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Kuvandudzwa kwetekinoroji yehydrogen kuri pakati pehupfumi hwenzvimbo dzakasvibira. Sechinodiwa kuti pave nekuchengetwa kwehydrogen, zvinhu zvinoshanda uye zvakagadzikana zvinoita kuti hydrogenation (de)hydrogenation reaction iite zvinodiwa. Kusvika pari zvino, nzvimbo iyi yave ichitongwa nekushandiswa kwesimbi dzinokosha dzinodhura. Pano, tinokurudzira catalyst itsva inodhura zvishoma yecobalt-based catalyst (Co-SAs/NPs@NC) umo nzvimbo dzesimbi imwe chete dzakapararira zvakanyanya dzinobatanidzwa pamwe chete ne nanoparticles dzakanaka kuti dzibudirire kuita kuti formic acid dehydrogenation ishande zvakanaka. Tichishandisa zvinhu zvakanakisisa zveCoN2C2 units dzakapararira neatomu uye nanoparticles dzakavharirwa dzehukuru hwe7-8 nm, tichishandisa propylene carbonate se solvent, gasi rakanakisisa re1403.8 ml g-1 h-1 rakawanikwa, uye hapana kurasikirwa kwakaitika mushure me5 cycles. chiitiko, chiri nani ka15 pane commercial Pd/C. Kuedza kweIn situ assay kunoratidza kuti, zvichienzaniswa ne single metal atomu ne nanoparticle catalysts zvine chekuita nazvo, Co-SAs/NPs@NC inowedzera adsorption uye activation ye key monodentate intermediate HCOO*, nokudaro zvichikurudzira CH bond cleavage inotevera. Kuverenga kwedzidziso kunoratidza kuti kubatanidzwa kwe cobalt nanoparticles kunokurudzira kushandurwa kwe d-band centre ye single Co atom kuita active site, nokudaro zvichiwedzera coupling pakati pe carbonyl O ye HCOO* intermediate neCo centre, nokudaro zvichideredza energy barrier.
Hydrogen inoonekwa senzira yakakosha yekutakura simba pakuchinja kwesimba pasi rose uye inogona kuva chinhu chikuru chinoita kuti carbon neutrality isashande1. Nekuda kwehunhu hwayo hwepanyama hwakadai sekubvira uye kusimba kwakaderera, kuchengetwa kwakachengeteka uye kwakanaka uye kutakurwa kwehydrogen zvinhu zvakakosha mukubudirira kwehupfumi hwehydrogen2,3,4. Zvinotakura hydrogen yemvura (LOHCs), iyo inochengeta nekuburitsa hydrogen kuburikidza nemakemikari, yakakurudzirwa semhinduro. Zvichienzaniswa nehydrogen yemamorekuru, zvinhu zvakadaro (methanol, toluene, dibenzyltoluene, nezvimwewo) zviri nyore uye zviri nyore kubata5,6,7. Pakati pemaLOHC akasiyana-siyana echinyakare, formic acid (FA) ine chepfu shoma (LD50: 1.8 g/kg) uye H2 kugona kwe53 g/L kana 4.4 wt%. Zvinoshamisa kuti, FA ndiyo yega LOHC inogona kuchengeta nekuburitsa hydrogen mumamiriro ekunze akapfava kana paine macatalysts akakodzera, nokudaro isingade simba guru rekunze rinopinda1,8,9. Kutaura zvazviri, zvinhu zvakawanda zvesimbi zvine hunhu hwakanaka zvakagadzirwa kuti zvibvise hydrogen ye formic acid, semuenzaniso, zvinhu zvesimbi zvine hunhu hwe palladium zvinoshanda ka50-200 kupfuura zvinhu zvesimbi zvisingadhuri10,11,12. Zvisinei, kana ukafunga nezvemutengo wesimbi dzinoshanda, semuenzaniso, palladium inodhura kanopfuura ka1000.
Cobalt, Kutsvaga kwezvinhu zvinogadzira simbi zvine simba uye zvakagadzikana zvakasiyana-siyana kuri kuramba kuchikwezva kufarira kwevaongorori vazhinji muzvidzidzo zvedzidzo neindasitiri13,14,15.
Kunyangwe hazvo ma catalysts asingadhuri akavakirwa paMo neCo, pamwe chete nema nanocatalysts akagadzirwa kubva ku noble/base metal alloys, 14,16 akagadzirwa kuti abvise hydrogenation yeFA, kudzimwa kwawo zvishoma nezvishoma panguva ye reaction hakudzivisiki nekuda kwekugara kwenzvimbo dzinoshanda dzesimbi, CO2, neH2O nemaproton. kana kuti formate anions (HCOO-), kusvibiswa kweFA, kuunganidzwa kwezvikamu uye poisonation yeCO17,18. Isu nevamwe munguva pfupi yapfuura takaratidza kuti ma single-atom catalysts (SACs) ane nzvimbo dzakapararira zvakanyanya dzeCoIINx senzvimbo dzinoshanda anovandudza reactivity uye resistance ye acid ye formic acid dehydrogenation zvichienzaniswa ne nanoparticles17,19,20,21,22,23,24. Muzvinhu izvi zveCo-NC, ma N atomu anoshanda senzvimbo huru dzekusimudzira FA deprotonation ukuwo achivandudza kugadzikana kwechimiro kuburikidza nekubatana ne central Co atomu, nepo ma Co atomu achipa H adsorption nzvimbo uye achikurudzira CH22 scission, 25,26. Zvinosuwisa kuti kushanda nekugadzikana kwezvishandiso izvi zvichiri kure nezvinoita zvesimbi zvemazuva ano zvakafanana uye zvakasiyana (Mufananidzo 1) 13.
Simba rakawandisa rinobva kuzvinhu zvinogona kushandiswazve zvakaita sezuva kana mhepo rinogona kugadzirwa nemagetsi emagetsi emvura. Hydrogen inogadzirwa inogona kuchengetwa uchishandisa LOHC, mvura ine hydrogenation uye dehydrogenation zvinodzoserwa. Padanho re dehydrogenation, chigadzirwa chega ihydrogen, uye mvura inotakura inodzoserwa kumamiriro ayo ekutanga uye hydrogenated zvakare. Hydrogen inogona kuzopedzisira yashandiswa muzviteshi zvepeturu, mabhatiri, zvivakwa zvemaindasitiri, nezvimwewo.
Munguva pfupi yapfuura, zvakanzi mashandiro emukati meSACs chaiwo anogona kuwedzerwa kana paine maatomu esimbi akasiyana kana mamwe masimbi anopiwa nenanoparticles (NPs) kana nanoclusters (NCs)27,28. Izvi zvinovhura mikana yekuwedzera adsorption uye activation ye substrate, pamwe nekuchinja kwe geometry uye electronic structure yenzvimbo dzemonatomic. Nenzira iyi, substrate adsorption/activation inogona kugadziriswa, zvichipa kushanda kwakanaka kwecatalytic29,30. Izvi zvinotipa pfungwa yekugadzira zvinhu zvecatalytic zvakakodzera nenzvimbo dzinoshanda dzehybrid. Kunyangwe maSACs akavandudzwa akaratidza kugona kukuru mumhando dzakasiyana dzecatalytic application31,32,33,34,35,36, maererano neruzivo rwedu, basa rawo mukuchengetedza hydrogen harina kujeka. Panyaya iyi, tinoshuma nzira inoshanda uye yakasimba yekugadzira cobalt-based hybrid catalysts (Co-SAs/NPs@NCs) ine nanoparticles dzakatsanangurwa uye nzvimbo dzesimbi dzakasiyana. Co-SAs/NPs@NC yakagadziriswa inoratidza kushanda kwakanaka kwe formic acid dehydrogenation, izvo zviri nani pane non-noble nanostructured catalysts (dzakadai seCoNx, single cobalt atoms, cobalt@NC uye γ-Mo2N) uye kunyange noble metal catalysts. Kutsanangurwa kwenzvimbo uye kuverenga kweDFT kwe active catalysts kunoratidza kuti nzvimbo dzesimbi imwe neimwe dzinoshanda se active sites, uye nanoparticles yeiyi innovation inowedzera d-band centre yemaatomu eCo, inokurudzira adsorption uye activation yeHCOO*, nokudaro ichideredza simba re reaction.
Zeolite imidazolate frameworks (ZIFs) imhando nhatu dzakanyatsotsanangurwa dzinopa catalysts yezvinhu zvakasanganiswa nenitrogen (metal-NC catalysts) kutsigira mhando dzakasiyana dzesimbi37,38. Nokudaro, Co(NO3)2 neZn(NO3)2 zvinosangana ne2-methylimidazole mumethanol kuti zvigadzire simbi dzakafanana mumushonga. Mushure mekutenderedza nekuomesa, CoZn-ZIF yakapiswa pakupisa kwakasiyana (750–950 °C) mumhepo ye6% H2 ne94% Ar. Sezvakaratidzwa mumufananidzo uri pazasi, zvinhu zvinobuda zvine hunhu hwakasiyana hwenzvimbo inoshanda uye zvinonzi Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-750 (Mufananidzo 2a). ). Kuongororwa kwakananga kwemamwe matanho akakosha mukuita kwekugadzira kwakatsanangurwa muMifananidzo 1 ne2. C1-C3. Kuchinja kweX-ray diffraction (VTXRD) kwakaitwa kuti kutariswe kushanduka kwe catalyst. Kana tembiricha ye pyrolysis yasvika 650 °C, XRD pattern inochinja zvakanyanya nekuda kwekuputsika kwechimiro chekristaro chakarongwa cheZIF (Mufananidzo S4) 39. Sezvo tembiricha ichiwedzera, misoro miviri yakafara inoonekwa mumapatani eXRD eCo-SAs/NPs@NC-850 neCo-SAs/NPs@NC-750 pa20–30° ne40–50°, zvichimiririra peak ye amorphous carbon (Mufananidzo C5). 40. Zvakakosha kuziva kuti misoro mitatu chete ndiyo yakaonekwa pa44.2°, 51.5° ne75.8°, iri ye metallic cobalt (JCPDS #15-0806), uye 26.2°, iri ye graphitic carbon (JCPDS # 41-1487). X-ray spectrum yeCo-SAs/NPs@NC-950 inoratidza kuvapo kwe graphite-like encapsulated cobalt nanoparticles pa catalyst41,42,43,44. Raman spectrum inoratidza kuti Co-SAs/NPs@NC-950 inoita kunge ine D neG peaks dzakasimba uye dzakatetepa kupfuura dzimwe samples, zvichiratidza mwero wepamusoro we graphitization (Mufananidzo S6). Pamusoro pezvo, Co-SAs/NPs@NC-950 inoratidza nzvimbo yepamusoro yeBrunner-Emmett-Taylor (BET) uye pore volume (1261 m2 g-1 uye 0.37 cm3 g-1) kupfuura dzimwe samples uye mazhinji maZIFs materials ari NC derivatives. (Mufananidzo S7 neTable S1). Atomic absorption spectroscopy (AAS) inoratidza kuti cobalt content yeCo-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 uye Co-SAs/NPs@ iri 2.69 wt.%, 2.74 wt.% uye 2.73 wt.%. NC-750 zvichiteerana (Tafura S2). Zn content yeCo-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-750 inowedzera zvishoma nezvishoma, izvo zvinokonzerwa nekuwedzera kudzikira uye volatilization yemayuniti eZn. Kuwedzera kwekushisa kwepyrolysis (Zn, boiling point = 907 °C) 45.46. Elemental analysis (EA) yakaratidza kuti chikamu cheN chinoderera nekuwedzera kwekupisa kwepyrolysis, uye huwandu hweO2 hwakakwira hunogona kunge hwakakonzerwa nekunyudzwa kwemolecular O2 kubva pakusangana nemhepo. (Tafura S3). Pahuwandu hwakati hwe cobalt, nanoparticles uye isolated coatoms zvinogara pamwe chete, zvichikonzera kuwedzera kukuru kwebasa re catalyst, sezvakakurukurwa pazasi.
Dhiyagiramu yemufananidzo wekugadzirwa kweCo-SA/NPs@NC-T, uko T iri tembiricha yepyrolysis (°C). b mufananidzo weTEM. c Mufananidzo weCo-SAs/NPs@NC-950 AC-HAADF-STEM. Maatomu eCo imwe chete ane madenderedzwa matsvuku. d EDS spectrum yeCo-SA/NPs@NC-950.
Zvinonyanya kukosha kuti transmission electron microscopy (TEM) yakaratidza kuvapo kwemhando dzakasiyana dze cobalt nanoparticles (NPs) dzine avhareji yehukuru hwe 7.5 ± 1.7 nm chete mu Co-SAs/NPs@NC-950 (Mifananidzo 2 b na S8). Aya ma nanoparticles akavharirwa ne graphite-like carbon doped ne nitrogen. Lattice fringe spacing ye 0.361 ne 0.201 nm inoenderana ne graphitic carbon (002) uye metallic Co (111) particles, zvichiteerana. Pamusoro pezvo, high-angle aberration-corrected annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) yakaratidza kuti Co NPs mu Co-SAs/NPs@NC-950 dzakanga dzakakomberedzwa ne atomic cobalt yakawanda (Mufananidzo 2c). Zvisinei, ma atomu e cobalt akapararira neatomu chete ndiwo akaonekwa pakutsigira mamwe ma samples maviri (Mufananidzo S9). Mufananidzo weEnergy dispersive spectroscopy (EDS) HAADF-STEM unoratidza kupararira kwakafanana kweC, N, Co uye Co NPs dzakaparadzaniswa muCo-SAs/NPs@NC-950 (Mufananidzo 2d). Mhedzisiro iyi yese inoratidza kuti nzvimbo dzeCo dzakapararira neatomu uye nanoparticles dzakavharirwa muN-doped graphite-like carbon zvinobatanidzwa zvinobudirira kune NC substrates muCo-SAs/NPs@NC-950, ukuwo nzvimbo dzesimbi dzakaparadzaniswa chete.
Mamiriro e valence uye kuumbwa kwemakemikari kwezvinhu zvakawanikwa zvakadzidzwa ne X-ray photoelectron spectroscopy (XPS). XPS spectra yema catalysts matatu yakaratidza kuvapo kwezvinhu Co, N, C uye O, asi Zn yaivepo chete muCo-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-750 (Mufananidzo 2). ). C10). Sezvo tembiricha ye pyrolysis ichiwedzera, huwandu hwese hwe nitrogen hunoderera sezvo mhando dze nitrogen dzichiva dzisina kugadzikana uye dzichiora kuita magasi eNH3 neNOx pakupisa kwakanyanya (Tafura S4) 47. Saka, huwandu hwese hwekabhoni hwakawedzera zvishoma nezvishoma kubva kuCo-SAs/NPs@NC-750 kuenda kuCo-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-950 (Mifananidzo S11 neS12). Sample yakapiswa pakupisa kwakanyanya ine chikamu chidiki chemaatomu e nitrogen, zvinoreva kuti huwandu hweNC carriers muCo-SAs/NPs@NC-950 hunofanira kunge huri pasi pehuri mune mamwe ma samples. Izvi zvinotungamira mukupiswa kwakasimba kwezvikamu zve cobalt. O 1s spectrum inoratidza misoro miviri C=O (531.6 eV) uye C–O (533.5 eV), zvichiteerana (Mufananidzo S13) 48. Sezvakaratidzwa muMufananidzo 2a, iyo N 1s spectrum inogona kugadziriswa kuita misoro mina ye pyridine nitrogen N (398.4 eV), pyrrole N (401.1 eV), graphite N (402.3 eV) uye Co-N (399.2 eV). Mabhandi e Co-N aripo musampuli dzese nhatu, zvichiratidza kuti mamwe maatomu e N akabatana nenzvimbo dze monometallic, asi hunhu hwacho hunosiyana zvakanyanya49. Kushandiswa kwekupisa kwakanyanya kwe pyrolysis kunogona kuderedza zvakanyanya huwandu hwemhando dzeCo-N kubva pa43.7% muCo-SA/NPs@NC-750 kusvika pa27.0% muCo-SAs/NPs@NC-850 uye Co 17.6%@ NC-950. mu -CA/NPs, izvo zvinoenderana nekuwedzera kwehuwandu hweC (Mufananidzo 3a), zvichiratidza kuti nhamba yavo yeCo-N coordination inogona kuchinja uye kutsiviwa zvishoma nemaatomu eC50. Zn 2p spectrum inoratidza kuti chinhu ichi chiripo zvakanyanya muchimiro cheZn2+. (Mufananidzo S14) 51. Iyo spectrum yeCo 2p inoratidza peaks mbiri dzakatanhamara pa780.8 ne796.1 eV, idzo dzinonzi dzakabva kuCo 2p3/2 neCo 2p1/2, zvichiteerana (Mufananidzo 3b). Zvichienzaniswa neCo-SAs/NPs@NC-850 neCo-SAs/NPs@NC-750, iyo Co-N peak muCo-SAs/NPs@NC-950 inotamisirwa kudivi rakanaka, zvichiratidza kuti iyo single Co atomu kumusoro -SAs/NPs@NC-950 ine mwero wepamusoro wekupera kwemaerekitironi, zvichikonzera mamiriro ekuwedzera kweoxidation. Zvakakosha kuziva kuti Co-SAs/NPs@NC-950 chete ndiyo yakaratidza kukwirira kushoma kwe zero-valent cobalt (Co0) pa778.5 eV, izvo zvinoratidza kuvapo kwe nanoparticles dzinobva mukuunganidzwa kweSA cobalt pakupisa kwakanyanya.
a N 1s uye b Co 2p spectra yeCo-SA/NPs@NC-T. c XANES uye d FT-EXAFS spectra yeCo-K-edge yeCo-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-750. e WT-EXAFS contour plots yeCo-SAs/NPs@NC-950, Co-SAs/NPs@NC-850, uye Co-SAs/NPs@NC-750. f FT-EXAFS fitting curve yeCo-SA/NPs@NC-950.
Nguva yakavharirwa X-ray absorption spectroscopy (XAS) yakashandiswa kuongorora chimiro chemagetsi uye mamiriro ekubatana kwemhando dzeCo mumuenzaniso wakagadzirwa. Cobalt valence states muCo-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-750. Chimiro cheEdge chakaratidzwa ne normalized near-field X-ray absorption paCo-K edge (XANES) spectrum. Sezvakaratidzwa muMufananidzo 3c, absorption iri pedyo nemupendero wemasampule matatu iri pakati peCo neCoO foils, zvichiratidza kuti valence state yeCo species iri kubva pa0 kusvika +253. Pamusoro pezvo, shanduko kune yakaderera simba yakaonekwa kubva kuCo-SAs/NPs@NC-950 kuenda kuCo-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-750, zvichiratidza kuti Co-SAs/NPs@NC-750 ine yakaderera oxidation state. Reverse order. Zvichienderana nemhedzisiro yekubatanidza mutsara, mamiriro eCo valence eCo-SAs/NPs@NC-950 anofungidzirwa kuva +0.642, ayo ari pasi pane mamiriro eCo valence eCo-SAs/NPs@NC-850 (+1.376). Co-SA/NP @NC-750 (+1.402). Mhedzisiro iyi inoratidza kuti avhareji yemamiriro eoxidation ecobalt particles muCo-SAs/NPs@NC-950 yakaderedzwa zvakanyanya, izvo zvinoenderana nemhedzisiro yeXRD neHADF-STEM uye zvinogona kutsanangurwa nekuvapo kwecobalt nanoparticles uye single cobalt. Maatomu eCo 41. Fourier transform X-ray absorption fine structure (FT-EXAFS) spectrum yeCo K-edge inoratidza kuti peak huru pa1.32 Å ndeyeCo-N/Co-C shell, nepo nzira yekupararira yeCo-Co yesimbi iri pa2.18 chete muCo-SAs Å inowanikwa mu /NPs@NC-950 (Mufananidzo 3d). Uyezve, wavelet transform (WT) contour plot inoratidza maximum intensity pa6.7 Å-1 inosanganisirwa neCo-N/Co-C, nepo Co-SAs/NPs@NC-950 chete inoratidza maximum intensity inosanganisirwa ne8.8. Imwe intensity maximum iri paÅ−1 kuCo-Co bond (Mufananidzo 3e). Pamusoro pezvo, ongororo yeEXAFS yakaitwa nemurenda yakaratidza kuti pakupisa kwepyrolysis kwe750, 850 uye 950 °C, nhamba dzeCo-N coordinate dzaive 3.8, 3.2 uye 2.3, zvichiteerana, uye nhamba dzeCo-C coordinate dzaive 0. 0.9 uye 1.8 (Mufananidzo 3f, S15 uye Tafura S1). Zvakanyanya, mhedzisiro yazvino inogona kuverengerwa nekuvapo kwemayuniti eCoN2C2 akapararira neatomu uye nanoparticles muCo-SAs/NPs@NC-950. Kusiyana neizvi, muCo-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-750, mayuniti eCoN3C neCoN4 chete ndiwo aripo. Zviri pachena kuti nekuwedzera kwekushisa kwepyrolysis, maatomu eN muyuniti yeCoN4 anotsiviwa zvishoma nezvishoma nemaatomu eC, uye cobalt CA inoungana kuti igadzire nanoparticles.
Mamiriro ekugadzirisa akambodzidzwa kare akashandiswa kudzidza mhedzisiro yemamiriro ekugadzirira pahunhu hwezvinhu zvakasiyana-siyana (Mufananidzo S16)17,49. Sezvakaratidzwa muMufananidzo 4 a, basa reCo-SAs/NPs@NC-950 rakakwira zvakanyanya kupfuura reCo-SAs/NPs@NC-850 uye Co-SAs/NPs@NC-750. Zvinonyanya kukosha kuti, sampuro dzese nhatu dzeCo dzakagadzirwa dzakaratidza kushanda kwepamusoro kana tichienzanisa nemidziyo yesimbi inokosha yekutengeserana (Pd/C uye Pt/C). Pamusoro pezvo, sampuro dzeZn-ZIF-8 neZn-NC dzakanga dzisingashande pakubvisa hydrogenation yeformic acid, zvichiratidza kuti Zn particles hadzisi nzvimbo dzinoshanda, asi mhedzisiro yadzo pabasa haina kukosha. Pamusoro pezvo, basa reCo-SAs/NPs@NC-850 neCo-SAs/NPs@NC-750 rakaitwa secondary pyrolysis pa950°C kweawa imwe chete, asi raive rakaderera pane reCo-SAs/NPs@NC-750. @NC-950 (Mufananidzo S17). Kurongeka kwechimiro chezvinhu izvi kwakaratidza kuvapo kweCo nanoparticles muzviyero zvakadzoserwazve, asi nzvimbo yakaderera uye kusavapo kwekabhoni yakaita segraphite kwakaita kuti pave nebasa rakaderera zvichienzaniswa neCo-SAs/NPs@NC-950 (Mufananidzo S18–S20). Basa remasamples ane huwandu hwakasiyana hweCo precursor rakaenzaniswawo, nebasa repamusoro-soro rinoratidzwa pakuwedzera kwe3.5 mol (Tafura S6 neMufananidzo S21). Zviri pachena kuti kuumbwa kwenzvimbo dzakasiyana dzesimbi kunokanganiswa nehuwandu hwehydrogen mumhepo yepyrolysis nenguva yepyrolysis. Nokudaro, zvimwe zvinhu zveCo-SAs/NPs@NC-950 zvakaongororwa kuti zvionekwe kuti zvine chekuita neformic acid dehydrogenation activity. Zvinhu zvese zvakaratidza kushanda zvakanaka kusvika pakati nepakati; zvisinei, hapana chimwe chazvo chaive nani kupfuura Co-SAs/NPs@NC-950 (Mufananidzo S22 neS23). Kurongeka kwechimiro chezvinhu zvakaratidza kuti nekuwedzera kwenguva ye pyrolysis, huwandu hwenzvimbo dze monoatomic Co-N hunoderera zvishoma nezvishoma nekuda kwekuunganidzwa kwemaatomu esimbi kuita nanoparticles, izvo zvinotsanangura musiyano webasa pakati pemasampuli ane nguva ye pyrolysis ye100-2000. musiyano. 0.5 h, 1 h, uye 2 h (Mifananidzo S24–S28 neTafura S7).
Grafu yehuwandu hwegasi uchienzaniswa nenguva inowanikwa panguva yekubviswa kwehydrogen mumafuta uchishandisa macatalyst akasiyana-siyana. Mamiriro ekuita: PC (10 mmol, 377 μl), catalyst (30 mg), PC (6 ml), Tback: 110 °C, Tactical: 98 °C, zvikamu zvina b Co-SAs/NPs@NC-950 (30 mg), solvents dzakasiyana-siyana. c Kuenzanisa kwemazinga ekushanduka kwegasi emacatalyst akasiyana-siyana mu organic solvents pa85–110 °C. d Co-SA/NPs@NC-950 recycling experiment. Mamiriro ekuita: FA (10 mmol, 377 µl), Co-SAs/NPs@NC-950 (30 mg), solvent (6 ml), Tset: 110 °C, Tactual: 98 °C, reaction cycle yega yega inotora awa imwe . Error bars dzinomiririra standard deviations dzakaverengerwa kubva ku active tests nhatu.
Kazhinji, kushanda zvakanaka kweFA dehydrogenation catalysts kunoenderana zvikuru nemamiriro ekuita reaction, kunyanya solvent inoshandiswa8,49. Pakushandisa mvura se solvent, Co-SAs/NPs@NC-950 yakaratidza kuti ndiyo yakanyanya kukwira yekutanga reaction rate, asi deactivation yakaitika, pamwe nekuda kwemaproton kana H2O18 ari munzvimbo dzinoshanda. Kuedzwa kwe catalyst mu organic solvents dzakadai se1,4-dioxane (DXA), n-butyl acetate (BAC), toluene (PhMe), triglyme uye cyclohexanone (CYC) hakuna kuratidzawo kuvandudzika, uye mu propylene carbonate (PC) ) (Mufananidzo 4b neTafura S8). Saizvozvowo, zvinowedzera zvakaita se triethylamine (NEt3) kana sodium formate (HCCONA) hazvina kuwedzera mhedzisiro yakanaka pakushanda kwe catalyst (Mufananidzo S29). Mumamiriro ezvinhu akanaka ekuita, goho regesi rakasvika 1403.8 mL g−1 h−1 (Mufananidzo S30), iro raive rakakwira zvakanyanya kupfuura ese maCo catalysts akambotaurwa (kusanganisira SAC17, 23, 24). Mukuyedza kwakasiyana-siyana, kusasanganisa ma "reactions" mumvura uye ne "formate additives", dehydrogenation uye dehydration selectivity yakawanikwa kusvika 99.96% (Tafura S9). Simba re "activation" rakaverengerwa i88.4 kJ/mol, rinoenzana nesimba re "activation" re "noble metal catalysts" (Mufananidzo S31 neTafura S10).
Pamusoro pezvo, takaenzanisa zvimwe zvinhu zvakasiyana-siyana zvinokonzera kusvibiswa kweasidhi yeformic pasi pemamiriro akafanana (Mufananidzo 4c, matafura S11 naS12). Sezvakaratidzwa muMufananidzo 3c, mwero wekugadzirwa kwegasi weCo-SAs/NPs@NC-950 unopfuura wezvinhu zvinonyanya kuzivikanwa zvesimbi dzesimbi dzakasiyana-siyana uye wakakwira ka15 ne15 kupfuura we5% Pd/C yekutengeserana uye 5% Pd/C, zvichiteerana, ne10 kamwe chete. % Pt/C catalyst.
Chinhu chakakosha pakushandiswa kwezvishandiso zve (de)hydrogenation catalysts ndiko kugadzikana kwazvo. Nokudaro, kuyedza kwakatevedzana kwekushandisa Co-SAs/NPs@NC-950 kwakaitwa. Sezvakaratidzwa muMufananidzo 4 d, basa rekutanga uye kusarudzwa kwezvinhu zvakaramba zvisina kuchinja mukati menguva shanu dzakatevedzana (onawo Tafura S13). Miedzo yenguva refu yakaitwa uye kugadzirwa kwegasi kwakawedzera mumutsara kwemaawa makumi manomwe nemaviri (Mufananidzo S32). Kuwanda kwecobalt muCo-SA/NPs@NC-950 yakashandiswa kwaive 2.5 wt%, iyo yaive pedyo zvikuru neyecatalyst itsva, zvichiratidza kuti pakanga pasina leaching iri pachena yecobalt (Tafura S14). Hapana kuchinja kwemavara kana kuunganidzwa kwezvidimbu zvesimbi kwakaonekwa pamberi uye mushure mekuita (Mufananidzo S33). AC-HAADF-STEM neEDS zvezvinhu zvakashandiswa mukuyedza kwenguva refu zvakaratidza kuchengetedza uye kupararira kwakafanana kwenzvimbo dzekupararira kweatomu uye hapana shanduko huru dzechimiro (Mifananidzo S34 neS35). Mapoka eCo0 neCo-N achiripo muXPS, zvichiratidza kuti Co-NPs nenzvimbo dzesimbi dzakasiyana-siyana dziripo, izvo zvinosimbisawo kugadzikana kweCo-SAs/NPs@NC-950 catalyst (Mufananidzo S36).
Kuti tizive nzvimbo dzinonyanya kushanda dzinokonzera kudonha kweasidhi yeformic acid, zvinhu zvakasarudzwa zvine centre imwe chete yesimbi (CoN2C2) kana Co NP zvakagadzirwa zvichibva pane zvidzidzo zvekare17. Kurongeka kwebasa rekubvisa hydrogen yeformic acid rakaonekwa pasi pemamiriro akafanana ndiCo-SAs/NPs@NC-950 > Co SA > Co NP (Tafura S15), zvichiratidza kuti nzvimbo dzeCoN2C2 dzakapararira neatomu dzinoshanda kupfuura NPs. Kinetics ye reaction inoratidza kuti kushanduka kwehydrogen kunotevera kinetics ye reaction yekutanga, asi materu ema curves akati wandei pane cobalt content akasiyana haana kufanana, zvichiratidza kuti kinetics haingotsamiri pa formic acid chete, asiwo pane active site (Mufananidzo 2). C37). Zvimwe zvidzidzo zve kinetic zvakaratidza kuti, tichifunga nezvekushaikwa kwe cobalt metal peaks mu X-ray diffraction analysis, kinetic order ye reaction maererano ne cobalt content yakawanikwa iri 1.02 pamazinga akaderera (pasi pe2.5%), zvichiratidza kupararira kwakafanana kwe monoatomic cobalt centers. main. nzvimbo inoshanda (mifananidzo S38 naS39). Kana huwandu hweCo particles hwasvika 2.7%, r inowedzera kamwe kamwe, zvichiratidza kuti nanoparticles dzinoshanda zvakanaka nemaatomu ega ega kuti dziwane basa rakawanda. Sezvo huwandu hweCo particles huchiwedzera, curve yacho inova isina kurongeka, iyo inobatanidzwa nekuwedzera kwehuwandu hwenanoparticles uye kudzikira kwenzvimbo dzemonatomic. Saka, kuvandudzwa kweLC dehydrogenation performance yeCo-SA/NPs@NC-950 kunobva mukushanda pamwe chete kwenzvimbo dzesimbi dzega dzega uye nanoparticles.
Chidzidzo chakadzama chakaitwa uchishandisa in situ diffuse reflectance Fourier transform (in situ DRIFT) kuti uone reaction intermediates mukuita. Mushure mekudziya samples kune tembiricha dzakasiyana dzereaction mushure mekuwedzera formic acid, seti mbiri dzema frequency dzakaonekwa (Mufananidzo 5a). Ma peak matatu eHCOOH* anoonekwa pa1089, 1217 uye 1790 cm-1, ayo anokonzerwa ne out-of-plane CH π (CH) stretching vibration, CO ν (CO) stretching vibration uye C=O ν (C=O) stretching vibration, 54, 55 zvichiteerana. Imwe seti yema peaks pa1363 uye 1592 cm-1 inoenderana ne symmetric OCO vibration νs(OCO) uye asymmetric OCO stretching vibration νas(OCO)33.56 HCOO*, zvichiteerana. Sezvo reaction ichienderera mberi, ma peaks emhando dzeHCOOH* neHCOO* anonyangarika zvishoma nezvishoma. Kazhinji, kuora kwe formic acid kunosanganisira matanho matatu makuru: (I) kunyudzwa kwe formic acid panzvimbo dzinoshanda, (II) kubviswa kweH kuburikidza nenzira ye formate kana carboxylate, uye (III) kusanganiswa kwe H mbiri dzakanyudzwa kuti dzigadzire hydrogen. HCOO* ne COOH* ndizvo zvinhu zvakakosha pakusarudza nzira dze formate kana carboxylate, zvichiteerana57. Tichishandisa sisitimu yedu ye catalytic, chete HCOO* peak ndiyo yakaonekwa, zvichiratidza kuti kuora kwe formic acid kunoitika chete kuburikidza nenzira ye formic acid58. Zvakafanana zvakaitwa patembiricha yakaderera ye78 °C ne88 °C (mufananidzo S40).
Maonero eDRIFT eHCOOH dehydrogenation aripo paCo-SAs/NPs@NC-950 uye b Co SAs. Ngano iyi inoratidza nguva dzekuita panzvimbo. c Kuchinja kwehuwandu hwegasi hunogadzirwa uchishandisa ma reagents akasiyana-siyana ekunyora ma isotope nekufamba kwenguva. d Kinetic isotope effect data.
Kuedza kwakafanana kweDRIFT kwakaitwa pazvinhu zvine chekuita neCo NP neCo SA kuti vadzidze mhedzisiro yekubatana muCo-SA/NPs@NC-950 (Mifananidzo 5 b naS41). Zvinhu zvese izvi zvinoratidza maitiro akafanana, asi hunhu hwepamusoro hweHCOOH* neHCOO* hwakachinjwa zvishoma, zvichiratidza kuti kuunzwa kweCo NPs kunochinja chimiro chemagetsi chenzvimbo yemonoatomic. Hunhu hwepamusoro hweνas(OCO) hunoonekwa muCo-SAs/NPs@NC-950 neCo SA asi kwete muCo NPs, zvichiratidzawo kuti pakati peiyo inoumbwa pakuwedzerwa kweformic acid imonodentate formic acid yakatarisana nepamusoro pemunyu. uye inonamirwa paSA senzvimbo inoshanda 59. Zvakakosha kuziva kuti kuwedzera kukuru kwekuzunguzika kwehunhu hwepamusoro hwepamusoro hweπ(CH) uye ν(C = O) kwakaonekwa, izvo zvinoita sekunge zvakakonzera kukanganisa kweHCOOH* uye zvakaita kuti reaction iite nyore. Nekuda kweizvozvo, hunhu hwepamusoro hweHCOOH* neHCOO* muCo-SAs/NPs@NC hwakapotsa hwanyangarika mushure memaminitsi maviri ekuita, izvo zvinokurumidza kupfuura zve monometallic (maminitsi matanhatu) uye nanoparticle-based catalysts (maminitsi gumi nemaviri). . Mhedzisiro iyi yese inosimbisa kuti nanoparticle doping inowedzera adsorption uye activation ye intermediates, nokudaro ichikurumidzisa maitiro akataurwa pamusoro apa.
Kuti tinyatsoongorora nzira ye reaction uye kuona danho rekuona mwero (RDS), KIE effect yakaitwa paine Co-SAs/NPs@NC-950. Pano, ma isotopes akasiyana e formic acid akadai seHCOOH, HCOOD, DCOOH neDCOOD anoshandiswa muzvidzidzo zveKIE. Sezvakaratidzwa muMufananidzo 5c, mwero we dehydrogenation unoderera nenzira inotevera: HCOOH > HCOOD > DCOOH > DCOOD. Pamusoro pezvo, kukosha kweKHCOOH/KHCOOD, KHCOOH/KDCOOH, KHCOOD/KDCOOD neKDCOOH/KDCOOD kwakaverengerwa se1.14, 1.71, 2.16 uye 1.44, zvichiteerana (Mufananidzo 5d). Saka, kutsemuka kweCH bond muHCOO* kunoratidza kH/kD values ​​​​>1.5, zvichiratidza mhedzisiro huru yekinetic60,61, uye zvinoita sekunge inomiririra RDS yeHCOOH dehydrogenation paCo-SAs/NPs@NC-950.
Pamusoro pezvo, kuverenga kweDFT kwakaitwa kuti kunzwisise mhedzisiro ye doped nanoparticles pabasa reCo-SA. MaCo-SAs/NPs@NC neCo-SA models akavakwa zvichibva pakuyedza kwakaratidzwa uye mabasa ekare (Mifananidzo 6a neS42)52,62. Mushure mekugadzirisa geometric, maCo6 nanoparticles madiki (CoN2C2) akabatana nemayuniti emonoatomic akaonekwa, uye kureba kweCo-C neCo-N bond muCo-SA/NPs@NC kwakaonekwa kuva 1.87 Å ne1.90 Å, zvichiteerana. , izvo zvinoenderana nemhedzisiro yeXAFS. Calculated partial density of states (PDOS) inoratidza kuti single Co metal atomu ne nanoparticle composite (Co-SAs/NPs@NC) zvinoratidza hybridization yakakwira pedyo neFermi level zvichienzaniswa neCoN2C2, zvichikonzera HCOOH. Kutamiswa kwemaerekitironi kwakaora kunoshanda zvakanyanya (Mifananidzo 6b neS43). Nzvimbo dze d-band dzinoenderana dzeCo-SAs/NPs@NC neCo-SA dzakaverengerwa kuva -0.67 eV uye -0.80 eV, zvichiteerana, pakati padzo kuwedzera kweCo-SAs/NPs@NC kwaive 0.13 eV, izvo zvakabatsira kuti mushure mekuunzwa kweNP, kunyudzwa kwezvikamu zveHCOO* nechimiro chemagetsi chakagadziriswa cheCoN2C2 kunoitika. Musiyano muhuwandu hwechaji unoratidza gore guru remaerekitironi rakakomberedza block yeCoN2C2 ne nanoparticle, zvichiratidza kudyidzana kwakasimba pakati pazvo nekuda kwekuchinjana kwemaerekitironi. Pamwe chete neBader charge analysis, zvakaonekwa kuti atomically dispersed Co yakarasikirwa ne1.064e muCo-SA/NPs@NC uye 0.796e muCo SA (Mufananidzo S44). Mhedzisiro iyi inoratidza kuti kubatanidzwa kwe nanoparticles kunotungamira mukupera kwemaerekitironi eCo sites, zvichikonzera kuwedzera kweCo valence, izvo zvinoenderana nemhedzisiro yeXPS (Mufananidzo 6c). Hunhu hwekubatana kweCo-O hwekudzvinyirirwa kweHCOO paCo-SAs/NPs@NC neCo SA hwakaongororwa nekuverenga crystalline orbital Hamiltonian group (COHP)63. Sezvakaratidzwa muMufananidzo 6 d, kunaka kwe-negative uye kwakanaka kwe-COHP kunoenderana nemamiriro ekudzivirira kubatana uye mamiriro ekubatanidza, zvichiteerana. Simba rekubatana kweCo-O rakadzvinyirirwa neHCOO (Co-carbonylOH HCOO*) rakaongororwa nekubatanidza kukosha kwe-COHP, uko kwaive 3.51 uye 3.38 kweCo-SAs/NPs@NC neCo-SA, zvichiteerana. Kudzvinyirirwa kweHCOOH kwakaratidzawo mhedzisiro yakafanana: kuwedzera kwehuwandu hwakakosha hwe-COHP mushure mekudhakwa kwenanoparticle kunoratidza kuwedzera kwekubatana kweCo-O, nokudaro zvichikurudzira kushanda kweHCOO neHCOOH (Mufananidzo S45).
Co-SA/NPs@NC-950 chimiro che lattice. b PDOS Co-SA/NP@NC-950 uye Co SA. c 3D isosurface yemusiyano mukuwanda kwecharge kweHCOOH adsorption paCo-SA/NPs@NC-950 uye Co-SA. (d) pCOHP yemabond eCo-O akafukidzwa neHCOO paCo-SA/NPs@NC-950 (kuruboshwe) uye Co-SA (kurudyi). e Reaction pathway yeHCOOH dehydrogenation paCo-SA/NPs@NC-950 uye Co-SA.
Kuti tinzwisise zviri nani mashandiro epamusoro ekubvisa hydrogenation eCo-SA/NPs@NC, nzira yekuita uye simba zvakasarudzwa. Kunyanya, FA dehydrogenation inosanganisira matanho mashanu, anosanganisira kushandurwa kweHCOOH kuita HCOOH*, HCOOH* kuita HCOO* + H*, HCOO* + H* kuita 2H* + CO2*, 2H* + CO2* kuita 2H* + CO2, uye 2H* muH2 (Mufananidzo 6e). Simba readsorption remamorekuru eformic acid pamusoro pe catalyst kuburikidza necarboxylic oxygen rakaderera pane kuburikidza nehydroxyl oxygen (Mifananidzo S46 naS47). Zvadaro, nekuda kwesimba rakaderera, adsorbate inonyanya kupfuura OH bond cleavage kuti igadzire HCOO* pane CH bond cleavage kuti igadzire COOH*. Panguva imwe chete, HCOO* inoshandisa monodentate adsorption, iyo inokurudzira kuputsika kwezvisungo uye kuumbwa kweCO2 neH2. Mhedzisiro iyi inoenderana nekuvapo kwenhamba ye νas(OCO) mu in situ DRIFT, zvichiratidza kuti FA degradation inoitika kuburikidza nenzira ye formate mukudzidza kwedu. Zvakakosha kuziva kuti zvichienderana nekuyera kweKIE, CH dissociation ine simba re reaction rakakwirira kupfuura mamwe matanho e reaction uye inomiririra RDS. Simba re optimal Co-SAs/NPs@NC catalyst system rakaderera ne 0.86 eV pane reCo-SA (1.2 eV), izvo zvinovandudza zvakanyanya kushanda kwe dehydrogenation. Zvakakosha kuti, kuvapo kwe nanoparticles kunodzora chimiro che electronic che atomically dispersed coactive sites, izvo zvinowedzera adsorption uye activation ye intermediates, nokudaro zvichideredza reaction barrier uye kukurudzira kugadzirwa kwe hydrogen.
Muchidimbu, tinoratidza kekutanga kuti mashandiro ekugadzira hydrogen catalysts anogona kuvandudzwa zvakanyanya nekushandisa zvinhu zvine monometallic centers dzakapararira zvakanyanya uye nanoparticles diki. Pfungwa iyi yakasimbiswa nekugadzirwa kwe cobalt-based single-metal catalysts dzakagadziriswa ne nanoparticles (Co-SAs/NPs@NC), pamwe nezvinhu zvine chekuita ne single-metal centers (CoN2C2) kana Co NPs chete. Zvinhu zvese zvakagadzirwa nenzira iri nyore ye pyrolysis. Kuongorora kwechimiro kunoratidza kuti catalyst yakanakisa (Co-SAs/NPs@NC-950) ine mayuniti eCoN2C2 akapararira neatomu uye nanoparticles diki (7-8 nm) dzakasanganiswa ne nitrogen ne graphite-like carbon. Ine gasi rakanaka kwazvo rinosvika 1403.8 ml g-1 h-1 (H2:CO2 = 1.01:1), H2 uye CO selectivity ye99.96% uye inogona kuramba ichishanda kwemazuva akati wandei. Basa re catalyst iyi rinodarika basa remamwe ma catalysts eCoSA nePd/C kane ka4 neka15, zvichiteerana. Kuedza kweDRIFT munzvimbo iyi kunoratidza kuti kana tichienzanisa neCo-SA, Co-SAs/NPs@NC-950 inoratidza kudzvinyirirwa kwakasimba kweHCOO*, izvo zvakakosha panzira yeforme, uye ma nanoparticles edopant anogona kukurudzira HCOO* activation uye C-H acceleration. Kutsemuka kwebond kwakazivikanwa seRDS. Kuverengera kwedzidziso kunoratidza kuti CoNP doping inowedzera d-band centre yemaatomu eCo imwe chete ne0.13 eV kuburikidza nekudyidzana, zvichiwedzera kudzvinyirirwa kweHCOOH* neHCOO* intermediates, nokudaro zvichideredza reaction barrier kubva pa1.20 eV yeCo SA kusvika pa0 .86 eV. Ndiye ane basa rekushanda kwakanaka.
Zvakanyanya, tsvakiridzo iyi inopa mazano ekugadzira zvinhu zvitsva zvinogadzira simbi zvine atomu imwe chete uye inosimudzira kunzwisisa kwekuvandudza mashandiro ekugadzira simbi kuburikidza nekubatana kwenzvimbo dzesimbi dzine saizi dzakasiyana. Tinotenda kuti nzira iyi inogona kuwedzerwa nyore nyore kune dzimwe nzira dzakawanda dzekugadzira simbi.
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%) yakatengwa kubva kuMcLean, China. Formic acid (HCOOH, 98%) yakatengwa kubva kuRhawn, China. Zvese zvinoshandiswa zvakashandiswa zvakananga pasina kucheneswa kwekuwedzera, uye mvura yakachena kwazvo yakagadzirwa uchishandisa sisitimu yekuchenesa yakachena kwazvo. Pt/C (5% mass loading) uye Pd/C (5% mass loading) zvakatengwa kubva kuSigma-Aldrich.
Kugadzirwa kweCoZn-ZIF nanocrystals kwakaitwa zvichibva pane nzira dzakamboshandiswa kare pamwe nekumwe kuchinja23,64. Kutanga, 30 mmol Zn(NO3)2·6H2O (8.925 g) uye 3.5 mmol Co(NO3)2·6H2O (1.014 g) zvakasanganiswa zvikanyungudutswa mu300 ml yemethanol. Zvadaro, 120 mmol ye2-methylimidazole (9.853 g) yakanyungudutswa mu100 ml yemethanol ndokuwedzerwa kune mhinduro iri pamusoro. Musanganiswa wacho wakakurunga patembiricha yemumba kwemaawa makumi maviri nemana. Pakupedzisira, chigadzirwa chacho chakaparadzaniswa ne centrifugation pa6429 g kwemaminitsi gumi uye chakagezwa zvakanaka ne methanol katatu. Upfu hwakabuda hwakaomeswa mu vacuum pa60°C husiku hwese usati washandisa.
Kuti igadzire Co-SAs/NPs@NC-950, upfu hwakaoma hweCoZn-ZIF hwakaiswa pyrolysis pa950 °C kweawa imwe chete mumhepo inoyerera ye6% H2 + 94% Ar, nekupisa kwe5 °C/min. Sampuro yakazotonhodzwa kusvika patembiricha yemukamuri kuti iwane Co-SA/NPs@NC-950. Kune Co-SAs/NPs@NC-850 kana Co-SAs/NPs@NC-750, tembiricha yepyrolysis yakachinjwa kusvika 850 ne750 °C, zvichiteerana. Sampuro dzakagadzirwa dzinogona kushandiswa pasina kumwe kugadziriswa, senge acid etching.
Kuyerwa kweTEM (transmission electron microscopy) kwakaitwa paThermo Fisher Titan Themis 60-300 "cube" microscope ine image aberration corrector uye 300 kV probe shaping lens. Kuedza kweHAADF-STEM kwakaitwa uchishandisa FEI Titan G2 neFEI Titan Themis Z microscopes dzakagadzirwa nema probes uye image correctors, uye DF4 four-segment detectors. EDS elemental mapping images yakawanikwawo paFEI Titan Themis Z microscope. XPS analysis yakaitwa paX-ray photoelectron spectrometer (Thermo Fisher model ESCALAB 250Xi). XANES neEXAFS Co K-edge spectra zvakaunganidzwa uchishandisa XAFS-500 table (China Spectral Instruments Co., Ltd.). Co content yakatsanangurwa neatomic absorption spectroscopy (AAS) (PinAAcle900T). Ma spectra eX-ray diffraction (XRD) akanyorwa paX-ray diffractometer (Bruker, Bruker D8 Advance, Germany). Nitrogen adsorption isotherms akawanikwa achishandisa physical adsorption apparatus (Micromeritics, ASAP2020, USA).
Kubviswa kwehydrogen mumuviri kwakaitwa mumhepo ine argon nemhepo yakabviswa zvichienderana nenzira yakajairika yeSchlenk. Mudziyo wereaction wakabviswa wozozadzwa neargon katanhatu. Batidza mvura yecondenser woisa catalyst (30 mg) uye solvent (6 ml). Pisa mudziyo kusvika patembiricha yaunoda uchishandisa thermostat woisiya yakaenzana kwemaminitsi makumi matatu. Formic acid (10 mmol, 377 μL) yakabva yawedzerwa mumudziyo wereaction pasi peargon. Tendeudza vharuvhu yeburette ine nzira nhatu kuti uderedze kudzvanywa kwereactor, woivhara zvakare, wotanga kuyera huwandu hwegasi rinogadzirwa uchishandisa burette yemaoko (Mufananidzo S16). Mushure menguva inodiwa kuti reaction ipere, sampuro yegasi yakaunganidzwa kuti iongororwe neGC uchishandisa sirinji isina gas-tight yakacheneswa neargon.
Kuedza kweDRIFT kwakaitwa paFourier transform infrared (FTIR) spectrometer (Thermo Fisher Scientific, Nicolet iS50) yakashongedzwa ne mercury cadmium telluride (MCT) detector. Catalyst powder yakaiswa mu reaction cell (Harrick Scientific Products, Praying Mantis). Mushure mekurapa catalyst nerwizi rweAr (50 ml/min) patembiricha yemumba, sampuro yakapiswa kusvika patembiricha yakatarwa, yozoiswa mabubble neAr (50 ml/min) muHCOOH solution ndokudururwa mu in-situ reaction cell. kuti iite reaction. Model heterogeneous catalytic processes. Infrared spectra dzakanyorwa panguva dzakasiyana kubva pamasekonzi 3.0 kusvika awa imwe.
HCOOH, DCOOH, HCOOD neDCOOD zvinoshandiswa sezvinhu zvinoumba propylene carbonate. Zvimwe zvinhu zvinoenderana nemaitiro eHCOOH ekubvisa hydrogenation.
Kuverenga kwekutanga kwakaitwa uchishandisa density functional theory framework mukati meVienna Ab initio modeling package (VASP 5.4.4) 65,66. Sero re superunit rine graphene surface (5 × 5) rine transverse dimension yeinenge 12.5 Å rakashandiswa se substrate yeCoN2C2 neCoN2C2-Co6. Daro re vacuum rinodarika 15 Å rakawedzerwa kudzivirira kusangana pakati pezvikamu zve substrate zviri pedyo. Kubatana pakati pe ions nema electrons kunotsanangurwa nenzira ye projected amplified wave (PAW) method65,67. Basa rePerdue-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) ne van der Waals correction yakakurudzirwa naGrimm68,69 rakashandiswa. Zvinodiwa zve convergence ye total energy and force i10−6 eV/atomu uye 0.01 eV/Å. Kuganhurirwa kwesimba kwakaiswa pa600 eV uchishandisa grid yeMonkhorst-Pack 2 × 2 × 1 K-point. Pseudopotential inoshandiswa mumuenzaniso uyu yakavakwa kubva mu electronic configuration kuenda kuC 2s22p2 state, N 2s22p3 state, Co 3d74s2 state, H 1 s1 state, uye O 2s22p4 state. Musiyano we adsorption energy uye electron density mutsauko unoverengerwa nekubvisa simba re gas phase uye surface species kubva kusimba re adsorbed system zvichienderana ne adsorption kana interface models70,71,72,73,74. Gibbs free energy correction inoshandiswa kushandura DFT energy kuita Gibbs free energy uye inofunga nezve vibrational contributions kune entropy uye zero point energy75. Nzira ye ascending image-nudging elastic band (CI-NEB) yakashandiswa kutsvaga transition state ye reaction76.
Ruzivo rwese rwakawanikwa uye rwakaongororwa panguva yekudzidza uku rwuri muchinyorwa uye mune zvimwe zvinyorwa kana kuti runowanikwa kubva kumunyori anoenderana narwo kana zvikakumbirwa zvine musoro. Ruzivo rwechitubu rwunopihwa kuchinyorwa chino.
Kodhi yese inoshandiswa mukuenzanisa kunoenderana nechinyorwa chino inowanikwa kubva kuvanyori vanoenderana kana ikakumbirwa.
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