anyinɔnɔ dzi.
a N 1s kple b Co 2p spektrum siwo le Co-SA/NPs@NC-T. c XANES kple d FT-EXAFS spektrum siwo nye Co-K-nugbɔ ƒe Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750. e WT-EXAFS ƒe nɔnɔmetata siwo nye Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850, kple Co-SAs/NPs@NC-750 ƒe nɔnɔmetatawo. f FT-EXAFS ƒe ƒomedodo ƒe ʋuʋudedi na Co-SA/NPs@NC-950.
Emegbe wozã X-ray absorption spectroscopy (XAS) si wotu ɖe ɣeyiɣi dzi tsɔ ku Co ƒomevi siwo le kpɔɖeŋu si wodzra ɖo me ƒe elektrɔnik wɔwɔme kple woƒe ɖoɖowɔwɔ ƒe nɔnɔme me. Cobalt valence nɔnɔmewo le Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 Edge ƒe wɔwɔme si woɖe fia to normalized near-field X-ray absorption le Co-K edge (XANES) spectrum me. Abe alesi woɖee fia le nɔnɔmetata 3c me ene la, xɔxlɔ̃ si te ɖe kpɔɖeŋu etɔ̃awo ƒe go ŋu la le Co kple CoO ƒe agbalẽviwo dome, si fia be Co ƒomeviwo ƒe valence nɔnɔme tso 0 va ɖo +253. Gakpe ɖe eŋu la, wokpɔ tɔtrɔ yi ŋusẽ si bɔbɔ wu gbɔ tso Co-SAs/NPs@NC-950 yi Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750, si ɖee fia be Co-SAs/ NPs@NC-750 ƒe oxidation nɔnɔme le bɔbɔe wu. Trɔ ɖoɖo si nu wole. Le linear combination fitting ƒe emetsonuwo nu la, wobu Co-SAs/NPs@NC-950 ƒe Co valence nɔnɔme be enye +0.642, si bɔbɔ wu Co-SAs/NPs@NC-850 ƒe Co valence nɔnɔme (+1.376). Co-SA/NP @NC-750 (+1.402) ƒe ƒuƒoƒo. Nusiwo do tso eme siawo ɖee fia be cobalt ƒe akpa siwo le Co-SAs/NPs@NC-950 me ƒe oxidation nɔnɔme le mama dedie nu dzi ɖe kpɔtɔ ŋutɔ, si sɔ kple XRD kple HADF-STEM ƒe emetsonuwo eye woate ŋu aɖe eme to cobalt nanoparticles kple cobalt ɖeka ƒe anyinɔnɔ ɖekae me. . Co atoms 41. Fourier transform X-ray absorption fine structure (FT-EXAFS) spectrum of the Co K-edge ɖee fia be ta vevitɔ si le 1.32 Å nye Co-N/Co-C shell tɔ, esime ga Co -Co ƒe kakamɔ le 2.18 le Co-SAs Å si wokpɔ le /NPs@NC-950 me ko (Fig. 3d). Gawu la, wavelet transform (WT) contour plot ɖe ŋusẽ si sɔ gbɔ wu fia le 6.7 Å-1 si wogblɔ be Co-N/Co-C gbɔe wòtso, esime Co-SAs/NPs@NC-950 koe ɖe ŋusẽ si sɔ gbɔ wu si wogblɔ be enye 8.8 fia. Sesẽƒe bubu si sɔ gbɔ wu le Å−1 na Co–Co ƒe kadodoa (Fig. 3e). Gakpe ɖe eŋu la, EXAFS numekuku si aƒehayala wɔ ɖee fia be le dzoxɔxɔ si nye pyrolysis si nye 750, 850 kple 950 °C me la, Co-N ƒe ɖoɖowɔwɔ ƒe xexlẽdzesiwo nye 3.8, 3.2 kple 2.3, eye Co-C ƒe ɖoɖowɔwɔ ƒe xexlẽdzesiwo nye 0. 0.9 kple 1.8 (Fig. 3f, S15 kple Table S1). Ne míagblɔe tututu la, woate ŋu agblɔ be nusiwo do tso eme yeyetɔ kekeake tso CoN2C2 ƒe akpa siwo kaka ɖe atɔm me kple nanoparticles ƒe anyinɔnɔ le Co-SAs/NPs@NC-950 me gbɔ. To vovo na esia la, le Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 me la, CoN3C kple CoN4 ƒe akpawo koe le eme. Edze ƒã be ne dzoxɔxɔ si wotsɔna ƒoa dzoe le dzidzim ɖe edzi la, vivivi la, wotsɔa C atɔmwo ɖɔlia N atɔm siwo le CoN4 ƒe akpaa me, eye cobalt CA ƒoa ƒu wɔa nanoparticles.
Wozã nuwɔna ƒe nɔnɔme siwo ŋu wosrɔ̃ nu tsoe va yi tsɔ srɔ̃ nu tso ŋusẽ si dzadzraɖo ƒe nɔnɔmewo kpɔna ɖe nu vovovowo ƒe nɔnɔmewo dzi (Fig. S16)17,49. Abe alesi woɖee fia le nɔnɔmetata 4 a me ene la, Co-SAs/NPs@NC-950 ƒe dɔwɔwɔ sɔ gbɔ ŋutɔ wu Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 tɔ. Eɖe dzesi be Co ƒe kpɔɖeŋu etɔ̃ siwo katã wodzra ɖo la ɖe dɔwɔwɔ nyuie wu fia ne wotsɔe sɔ kple ga xɔasi siwo wotsɔna dzraa nu siwo wozãna ɖaa (Pd/C kple Pt/C). Tsɔ kpe ɖe eŋu la, Zn-ZIF-8 kple Zn-NC ƒe kpɔɖeŋuawo mewɔ dɔ ɖe formic acid dehydrogenation ŋu o, si fia be Zn ƒe akpawo menye teƒe siwo wɔa dɔ o, gake woƒe ŋusẽkpɔɖeamedzi ɖe dɔwɔwɔ dzi mede naneke kura o. Tsɔ kpe ɖe eŋu la, Co-SAs/NPs@NC-850 kple Co-SAs/NPs@NC-750 ƒe dɔwɔwɔ to dzobibi evelia me le 950°C hena gaƒoƒo 1, gake eɖiɖi wu Co-SAs/NPs@NC-750 tɔ. @NC-950 (Nɔnɔmetata S17). Nu siawo ƒe wɔwɔme ƒe dzesiwo ɖe Co nanoparticles ƒe anyinɔnɔ fia le kpɔɖeŋu siwo wogbugbɔ pyrolyzed me, gake anyigba ƒe lolome tɔxɛ si le sue kple carbon si le abe graphite ene ƒe anyimanɔmanɔ na be dɔwɔwɔ bɔbɔ wu ne wotsɔe sɔ kple Co-SAs/NPs@NC-950 (Nɔnɔmetata S18–S20). Wotsɔ kpɔɖeŋu siwo me Co ŋgɔdola ƒe agbɔsɔsɔ vovovowo le ƒe dɔwɔwɔ hã sɔ kple wo nɔewo, eye woɖe dɔwɔwɔ si lolo wu fia le 3.5 mol ƒe tsɔtsɔ kpee me (Tabla S6 kple Nɔnɔmetata S21). Edze ƒã be haidrodzin si le dzoxɔxɔ ƒe yamenutome kple dzoxɔxɔ ƒe ɣeyiɣi kpɔa ŋusẽ ɖe ga ƒe titina vovovowo ƒe wɔwɔ dzi. Eyata woda Co-SAs/NPs@NC-950 nu bubuwo kpɔ hena formic acid dehydrogenation dɔwɔwɔ. Nusiwo katã wozã ɖee fia be wowɔa dɔ le mɔ si sɔ nu va ɖo nyuie ŋutɔ; ke hã, wo dometɔ aɖeke menyo wu Co-SAs/NPs@NC-950 o (Nɔnɔmetata S22 kple S23). Nusiwo wotsɔ wɔe ƒe wɔwɔme ƒe nɔnɔme ɖee fia be ne dzoxɔxɔ ƒe ɣeyiɣi le dzidzim ɖe edzi la, monoatomic Co-N ƒe nɔƒewo ƒe agbɔsɔsɔ dzi ɖena kpɔtɔna vivivi le ga atɔmwo ƒe ƒuƒoƒo ɖe nanoparticles me ta, si ɖe vovototo si le dɔwɔwɔ me le kpɔɖeŋu siwo ƒe dzoxɔxɔ ƒe ɣeyiɣi nye 100-2000 dome la me. vovototo. 0.5 h, 1 h, kple 2 h (Nɔnɔmetata S24–S28 kple Tabla S7).
Gas ƒe agbɔsɔsɔme ƒe nɔnɔmetata tsɔtsɔ sɔ kple ɣeyiɣi si wokpɔ le mɔ̃memi ƒe ƒuƒoƒo siwo me wodea tsii ƒe ɖeɖeɖa me to mɔ̃memi ƒe ƒuƒoƒo vovovowo zazã me. Nuwɔna ƒe nɔnɔmewo: PC (10 mmol, 377 μl), nusi naa nu ʋãna (30 mg), PC (6 ml), Tback: 110 °C, Aɖaŋuɖoɖo: 98 °C, akpa 4 b Co-SAs/NPs@NC-950 ( 30 mg), atike vovovowo. c Gas ƒe tɔtrɔ ƒe agbɔsɔsɔme si le heterogeneous catalysts me le organic solvents me le 85–110 °C me tsɔtsɔ sɔ kple wo nɔewo. d Co-SA/NPs@NC-950 ƒe nusiwo wogbugbɔ zãna ƒe dodokpɔ. Nuwɔna ƒe nɔnɔmewo: FA (10 mmol, 377 μl), Co-SAs/NPs@NC-950 (30 mg), atike (6 ml), Tset: 110 °C, Tactual: 98 °C, nuwɔna ƒe tsatsam ɖesiaɖe xɔa gaƒoƒo ɖeka . Vodada ƒe dzesiwo tsi tre ɖi na vovototo siwo woɖo ɖi siwo wobu tso dodokpɔ etɔ̃ siwo le dɔ wɔm me.
Le goawo katã me la, FA dehydrogenation catalysts ƒe dɔwɔwɔ nyuie nɔ te ɖe nuwɔna ƒe nɔnɔmewo dzi ŋutɔ, vevietɔ solvent si wozã8,49. Ne wozã tsi abe atike ene la, Co-SAs/NPs@NC-950 ɖee fia be gbãtɔ ƒe nuwɔna ƒe agbɔsɔsɔme si lolo wu, gake dɔmawɔmawɔ dzɔ, ɖewohĩ le proton alo H2O18 ƒe teƒe siwo le dɔ wɔm ta. Dodokpɔ le nusi naa nu ʋãna ŋu le lãmenugbagbeviwo abe 1,4-dioxane (DXA), n-butyl acetate (BAC), toluene (PhMe), triglyme kple cyclohexanone (CYC) hã meɖe ŋgɔyiyi aɖeke fia o, eye le propylene carbonate (PC) ) me (Fig. 4b kple Table S8). Nenema ke nusiwo wotsɔ kpe ɖe eŋu abe triethylamine (NEt3) alo sodium formate (HCCONa) megakpɔ ŋusẽ nyui aɖeke ɖe nusiwo naa nu ʋãna ƒe dɔwɔwɔ dzi o (Nɔnɔmetata S29). Le nuwɔna ƒe nɔnɔme nyuitɔ me la, gas ƒe ŋeŋe ɖo 1403.8 mL g−1 h−1 (Fig. S30), si lolo ŋutɔ wu Co ƒe nusiwo katã ŋu woka nya ta le va yi (siwo dome SAC17, 23, 24 hã le). Le dodokpɔ vovovowo me la, ne wometsɔ nuwɔna siwo wowɔ le tsi me kple esiwo wotsɔ formate kpe ɖe eŋu kpe ɖe eŋu o la, wokpɔ dehydrogenation kple dehydration selectivities si ade 99.96% (Table S9). Dɔwɔwɔ ƒe ŋusẽ si wobu akɔntae nye 88.4 kJ/mol, si sɔ kple ga bubumewo ƒe dɔwɔwɔ ƒe ŋusẽ (Nɔnɔmetata S31 kple Tabla S10).
Tsɔ kpe ɖe eŋu la, míetsɔ heterogeneous catalysts bubu geɖewo sɔ kple formic acid dehydrogenation le nɔnɔme mawo tɔgbe me (Fig. 4c, tables S11 kple S12). Abe alesi woɖee fia le nɔnɔmetata 3c me ene la, Co-SAs/NPs@NC-950 ƒe gas ƒe wɔwɔme sɔ gbɔ wu esi wonya wu heterogeneous base metal catalysts eye wòsɔ gbɔ wu esi wodzrana 5% Pd/C kple 5% Pd/C, zi gbɔ zi 10 zi gbɔ zi 10. % Pt/C nusi naa nu ʋãna.
Nu vevi aɖe si le (de)hydrogenation catalysts zazã ŋutɔŋutɔ ɖesiaɖe me enye woƒe liƒo. Eyata wowɔ nusiwo wogbugbɔ zãna ƒe dodokpɔ vovovowo to Co-SAs/NPs@NC-950 zazã me. Abe alesi woɖee fia le nɔnɔmetata 4 d me ene la, nusi wowɔ le gɔmedzedzea me kple eƒe tiatiawɔwɔ metrɔ le duƒuƒu atɔ̃ siwo kplɔ wo nɔewo ɖo me o (kpɔ Tabla S13 hã). Wowɔ dodokpɔ siwo xɔ ɣeyiɣi didi eye gas wɔwɔ dzi ɖe edzi le fli me le gaƒoƒo 72 me (Nɔnɔmetata S32). Cobalt ƒe agbɔsɔsɔ si le Co-SA/NPs@NC-950 si wozã me nye 2.5 wt%, si te ɖe nusi doa ŋusẽ nu yeyea tɔ ŋu ŋutɔ, si fia be cobalt ƒe ʋuʋu si dze ƒã aɖeke menɔ anyi o (Tabla S14). Womekpɔ amadede ƒe tɔtrɔ alo ga ƒe akpa aɖewo ƒe ƒuƒoƒo si dze ƒã do ŋgɔ na nuwɔna la kple emegbe o ( Nɔnɔmetata S33 ). AC-HAADF-STEM kple EDS ƒe nusiwo wozã le dodokpɔ siwo xɔ ɣeyiɣi didi me ɖee fia be atɔm ƒe kaka teƒewo lé wo ɖe te eye wokaka ɖekae eye tɔtrɔ ɖedzesi aɖeke meva le xɔtuɖoɖo me o (Nɔnɔmetata S34 kple S35). Co0 kple Co-N ƒe taƒoƒo siwo ɖe dzesi la gakpɔtɔ li le XPS me, si ɖo kpe Co NPs kple ga teƒe ɖekaɖekawo ƒe anyinɔnɔ ɖekae dzi, si hã ɖo kpe Co-SAs/NPs@NC-950 catalyst ƒe liƒo dzi (Nɔnɔmetata S36).
Be woade dzesi teƒe siwo wɔa dɔ wu siwo kpɔa formic acid dehydrogenation dzi la, wotu nu tiatia siwo me ga ƒe titina ɖeka ko (CoN2C2) alo Co NP le la ɖo ɖe numekuku siwo wowɔ va yi dzi17. Ðoɖo si nu formic acid dehydrogenation ƒe dɔwɔwɔ le si wokpɔ le nɔnɔme mawo ke me enye Co-SAs/NPs@NC-950 > Co SA > Co NP (Tabla S15), si fia be CoN2C2 teƒe siwo kaka ɖe atɔm me la wɔa dɔ wu NPs . Nuwɔna ƒe ʋuʋu ɖee fia be haidrodzin ƒe nɔnɔmetɔtrɔ kplɔa nuwɔna ƒe ʋuʋu le ɖoɖo gbãtɔ nu, gake ʋuʋudedi geɖe ƒe dzidzeme le cobalt ƒe agbɔsɔsɔ vovovowo me mesɔ o, si ɖee fia be menye formic acid ɖeɖeko dzie ʋuʋua nɔ te ɖo o, ke boŋ teƒe si wòle dɔ wɔm le hã (Fig. 2). C37). Ʋuʋu ŋuti numekuku bubuwo ɖee fia be, ne míebu cobalt ga ƒe taƒoƒo ƒe anyimanɔmanɔ le X-ray diffraction numekuku me ta la, wokpɔe be ʋuʋu ƒe ɖoɖo si nu nuwɔna la le le cobalt ƒe agbɔsɔsɔ gome nye 1.02 le agbɔsɔsɔ si bɔbɔ wu me (si mede 2.5%) o, si fia be monoatomic cobalt titinawo ƒe mama ɖekae kloe. ŋutᴐ. teƒe si le dɔ wɔm (nɔnɔmetata S38 kple S39). Ne Co ƒe akpa siwo le eme ɖo 2.7% la, kasia r dzina ɖe edzi, si fia be nanoparticles la wɔa dɔ nyuie kple atɔm ɖekaɖekawo be woakpɔ dɔwɔwɔ si lolo wu. Ne Co ƒe akpa siwo le eme le dzidzim ɖe edzi la, fli la va zua nonlinear, si do ƒome kple nanoparticles ƒe xexlẽme ƒe dzidziɖedzi kple monotomic ƒe nɔƒewo dzi ɖeɖe kpɔtɔ. Eyata Co-SA/NPs@NC-950 ƒe LC dehydrogenation dɔwɔwɔ si nyo wu la tso ga teƒe ɖekaɖekawo kple nanoparticles ƒe nuwɔwɔ aduadu ƒe nuwɔna gbɔ.
Wowɔ numekuku deto aɖe to in situ diffuse reflectance Fourier transform (in situ DRIFT) zazã me tsɔ de dzesi nuwɔna ƒe domedomenuwo le ɖoɖoa me. Esi wodo dzo na kpɔɖeŋuawo ɖe dzoxɔxɔ vovovowo me le formic acid dede eme vɔ megbe la, wokpɔ zi gbɔ zi eve ƒe hatsotsowo (Fig. 5a). HCOOH* ƒe taƒoƒo etɔ̃ siwo ɖe dzesi la dzena le 1089, 1217 kple 1790 cm-1, siwo wogblɔ be etso CH π (CH) ƒe ʋuʋu le yameʋua godo, CO ν (CO) keke ƒe ʋuʋu kple C=O ν (C=O) keke ƒe ʋuʋu gbɔ, 54, 55 . Taƒoƒo bubu si le 1363 kple 1592 cm-1 sɔ kple OCO ƒe ʋuʋu si sɔ kple wo nɔewo νs(OCO) kple OCO ƒe ʋuʋu si mesɔ o νas(OCO)33.56 HCOO*, le wo nɔewo yome. Ne nuwɔna la le edzi yim la, HCOOH* kple HCOO* ƒomeviwo ƒe taƒoƒo siwo sɔ gbɔ wu la nu yina vivivi. Le nyateƒe me la, formic acid ƒe gbegblẽ lɔ afɔɖeɖe vevi etɔ̃ ɖe eme: (I) formic acid ƒe xɔxlɔ̃ le teƒe siwo le dɔ wɔm, (II) H ɖeɖe ɖa to formate alo carboxylate mɔ dzi, kple (III) H eve siwo woxɔ la ƒoƒo ƒu be woawɔ hydrogen. HCOO* kple COOH* nye dometsonu veviwo le formate alo carboxylate mɔwo nyanya me, le wo nɔewo yome57. Le míaƒe catalytic system zazã me la, HCOO* ƒe taƒoƒo si ɖe dzesi la koe dze, si fia be formic acid ƒe gbegblẽ dzɔna to formic acid ƒe mɔ dzi ko58. Wokpɔ nu mawo tɔgbe le dzoxɔxɔ si bɔbɔ wu 78 °C kple 88 °C (nɔnɔmetata S40).
In situ DRIFT spektrum of HCOOH dehydrogenation le Co-SAs/NPs@NC-950 kple b Co SAs dzi. Xotutua fia ɣeyiɣi siwo me wowɔa nu le teƒea. c Gas ƒe agbɔsɔsɔme ƒe tɔtrɔ si wowɔ to isotope labeling reagents vovovowo zazã me le ɣeyiɣi aɖe megbe. d Kinetic isotope ƒe ŋusẽkpɔɖeamedzi ŋuti nyatakakawo.
Wowɔ DRIFT dodokpɔ mawo tɔgbe le teƒea le nusiwo do ƒome kplii Co NP kple Co SA dzi be woasrɔ̃ nu tso dɔwɔwɔ aduadu ƒe ŋusẽkpɔɖeamedzi ŋu le Co-SA/NPs@NC-950 ( Nɔnɔmetata 5 b kple S41). Nu eveawo siaa ɖea nɔnɔme ɖeka tɔgbe fiana, gake HCOOH * kple HCOO * ƒe taƒoƒo siwo ɖe dzesi la trɔ vie, si fia be Co NPs ƒe dodo trɔa elektrɔnik wɔwɔme si le monoatomic titina. νas(OCO) ƒe taƒoƒo si ɖe dzesi la dzena le Co-SAs/NPs@NC-950 kple Co SA me gake menye le Co NPs me o, si gaɖee fia be domedome si dzɔna ne wotsɔ formic acid kpe ɖe eŋu la nye monodentate formic acid si le tsitre ɖe yameʋu dze ƒe anyigba dzi. eye woxɔna ɖe SA dzi abe teƒe si le dɔ wɔm ene 59 . Enyo be míade dzesii be wokpɔ dzidziɖedzi gã aɖe le ʋuʋudedi siwo le dzesi ƒe ta siwo nye π(CH) kple ν(C = O) me, si edze abe ena HCOOH * tɔtɔ eye wòna nuwɔna la nɔ bɔbɔe ene. Esia wɔe be HCOOH * kple HCOO * ƒe taƒoƒo siwo ɖe dzesi le Co-SAs/NPs@NC me bu kloe le miniti 2 ƒe dɔwɔwɔ megbe, si le kabakaba wu esi le monometallic (min 6) kple nanoparticle-based catalysts (min 12) me. . Nusiwo katã do tso eme siawo ɖo kpe edzi be nanoparticle doping doa domedomenuwo ƒe adsorption kple dɔwɔwɔ ɖe ŋgɔ, si wɔnɛ be nuwɔna siwo wodo ɖa le etame la wɔa dɔ kabakaba.
Be woagaku nu me le nuwɔna ƒe mɔnu ŋu eye woanya afɔɖeɖe si dea dzesi afɔɖeɖe (RDS) la, wowɔ KIE ƒe ŋusẽkpɔɖeamedzi le Co-SAs/NPs@NC-950 ƒe anyinɔnɔ me. Le afisia la, wozãa formic acid isotope vovovowo abe HCOOH, HCOOD, DCOOH kple DCOOD hena KIE numekukuwo. Abe alesi woɖee fia le nɔnɔmetata 5c me ene la, dehydrogenation ƒe agbɔsɔsɔme dzi ɖena kpɔtɔna le ɖoɖo si gbɔna nu: HCOOH > HCOOD > DCOOH > DCOOD. Gakpe ɖe eŋu la, wobu KHCOOH/KHCOOD, KHCOOH/KDCOOH, KHCOOD/KDCOOD kple KDCOOH/KDCOOD ƒe asixɔxɔwo be enye 1.14, 1.71, 2.16 kple 1.44 (Fig. 5d). Eyata CH ƒe kadodo ƒe mama le HCOO * me ɖea kH/kD ƒe asixɔxɔ >1.5 fiana, si fia be ʋuʋudedi ƒe ŋusẽkpɔɖeamedzi gã aɖe le eŋu60,61, eye edze abe etsi tre ɖi na RDS si nye HCOOH dehydrogenation le Co-SAs/NPs@NC-950 dzi ene.
Tsɔ kpe ɖe eŋu la, wowɔ DFT akɔntabubuwo be woase ŋusẽ si doped nanoparticles kpɔna ɖe Co-SA ƒe dɔwɔwɔ ŋutɔŋutɔ dzi gɔme. Wotu Co-SAs/NPs@NC kple Co-SA ƒe kpɔɖeŋuwo ɖe dodokpɔ siwo woɖe fia kple dɔ siwo wowɔ va yi dzi (Fig. 6a kple S42)52,62. Le geometric optimization megbe la, wode dzesi Co6 nanoparticles suewo (CoN2C2) siwo nɔa anyi ɖekae kple monoatomic units, eye wokpɔe be Co-C kple Co-N ƒe kadodo ƒe didime le Co-SA/NPs@NC me nye 1.87 Å kple 1.90 Å, le wo nɔewo yome. , si sɔ kple XAFS ƒe emetsonuwo. Akɔntabubu ƒe akpa aɖe ƒe kpekpeme (PDOS) ɖee fia be Co ga atɔm ɖeka kple nanoparticle composite (Co-SAs/NPs@NC) ɖea hybridization si lolo wu fiana le Fermi ƒe seƒe gbɔ ne wotsɔe sɔ kple CoN2C2, si wɔnɛ be HCOOH dona. Elektrɔn ƒe asitɔtrɔ si gblẽ la wɔa dɔ nyuie wu ( Nɔnɔmetata 6b kple S43). Wobu akɔnta be Co-SAs/NPs@NC kple Co-SA ƒe d-band titina siwo sɔ la nye -0.67 eV kple -0.80 eV, le wo dome, siwo dometɔ aɖewoe nye Co-SAs/NPs@NC ƒe dzidziɖedzi nye 0.13 eV, si na be le NP ƒe dodo megbe la, HCOO* ƒe akpa suewo ƒe adsorption to CoN2C2 ƒe elektrɔnik wɔwɔme si wotrɔ asi le dzi dzɔna. Vovototo si le charge density me ɖe elektrɔnik alilikpo gã aɖe si ƒo xlã CoN2C2 block kple nanoparticle fia, si fia be kadodo sesẽ aɖe le wo dome le elektrɔnik ƒe asitɔtrɔ ta. Ne wotsɔ Bader ƒe charge numekuku kpe ɖe eŋu la, wokpɔe be Co si kaka ɖe atɔm me bu 1.064e le Co-SA/NPs@NC me eye 0.796e le Co SA me ( Nɔnɔmetata S44 ). Nusiwo do tso eme siawo ɖee fia be nanoparticles ƒe ƒoƒo ɖekae hea elektrɔnik ƒe vɔvɔ le Co teƒewo vɛ, si wɔnɛ be Co valence dzina ɖe edzi, si sɔ kple XPS ƒe emetsonuwo (Fig. 6c). Woda Co-O ƒe kadodo ƒe nɔnɔmewo kpɔ le HCOO ƒe adsorption ɖe Co-SAs/NPs@NC kple Co SA dzi to akɔntabubu le kristalo orbital Hamiltonian ƒuƒoƒo (COHP)63 me. Abe alesi woɖee fia le nɔnɔmetata 6 d me ene la, -COHP ƒe asixɔxɔ manyomanyo kple nyuitɔ sɔ kple antibonding nɔnɔme kple kadodo ƒe nɔnɔme, ɖe wo nɔewo yome. Woda Co-O si HCOO (Co-carbonyl O HCOO*) xɔ ƒe kadodo ƒe ŋusẽ kpɔ to -COHP ƒe asixɔxɔwo ƒoƒo ƒu me, siwo nye 3.51 kple 3.38 na Co-SAs/NPs@NC kple Co-SA, le wo nɔewo yome. HCOOH adsorption hã ɖe emetsonu mawo tɔgbe fia: -COHP ƒe asixɔxɔ vevi ƒe dzidziɖedzi le nanoparticle doping megbe ɖee fia be Co-O ƒe kadodo dzi ɖe edzi, si to esia me do HCOO kple HCOOH ƒe dɔwɔwɔ ɖe ŋgɔ ( Nɔnɔmetata S45 ).
Co-SA/NPs@NC-950 ƒe xɔtuɖoɖo. b PDOS Co-SA/NP@NC-950 kple Co SA. c 3D isosurface ƒe vovototo si le charge densities me le HCOOH adsorption le Co-SA / NPs@NC-950 kple Co-SA. (d) pCOHP si nye Co-O kadodo siwo HCOO xɔ le Co-SA/NPs@NC-950 (miame) kple Co-SA (ɖusime). e HCOOH dehydrogenation ƒe nuwɔna ƒe mɔnu le Co-SA/NPs@NC-950 kple Co-SA dzi.
Be woase Co-SA/NPs@NC ƒe dehydrogenation dɔwɔwɔ si de ŋgɔ wu gɔme nyuie wu la, wokpɔ alesi wowɔa nui kple ŋusẽ. Etɔxɛe la, FA dehydrogenation lɔ afɔɖeɖe atɔ̃ ɖe eme, siwo dometɔ aɖewoe nye HCOOH ƒe tɔtrɔ wòazu HCOOH*, HCOOH* wòazu HCOO* + H*, HCOO* + H* wòazu 2H* + CO2*, 2H* + CO2* wòazu 2H* + CO2, kple 2H* wòazu 2H* + CO2, kple 2H* le H2 me (Fig. 6e). Formic acid molecule siwo le nusi naa nu ʋãna ƒe anyigba dzi ƒe adsorption ŋusẽ to carboxylic oxygen dzi le ʋɛ wu to hydroxyl oxygen dzi (Nɔnɔmetata S46 kple S47). Emegbe le ŋusẽ si bɔbɔ ɖe anyi ta la, elɔ̃na be adsorbate la to OH kadodo ƒe mama me be wòawɔ HCOO* tsɔ wu CH ƒe kadodo ƒe mama be wòawɔ COOH *. Le ɣeyiɣi ma ke me la, HCOO* zãa monodentate adsorption, si doa kadodowo ƒe gbagbã kple CO2 kple H2 ƒe wɔwɔ ɖe ŋgɔ. Nusiwo do tso eme siawo sɔ kple νas(OCO) ƒe taƒoƒo ƒe anyinɔnɔ le in situ DRIFT, si gaɖee fia be FA ƒe gbegblẽ dzɔna to formate mɔ dzi le míaƒe numekukua me. Ele vevie be míade dzesii be le KIE ƒe dzidzenuwo nu la, CH ƒe mama ƒe mɔxenu le nuwɔna ƒe ŋusẽ si lolo wu nuwɔna ƒe afɔɖeɖe bubuwo eye wòtsi tre ɖi na RDS. Ŋusẽ ƒe mɔxenu si le Co-SAs/NPs@NC catalyst system nyuitɔ me la le 0.86 eV si le ʋɛ wu Co-SA tɔ (1.2 eV), si na dehydrogenation ƒe dɔwɔwɔ bliboa nyo ɖe edzi ŋutɔ. Eɖe dzesi be nanoparticles ƒe anyinɔnɔ ɖɔa elektrɔnik wɔwɔme si le atɔm me kaka coactive teƒewo dzi, si gadzia domedomenuwo ƒe adsorption kple dɔwɔwɔ ɖe edzi, si wɔnɛ be nuwɔna ƒe mɔxenu dzi ɖena kpɔtɔna eye wòdoa hydrogen wɔwɔ ɖe ŋgɔ.
Kpuie ko la, míeɖee fia zi gbãtɔ be woate ŋu ana haidrodzin wɔwɔ ƒe nusiwo naa nu ʋãna ƒe dɔwɔwɔ nanyo ɖe edzi ŋutɔ to nusiwo me monometallic titina siwo woma ŋutɔ kple nanoparticles suewo zazã me. Woɖo kpe nukpɔsusu sia dzi to cobalt-si wotu ɖe ga ɖeka ƒe nusiwo wotsɔna ʋãa nu siwo ŋu wotrɔ asi le kple nanoparticles (Co-SAs/NPs@NC), kpakple nusiwo do ƒome kplii siwo ƒe titina ga ɖeka ko (CoN2C2) alo Co NPs le la wɔwɔ me. Wotsɔ afɔɖeɖe ɖeka ƒe dzotɔtɔ mɔnu bɔbɔe aɖe dzra nuwo katã ɖo. Dɔwɔnu me dzodzro ɖee fia be nusi ʋãa nu nyuitɔ kekeake (Co-SAs/NPs@NC-950) nye CoN2C2 ƒe akpa siwo kaka ɖe atɔm me kple nanoparticles suewo (7-8 nm) siwo wotsɔ nitrogen kple carbon si le abe graphite ene dope ɖe eme. Gas ƒe dɔwɔwɔ nyuie ŋutɔ le esi va ɖo 1403.8 ml g-1 h-1 (H2:CO2 = 1.01:1), H2 kple CO tiatia 99.96% eye ateŋu alé dɔwɔwɔ madzudzɔmadzudzɔe me ɖe asi ŋkeke geɖe. Nusiwo naa nu ʋãna sia ƒe dɔwɔwɔ wu Co SA kple Pd/C nusiwo naa nu ʋãna aɖewo ƒe dɔwɔwɔ zi gbɔ zi 4 kple 15. DRIFT dodokpɔ siwo wowɔ le teƒea ɖee fia be ne wotsɔe sɔ kple Co-SA la, Co-SAs/NPs@NC-950 ɖea HCOO * ƒe monodentate adsorption sesẽ wu fiana, si le vevie na formate mɔa, eye dopant nanoparticles ate ŋu ado HCOO * ƒe dɔwɔwɔ kple C–H ƒe ablaɖeɖe ɖe ŋgɔ . Wode dzesi kadodoa ƒe mama be enye RDS. Nukpɔsusu ƒe akɔntabubuwo ɖee fia be Co NP doping dzia Co atɔm ɖeka ƒe d-band titina ɖe edzi 0.13 eV to kadodo me, si doa ŋusẽ HCOOH * kple HCOO * domedomenuwo ƒe adsorption, si wɔnɛ be woɖea nuwɔna ƒe mɔxenu dzi kpɔtɔna tso 1.20 eV na Co SA va ɖo 0 .86 eV. Eƒe agbanɔamedzie wònye be wòawɔ dɔ ɖedzesi aɖe.
Le mɔ si keke ta wu nu la, numekuku sia naa susuwo le atɔm ɖeka ƒe ga si wotsɔna ʋãa nu yeyewo ƒe wɔwɔme ŋu eye wòdoa gɔmesese ɖe ŋgɔ le alesi woawɔ ana nusiwo naa nu ʋãna ƒe dɔwɔwɔ nanyo ɖe edzi to ga ƒe titina siwo ƒe lolome to vovo ƒe dɔwɔwɔ aduadu ƒe ŋusẽkpɔɖeamedzi me. Míexɔe se be woate ŋu akeke mɔnu sia ɖe enu bɔbɔe ɖe nusiwo naa nu ʋãna ƒe ɖoɖo bubu geɖe ŋu.
Woƒle 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%) tso McLean, China. Woƒle formic acid (HCOOH, 98%) tso Rhawn, China. Wozã reagents katã tẽ evɔ womekɔ wo ŋu kpee o, eye wozã ultrapure purification system tsɔ dzra tsi si le dzadzɛ ŋutɔ ɖo. Woƒle Pt/C (5% mass loading) kple Pd/C (5% mass loading) tso Sigma-Aldrich gbɔ.
Wowɔ CoZn-ZIF nanocrystals ƒe wɔwɔme ɖe mɔnu siwo wozã va yi dzi kple tɔtrɔ aɖewo23,64. Gbã la, wotsaka 30 mmol Zn(NO3)2·6H2O (8.925 g) kple 3.5 mmol Co(NO3)2·6H2O (1.014 g) eye wotsɔe ƒo ɖe methanol ml 300 me. Emegbe wotsɔ 2-methylimidazole (9.853 g) mmol 120 de methanol ml 100 me eye wotsɔe de tsi si le etame la me. Woʋuʋua atike si wotsɔ tsakae la le xɔme ƒe dzoxɔxɔ nu gaƒoƒo 24 sɔŋ. Mlɔeba la, woɖe nusi wowɔ la ɖe vovo to centrifugation me le 6429 g me hena miniti 10 eye woklɔe nyuie kple methanol zi etɔ̃. Wotsɔa aŋɔ si do tso eme la ƒua gbe le dzoxɔxɔ si nye 60°C me zã bliboa hafi zãe.
Be woawɔ Co-SAs/NPs@NC-950 la, wotsɔ dzo ƒo CoZn-ZIF ƒuƒu ƒuƒu le 950 °C hena gaƒoƒo 1 le gas ƒe sisi si nye 6% H2 + 94% Ar me, kple dzoxɔxɔ ƒe agbɔsɔsɔme si nye 5 °C/min. Emegbe wofa kpɔɖeŋua ɖe xɔme ƒe dzoxɔxɔ nu be woakpɔ Co-SA/NPs@NC-950. Le Co-SAs/NPs@NC-850 alo Co-SAs/NPs@NC-750 gome la, wotrɔ dzoxɔxɔ si wotsɔna ƒoa dzoe va ɖo 850 kple 750 °C. Woate ŋu azã kpɔɖeŋu siwo wodzra ɖo evɔ womawɔ dɔ bubu aɖeke le wo ŋu o, abe acid etching ene.
Wowɔ TEM (transmission electron microscopy) dzidzedzewo le Thermo Fisher Titan Themis 60-300 “cube” nusuekpɔmɔ̃ si me wotsɔ nɔnɔmetata ƒe tɔtrɔ ɖɔɖɔɖonu kple 300 kV probe shaping lens ɖo. Wowɔ HAADF-STEM dodokpɔwo to FEI Titan G2 kple FEI Titan Themis Z nusuekpɔmɔ̃ siwo ŋu wotsɔ nukpɔmɔ̃wo kple nɔnɔmetata ɖɔɖɔɖonuwo ɖo, kple DF4 ƒe akpa ene ƒe nukpɔmɔ̃wo zazã me. Woxɔ EDS elemental mapping nɔnɔmetatawo hã le FEI Titan Themis Z nusuekpɔmɔ̃ dzi. Wowɔ XPS numekuku le X-ray photoelectron spectrometer (Thermo Fisher model ESCALAB 250Xi) dzi. Wozã XAFS-500 kplɔ̃ (China Spectral Instruments Co., Ltd.) tsɔ ƒo XANES kple EXAFS Co K-edge spectra nu ƒu. Wotsɔ atɔm ƒe xɔxlɔ̃ ƒe keklẽŋusẽ (AAS) (PinAAcle900T) de dzesi Co ƒe agbɔsɔsɔ. Woŋlɔ X-ray diffraction (XRD) spectra ɖe X-ray diffractometer (Bruker, Bruker D8 Advance, Germany) dzi. Wozã dzɔdzɔmeŋusẽ ƒe xɔxlɔ̃ ƒe mɔ̃ (Micromeritics, ASAP2020, USA) tsɔ kpɔ nitrogen ƒe xɔxlɔ̃ ƒe isotherms.
Wowɔ dehydrogenation reaction la le argon yamenutome eye woɖe ya ɖa le Schlenk ƒe mɔnu si wozãna ɖaa nu. Woɖe nugo si me wowɔa nu le la ɖa eye wogade argon eme zi 6. Trɔ condenser tsidzɔƒea eye nàtsɔ catalyst (30 mg) kple solvent (6 ml) akpe ɖe eŋu. Zã dzoxɔxɔdzidzenu nàtsɔ ado dzo nugoe la ɖe dzoxɔxɔ si nèdi nu eye nàna wòada asɔ aɖabaƒoƒo 30. Emegbe wotsɔ formic acid (10 mmol, 377 μL) de nugo si me wowɔa nu le la me le argon te. Trɔ mɔ etɔ̃ ƒe burette ƒe ʋuƒoa be wòaɖe yaƒoƒo dzi akpɔtɔ le reactor la me, gatue ake, eye nàdze gas si dona ƒe lolome dzidzedze gɔme to asi burette zazã me (Nɔnɔmetata S16). Le ɣeyiɣi si hiã hafi nuwɔna la nawu enu megbe la, woƒo gas ƒe kpɔɖeŋu nu ƒu hena GC numekuku to gas-tight syringe si wotsɔ argon kɔ la zazã me.
Wowɔ DRIFT dodokpɔwo le teƒea le Fourier transform infrared (FTIR) spectrometer (Thermo Fisher Scientific, Nicolet iS50) si me mercury cadmium telluride (MCT) detector le la dzi. Wotsɔ atike si naa nu ʋãna la de lãmenugbagbevi si me wowɔa nu le (Harrick Scientific Products, Praying Mantis) me. Esi wotsɔ Ar ƒe sisi (50 ml/min) wɔ dɔ le nusi naa nu ʋãna ŋu le xɔme ƒe dzoxɔxɔ nu vɔ la, wodo dzo na kpɔɖeŋua va ɖo dzoxɔxɔ si wona, emegbe wotsɔ Ar (50 ml/min) ƒoe ɖe HCOOH tsi me eye wokɔe ɖe in-situ reaction cell la me. hena nuwɔna ɖe eŋu. Kpɔɖeŋu heterogeneous catalytic dɔwɔwɔwo. Woŋlɔ infrared spectra le dometsotso siwo tso sɛkɛnd 3.0 va ɖo gaƒoƒo 1 me.
Wozãa HCOOH, DCOOH, HCOOD kple DCOOD abe nusiwo woatsɔ awɔ dɔe ene le propylene carbonate me. Nɔnɔme susɔeawo sɔ kple HCOOH dehydrogenation ƒe ɖoɖoa.
Wowɔ gɔmeɖose gbãtɔwo ƒe akɔntabubuwo to density functional theory framework zazã me le Vienna Ab initio modeling package (VASP 5.4.4) 65,66 me. Wozã lãmenugbagbevi si ƒe lolome nye superunit si ƒe graphene ƒe anyigba (5 × 5) si ƒe didime anɔ abe 12.5 Å ene abe nusi woatsɔ awɔ CoN2C2 kple CoN2C2-Co6 ƒe gɔmeɖoanyi ene. Wotsɔ vacuum ƒe didime si wu 15 Å kpe ɖe eŋu be woaƒo asa na kadodo si anɔ anyigba ƒe ƒuƒoƒo siwo te ɖe wo nɔewo ŋu dome. Woɖea ion kple elektrɔnik dome kadodo me to projected amplified wave (PAW) mɔnu dzi65,67. Wozã Perdue-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) dɔwɔwɔ kple van der Waals ɖɔɖɔɖo si Grimm68,69 do ɖa. Ŋusẽ kple ŋusẽ bliboa ƒe ƒoƒo ɖekae ƒe dzidzenuwoe nye 10−6 eV/atɔm kple 0.01 eV/Å. Wozã Monkhorst-Pack 2 × 2 × 1 K-point grid tsɔ ɖo ŋusẽ ƒe ɖeɖeɖa ɖe 600 eV dzi. Wotu pseudopotential si wozã le kpɔɖeŋu sia me tso elektrɔnik ɖoɖowɔwɔ me yi C 2s22p2 nɔnɔme, N 2s22p3 nɔnɔme, Co 3d74s2 nɔnɔme, H 1 s1 nɔnɔme, kple O 2s22p4 nɔnɔme me. Wobu akɔnta le adsorption ŋusẽ kple electron density ƒe vovototo to gas phase kple surface ƒomeviwo ƒe ŋusẽ ɖeɖeɖa tso adsorbed system ƒe ŋusẽ me le adsorption alo interface models nu70,71,72,73,74. Wozãa Gibbs ƒe ŋusẽ si me ablɔɖe mele o ɖɔɖɔɖo tsɔ trɔa DFT ŋusẽ wòzua Gibbs ƒe ŋusẽ si me ablɔɖe mele o eye wòbua ʋuʋudedi ƒe akpa si wòwɔna ɖe entropy kple zero point ŋusẽ ŋu75. Wozã ascending image-nudging elastic band (CI-NEB) mɔnu tsɔ di tɔtrɔ ƒe nɔnɔme si le nuwɔna la me76.
Nyatakaka siwo katã woxɔ hedzro le numekuku sia me la le nyatia kple kpeɖeŋutɔ bubuwo me alo woate ŋu axɔ wo tso agbalẽŋlɔla si sɔ kplii gbɔ ne wobia wo nyuie. Wotsɔ nyatakakatsoƒewo na nyati sia.
Woate ŋu akpɔ kɔpi siwo katã wozã le nɔnɔmetata siwo kpe ɖe nyati sia ŋu me tso agbalẽŋlɔla siwo sɔ kplii gbɔ ne wobia.
Dutta, I. kple ame bubuwo. Formic acid doa alɔ gazazã si me carbon mesɔ gbɔ ɖo o. dɔwɔnyaɖɔnya. Ŋusẽnu siwo wozãna. 12, 2103799 (ƒe 2022) me.
Wei, D., Sang, R., Sponholz, P., Junge, H. kple Beller, M. Carbon dioxide ƒe hydrogenation si woate ŋu atrɔ azu formic acid to Mn-claw complexes zazã me le lysine ƒe anyinɔnɔ me. Nat. Ŋusẽ 7, 438-447 (2022).
Wei, D. kple ame bubuwo. Towards a hydrogen economy: heterogeneous catalysts ƒe ŋgɔyiyi hena haidrodzin dzraɖo kple asiɖeɖe le eŋu ƒe atikeŋutinunya. ACS Ŋusẽ Ŋuti Lɛtawo. 7, 3734-3752 (ƒe 2022) ƒe xexlẽme.
Modisha PM, Ouma SNM, Garijirai R., Wasserscheid P. kple Bessarabov D. Mɔkpɔkpɔwo na haidrodzin dzadzraɖo to tsi lãmenugbagbeviwo ƒe haidrodzin tsɔlawo zazã me. Ŋusẽ ƒe Mɔ̃memiwo 33, 2778-2796 (2019).
Niermann, M., Timmerberg, S., Drunert, S. kple Kaltschmitt, M. Tsi lãmenugbagbeviwo ƒe haidrodzin tsɔlawo kple mɔnu bubuwo na dukɔwo dome haidrodzin yeye tsɔtsɔ yi teƒe bubuwo. doe ɖe ŋgᴐ. de megbe. ŋusẽ. Ʋuʋu 135, 110171 (ƒe 2021).
Preister P, Papp K kple Wasserscheid P. Tsi lãmenugbagbeviwo ƒe haidrodzin tsɔlawo (LOHC): ɖo ta haidrodzin ƒe ganya si me haidrodzin mele o gbɔ. mᴐbibia. Dzɔdzɔmeŋusẽŋununya. dɔwɔnu si woatsɔ awɔ dɔe. 50, 74-85 (2017) Ƒe 2017 me.
Chen, Z. kple ame bubuwo. Palladium ƒe nusiwo ŋu kakaɖedzi le ƒe wɔwɔme hena formic acid dehydrogenation. AKS ƒe agbalẽdzraɖoƒe. 13, 4835-4841 (ƒe 2023) ƒe xexlẽme.
Sun, Q., Wang, N., Xu, Q. kple Yu, J. Nanopore-do alɔ ga nanocatalysts na haidrodzin wɔwɔ nyuie tso tsi-fase haidrodzin nudzraɖoƒe atikewo. dɔwɔnyaɖɔnya. Mat. 32, ƒe 2001818 (ƒe 2020).
Seraj, JJA, kple ame bubuwo. Nusi naa formic acid dzadzɛ ƒe dehydrogenation ɖeɖeɖa nyuie. Nat. ka nyata. 7, ƒe 11308 (ƒe 2016).
Kar S, Rauch M, Leitus G, Ben-David Y. kple Milstein D. . Tsiɖeɖe le formic acid dzadzɛ me nyuie si me wometsɔa nu kpena ɖe eŋu o. Nat. Gatar ƒe ŋkɔ. 4, ƒe 193-201 (ƒe 2021).
Li, S. kple ame bubuwo. Gɔmeɖose bɔbɔe siwo wɔa dɔ nyuie na heterogeneous formic acid dehydrogenation catalysts ƒe ɖoɖowɔwɔ si me susu le. dɔwɔnyaɖɔnya. Mat. 31, ƒe 1806781 (ƒe 2019).
Liu, M. kple ame bubuwo. Heterogeneous catalysis na formic acid-si wotu ɖe carbon dioxide hydrogen dzraɖoƒe mɔ̃ɖaŋununya. dɔwɔnyaɖɔnya. Ŋusẽnu siwo wozãna. 12, ƒe 2200817 (ƒe 2022).