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Horumarinta teknoolojiyada haydarojiinku waxay ku jirtaa xudunta dhaqaalaha cagaaran. Si loo xaqiijiyo kaydinta haydarojiin, waxaa loo baahan yahay kiciyeyaasha firfircoon oo deggan ee falgalka haydarojiinaynta (de) hydrogenation. Ilaa hadda, aaggan waxaa ku badan isticmaalka biraha qaaliga ah ee qaaliga ah. Halkan, waxaan soo jeedinaynaa kiciye cusub oo qiimo jaban oo ku salaysan kobalt (Co-SAs/NPs@NC) kaas oo goobaha birta ah ee aadka u kala firirsan si isku mid ah loogu daro nanoparticles khafiif ah si loo gaaro fuuq-baxa aashitada formic oo hufan. Iyada oo la adeegsanayo agabka ugu fiican ee cutubyada CoN2C2 ee atomiga ku kala firirsan iyo nanoparticles-ka la dahaadhay ee cabbirka 7-8 nm, iyadoo la isticmaalayo propylene carbonate oo ah dareere, wax soo saar gaas oo aad u fiican oo ah 1403.8 ml g-1 h-1 ayaa la helay, mana jirin wax khasaare ah ka dib 5 wareeg. dhaqdhaqaaqa, kaas oo 15 jeer ka fiican Pd/C ganacsiga. Tijaabooyinka tijaabada goobta waxay muujinayaan in, marka la barbar dhigo atamka birta ah ee hal-halka ah iyo kaaliyayaasha nanoparticle ee la xiriira, Co-SAs/NPs@NC waxay kor u qaadaan nuugista iyo kicinta furaha monodentate-ka dhexe ee HCOO*, taasoo kor u qaadaysa kala-goynta xiriirka CH ee xiga. Xisaabinta aragtiyeed waxay muujinaysaa in isku-darka nanoparticles-ka kobalt ay kor u qaaddo beddelka xarunta d-band ee atam Co hal ah oo loo beddelo goob firfircoon, taasoo kor u qaadaysa isku-xidhka u dhexeeya carbonyl O ee dhexe ee HCOO* iyo xarunta Co, taasoo hoos u dhigaysa caqabadda tamarta.
Haydarojiin waxaa loo arkaa inay tahay side tamar muhiim u ah kala-guurka tamarta adduunka ee hadda jira waxayna noqon kartaa darawal muhiim ah oo lagu gaaro dhexdhexaadnimada kaarboon1. Sababtoo ah sifooyinkeeda jireed sida gubashada iyo cufnaanta yar, kaydinta ammaan ah oo hufan iyo gaadiidka haydarojiin waa arrimo muhiim ah oo lagu xaqiijinayo dhaqaalaha haydarojiin2,3,4. Sideyaasha haydarojiin ee dareeraha ah (LOHCs), kuwaas oo kaydiya oo sii daaya haydarojiin iyada oo loo marayo falgallada kiimikada, ayaa loo soo jeediyay xal ahaan. Marka la barbardhigo haydarojiin molecular, walxaha noocaas ah (methanol, toluene, dibenzyltoluene, iwm.) waa kuwo fudud oo ku habboon in la maareeyo5,6,7. LOHC-yada dhaqameed ee kala duwan, aashitada formic (FA) waxay leedahay sun yar (LD50: 1.8 g/kg) iyo awoodda H2 ee 53 g/L ama 4.4 wt%. Waxaa xusid mudan, FA waa LOHC-ga kaliya ee kaydin kara oo sii dayn kara haydarojiin xaalado khafiif ah iyadoo ay joogaan kiciyeyaasha ku habboon, sidaas darteed uma baahna wax soo saar tamar dibadeed oo weyn1,8,9. Xaqiiqdii, kiciyeyaal badan oo biraha sharafta leh ayaa loo sameeyay si loo baabi'iyo fuuq-baxa asiidhka formic, tusaale ahaan, kiciyeyaasha ku salaysan palladium waxay 50-200 jeer ka firfircoon yihiin kiciyeyaasha biraha ee aan qaali ahayn10,11,12. Si kastaba ha ahaatee, haddii aad tixgeliso qiimaha biraha firfircoon, tusaale ahaan, palladium wuxuu ka qaalisan yahay in ka badan 1000 jeer.
Cobalt, Raadinta kiciyeyaasha biraha saldhigga ah ee aadka u firfircoon oo deggan ayaa sii wadda inay soo jiidato xiisaha cilmi-baarayaal badan oo ku jira akadeemiyadda iyo warshadaha13,14,15.
In kasta oo kaaliyayaasha aan qaali ahayn ee ku salaysan Mo iyo Co, iyo sidoo kale nanocatalysts-ka laga sameeyay biraha sharafta leh/saldhigga ah, 14,16 loo sameeyay ka-saarista FA, joojinta tartiib tartiib ah inta lagu jiro falcelinta waa lama huraan sababtoo ah qabsashada goobaha firfircoon ee biraha, CO2, iyo H2O iyadoo la adeegsanayo protons. ama anions format (HCOO-), wasakheynta FA, isu-ururinta walxaha iyo sumowga CO ee suurtagalka ah17,18. Annaga iyo kuwa kale dhawaan waxaan tusnay in kaaliyayaasha hal-atom (SACs) oo leh goobo CoIINx oo aad u kala firirsan sida goobo firfircoon ay hagaajiyaan falcelinta iyo iska caabbinta aashitada ee ka-saarista aashitada formic marka la barbar dhigo nanoparticles17,19,20,21,22,23,24. Agabkan Co-NC, atamka N waxay u adeegaan sidii goobo waaweyn si kor loogu qaado ka-saarista FA iyadoo la xoojinayo xasilloonida qaab-dhismeedka iyada oo loo marayo isku-dubaridka atomka Co dhexe, halka atamka Co ay bixiyaan goobaha nuugista H iyo kor u qaadista xoqidda CH22, 25,26. Nasiib darro, dhaqdhaqaaqa iyo xasilloonida kiciyeyaashan ayaa weli ka fog kiciyeyaasha birta qaaliga ah ee casriga ah ee isku midka ah iyo kuwa aan kala sooca lahayn (Jaantuska 1) 13.
Tamarta xad-dhaafka ah ee ka timaadda ilo dib loo cusboonaysiin karo sida qorraxda ama dabaysha waxaa lagu soo saari karaa elektrolisis biyo ah. Haydarojiinta la soo saaro waxaa lagu kaydin karaa iyadoo la adeegsanayo LOHC, dareere ay haydarojiinta iyo hawo-qaadistuba dib u soo celin karaan. Tallaabada hawo-qaadista, badeecada kaliya waa haydarojiinta, dareeraha side-ka ahna waxaa lagu soo celiyaa xaaladdiisii ​​​​asalka ahayd oo mar kale lagu shubaa haydarojiinta. Haydarojiinta ugu dambeyntii waxaa loo isticmaali karaa saldhigyada shidaalka, baytariyada, dhismayaasha warshadaha, iyo waxyaabo kaloo badan.
Dhawaan, waxaa la soo sheegay in dhaqdhaqaaqa gudaha ee SAC-yada gaarka ah lagu xoojin karo joogitaanka atamka birta kala duwan ama goobaha birta dheeraadka ah ee ay bixiyaan nanoparticles (NPs) ama nanoclusters (NCs)27,28. Tani waxay fureysaa fursadaha nuugista iyo kicinta substrate-ka, iyo sidoo kale habaynta joomatari iyo qaab-dhismeedka elektaroonigga ah ee goobaha monatomic. Sidan, nuugista/dhaqdhaqaaqa substrate-ka waa la hagaajin karaa, taasoo bixinaysa hufnaan guud oo ka wanaagsan 29,30. Tani waxay na siinaysaa fikradda ah abuurista agabyada catalytic ee ku habboon goobaha firfircoon ee isku-dhafka ah. In kasta oo SAC-yada la hagaajiyay ay muujiyeen awood weyn oo ku jirta codsiyo catalytic ah oo ballaaran31,32,33,34,35,36, sida ugu wanaagsan ee aan ognahay, doorkooda kaydinta haydarojiin ma cadda. Arrintan awgeed, waxaan soo sheegaynaa istaraatiijiyad kala duwan oo adag oo loogu talagalay isku-darka katalystayaasha isku-dhafka ah ee ku salaysan kobalt (Co-SAs/NPs@NCs) oo ka kooban nanoparticles qeexan iyo xarumaha birta shaqsiga ah. Co-SAs/NPs@NC ee la hagaajiyay waxay muujinayaan waxqabad heer sare ah oo fuuq-baxa aashitada formic acid, kaas oo ka wanaagsan kaaliyayaasha nanostructured-ka aan sharafta lahayn (sida CoNx, atamka kobalt-ka keli ah, cobalt@NC iyo γ-Mo2N) iyo xitaa kaaliyayaasha birta sharafta leh. Astaamaha gudaha iyo xisaabinta DFT ee kaaliyayaasha firfircoon waxay muujinayaan in goobaha birta shaqsiga ah ay u adeegaan sidii goobo firfircoon, nanoparticles-ka ikhtiraacan hadda jirana waxay xoojiyaan xarunta d-band ee atamka Co, waxay kor u qaadaan nuugista iyo kicinta HCOO*, taasoo hoos u dhigaysa caqabadda tamarta ee falcelinta.
Qaab-dhismeedka imidazolate ee Zeolite (ZIFs) waa horudhac saddex-geesood ah oo si fiican loo qeexay kuwaas oo bixiya kiciyeyaasha walxaha kaarboonka ee lagu dahaadhay nitrogen (kaaliyayaasha birta-NC) si ay u taageeraan noocyada kala duwan ee biraha37,38. Sidaa darteed, Co(NO3)2 iyo Zn(NO3)2 waxay isku daraan 2-methylimidazole ee methanol si ay u sameeyaan isku-dhafka birta ee u dhigma ee xalka. Ka dib markii la centrifugation iyo qalajin, CoZn-ZIF waxaa lagu dahaadhay heerkul kala duwan (750–950 °C) jawi ah 6% H2 iyo 94% Ar. Sida lagu muujiyey jaantuska hoose, walxaha ka dhashay waxay leeyihiin astaamo goob firfircoon oo kala duwan waxaana loogu magac daray Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750 (Jaantuska 2a). ) . Indha-indheyn tijaabo ah oo gaar ah oo ku saabsan tallaabooyin muhiim ah oo ku saabsan habka isku-darka waxaa lagu faahfaahiyay Jaantusyada 1 iyo 2. C1-C3. Kala-soocidda raajada X-ray (VTXRD) heerkulka isbeddelka ah ayaa la sameeyay si loola socdo isbeddelka kiciyaha. Marka heerkulka pyrolysis-ku gaaro 650 °C, qaabka XRD si weyn ayuu isu beddelaa sababtoo ah burburka qaab-dhismeedka kiristaalka ee la kala diray ee ZIF (Jaantuska S4) 39. Marka heerkulku sii kordho, laba meelood oo ballaaran ayaa ka muuqda qaababka XRD ee Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750 20-30 ° iyo 40-50 °, taasoo ka dhigan meesha ugu sarreysa ee kaarboon aan qaab lahayn (Jaantuska C5). 40. Waxaa xusid mudan in saddex meelood oo astaamo ah oo keliya lagu arkay 44.2 °, 51.5 ° iyo 75.8 °, oo ka tirsan kobalt-ka birta ah (JCPDS #15-0806), iyo 26.2 °, oo ka tirsan kaarboon garaafig ah (JCPDS # 41-1487). Muuqaalka X-ray ee Co-SAs/NPs@NC-950 wuxuu muujinayaa jiritaanka nanoparticles-ka kobalt ee la mid ah graphite-ka ee ku jira catalyst41,42,43,44. Muuqaalka Raman wuxuu muujinayaa in Co-SAs/NPs@NC-950 ay u muuqato inay leedahay meelaha ugu sarreeya D iyo G oo ka xoog badan oo ka cidhiidhisan muunadaha kale, taasoo muujinaysa heer sare oo garaafis ah (Jaantuska S6). Intaa waxaa dheer, Co-SAs/NPs@NC-950 waxay muujinaysaa bedka dusha sare ee Brunner-Emmett-Taylor (BET) iyo mugga daloolka (1261 m2 g-1 iyo 0.37 cm3 g-1) marka loo eego muunadaha kale, ZIF-yaduna badankood waa walxo NC ah oo laga soocay (Jaantuska S7 iyo Shaxda S1). Baaritaanka nuugista atomka (AAS) wuxuu muujinayaa in maadada kobalt ee Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@ ay tahay 2.69 wt.%, 2.74 wt.% iyo 2.73 wt.%. NC-750 siday u kala horreeyaan (Jadwalka S2). Qodobbada Zn ee Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750 ayaa si tartiib tartiib ah u kordha, taas oo loo aaneynayo hoos u dhaca iyo isbeddelka unugyada Zn. Kordhinta heerkulka pyrolysis (Zn, barta karkaraya = 907 °C) 45.46. Falanqaynta walxaha (EA) waxay muujisay in boqolkiiba N ay hoos u dhacdo marka heerkulka pyrolysis uu sii kordho, iyo heerka O ee sare waxaa laga yaabaa inuu sabab u yahay nuugista O2 molecular ka soo gaarista hawada. (Jadwalka S3). Marka la eego tiro gaar ah oo kobalt ah, nanoparticles iyo coatoms go'doonsan ayaa wada nool, taasoo keentay koror weyn oo ku yimaada dhaqdhaqaaqa kiciyaha, sida hoos looga hadlay.
Jaantuska jaantuska ee isku-darka Co-SA/NPs@NC-T, halkaas oo T ay tahay heerkulka pyrolysis (°C). b Sawirka TEM. c Sawirka Co-SAs/NPs@NC-950 AC-HAADF-STEM. Atomyada hal-Co waxaa lagu calaamadeeyay goobo cas. d spectrum EDS ee Co-SA/NPs@NC-950.
Si gaar ah, mikroskoobka elektaroonigga gudbinta (TEM) wuxuu muujiyay jiritaanka nanoparticles kala duwan oo kobalt ah (NPs) oo leh celcelis ahaan cabbirkiisu yahay 7.5 ± 1.7 nm oo keliya Co-SAs/NPs@NC-950 (Jaantusyada 2 b iyo S8). Nanoparticles-kan waxaa lagu dahaadhay kaarboon graphite u eg oo lagu dahaadhay nitrogen. Kala fogaanshaha shabagga ee 0.361 iyo 0.201 nm waxay u dhigantaa walxaha kaarboon garaafiga ah (002) iyo Co (111) ee birta ah, siday u kala horreeyaan. Intaa waxaa dheer, mikroskoobka elektaroonigga gudbinta sawirka geeska sare ee la saxay ee annular-aberration-saxaya ee sawir-gacmeedka mugdiga ah ee annular-madow (AC-HAADF-STEM) wuxuu shaaca ka qaaday in Co NPs ee Co-SAs/NPs@NC-950 ay ku hareeraysan yihiin kobalt atomi ah oo badan (Jaantuska 2c). Si kastaba ha ahaatee, kaliya atamka kobalt ee atomi ahaan lagu kala firdhiyey ayaa lagu arkay taageerada labada muunadood ee kale (Jaantuska S9). Sawirka HAADF-STEM ee kala firdhisan tamarta (EDS) wuxuu muujinayaa qaybinta isku midka ah ee C, N, Co iyo Co NPs-ka kala soocan ee Co-SAs/NPs@NC-950 (Jaantuska 2d). Dhammaan natiijooyinkan waxay muujinayaan in xarumaha Co ee kala firdhisan atomiga iyo nanoparticles-ka lagu dahaadhay kaarboon graphite-ka u eg N-doped si guul leh loogu dhejiyay substrate-ka NC ee Co-SAs/NPs@NC-950, halka xarumaha birta ee go'doonsan oo keliya.
Xaaladda qiimaha iyo halabuurka kiimikada ee agabka la helay waxaa lagu bartay sawir-qaadista sawir-qaadista X-ray (XPS). Jaantuska XPS ee saddexda katalis ayaa muujiyay jiritaanka walxaha Co, N, C iyo O, laakiin Zn wuxuu ku jiray oo keliya Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750 (Jaantuska 2). ). C10). Marka heerkulka pyrolysis uu kordho, wadarta guud ee nitrogen-ka ayaa hoos u dhacda marka noocyada nitrogen ay noqdaan kuwo aan degganayn oo ay u burburaan gaasaska NH3 iyo NOx heerkul sare (Jadwalka S4) 47. Sidaa darteed, wadarta guud ee kaarboonka ayaa si tartiib tartiib ah uga korodhay Co-SAs/NPs@NC-750 una gudubtay Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-950 (Jaantusyada S11 iyo S12). Muunada pyrolyzed heerkulka sare waxay leedahay qayb hoose oo ka mid ah atamka nitrogen, taasoo la macno ah in tirada sideyaasha NC ee Co-SAs/NPs@NC-950 ay tahay inay ka yar tahay tan muunadaha kale. Tani waxay keenaysaa in sintering xooggan lagu sameeyo walxaha kobalt. Jaantuska O1s wuxuu muujinayaa laba meelood oo C=O ah (531.6 eV) iyo C–O (533.5 eV), siday u kala horreeyaan (Jaantuska S13) 48. Sida ku cad Jaantuska 2a, spectrum-ka N1s waxaa lagu xallin karaa afar meelood oo astaamo ah oo ah pyridine nitrogen N (398.4 eV), pyrrole N (401.1 eV), graphite N (402.3 eV) iyo Co-N (399.2 eV). Xidhmooyinka Co-N waxay ku jiraan dhammaan saddexda muunadood, taasoo muujinaysa in qaar ka mid ah atamka N ay isku xiran yihiin goobaha monometallic, laakiin astaamaha ayaa si weyn u kala duwan49. Codsiga heerkulka pyrolysis-ka sare wuxuu si weyn u yareyn karaa waxa ku jira noocyada Co-N laga bilaabo 43.7% Co-SA/NPs@NC-750 ilaa 27.0% Co-SAs/NPs@NC-850 iyo Co 17.6%@ NC-950. ee -CA/NPs, taas oo u dhiganta kororka ku jira C (Jaantuska 3a), taasoo muujinaysa in tirada isku-dubaridka Co-N ay isbeddeli karto oo qayb ahaan lagu beddeli karo atamka C50. Jaantuska Zn 2p wuxuu muujinayaa in curiyahani uu inta badan ku jiro qaabka Zn2+. (Jaantuska S14) 51. Jaantuska Co 2p wuxuu muujinayaa laba meelood oo caan ah oo ah 780.8 iyo 796.1 eV, kuwaas oo loo aaneynayo Co 2p3/2 iyo Co 2p1/2, siday u kala horreeyaan (Jaantuska 3b). Marka la barbardhigo Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750, meesha ugu sarreysa ee Co-N ee Co-SAs/NPs@NC-950 waxaa loo wareejiyay dhinaca togan, taasoo muujinaysa in atamka Co ee keliya ee dusha sare -SAs/NPs@NC-950 uu leeyahay heer sare oo ah yaraanta elektarooniga, taasoo keenta xaalad oksaydh oo sareysa. Waxaa xusid mudan in Co-SAs/NPs@NC-950 oo keliya ay muujiyeen heerka ugu sarreeya ee kobalt eber-valent (Co0) oo daciif ah 778.5 eV, taasoo caddaynaysa jiritaanka nanoparticles-ka ka dhashay isku-darka kobalt SA heerkulka sare.
a N 1s iyo b Co 2p spectra ee Co-SA/NPs@NC-T. c XANES iyo d FT-EXAFS spectra ee Co-K-gees ee Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750. e Jaantusyada qaab-dhismeedka WT-EXAFS ee Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850, iyo Co-SAs/NPs@NC-750. f FT-EXAFS qalooca ku habboon ee Co-SA/NPs@NC-950.
Dabadeed, baaritaanka nuugista raajada X-ray ee waqtiga xiran (XAS) ayaa loo isticmaalay in lagu falanqeeyo qaab-dhismeedka elektaroonigga ah iyo jawiga isku-dubaridka ee noocyada Co ee muunadda la diyaariyey. Heerarka valence ee Cobalt ee qaab-dhismeedka Co-SAs/NPs@NC-950, Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750 Edge ayaa lagu muujiyay nuugista raajada X-ray ee goobta u dhow ee muuqaalka geeska Co-K (XANES). Sida lagu muujiyey Jaantuska 3c, nuugista u dhow geeska saddexda muunad waxay ku taal inta u dhaxaysa foils-ka Co iyo CoO, taasoo muujinaysa in xaaladda valence ee noocyada Co ay u dhaxayso 0 ilaa +253. Intaa waxaa dheer, waxaa la arkay u gudubka tamarta hoose laga bilaabo Co-SAs/NPs@NC-950 ilaa Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750, taasoo muujinaysa in Co-SAs/NPs@NC-750 uu leeyahay xaalad oksaydh oo hoose. Kala-horjeedka. Sida laga soo xigtay natiijooyinka isku-dhafka toosan, xaaladda isku-dhafka ah ee Co-SAs/NPs@NC-950 waxaa lagu qiyaasay inay tahay +0.642, taasoo ka hooseysa xaaladda isku-dhafka ah ee Co-SAs/NPs@NC-850 (+1.376). Co-SA/NP @NC-750 (+1.402). Natiijooyinkani waxay muujinayaan in celceliska heerka oksaydhka ee walxaha kobalt ee Co-SAs/NPs@NC-950 uu si weyn hoos ugu dhacay, taas oo la jaanqaadaysa natiijooyinka XRD iyo HADF-STEM waxaana lagu sharxi karaa wada noolaanshaha nanoparticles-ka kobalt iyo kobalt-ka keli ah. . Atomyada Co 41. Qaab-dhismeedka nuugista raajada X-ray ee qaabka fine (FT-EXAFS) ee Co-geel wuxuu muujinayaa in meesha ugu sarreysa ee 1.32 Å ay ka tirsan tahay qolofka Co-N/Co-C, halka waddada kala firdhinta ee Co-Co birta ah ay tahay 2.18 oo keliya Co-SAs Å oo laga helo /NPs@NC-950 (Jaantuska 3d). Intaa waxaa dheer, sawirka qaab-dhismeedka isbeddelka hirarka (WT) wuxuu muujinayaa xoogga ugu badan ee 6.7 Å-1 oo loo aaneynayo Co-N/Co-C, halka Co-SAs/NPs@NC-950 oo keliya uu muujinayo xoogga ugu badan ee loo aaneynayo 8.8. Xoogga ugu badan ee ugu badan wuxuu ku jiraa Å−1 xiriirka Co-Co (Jaantuska 3e). Intaa waxaa dheer, falanqaynta EXAFS ee uu sameeyay kireystaha ayaa muujisay in heerkulka pyrolysis-ka ee 750, 850 iyo 950 °C, lambarrada isku-dubaridka Co-N ay ahaayeen 3.8, 3.2 iyo 2.3, siday u kala horreeyaan, lambarrada isku-dubaridka Co-C-na waxay ahaayeen 0. 0.9 iyo 1.8 (Jaantuska 3f, S15 iyo Shaxda S1). Si gaar ah, natiijooyinka ugu dambeeyay waxaa loo aanayn karaa joogitaanka cutubyada CoN2C2 ee atomiga ku kala firirsan iyo nanoparticles-ka ee Co-SAs/NPs@NC-950. Taas bedelkeeda, Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750, kaliya cutubyada CoN3C iyo CoN4 ayaa jira. Waa iska cad in marka heerkulka pyrolysis-ka uu sii kordho, atamka N ee cutubka CoN4 si tartiib tartiib ah loogu beddelo atamka C, iyo isku-darka kobalt CA si ay u sameeyaan nanoparticles.
Xaaladaha falcelinta ee hore loo bartay ayaa loo isticmaalay in lagu barto saameynta xaaladaha diyaarinta ee sifooyinka agabyada kala duwan (Jaantuska S16)17,49. Sida ku cad Jaantuska 4 a, dhaqdhaqaaqa Co-SAs/NPs@NC-950 ayaa si weyn uga sarreeya kan Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750. Si gaar ah, saddexda muunadood ee Co ee la diyaariyey waxay muujiyeen waxqabad ka sarreeya marka la barbar dhigo kiciyeyaasha biraha qaaliga ah ee ganacsiga caadiga ah (Pd/C iyo Pt/C). Intaa waxaa dheer, muunadaha Zn-ZIF-8 iyo Zn-NC waxay ahaayeen kuwo aan firfircoonayn oo ku wajahan fuuq-baxa aashitada formic, taasoo muujinaysa in walxaha Zn aysan ahayn goobo firfircoon, laakiin saameyntooda ay ku leeyihiin dhaqdhaqaaqa waa mid aan la taaban karin. Intaa waxaa dheer, dhaqdhaqaaqa Co-SAs/NPs@NC-850 iyo Co-SAs/NPs@NC-750 waxaa lagu sameeyay pyrolysis labaad heerkul ah 950°C muddo 1 saac ah, laakiin wuxuu ka hooseeyay kan Co-SAs/NPs@NC-750. @NC-950 (Jaantuska S17). Astaamaha qaab-dhismeedka ee agabkan waxay muujiyeen joogitaanka nanoparticles-ka Co ee muunadaha dib loo habeeyey, laakiin aagga dusha sare ee gaarka ah ee hooseeya iyo maqnaanshaha kaarboonka u eg graphite ayaa sababay dhaqdhaqaaq hooseeya marka la barbar dhigo Co-SAs/NPs@NC-950 (Jaantuska S18–S20). Dhaqdhaqaaqa muunadaha leh xaddi kala duwan oo hordhaca Co ah ayaa sidoo kale la barbar dhigay, iyadoo dhaqdhaqaaqa ugu sarreeya lagu muujiyay 3.5 mol oo lagu daray (Jadwalka S6 iyo Jaantuska S21). Waa iska cad in sameynta xarumaha birta kala duwan ay saameeyaan waxa ku jira hydrogen ee jawiga pyrolysis iyo waqtiga pyrolysis-ka. Sidaa darteed, agabka kale ee Co-SAs/NPs@NC-950 ayaa lagu qiimeeyay dhaqdhaqaaqa fuuq-baxa aashitada formic. Dhammaan agabku waxay muujiyeen waxqabad dhexdhexaad ah ilaa mid aad u wanaagsan; si kastaba ha ahaatee, midkoodna kama fiicnayn Co-SAs/NPs@NC-950 (Jaantusyada S22 iyo S23). Astaamaha qaab-dhismeedka ee walaxda ayaa muujiyay in iyadoo la kordhinayo waqtiga pyrolysis-ka, nuxurka boosaska monoatomic Co-N ayaa si tartiib tartiib ah u yaraada sababtoo ah isku-darka atamka birta ah ee nanoparticles-ka, taas oo sharraxaysa farqiga u dhexeeya dhaqdhaqaaqa u dhexeeya muunadaha leh waqtiga pyrolysis-ka ee 100-2000. farqiga. 0.5 saacadood, 1 saac, iyo 2 saacadood (Jaantusyada S24–S28 iyo Shaxda S7).
Shaxda mugga gaaska iyo waqtiga la helay intii lagu jiray fuuq-baxa isku-darka shidaalka iyadoo la adeegsanayo kaaliyayaasha kala duwan. Xaaladaha falcelinta: PC (10 mmol, 377 μl), kaaliyayaasha (30 mg), PC (6 ml), Tback: 110 °C, Tactical: 98 °C, 4 qaybood b Co-SAs/NPs@NC-950 (30 mg), dareereyaal kala duwan. c Isbarbardhigga heerarka isbeddelka gaaska ee kaaliyayaasha kala duwan ee dareereyaasha dabiiciga ah ee 85-110 °C. d Tijaabada dib-u-warshadaynta Co-SA/NPs@NC-950. Xaaladaha falcelinta: FA (10 mmol, 377 µl), Co-SAs/NPs@NC-950 (30 mg), dareere (6 ml), Tset: 110 °C, Tactual: 98 °C, wareeg kasta oo falcelin ah wuxuu socdaa hal saac. Baararka qaladku wuxuu matalaa leexashada caadiga ah ee laga xisaabiyay saddex tijaabo oo firfircoon.
Guud ahaan, waxtarka kaaliyayaasha ka-hortagga fuuq-baxa ee FA waxay aad ugu tiirsan yihiin xaaladaha falgalka, gaar ahaan dareeraha loo isticmaalay8,49. Marka biyaha loo isticmaalayo sidii dareere, Co-SAs/NPs@NC-950 waxay muujisay heerka falcelinta ugu sarreysa ee bilowga ah, laakiin joojinta ayaa dhacday, laga yaabee inay sabab u tahay protons ama H2O18 oo ku jira goobaha firfircoon. Tijaabada kaaliyayaasha ee dareerayaasha dabiiciga ah sida 1,4-dioxane (DXA), n-butyl acetate (BAC), toluene (PhMe), triglyme iyo cyclohexanone (CYC) sidoo kale ma muujin wax horumar ah, iyo propylene carbonate (PC) ) (Jaantuska 4b iyo Shaxda S8). Sidoo kale, waxyaabaha lagu daro sida triethylamine (NET3) ama sodium formate (HCCONa) ma lahayn saameyn wanaagsan oo dheeraad ah oo ku saabsan waxqabadka kaaliyayaasha (Jaantuska S29). Xaaladaha falcelinta ugu wanaagsan, wax soo saarka gaaska wuxuu gaaray 1403.8 mL g−1 h−1 (Jaantuska S30), kaas oo si weyn uga sarreeyay dhammaan kaaliyayaasha Co ee hore loo soo sheegay (oo ay ku jiraan SAC17, 23, 24). Tijaabooyin kala duwan, marka laga reebo falcelinta biyaha iyo waxyaabaha lagu daro qaab-dhismeedka, waxaa la helay xulashooyin kala duwan oo ah dehydrogenation iyo fuuq-baxa ilaa 99.96% (Jadwalka S9). Tamarta kicinta ee la xisaabiyay waa 88.4 kJ/mol, taas oo la barbar dhigi karo tamarta kicinta ee kaaliyayaasha birta sharafta leh (Jaantuska S31 iyo Shaxda S10).
Intaa waxaa dheer, waxaan isbarbar dhignay tiro ka mid ah kiciyeyaasha kale ee kala duwan ee loogu talagalay fuuq-baxa aashitada formic xaaladaha la midka ah (Jaantuska 4c, jadwalka S11 iyo S12). Sida ku cad Jaantuska 3c, heerka wax soo saarka gaaska ee Co-SAs/NPs@NC-950 wuxuu ka badan yahay kaaliyayaasha birta ee ugu caansan ee kala duwan waana 15 iyo 15 jeer ka sarreeya kan ganacsiga 5% Pd/C iyo 5% Pd/C, siday u kala horreeyaan, 10 jeer. % Pt/C kaaliyayaasha.
Astaan ​​muhiim ah oo ka mid ah codsi kasta oo wax ku ool ah oo ka mid ah kiciyeyaasha hawo-mareenka (de) waa xasilloonidooda. Sidaa darteed, taxane ah tijaabooyin dib-u-warshadayn ah oo la adeegsanayo Co-SAs/NPs@NC-950 ayaa la sameeyay. Sida ku cad Jaantuska 4 d, dhaqdhaqaaqa bilowga ah iyo xulashada walaxda ayaa isbeddelay shan jeer oo isku xigta (fiiri Shaxda S13). Tijaabooyin muddo dheer ah ayaa la sameeyay wax soo saarka gaaskana si toosan ayuu u kordhay 72 saacadood (Jaantuska S32). Waxyaabaha ku jira kobalt ee Co-SA/NPs@NC-950 ee la isticmaalay waxay ahaayeen 2.5 wt%, taas oo aad ugu dhowayd kan kobalt ee cusub, taasoo muujinaysa inaysan jirin wax cad oo ka soo baxaya kobalt (Jadwalka S14). Isbeddel midab ama isku-darka walxaha birta ah lama arag ka hor iyo ka dib falcelinta (Jaantuska S33). AC-HAADF-STEM iyo EDS ee agabka lagu dabaqay tijaabooyinka muddada dheer waxay muujiyeen haynta iyo kala-fidinta isku midka ah ee goobaha kala-fidinta atomiga iyo inaysan jirin isbeddello qaab-dhismeed oo muhiim ah (Jaantusyada S34 iyo S35). Meelaha ugu sarreeya ee astaamaha Co0 iyo Co-N ayaa weli ka jira XPS, taasoo caddaynaysa wada noolaanshaha Co NPs iyo goobaha birta gaarka ah, taas oo sidoo kale xaqiijinaysa xasilloonida Co-SAs/NPs@NC-950 catalyst (Jaantuska S36).
Si loo aqoonsado goobaha ugu firfircoon ee mas'uulka ka ah fuuq-baxa aashitada formic, agab la xushay oo leh hal xarun bir ah (CoN2C2) ama Co NP ayaa la diyaariyey iyadoo lagu saleynayo daraasado hore17. Nidaamka dhaqdhaqaaqa fuuq-baxa aashitada formic ee lagu arkay xaalado isku mid ah waa Co-SAs/NPs@NC-950 > Co SA > Co NP (Jadwalka S15), taasoo tilmaamaysa in goobaha CoN2C2 ee atomiga ah ay ka firfircoon yihiin NPs. Kinetics-ka falcelinta waxay muujinayaan in horumarka haydarojiinku uu raaco kinetics-ka falcelinta heerka koowaad, laakiin jaranjarooyinka dhowr qaloocood ee ku jira waxyaabaha kala duwan ee kobalt ma aha isku mid, taasoo muujinaysa in kinetics-ku aysan ku xirnayn oo keliya aashitada formic, laakiin sidoo kale goobta firfircoon (Jaantuska 2). C37). Daraasado dheeraad ah oo kinetic ah ayaa muujiyay in, marka la eego maqnaanshaha meelaha ugu sarreeya ee birta kobalt ee falanqaynta kala-soocidda X-ray, nidaamka kinetic-ga ee falcelinta marka loo eego waxyaabaha kobalt ah waxaa la ogaaday inay tahay 1.02 heerarka hoose (ka yar 2.5%), taasoo muujinaysa qaybinta ku dhawaad ​​​​isku mid ah ee xarumaha kobalt monoatomic. ugu weyn. goobta firfircoon (Jaantusyada S38 iyo S39). Marka nuxurka walxaha Co uu gaaro 2.7%, r si lama filaan ah ayuu u kordhaa, taasoo muujinaysa in nanoparticles-ku si fiican ula falgalaan atomyada shaqsiga ah si ay u helaan dhaqdhaqaaq sare. Marka nuxurka walxaha Co uu sii kordho, qalooca wuxuu noqdaa mid aan toosnayn, kaas oo lala xiriiriyo kororka tirada nanoparticles-ka iyo hoos u dhaca boosaska monatomic-ka. Sidaa darteed, waxqabadka dehydrogenation-ka LC ee la hagaajiyay ee Co-SA/NPs@NC-950 wuxuu ka dhashaa dhaqanka iskaashiga ee goobaha birta shaqsiga ah iyo nanoparticles-ka.
Daraasad qoto dheer ayaa la sameeyay iyadoo la adeegsanayo in situ diffuse reflection Fourier transform (in situ DRIFT) si loo aqoonsado dhexdhexaadiyeyaasha falcelinta ee habka. Ka dib markii la kululeeyo muunadaha heerkulka falcelinta ee kala duwan ka dib markii lagu daray formic acid, laba nooc oo soo noqnoqosho ah ayaa la arkay (Jaantuska 5a). Saddex meelood oo astaamo ah oo HCOOH* ah ayaa ka muuqda 1089, 1217 iyo 1790 cm-1, kuwaas oo loo aaneynayo gariirka fidinta CH π (CH) ee ka baxsan diyaaradda, gariirka fidinta CO ν (CO) iyo gariirka fidinta C=O ν (C=O) ee ka baxsan diyaaradda, 54, 55 siday u kala horreeyaan. Qayb kale oo ah meelaha ugu sarreeya ee 1363 iyo 1592 cm-1 waxay u dhigantaa gariirka OCO ee isku-dhafan νs (OCO) iyo gariirka fidinta OCO ee aan isku-dhafanayn νas (OCO)33.56 HCOO*, siday u kala horreeyaan. Marka falcelintu socoto, meelaha ugu sarreeya ee qaraabada ah ee noocyada HCOOH* iyo HCOO* ayaa si tartiib tartiib ah u baaba'aya. Guud ahaan, kala-goynta asiidhka formic waxay ku lug leedahay saddex tallaabo oo muhiim ah: (I) nuugista asiidhka formic ee goobaha firfircoon, (II) ka saarista H iyada oo loo marayo marinka qaabaysan ama carboxylate, iyo (III) isku-darka laba H oo la nuugay si loo soo saaro haydarojiin. HCOO* iyo COOH* waa dhexdhexaadiyayaal muhiim ah oo lagu go'aaminayo marinnada qaabaysan ama carboxylate, siday u kala horreeyaan57. Iyada oo la adeegsanayo nidaamkayaga katalytic-ga, kaliya meesha ugu sarreysa ee HCOO* ee astaamaha ah ayaa soo muuqatay, taasoo muujinaysa in kala-goynta asiidhka formic ay dhacdo oo keliya iyada oo loo marayo marinka asiidhka formic58. Indha-indhayn la mid ah ayaa lagu sameeyay heerkul hoose oo ah 78 °C iyo 88 °C (Jaantuska S40).
In situ DRIFT spectra ee dehydrogenation HCOOH ee Co-SAs/NPs@NC-950 iyo b Co SAs. Halyeeygu wuxuu tilmaamayaa waqtiyada falcelinta goobta. c Kala duwanaanshaha mugga gaaska ee la soo saaro iyadoo la adeegsanayo falgalayaasha calaamadaynta isotope ee kala duwan waqti ka dib. d Xogta saameynta isotope-ka Kinetic.
Tijaabooyin la mid ah oo ku saabsan goobta ayaa lagu sameeyay walxaha la xiriira Co NP iyo Co SA si loo barto saameynta isku-dhafka ah ee Co-SA/NPs@NC-950 (Jaantusyada 5 b iyo S41). Labada agabba waxay muujinayaan isbeddello isku mid ah, laakiin meelaha ugu sarreeya ee astaamaha HCOOH* iyo HCOO* ayaa si yar loo beddelay, taasoo muujinaysa in soo bandhigidda Co NPs ay beddesho qaab-dhismeedka elektaroonigga ah ee xarunta monoatomic-ka. Meel sare oo sifo ah νas(OCO) ayaa ka muuqata Co-SAs/NPs@NC-950 iyo Co SA laakiin aan ku jirin Co NPs, taasoo sii tilmaamaysa in dhexdhexaadka la sameeyay markii lagu daray formic acid uu yahay monodentate formic acid oo ku toosan dusha sare ee milixda diyaaradda. waxaana lagu nuugaa SA sida goobta firfircoon 59. Waxaa xusid mudan in la arkay koror weyn oo ku yimid gariirka meelaha ugu sarreeya ee astaamaha π(CH) iyo ν(C = O), taasoo si muuqata u horseeday qallooc HCOOH* oo fududeysay falcelinta. Natiijo ahaan, meelaha ugu sarreeya ee astaamaha HCOOH* iyo HCOO* ee Co-SAs/NPs@NC waxay ku dhawaad ​​​​baaba'een ka dib 2 daqiiqo oo falcelin ah, taas oo ka dhaqso badan tan monometallic (6 daqiiqo) iyo kaaliyeyaasha ku salaysan nanoparticle (12 daqiiqo). Dhammaan natiijooyinkan waxay xaqiijinayaan in daawada nanoparticle ay kor u qaaddo nuugista iyo kicinta dhexdhexaadiyeyaasha, taasoo dardar gelinaysa falcelinta kor ku xusan.
Si loo sii falanqeeyo dariiqa falcelinta loona go'aamiyo tallaabada go'aaminta heerka (RDS), saameynta KIE waxaa lagu sameeyay iyadoo ay joogaan Co-SAs/NPs@NC-950. Halkan, isotopes kala duwan oo aashitada formic ah sida HCOOH, HCOOD, DCOOH iyo DCOOD ayaa loo isticmaalaa daraasadaha KIE. Sida ku cad Jaantuska 5c, heerka fuuq-baxa ayaa hoos ugu dhacaya nidaamka soo socda: HCOOH > HCOOD > DCOOH > DCOOD. Intaa waxaa dheer, qiimaha KHCOOH/KHCOOD, KHCOOH/KDCOOH, KHCOOD/KDCOOD iyo KDCOOH/KDCOOD waxaa loo xisaabiyay 1.14, 1.71, 2.16 iyo 1.44, siday u kala horreeyaan (Jaantuska 5d). Sidaa darteed, kala-goynta xidhmooyinka CH ee HCOO* waxay muujinaysaa qiimayaasha kH/kD >1.5, taasoo muujinaysa saameyn weyn oo ku saabsan dhaqdhaqaaqa jidhka 60,61, waxayna u muuqataa inay matasho RDS ee fuuq-baxa HCOOH ee Co-SAs/NPs@NC-950.
Intaa waxaa dheer, xisaabinta DFT ayaa la sameeyay si loo fahmo saameynta nanoparticles-ka la dahaadhay ee ku leeyihiin dhaqdhaqaaqa gudaha ee Co-SA. Moodooyinka Co-SAs/NPs@NC iyo Co-SA waxaa lagu dhisay iyadoo lagu saleynayo tijaabooyinka la muujiyay iyo shaqooyinkii hore (Jaantusyada 6a iyo S42)52,62. Ka dib hagaajinta joomatari, nanoparticles-ka yar yar ee Co6 (CoN2C2) oo la nool cutubyo monoatomic ah ayaa la aqoonsaday, dhererka isku-xidhka Co-C iyo Co-N ee Co-SA/NPs@NC waxaa la go'aamiyay inay yihiin 1.87 Å iyo 1.90 Å, siday u kala horreeyaan. , taas oo la jaanqaadaysa natiijooyinka XAFS. Cufnaanta qayb ahaan ee la xisaabiyay ee xaaladaha (PDOS) waxay muujinaysaa in atamka birta Co iyo isku-darka nanoparticle-ka hal-hal ah (Co-SAs/NPs@NC) ay muujiyaan isku-dhaf sare oo u dhow heerka Fermi marka la barbar dhigo CoN2C2, taasoo keentay HCOOH. Wareejinta elektaroonigga ee burburtay ayaa ka waxtar badan (Jaantusyada 6b iyo S43). Xarumaha d-band ee u dhigma ee Co-SAs/NPs@NC iyo Co-SA waxaa loo xisaabiyay inay yihiin -0.67 eV iyo -0.80 eV, siday u kala horreeyaan, kuwaas oo ay ka mid yihiin kororka Co-SAs/NPs@NC uu ahaa 0.13 eV, kaas oo gacan ka geystay in ka dib markii la soo bandhigay NP, nuugista walxaha HCOO* iyadoo la adeegsanayo qaab-dhismeedka elektaroonigga ah ee la waafajiyay ee CoN2C2 ay dhacdo. Farqiga cufnaanta dallacaadda wuxuu muujinayaa daruur elektaroonik ah oo weyn oo ku wareegsan baloogga CoN2C2 iyo nanoparticle, taasoo muujinaysa is-dhexgal xooggan oo u dhexeeya iyaga oo ay ugu wacan tahay is-weydaarsiga elektaroonigga. Marka lagu daro falanqaynta dallacaadda Bader, waxaa la ogaaday in Co si atomi ah loo kala firdhiyey uu lumiyay 1.064e Co-SA/NPs@NC iyo 0.796e Co SA (Jaantuska S44). Natiijooyinkani waxay muujinayaan in isku-darka nanoparticles uu horseedo yaraanta elektaroonigga ee goobaha Co, taasoo keentay koror ku yimaada qiimaha Co, kaas oo la jaanqaadaya natiijooyinka XPS (Jaantuska 6c). Astaamaha isdhexgalka Co-O ee nuugista HCOO ee Co-SAs/NPs@NC iyo Co SA waxaa lagu falanqeeyay iyadoo la xisaabinayo kooxda Hamiltonian orbital crystalline (COHP)63. Sida ku cad Jaantuska 6 d, qiimayaasha taban iyo kuwa togan ee -COHP waxay u dhigmaan xaaladda ka hortagga isku xidhka iyo xaaladda isku xidhka, siday u kala horreeyaan. Xoogga isku xidhka ee Co-O oo ay nuugto HCOO (Co-carbonylO HCOO*) waxaa lagu qiimeeyay iyadoo la isku darayo qiimayaasha -COHP, kuwaas oo ahaa 3.51 iyo 3.38 Co-SAs/NPs@NC iyo Co-SA, siday u kala horreeyaan. Adkeysiga HCOOH sidoo kale wuxuu muujiyay natiijooyin la mid ah: kororka qiimaha isku dhafan ee -COHP ka dib daawaynta nanoparticle waxay muujinaysaa koror ku yimaada isku xidhka Co-O, taasoo kor u qaadaysa kicinta HCOO iyo HCOOH (Jaantuska S45).
Qaab-dhismeedka shabagga Co-SA/NPs@NC-950. b PDOS Co-SA/NP@NC-950 iyo Co SA. c Kala-soocid 3D ah oo ku saabsan farqiga cufnaanta mas'uuliyadda ee nuugista HCOOH ee Co-SA/NPs@NC-950 iyo Co-SA. (d) pCOHP oo ku saabsan xidhmooyinka Co-O oo ay HCOO ku nuugtay Co-SA/NPs@NC-950 (bidix) iyo Co-SA (midig). e Jidka falcelinta ee ka-saarista HCOOH ee Co-SA/NPs@NC-950 iyo Co-SA.
Si loo fahmo waxqabadka sare ee fuuq-baxa ee Co-SA/NPs@NC, wadada falcelinta iyo tamarta ayaa la go'aamiyay. Gaar ahaan, fuuq-baxa FA wuxuu ku lug leeyahay shan tallaabo, oo ay ku jiraan beddelka HCOOH una beddelaya HCOOH*, HCOOH* una beddelaya HCOO* + H*, HCOO* + H* una beddelaya 2H* + CO2*, 2H* + CO2* una beddelaya 2H* + CO2, iyo 2H* ee H2 (Sawirka 6e). Tamarta nuugista ee molecules-ka asiidhka formic ee dusha sare ee kiciyaha iyada oo loo marayo oksijiinta carboxylic waa ka hooseysaa iyada oo loo marayo oksijiinta hydroxyl (Sawirrada S46 iyo S47). Dabadeed, sababtoo ah tamarta hoose, adsorbate-ku wuxuu doorbidaa inuu maro kala-goynta xiriirka OH si uu u sameeyo HCOO* halkii uu ka ahaan lahaa kala-goynta xiriirka CH si uu u sameeyo COOH*. Isla mar ahaantaana, HCOO* wuxuu isticmaalaa nuugista monodentate, taas oo kor u qaadaysa jebinta xiriirka iyo sameynta CO2 iyo H2. Natiijooyinkani waxay la jaan qaadayaan joogitaanka heerka ugu sarreeya ee νas (OCO) ee ku jira DRIFT gudaha goobta, taasoo sii tilmaamaysa in burburka FA uu ka dhaco marinnada qaabaysan ee daraasaddeenna. Waa muhiim in la ogaado in sida ku cad cabbirrada KIE, kala-goynta CH waxay leedahay caqabad tamar falgal oo aad uga sarreysa tallaabooyinka kale ee falgalka waxayna u taagan tahay RDS. Caqabadda tamarta ee nidaamka kataliyaha ee ugu wanaagsan ee Co-SAs/NPs@NC waa 0.86 eV ka hooseeya kan Co-SA (1.2 eV), kaas oo si weyn u hagaajiya waxtarka guud ee fuuq-baxa. Waxaa xusid mudan, joogitaanka nanoparticles wuxuu nidaamiyaa qaab-dhismeedka elektaroonigga ah ee goobaha coactive ee atomiga ku kala firirsan, kaas oo sii xoojiya nuugista iyo kicinta dhexdhexaadiyeyaasha, taasoo hoos u dhigaysa caqabadda falgalka iyo kor u qaadista wax soo saarka hydrogen.
Marka la soo koobo, waxaan markii ugu horreysay muujineynaa in waxqabadka kicinta ee kiciyeyaasha wax soo saarka haydarojiinta si weyn loo horumarin karo iyadoo la adeegsanayo agab leh xarumo monometallic ah oo aad u baahsan iyo nanoparticles yar yar. Fikraddan waxaa lagu xaqiijiyay isku-darka kiciyeyaasha hal-birta ah ee ku salaysan kobalt oo lagu beddelay nanoparticles (Co-SAs/NPs@NC), iyo sidoo kale agabyada la xiriira oo leh xarumo bir ah oo keliya (CoN2C2) ama Co NPs. Dhammaan agabka waxaa lagu diyaariyey hab fudud oo pyrolysis hal-tallaabo ah. Falanqaynta qaab-dhismeedka waxay muujinaysaa in kiciyeyaasha ugu fiican (Co-SAs/NPs@NC-950) ay ka kooban yihiin cutubyo CoN2C2 oo atomi ahaan kala firdhisan iyo nanoparticles yar yar (7-8 nm) oo lagu dahaadhay nitrogen iyo kaarboon u eg graphite. Waxay leedahay wax soo saar gaas oo aad u fiican ilaa 1403.8 ml g-1 h-1 (H2:CO2 = 1.01:1), xulashada H2 iyo CO ee 99.96% waxayna sii wadi kartaa firfircooni joogto ah dhowr maalmood. Dhaqdhaqaaqa kicintani wuxuu ka badan yahay dhaqdhaqaaqa qaar ka mid ah kiciyeyaasha Co SA iyo Pd/C 4 iyo 15 jeer, siday u kala horreeyaan. Tijaabooyinka DRIFT ee goobta ayaa muujinaya in marka la barbar dhigo Co-SA, Co-SAs/NPs@NC-950 ay muujiyaan nuugista monodentate ee xooggan ee HCOO*, taas oo muhiim u ah waddada qaabaysan, nanoparticles-ka dopant-na waxay kor u qaadi karaan kicinta HCOO* iyo dardargelinta C-H. Kala-goynta xidhmada waxaa loo aqoonsaday RDS. Xisaabinta aragtiyeed waxay muujinaysaa in Co NP doping ay kordhiso xarunta d-band ee atamka Co-hal 0.13 eV iyada oo loo marayo isdhexgalka, taasoo kor u qaadaysa nuugista HCOOH* iyo dhexdhexaadiyeyaasha HCOO*, taasoo hoos u dhigaysa caqabadda falcelinta laga bilaabo 1.20 eV ee Co SA ilaa 0 .86 eV. Wuxuu mas'uul ka yahay waxqabad heer sare ah.
Si ballaaran, cilmi-baaristani waxay bixisaa fikrado ku saabsan naqshadeynta kiciyeyaasha birta hal-atomka cusub waxayna horumarisaa fahamka sida loo horumariyo waxqabadka kicinta iyada oo loo marayo saameynta isku-dhafka ah ee xarumaha birta ee cabbirro kala duwan. Waxaan aaminsanahay in habkan si fudud loogu fidin karo nidaamyada kale ee kicinta badan.
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%) waxaa laga soo iibsaday McLean, Shiinaha. Aashitada Formic (HCOOH, 98%) waxaa laga soo iibsaday Rhawn, Shiinaha. Dhammaan walxaha firfircoon waxaa si toos ah loo isticmaalay iyada oo aan la nadiifin dheeraad ah, biyaha ultrapure-ka ahna waxaa lagu diyaariyey nidaam nadiifin ultrapure ah. Pt/C (5% rarista tirada) iyo Pd/C (5% rarista tirada) waxaa laga soo iibsaday Sigma-Aldrich.
Isku-darka CoZn-ZIF nanocrystals waxaa lagu sameeyay iyadoo lagu saleynayo hababkii hore iyadoo wax laga beddelay 23,64. Marka hore, 30 mmol Zn(NO3)2·6H2O (8.925 g) iyo 3.5 mmol Co(NO3)2·6H2O (1.014 g) ayaa la isku qasay oo lagu milmay 300 ml oo methanol ah. Kadib, 120 mmol oo 2-methylimidazole (9.853 g) ayaa lagu milmay 100 ml oo methanol ah waxaana lagu daray xalka kor ku xusan. Isku darka waxaa lagu walaaqay heerkulka qolka muddo 24 saacadood ah. Ugu dambeyntii, badeecada waxaa lagu kala saaray centrifugation 6429 g muddo 10 daqiiqo ah waxaana si fiican loogu dhaqay methanol saddex jeer. Budada ka dhalatay waxaa lagu qalajiyey faakiyuum heerkul ah 60°C habeenkii ka hor inta aan la isticmaalin.
Si loo sameeyo Co-SAs/NPs@NC-950, budada CoZn-ZIF qalalan ayaa lagu shubay 950 °C muddo 1 saac ah iyadoo gaasku uu yahay 6% H2 + 94% Ar, iyadoo heerka kululaynta uu yahay 5 °C/daqiiqo. Kadib muunadda waxaa loo qaboojiyay heerkulka qolka si loo helo Co-SA/NPs@NC-950. Wixii Co-SAs/NPs@NC-850 ama Co-SAs/NPs@NC-750, heerkulka pyrolysis-ka waxaa loo kala duwanaa 850 iyo 750 °C, siday u kala horreeyaan. Shaybaarada la diyaariyey waxaa loo isticmaali karaa iyada oo aan la sii farsamayn, sida xoqidda aashitada.
Cabbiraadaha TEM (makroskoobka elektaroonigga gudbinta) waxaa lagu sameeyay mikroskoobka "cube" ee Thermo Fisher Titan Themis 60-300 oo lagu qalabeeyay sixitaan sawir oo aan la arki karin iyo muraayad qaabaynaysa baaritaanka 300 kV. Tijaabooyinka HAADF-STEM waxaa lagu sameeyay iyadoo la adeegsanayo mikroskoobyada FEI Titan G2 iyo FEI Titan Themis Z oo lagu qalabeeyay baaritaanno iyo saxayaal sawir, iyo qalabka ogaanshaha afar-qaybood ee DF4. Sawirada khariidaynta asaasiga ah ee EDS ayaa sidoo kale laga helay mikroskoobka FEI Titan Themis Z. Falanqaynta XPS waxaa lagu sameeyay mikroskoobka sawir-qaadaha X-ray (qaabka Thermo Fisher ESCALAB 250Xi). XANES iyo EXAFS Co K-edge spectra waxaa lagu soo ururiyay iyadoo la isticmaalayo miiska XAFS-500 (China Spectral Instruments Co., Ltd.). Waxyaabaha ku jira Co waxaa lagu go'aamiyay spectroscopy-ga nuugista atomiga (AAS) (PinAAcle900T). Muuqaallada kala-soocidda raajada (XRD) waxaa lagu duubay cabbiraha kala-soocidda raajada (Bruker, Bruker D8 Advance, Jarmalka). Kala-soocidda kala-soocidda raajada waxaa lagu helay iyadoo la adeegsanayo qalab nuugid jireed (Micromeritics, ASAP2020, USA).
Falcelinta fuuq-baxa waxaa lagu sameeyay jawi argon ah iyadoo hawada laga saarayo sida waafaqsan habka caadiga ah ee Schlenk. Weelka falgalka ayaa laga daadgureeyay oo lagu buuxiyay argon 6 jeer. Daar biyaha kondenserka oo ku dar kataliyaha (30 mg) iyo dareeraha (6 ml). Weelka ku kululee heerkulka la rabo adoo isticmaalaya heerkulbeegga oo u oggolow inuu isku dheelitirmo 30 daqiiqo. Aashitada Formic (10 mmol, 377 μL) ayaa markaa lagu daray weelka falgalka hoostiisa ee argon. Wareeji waalka burette-ka saddex-geesoodka ah si uu u yareeyo cadaadiska fal-galiyaha, dib u xidh, oo bilow cabbiraadda mugga gaaska la soo saaray iyadoo la adeegsanayo burette-ga gacanta lagu sameeyay (Jaantuska S16). Ka dib markii loo baahnaa in fal-galku dhammaado, muunad gaas ah ayaa loo ururiyay falanqaynta GC iyadoo la isticmaalayo sirinji gaas-ku-xidhan oo lagu nadiifiyay argon.
Tijaabooyinka DRIFT ee gudaha waxaa lagu sameeyay qalab cabbira Fourier transform infrared (FTIR) (Thermo Fisher Scientific, Nicolet iS50) oo lagu qalabeeyay qalabka lagu ogaado meerkuriga cadmium telluride (MCT). Budada kicinta waxaa la geliyay unug falgal ah (Harrick Scientific Products, Praying Mantis). Ka dib markii lagu daaweeyay kicinta durdur Ar ah (50 ml/daqiiqo) heerkulka qolka, muunadda waxaa lagu kululeeyay heerkul la bixiyay, ka dibna waxaa lagu xumbo Ar (50 ml/daqiiqo) xalka HCOOH waxaana lagu shubay unugga falgalka gudaha. si loogu falceliyo. Geedi socodka kicinta ee moodeelka kala duwan. Muuqaallada shucaaca ee infrared-ka ayaa la duubay muddooyin u dhexeeya 3.0 ilbiriqsi ilaa 1 saac.
HCOOH, DCOOH, HCOOD iyo DCOOD waxaa loo isticmaalaa sidii substrate-yo ku jira propylene carbonate. Xaaladaha haray waxay la jaan qaadayaan habka baabi'inta fuuq-baxa HCOOH.
Xisaabinta mabaadi'da koowaad waxaa lagu sameeyay iyadoo la adeegsanayo qaab-dhismeedka aragtida shaqada ee cufnaanta ee ku jirta xirmada moodeelka bilowga ah ee Vienna Ab (VASP 5.4.4) 65,66. Unug sare oo leh dusha sare ee graphene (5 × 5) oo leh cabbir isdhaafsan oo qiyaastii 12.5 Å ah ayaa loo isticmaalay substrate ahaan CoN2C2 iyo CoN2C2-Co6. Masaafada faakuumka oo ka badan 15 Å ayaa lagu daray si looga fogaado isdhexgalka lakabka substrate ee ku xiga. Isdhexgalka u dhexeeya ions iyo elektaroonada waxaa lagu sharraxay habka hirarka la ballaariyay (PAW) ee la saadaaliyay65,67. Shaqada qiyaasta guud ee Perdue-Burke-Ernzerhof (PBE) ee qiyaasta guud ee isku-dhafka (GGA) oo leh sixitaanka van der Waals ee uu soo jeediyay Grimm68,69 ayaa la isticmaalay. Shuruudaha isku-dhafka ee tamarta guud iyo xoogga waa 10−6 eV/atom iyo 0.01 eV/Å. Jarista tamarta waxaa lagu dejiyay 600 eV iyadoo la isticmaalayo shabaq dhibic Monkhorst-Pack 2 × 2 × 1 K. Awoodda been abuurka ah ee loo isticmaalay qaabkan waxaa laga dhisay qaabaynta elektaroonigga ah una gudbaysaa xaaladda C 2s22p2, xaaladda N 2s22p3, xaaladda Co 3d74s2, xaaladda H 1 s1, iyo xaaladda O 2s22p4. Kala duwanaanshaha tamarta nuugista iyo cufnaanta elektarooniga waxaa lagu xisaabiyaa iyadoo laga jarayo tamarta marxaladda gaaska iyo noocyada dusha sare ee tamarta nidaamka nuugista iyadoo loo eegayo qaababka nuugista ama is-dhexgalka70,71,72,73,74. Sixitaanka tamarta bilaashka ah ee Gibbs waxaa loo isticmaalaa in lagu beddelo tamarta DFT tamar xor ah oo Gibbs ah waxayna tixgelisaa tabarucaadka gariirka ee entropy iyo tamarta eber dhibic75. Habka kor u kaca sawirka-nuugista (CI-NEB) ayaa loo isticmaalay in lagu raadiyo xaaladda kala-guurka ee falcelinta76.
Dhammaan xogta la helay iyo kuwa la falanqeeyay inta lagu guda jiray daraasaddan waxaa lagu daray maqaalka iyo agabka dheeraadka ah ama waxaa laga heli karaa qoraaga u dhigma haddii si macquul ah loo codsado. Xogta isha waxaa loo bixiyay maqaalkan.
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