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Kapangidwe ndi kakulidwe ka zida zogwiritsira ntchito kwambiri zalandira chidwi kwambiri pakusankha kwa hydrogenation koma ndizovuta kwambiri.Apa ife lipoti monatomic RuNi aloyi (SAA) imene munthu Ru maatomu immobilized padziko Ni nanoparticles kudzera Ru-Ni kugwirizana, amene limodzi ndi elekitironi kusamutsa ku subsurface Ni kuti Ru.Kudziwa kwathu, chothandizira chabwino kwambiri cha 0.4% RuNi SAA nthawi yomweyo chinawonetsa ntchito zapamwamba (TOF mtengo: 4293 h-1) ndi chemoselectivity ya kusankha hydrogenation ya 4-nitrostyrene ku 4-aminostyrene (zokolola:> 99%), mlingo wapamwamba kwambiri ndi poyerekeza ndi odziwika heterogeneous catalysts.Mayesero a in situ ndi mawerengedwe owerengera amasonyeza kuti malo owonetserako a Ru-Ni, monga malo omwe akugwira ntchito mkati, amalimbikitsa kuthyoledwa kwa NO bond ndi chotchinga chochepa cha 0.28 eV.Kuphatikiza apo, synergistic Ru-Ni catalysis imakonda mapangidwe apakati (C8H7NO * ndi C8H7NOH *) ndikufulumizitsa sitepe yodziwika bwino (hydrogenation ya C8H7NOH *).
Ma amine onunkhira opangidwa ndi ntchito, zomangira zofunika zamankhwala abwino, ali ndi ntchito zofunika m'mafakitale popanga mankhwala, agrochemicals, pigment ndi ma polima1,2,3.Kuphatikizika kwa hydrogenation kwa mankhwala opezeka mosavuta a nitroaromatic mopitilira muyeso wosiyanasiyana kwakopa chidwi kwambiri ngati njira yosunga zachilengedwe komanso yobwezeretsanso pakupangira ma amine okhala ndi mtengo wowonjezera4,5,6,7.Komabe, kuchepetsa chemoselective kwa magulu a -NO2 pamene kusunga magulu ena ochepetsetsa monga alkenes, alkynes, halogens, kapena ketoni ndi ntchito yofunikira koma yovuta kwambiri8,9,10,11.Choncho, kugwiritsa ntchito mwanzeru zopangira zowonongeka kwa kuchepetsa kwenikweni kwa -NO2 magulu popanda kukhudza zomangira zina zochepetsera ndizofunika kwambiri12,13,14.Zambiri zopangira zitsulo zopanda zitsulo zafufuzidwa kuti zipangitse hydrogenation ya nitroarenes, koma zovuta zomwe zimachitika zimalepheretsa kugwiritsa ntchito kwawo15,16.Ngakhale zopangira zitsulo zodziwika bwino (monga Ru17, Pt18, 19, 20 kapena Pd21, 22, 23) zimagwira ntchito mocheperako, nthawi zambiri zimavutika ndi kukwera mtengo, kusankha kosakwanira, komanso kugwiritsa ntchito ma atomu ochepa.Chifukwa chake, kupeza zopangira zogwira ntchito kwambiri komanso zopangira ma chemoselective popanga mwanzeru komanso kukonza bwino kamangidwe kabwino kumakhalabe vuto lalikulu24,25,26.
Zothandizira za Monatomic Alloy (SAA) zimakhala ndi zitsulo zabwino kwambiri, mawonekedwe apadera a geometric ndi zamagetsi, zimapereka malo apadera ogwirira ntchito, ndikupereka magwiridwe antchito otsogola pophwanya mawonekedwe amtundu wa mizere27,28,29,30,31.Ma atomu amodzi okhala ndi ma atomu achitsulo ku SAA amatha kugwira ntchito ngati malo awiri ogwirira ntchito, kuthandizira kutsegulira kwa magawo angapo kapena kulola njira zosiyanasiyana zoyambira kuti zichitike pamasamba32,33,34.Kuonjezera apo, mayanjano a heterometallic pakati pa maatomu achitsulo osadetsedwa akutali ndi zitsulo zokhala ndi zitsulo zimatha kubweretsa zotsatira za idiosyncratic synergistic, ngakhale kumvetsetsa kwa zotsatira za synergistic zotere pakati pa magawo awiri azitsulo pamlingo wa atomiki kumakhalabe mkangano35,36,37,38.Pakuti hydrogenation wa functionalized nitroarenes, zipangizo zamagetsi ndi geometric malo yogwira ayenera kupangidwa m'njira kuti imathandizira kutsegula kwa magulu nitro okha.Monga lamulo, magulu a nitro omwe alibe ma elekitironi amakhala makamaka adsorbed pa nucleophilic zigawo za chothandizira pamwamba, pamene wotsatira hydrogenation njira, cooperative catalysis wa oyandikana malo yogwira adzakhala ndi mbali yofunika kulamulira reactivity ndi chemoselectivity4,25.Izi zidatipangitsa kuti tifufuze zothandizira za SAA ngati munthu amene angayembekezere kupititsa patsogolo mphamvu ya chemoselective hydrogenation ya nitroaromatic compounds, komanso kumveketsa bwino ubale womwe ulipo pakati pa kapangidwe ka malo ogwirira ntchito ndi magwiridwe antchito a atomiki.
Apa, zothandizira zochokera monatomic aloyi a RuNi anakonzedwa kutengera njira ya magawo awiri kupanga, kuphatikizapo structural-topological kusintha kwa layered hydroxide iwiri (LDH) kutsatiridwa ndi electro-kusamuka mankhwala.RuNi SAA ikuwonetsa bwino kwambiri (> 99% zokolola) pa chemoselective hydrogenation ya 4-nitrostyrene mpaka 4-aminostyrene yokhala ndi ma frequency frequency (TOF) mpaka ~ 4300 mol-mol Ru-1 h-1, yomwe ilipamwamba kwambiri. mlingo pakati pa heterogeneous catalysts olembetsedwa pamikhalidwe yofananira.Electron microscopy ndi spectroscopic characterization anasonyeza kuti akutali ma atomu a Ru amamwazikana padziko Ni nanoparticles (~ 8 nm), kupanga khola Ru-Ni mgwirizano, chifukwa zoipa Ru malo (Ruδ-) chifukwa ma elekitironi kusamutsidwa kuchokera subsurface Ni kuti Ru. .In situ FT-IR, maphunziro a XAFS ndi kuwerengetsa kwa density functional theory (DFT) adatsimikizira kuti masamba omwe ali pa Ru-Ni monga malo ogwirira ntchito amathandizira nitro.Activated adsorption (0.46 eV) imasiyana ndi ya monometallic nickel catalyst.(0.74 eV).Kuphatikiza apo, kusokonezeka kwa hydrogen kumachitika m'malo oyandikana nawo a Ni, ndikutsatiridwa ndi hydrogenation of intermediates (C8H7NO * ndi C8H7NOH *) m'malo a Ruδ.The synergistic zotsatira za thandizo doping mu RuNi SAA chothandizira kumabweretsa kwambiri nitroarenes hydrogenation ntchito ndi selectivity, amene angathe kuperekedwa kwa ena osowa wolemekezeka zitsulo chothandizira ntchito dongosolo tcheru zimachitikira.
Kutengera kusintha kwa structural topology of layered double hydroxide (LDH) precursors, tinakonza monometallic Ni waikamo pa amorphous Al2O3 gawo lapansi.Kenako, ya RuNi/Al2O3 bimetallic zitsanzo zosiyanasiyana Ru okhutira (0.1-2 wt %) anali molondola apanga ndi electrodisplacement kuti gawo ma atomu Ru padziko Ni nanoparticles (NPs) (mkuyu. 1a).Miyezo yophatikizika ya plasma atomic emission spectrometry (ICP-AES) idapereka momveka bwino mawonekedwe a Ru ndi Ni mu zitsanzo izi (Table Supplementary Table 1), yomwe ili pafupi ndi theoretical feedstock loading.Zithunzi za SEM (zowonjezera Chithunzi 1) ndi zotsatira za BET (Zifaniziro Zowonjezera 2-9 ndi Supplementary Table 1) zimasonyeza bwino kuti mawonekedwe a morphological ndi malo enieni a sampuli za RuNi / Al2O3 sizisintha zoonekeratu panthawi ya chithandizo cha electrochemical.- njira yosuntha.Chitsanzo cha X-ray (mkuyu 1b) chimasonyeza mndandanda wa zizindikiro pa 2θ 44.3 °, 51.6 °, ndi 76.1 °, kusonyeza magawo (111), (200), ndi (220) wa Ni (JCPDS 004-0850). ).Makamaka, zitsanzo za RuNi siziwonetsa zitsulo zachitsulo kapena oxidized Ru, zomwe zikuwonetsa kufalikira kwakukulu kwa mitundu ya Ru.Kufala elekitironi maikulosikopu (TEM) miyeso ya monometallic Ni ndi RuNi zitsanzo (mkuyu. 1c1-c8) amasonyeza kuti faifi tambala nanoparticles bwino omwazika ndi immobilized pa amorphous Al2O3 thandizo ndi ofanana tinthu kukula kwake (7.7-8.3 nm).Zithunzi za HRTEM (Mkuyu 1d1-d8) zimasonyeza nthawi yofanana ya lattice pafupifupi 0.203 nm mu zitsanzo za Ni ndi RuNi, zomwe zimagwirizana ndi ndege za Ni (111), komabe, m'mphepete mwa lattice ya Ru particles palibe.Izi zikuwonetsa kuti ma atomu a Ru amamwazikana kwambiri pachitsanzo ndipo samakhudza nthawi ya Ni lattice.Panthawiyi, 2 wt% Ru / Al2O3 idapangidwa ndi njira yowonetsera-deposition monga kulamulira, momwe magulu a Ru adagawidwa mofanana pamtunda wa gawo lapansi la Al2O3 (Supplementary Figs. 10-12).
a Scheme of the synthesis route for RuNi/Al2O3 samples, b X-ray diffraction pattern of Ni/Al2O3 ndi RuNi/Al2O3 zosiyanasiyana zitsanzo.c1−c8 TEM ndi d1−d8 HRTEM grating zithunzi ndi motsatira tinthu kukula magawidwe a monometallic Ni, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0, 8% wt., 1 wt.Chithunzi chamizeremizere.% ndi 2 wt.% RuNi."au" amatanthauza mayunitsi osagwirizana.
Ntchito yothandizira ya zitsanzo za RuNi idaphunziridwa ndi chemoselective hydrogenation ya 4-nitrostyrene (4-NS) mpaka 4-aminostyrene (4-AS).Kutembenuka kwa 4-NS pa gawo laling'ono la Al2O3 linali 0.6% pambuyo pa maola 3 (Supplementary Table 2), kusonyeza zotsatira zochepa za Al2O3.Monga momwe tawonetsera mkuyu.2a, choyambirira faifi tambala chothandizira anasonyeza otsika kwambiri chothandizira ntchito ndi 4-NS kutembenuka kwa 7.1% pambuyo 3 hours, pamene 100% kutembenuka chingapezeke pamaso pa monometallic Ru chothandizira pansi pa zinthu zomwezo.Zothandizira zonse za RuNi zikuwonetsa ntchito yowonjezereka ya hydrogenation (kutembenuka: ~ 100%, 3 h) poyerekeza ndi zitsanzo za monometallic, ndipo kuchuluka kwa zomwe anachita kunali kogwirizana ndi Ru okhutira.Izi zikutanthauza kuti ma particles a Ru amatenga gawo lalikulu panjira ya hydrogenation.Chochititsa chidwi n'chakuti kusankha kwa mankhwala (mkuyu 2b) kumasiyana kwambiri malinga ndi chothandizira.Kwa chothandizira chochepa kwambiri cha faifi tambala, chinthu chachikulu chinali 4-nitroethylbenzene (4-NE) (kusankha: 83.6%) ndi kusankha kwa 4-AC kunali 11.3%.Pankhani ya monometallic Ru, mgwirizano wa C = C mu 4-NS umakhala wovuta kwambiri ku hydrogenation kuposa -NO2, zomwe zimatsogolera kupanga 4-nitroethylbenzene (4-NE) kapena 4-aminoethyl benzene (4-AE);kusankha kwa 4-AC kunali 15.7% yokha.Chodabwitsa n'chakuti, RuNi chothandizira chokhala ndi ma Ru otsika (0.1-0.4 wt%) chinasonyeza kusankha bwino kwambiri (> 99%) ku 4-aminostyrene (4-AS), kusonyeza kuti ndi NO2 osati vinyl, ndi yapadera chemoselective.Pamene zomwe zili mu Ru zidadutsa 0.6 wt.%, kusankhidwa kwa 4-AS kunachepa kwambiri ndi kuwonjezeka kwa Ru, pamene kusankha kwa 4-AE kunakula m'malo mwake.Kwa chothandizira chomwe chili ndi 2 wt% RuNi, magulu onse a nitro ndi vinyl anali opangidwa ndi hydrogenated kwambiri ndi kusankha kwakukulu kwa 4-AE ya 98%.Kuphunzira mmene Ru kupezeka boma pa chothandizira anachita, 0,4 wt% Ru/Al2O3 zitsanzo anali okonzeka (Supplementary Figures 10, 13 ndi 14) imene Ru particles zambiri omwazikana monga munthu maatomu kutsatiridwa ndi ochepa Ru masango.(quasi-atomic Ru).Ntchito yothandizira (Supplementary Table 2) imasonyeza kuti 0.4 wt% Ru / Al2O3 imapangitsa kusankha kwa 4-AS (67.5%) poyerekeza ndi 2 wt% Ru / Al2O3 chitsanzo, koma ntchitoyo ndi yochepa kwambiri (kutembenuka: 12.9).%;3 maola).Malingana ndi chiwerengero cha malo azitsulo pamtunda wotsimikiziridwa ndi CO pulsed chemisorption miyeso, maulendo afupipafupi (TOFmetal) a chothandizira cha RuNi anapezedwa pa otsika 4-NS kutembenuka (Supplementary Fig. 15), yomwe inasonyeza mchitidwe woyamba kuwonjezeka ndiyeno kuchepetsa ndi kuwonjezeka kwa Ru loading (Supplementary Fig. 16).Izi zikusonyeza kuti si onse pamwamba zitsulo malo amachita ngati mbadwa yogwira malo kwa RuNi chothandizira.Kuonjezera apo, TOF ya chothandizira cha RuNi chinawerengedwa kuchokera ku malo a Ru kuti apitirize kuwulula ntchito yake yothandiza kwambiri (mkuyu 2c).Pamene zomwe zili mu Ru zikuwonjezeka kuchokera ku 0.1 wt.% mpaka 0.4 wt.% RuNi catalysts anasonyeza pafupifupi nthawi zonse TOF makhalidwe (4271-4293 h-1), zomwe zimasonyeza kumasulira kwa Ru particles mu atomiki kubalalitsidwa (mwina ndi mapangidwe RuNi SAA).) ndipo imakhala ngati tsamba lalikulu logwira ntchito.Komabe, ndi kuwonjezereka kwina kwa kukweza kwa Ru (mkati mwa 0.6-2 wt %), mtengo wa TOF umachepa kwambiri, zomwe zimasonyeza kusintha kwa mkati mwa malo ogwira ntchito (kuchokera ku atomiki kufalikira kwa Ru nanoclusters).Kuphatikiza apo, ku chidziwitso chathu, TOF ya chothandizira cha 0,4 wt% RuNi (SAA) ili pamlingo wapamwamba kwambiri pakati pa zopangira zitsulo zomwe zidanenedwa kale pansi pazikhalidwe zofananira (Zowonjezera Table 3), kuwonetsanso kuti ma aloyi a RuNi a monoatomic amapereka zinthu zabwino kwambiri zothandizira.chiwonetsero.Supplementary Figure 17 ikuwonetsa ntchito yothandiza ya 0.4 wt% RuNi (SAA) chothandizira pazovuta zosiyanasiyana ndi kutentha kwa H2, komwe kupanikizika kwa H2 kwa 1 MPa ndi kutentha kwa 60 ° C kunagwiritsidwa ntchito ngati magawo abwino kwambiri.chitsanzo chokhala ndi RuNi 0.4 wt.% (mkuyu 2d), ndipo palibe kuchepa kwakukulu kwa ntchito ndi zokolola zomwe zinawonedwa pazaka zisanu zotsatizana.Zithunzi za X-ray ndi TEM za 0.4 wt% RuNi chothandizira chogwiritsidwa ntchito pambuyo pa 5 cycles (Supplementary Figures 18 ndi 19) sanasonyeze kusintha kwakukulu mu kapangidwe ka kristalo, kusonyeza kukhazikika kwakukulu kwa kusankha kwa hydrogenation reaction.Kuonjezera apo, chothandizira cha 0.4 wt% RuNi (SAA) chimaperekanso zokolola zabwino kwambiri za amines za chemoselective hydrogenation ya mankhwala ena a nitroaromatic okhala ndi halogens, aldehydes, ndi magulu a hydroxyl (Supplementary Table 4), kusonyeza kugwiritsidwa ntchito kwake bwino.
a Catalytic kutembenuka ndi b kugawa kwa 4-nitrostyrene hydrogenation mankhwala pamaso pa monometallic Ni, Ru, ndi RuNi catalysts ndi zosiyanasiyana Ru content (0.1-2 wt %), c mu catalytic dynamic range, Turnover frequency (TOF) pa RuNi zothandizira c kutengera Ru pa mole.d Yesani mwayi wogwiritsanso ntchito 0.4 wt.% RuNi chothandizira pazaka zisanu zotsatizana zotsatizana.Ln (C0/C) zachokera anachita nthawi ya hydrogenation wa e-nitrobenzene ndi f-styrene ndi osakaniza nitrobenzene ndi styrene (1:1).Zomwe zimachitika: 1 mmol reagent, 8 ml solvent (ethanol), 0.02 g catalyst, 1 MPa H2, 60 ° C, maola 3.Mipiringidzo yolakwika imatanthauzidwa ngati kupatuka kokhazikika kwa zobwereza zitatu.
Kuti mufufuzenso kusiyana kwakukulu kwa chemoselective, hydrogenation ya styrene ndi nitrobenzene (1: 1) idachitikanso pamaso pa zopangira monometallic Ni, Ru, 0.4 wt% RuNi, ndi 2 wt% RuNi, motsatana (Mkuyu Wowonjezera. 20).Ngakhale kuti chemoselectivity ya zochita hydrogenation wa zinchito magulu n'zogwirizana, ndithudi pali kusiyana selectivity wa intramolecular ndi intermolecular hydrogenation chifukwa maselo allosteric zotsatira.Monga momwe tawonetsera mkuyu.2e,f, curve ln(C0/C) motsutsana ndi nthawi yochitira ikupereka mzere wowongoka kuchokera komwe unayambira, kusonyeza kuti nitrobenzene ndi styrene zonse zimatengera dongosolo lachinyengo.Zothandizira za faifi tambala wa monometallic zidawonetsa kutsika kwambiri kwa hydrogenation mlingo wa p-nitrobenzene (0.03 h-1) ndi styrene (0.05 h-1).Makamaka, ntchito yabwino ya styrene hydrogenation (kuchuluka kosalekeza: 0.89 h-1) inapezedwa pa chothandizira cha Ru monometallic, chomwe ndi chokwera kwambiri kuposa ntchito ya nitrobenzene hydrogenation (mlingo wosasintha: 0.18 h-1).Pankhani ya chothandizira chomwe chili ndi RuNi(SAA) 0.4 wt.% nitrobenzene hydrogenation ndi yabwino kwambiri kuposa styrene hydrogenation (mlingo wokhazikika: 1.90 h-1 vs. 0.04 h-1), kusonyeza zokonda za -NO2 gulu.pa C hydrogenation = chomangira C. Kwa chothandizira ndi 2 wt.% RuNi, mlingo wosasintha wa hydrogenation wa nitrobenzene (1.65 h-1) watsika poyerekeza ndi 0.4 wt.% RuNi (koma akadali apamwamba kuposa a mono-zitsulo chothandizira), pamene hydrogenation mlingo wa styrene chinawonjezeka kwambiri (mlingo mosalekeza: 0,68).h−1).Izi zikuwonetsanso kuti ndi synergistic effect pakati pa Ni ndi Ru, ntchito yothandizira ndi chemoselectivity kumagulu a -NO2 akuwonjezeka kwambiri poyerekeza ndi RuNi SAA.
Kuti muwone momwe zimabalalitsira zigawo za Ru ndi Ni, njira yojambula pogwiritsa ntchito ma electron microscopy yokhala ndi ma electron microscopy yokhala ndi aberration correction (AC-HAADF-STEM) ndi mapu opangidwa ndi mphamvu dispersive spectroscopy (EDS) anachitidwa.Mapu oyambirira a EMF a chitsanzo ndi 0,4 wt% RuNi okhutira (mkuyu 3a, b) amasonyeza kuti Ru ndi omwazika kwambiri mofananamo pa nickel nanoparticles, koma osati pa gawo lapansi la Al2O3, chithunzi chofananira cha AC-HAADF-STEM (Mkuyu. 3c) ikuwonetsa, Zitha kuwoneka kuti pamwamba pa Ni NPs pali mawanga ambiri owala a kukula kwa atomiki ya ma atomu a Ru (omwe amadziwika ndi mivi yabuluu), pomwe masango kapena Ru nanoparticles amawonedwa.Chithunzi 3d), kusonyeza mapangidwe a monatomic RuNi alloys.Kwa chitsanzo chokhala ndi RuNi 0.6 wt.% (mkuyu 3e), ma atomu a Ru osakwatiwa ndi kuchuluka kwa tinthu tating'ono ta Ru adawonedwa pa Ni NPs, zomwe zikuwonetsa kaphatikizidwe kakang'ono ka ma atomu a Ru chifukwa cha kuchuluka kwa katundu.Pankhani ya chitsanzo chokhala ndi 2 wt% RuNi yokhutira, magulu ambiri akuluakulu a Ru pa Ni NPs anapezeka mu chithunzi cha HAADF-STEM (Fig. 3f) ndi EDS elemental mapping (Supplementary Fig. 21), kusonyeza kudzikundikira kwakukulu kwa Ru. .
chithunzi cha HAADF-STEM, b chithunzi chofananira cha mapu a EDS, c chithunzi chapamwamba cha AC-HAADF-STEM, d chithunzi cha STEM chokulitsa ndi kugawa kwamphamvu kofanana kwa chitsanzo cha 0.4 wt% RuNi.(e, f) Zithunzi za AC-HAADF-STEM za zitsanzo zomwe zili ndi 0.6 wt.% RuNi ndi 2 wt.% RuNi, motero.
Poyerekeza ndi zitsanzo za Ni / Al2O3 ndi Ru / Al2O3, mawonekedwe a DRIFTS a CO adsorption in situ adachitidwa (mkuyu 4a) kuti apitirize kuphunzira zambiri zamapangidwe a zitsanzo zomwe zili ndi 0.4 wt.%, 0.6 wt.% ndi 2wt.% RuNi.Kutsatsa kwa CO pachitsanzo cha Ru/Al2O3 kumapereka chiwongola dzanja chachikulu pa 2060 cm-1 komanso nsonga ina yotakata pa 1849 cm-1 yolumikizidwa ndi kutsatsa kwa CO pa Ru ndikulumikiza ma atomu awiri oyandikana nawo, motsatana CO39,40.Kwa chitsanzo cha monometallic Ni, nsonga yamphamvu imawonedwa kokha pa 2057 cm-1, yomwe imadziwika ndi mzere wa CO41,42 m'dera la nickel.Kwa chitsanzo cha RuNi, kuwonjezera pa nsonga yaikulu pa 2056 cm-1, pali phewa losiyana lomwe limakhala ~ 2030 cm-1.Njira yoyenera kwambiri ya Gaussian idagwiritsidwa ntchito kuti iwononge kugawidwa kwa zitsanzo za RuNi mu 2000-2100 cm-1 ndi kugawa kwa CO m'dera la Ni (2056 cm-1) ndi Ru (2031-2039 cm) dera.Nsonga ziwiri zinali linearly adsorbed - 1) (mkuyu 4b).Chochititsa chidwi, kuchokera ku zitsanzo za Ru/Al2O3 (2060 cm-1) kupita ku zitsanzo za RuNi (2031-2039 cm-1), nsonga ya CO yokhudzana ndi mzere m'chigawo cha Ru imasintha kwambiri ndikuwonjezeka ndi kuchuluka kwa Ru.Izi zikuwonetsa kuwonjezeka kwa electronegativity ya ma particles a Ru mu chitsanzo cha RuNi, chomwe ndi zotsatira za kusamutsidwa kwa ma elekitironi kuchokera ku Ni kupita ku Ru, kuonjezera d-π ndemanga ya ma elekitironi kuchokera ku Ru kupita ku antibonding CO 2π* orbital.Kuonjezera apo, pa chitsanzo chomwe chili ndi 0.4 mass% RuNi, palibe nsonga ya adsorption yomwe inawonedwa, zomwe zimasonyeza kuti ma particles a Ru alipo ngati atomu a Nia (SAA).Pankhani ya zitsanzo ndi 0,6 wt.% RuNi ndi 2 wt.% RuNi, kukhalapo kwa bridging CO kumatsimikizira kukhalapo kwa Ru multimers kapena masango, zomwe zimagwirizana bwino ndi zotsatira za AC-HAADF-STEM.
a In situ CO-DRIFTS mawonekedwe a Ni/Al2O3, Ru/Al2O3 ndi 0.4 wt.%, 0.6 wt.%, 2 wt.% RuNi zitsanzo zokhala ndi mpweya wa helium mumtundu wa 2100-1500 cm-1 kwa mphindi 20.b Zowoneka bwino komanso zowoneka bwino za Gaussian za zitsanzo za RuNi/Al2O3 zokhala ndi nsonga zokhazikika ndi FWHM.c In situ Ru K-edge XANES spectra ndi d EXAFS Fourier amasintha mawonekedwe a zitsanzo zosiyanasiyana.Kusintha kwa mafunde olemera a K2 a XAFS K-edge Ru siginecha kutengera mawonekedwe a Morlet wa ma e Ru a zitsanzo za e Ru foil, f 0.4 wt% RuNi ndi g RuO2."au" amatanthauza mayunitsi osagwirizana.
Zowoneka bwino mu situ X-ray mayamwidwe kapangidwe ka X-ray mayamwidwe kapangidwe kake (XANES) sipekitiramu anachitidwa kuphunzira zipangizo zamagetsi ndi geometric ma RuNi zitsanzo ndi Ru zojambulazo ndi RuO2 zitsanzo.Monga momwe tawonetsera mkuyu.4c, pamene kutsitsa kwa Ru kumachepa, mphamvu ya mzere woyera imachepa pang'onopang'ono kuchokera ku zitsanzo za Ru / Al2O3 kupita ku zitsanzo za RuNi.Panthawiyi, mphamvu ya mzere woyera wa XANES spectrum pa K-m'mphepete mwa Ni imasonyeza kuwonjezeka pang'ono kuchokera ku chitsanzo choyambirira cha Ni kupita ku chitsanzo cha RuNi (Supplementary Fig. 22).Izi zikuwonetsa kusintha kwa kachulukidwe ka ma elekitironi ndi kugwirizanitsa chilengedwe cha mankhwala a Ru.Monga momwe chiwonetsero cha X-ray photoelectron spectroscopy (XPS) chikuwonekera (Supplementary Fig. 23), nsonga ya Ru0 ya chitsanzo cha RuNi inasunthira ku mphamvu yochepetsetsa yomangiriza ndipo nsonga ya Ni0 inasunthira ku mphamvu yomanga kwambiri poyerekeza ndi monometallic Ru ndi Ni., yomwe ikuwonetsanso kusamutsa kwa ma elekitironi kuchokera ku ma atomu a Ni kupita ku ma atomu a Ru ku RuNi SAA.The Bader charge analysis of the RuNi SAA(111) surface ikuwonetsa kuti ma atomu a Ru otalikirana amanyamula ma charger (Ruδ-) amasamutsidwa kuchokera ku subsurface Ni atomu (Supplementary Fig. 24), zomwe zimagwirizana ndi in situ DRIFTS ndi XPS zotsatira.Kuti tiphunzire mwatsatanetsatane kapangidwe ka Ru (mkuyu 4d), tidachita mayamwidwe a X-ray owoneka bwino owoneka bwino (EXAFS) mukusintha kwa Fourier.Zitsanzo zomwe zili ndi RuNi 0.4 wt.%. (Table Table 5 ndi Zowonjezera Zowonjezera 25-28) zimasonyeza kuti njira ya Ru-Ni ili ndi nambala yogwirizanitsa (CN) ya 5.4, pamene palibe Ru-Ru ndi Ru-O kugwirizana pa 0.4 wt.% RuNi chitsanzo.Izi zimatsimikizira kuti maatomu akuluakulu a Ru amamwazikana ndipo amazunguliridwa ndi Ni, kupanga aloyi ya monoatomic.Tiyenera kuzindikira kuti mphamvu yapamwamba (~ 2.4 Å) ya mgwirizano wa Ru-Ru ikuwoneka mu chitsanzo cha 0,6 wt.% RuNi ndipo imakwezedwa pachitsanzo ndi 2 wt.% RuNi.Makamaka, EXAFS curve fitting anasonyeza kuti Ru-Ru coordination manambala anawonjezeka kwambiri kuchokera 0 (0.4 wt.% RuNi) mpaka 2.2 (0.6 wt.% RuNi) ndipo zinawonjezeka mpaka 6.7 (2 wt.% .% RuNi), motero , kusonyeza kuti pamene katundu wa Ru akuwonjezeka, ma atomu a Ru amasonkhana pang'onopang'ono.K2-weighted wavelet transform (WT) ya Ru K-edge XAFS siginecha idagwiritsidwanso ntchito pophunzira momwe zimagwirizanirana ndi mitundu ya Ru.Monga momwe tawonetsera mkuyu.4e, Ru foil lobes pa 2.3 Å, 9.7 Å-1 amatchula zopereka za Ru-Ru.Mu chitsanzo munali RuNi 0,4 wt.% (mkuyu 4f) palibe lobes pa k = 9.7 Å-1 ndi 5.3 Å-1, kupatulapo chapakati chomangira cha Ru ndi ma atomu Ru ndi O maatomu (mkuyu 4g);Ru-Ni amawonedwa pa 2.1 Å, 7.1 Å-1, zomwe zimatsimikizira kupangidwa kwa SAA.Komanso, ndi EXAFS sipekitiramu pa K-m'mphepete Ni kwa zitsanzo zosiyana anasonyeza palibe kusiyana kwambiri (Supplementary mkuyu. 29), kusonyeza kuti kugwirizana dongosolo la Ni ndi zochepa kutengera pamwamba Ru maatomu.Mwachidule, zotsatira za AC-HAADF-STEM, in situ CO-DRIFTS, ndi mu situ XAFS zoyesera zatsimikizira kukonzekera bwino kwa zothandizira za RuNi SAA komanso kusinthika kwa ma particles a Ru pa Ni NPs kuchokera ku ma atomu amodzi kupita ku Ru multimers poonjezera Ru katundu.Kuonjezera apo, zithunzi za HAADF-STEM (Supplementary Fig. 30) ndi EXAFS spectra (Supplementary Fig. 31) ya RuNi SAA catalysts zomwe zimagwiritsidwa ntchito zimasonyeza kuti chikhalidwe chobalalika ndi dongosolo logwirizanitsa la ma atomu a Ru silinasinthe kwambiri pambuyo pa maulendo a 5, kutsimikizira. kuti chothandizira chokhazikika cha RuNi SAA .
Miyezo ya H2-TPD inachitidwa kuti iphunzire kutulutsa kwa hydrogen pazitsulo zosiyanasiyana ndipo zotsatira zake zimasonyeza kuti zonsezi zimakhala ndi mphamvu zowonongeka za H2 ndi chiwongoladzanja cha desorption pa ~ 100 ° C (Supplementary Fig. 32).Zotsatira za kusanthula kachulukidwe (Supplementary Fig. 33) sizinawonetse mgwirizano womveka bwino pakati pa reactivity ndi kuchuluka kwa hydrogen desorption.Kuonjezera apo, tinachita zoyeserera ndi D2 isotopu ndikupeza kinetic isotope effect (KIE) mtengo wa 1.31 (TOFH / TOFD) (Supplementary Fig. 34), kutanthauza kuti kutsegula ndi kusokoneza H2 ndizofunikira koma osati zochepetsera mlingo.Mawerengedwe a DFT anachitidwa kuti apitirize kufufuza khalidwe la adsorption ndi dissociation la haidrojeni pa RuNi SAA motsutsana ndi zitsulo Ni zokha (Supplementary Fig. 35).Kwa zitsanzo za RuNi SAA, mamolekyu a H2 amakonda chemisorb kuposa ma atomu a Ru omwe ali ndi mphamvu yotsatsa ya -0.76 eV.Pambuyo pake, haidrojeni imagawanika kukhala ma atomu awiri a H omwe ali pamtunda wa Ru-Ni RuNi SAA, ndikugonjetsa mphamvu ya 0.02 eV.Kuphatikiza pa malo a Ru, mamolekyu a H2 amathanso kukhala opangidwa ndi chemisorbed kumtunda kwa ma atomu a Ni oyandikana ndi Ru (mphamvu ya adsorption: -0.38 eV) kenako amasiyanitsidwa kukhala ma H awiri pamasamba a Ru-Ni ndi Ni-Ni.Chotchinga cha Atomiki 0.06 eV.M'malo mwake, zotchinga mphamvu kwa adsorption ndi dissociation mamolekyu H2 pa Ni(111) pamwamba ndi -0.40 eV ndi 0.09 eV, motero.Chotchinga chochepa kwambiri cha mphamvu ndi kusiyana kochepa kwambiri kumasonyeza kuti H2 imasiyanitsidwa mosavuta pamtunda wa Ni ndi RuNi surfactants (Ni-site kapena Ru-site), zomwe sizinthu zazikulu zomwe zimakhudza ntchito yake yothandizira.
Kutsatsa kokhazikika kwamagulu ena ogwira ntchito ndikofunikira pakusankha hydrogenation ya magawo.Choncho, tinachita mawerengedwe a DFT kuti tifufuze zosinthika zotheka za 4-NS adsorption ndi malo ogwira ntchito pamtunda wa RuNi SAA (111), ndipo zotsatira zowonjezera zikuwonetsedwa mu Supplementary Fig. 36e), momwe ma atomu a N ali mu malo opanda dzenje a Ru-Ni ndipo ma atomu awiri a O amalumikizidwa ndi mawonekedwe a Ru-Ni akuwonetsa mphamvu yotsika kwambiri (-3.14 eV).Izi zikusonyeza kuti thermodynamically yabwino adsorption ulamuliro poyerekeza ofukula ndi zina kufanana kasinthidwe (Supplementary Fig. 36a-d).Kuonjezera apo, pambuyo pa kulengeza kwa 4-HC pa RuNi SAA (111), kutalika kwa mgwirizano wa N-O1 (L (N-O1)) mu gulu la nitro chinawonjezeka kufika ku 1.330 Å (mkuyu 5a), yomwe ili yochuluka kwambiri. yaitali kuposa kutalika kwa mpweya 4- NS (1.244 Å) (Supplementary Mkuyu. 37), ngakhale kuposa L (N-O1) (1.315 Å) pa Ni (111).Izi zikuwonetsa kuti kutsatsa kokhazikitsidwa kwa ma N-O1 bond pamtunda wa RuNi PAA kumakulitsidwa kwambiri poyerekeza ndi Ni(111).
masanjidwe a Adsorption a 4-HC pa Ni(111) ndi RuNi SAA(111) (Eads) pamalo (mbali ndi mawonedwe apamwamba).Ru - violet, Ni - wobiriwira, C - lalanje, O - wofiira, N - buluu, H - woyera.b In situ FT-IR mawonekedwe a mpweya ndi chemisorbed 4-HC pa monometallic surfactants Ni, Ru, RuNi (0.4 wt. %) ndi 2 wt.% RuNi, motero.c Normalized in situ XANES and d-phase-corrected Fourier EXAFS at the Ru K-edge of 0.4 wt % RuNi PAA during 4-NS adsorption (RuNi SAA–4NS) and hydrogenation steps (RuNi SAA–4NS–H2) .Transformation spectra ;…e Projection density of states (PDOS) of the first surface of RuNi SAA(111), N-O1 in gaseous 4-NS and adsorbed 4-NS on RuNi SAA(111)."au" amatanthauza mayunitsi osagwirizana.
Kuti mupitirize kuyesa khalidwe la adsorption la 4-NS, mu situ FT-IR miyeso inachitidwa pa Ni monometallic, Ru monometallic, 0.4 wt% RuNi (SAA), ndi 2 wt% RuNi catalysts (Mkuyu 5b).Mawonekedwe a FT-IR a gaseous 4-NS adawonetsa nsonga zitatu pa 1603, 1528, ndi 1356 cm-1, zomwe zidapatsidwa ν(C=C), νas(NO2), ndi νs(NO2)46,47, 48.Pamaso pa monometallic Ni, ma redshift a magulu onse atatu amawonedwa: v(C=C) (1595 cm-1), νas(NO2) (1520 cm-1), ndi νs(NO2) (1351 cm-1) ., yomwe imasonyeza chemisorption ya magulu a C = C ndi -NO2 pamtunda wa Ni (mwinamwake, pakukonzekera kwa kufanana kwa adsorption).Kwa chitsanzo cha monometallic Ru, ma redshifts a magulu atatuwa (1591, 1514, ndi 1348 cm-1, motero) okhudzana ndi monometallic Ni adapezeka, zomwe zimasonyeza kuwonjezereka pang'ono kwa magulu a nitro ndi С=С zomangira pa Ru.Pankhani ya 0,4 wt.% RuNi (SAA), gulu la ν(C=C) lili pakati pa 1596 cm-1, lomwe lili pafupi kwambiri ndi gulu la monometallic Ni (1595 cm-1), kusonyeza kuti magulu a vinyl amakonda kutsatsa Ni pa RuNi. Zithunzi za SAA.Kuphatikiza apo, mosiyana ndi chothandizira cha monometallic, kuchulukira kwa gulu la νs(NO2) (1347 cm-1) ndikocheperako kuposa gulu la νas(NO2) (1512 cm-1) pa 0.4 wt.% RuNi (SAA) ), zomwe zakhala zikugwirizana ndi kudulidwa kwa NO bond ku -NO2 kupanga nitroso yapakatikati malinga ndi maphunziro apitalo49,50.Chochitika chofananacho chinawonedwanso pachitsanzo chokhala ndi RuNi 2 wt.%.Zotsatira zomwe zili pamwambazi zimatsimikizira kuti mphamvu ya synergistic ya bimetallic centers ku PAA RuNi imalimbikitsa polarization ndi dissociation ya magulu a nitro, zomwe zimagwirizana bwino ndi kasinthidwe koyenera kamene kamapezeka ndi mawerengedwe a DFT.
In situ XAFS spectroscopy idachitika kuti iphunzire kusinthika kwamphamvu kwa mawonekedwe amagetsi ndi kulumikizana kwa RuNi SAA panthawi ya 4-NS adsorption and catalytic reaction.Monga momwe tingawonere kuchokera ku K-edge XANES spectrum ya Ru (Mkuyu 5c), pambuyo pa adsorption ya 4-HC, 0.4 wt.% RuNi PAA, m'mphepete mayamwidwe kwambiri anasamukira ku mphamvu apamwamba, amene limodzi ndi kuwonjezeka mphamvu ya mzere woyera, zomwe zimasonyeza kuti Ru mitundu Tsankho makutidwe ndi okosijeni kumachitika chifukwa ma elekitironi kusamutsa kwa Ru kuti 4-NS.Kuphatikiza apo, Fourier yokonzedwa ndi gawo losintha mawonekedwe a EXAFS a adsorbed 4-NS RuNi SAA (mkuyu 5d) akuwonetsa kuwonjezereka kwa zizindikiro pa ~ 1.7 Å ndi ~ 3.2 Å, zomwe zimagwirizana ndi mapangidwe a Ru-O kugwirizana.Mawonekedwe a XANES ndi EXAFS a 0.4 wt% RuNi SAA adabwereranso kumalo awo oyambirira pambuyo pa jekeseni wa mphindi 30 wa gasi wa haidrojeni.Zochitika izi zikuwonetsa kuti magulu a nitro amagulitsidwa pamasamba a Ru kudzera pa ma bond a Ru-O potengera kuyanjana kwamagetsi.Ponena za mawonekedwe a XAFS a m'mphepete mwa Ni-K mu situ (Supplementary Fig. 38), palibe zosintha zodziwikiratu zomwe zidawonedwa, zomwe zitha kukhala chifukwa cha kuchepetsedwa kwa ma atomu a Ni mu gawo lalikulu pazigawo za Ni.The ananeneratu kachulukidwe wa limati (PDOS) wa RuNi SAA (mkuyu. 5e) limasonyeza kuti unoccupied boma la nitro gulu pamwamba pa Femi mlingo broadens ndi kusuntha m'munsimu Femi mlingo mu adsorbed boma, amene Komanso limasonyeza kuti ma elekitironi ku d- boma la RuNi SAA kusintha kupita kudziko lopanda anthu ku −NO2.The mlandu kachulukidwe kusiyana (Supplementary mkuyu. 39) ndi Bader mlandu kusanthula (Supplementary mkuyu. 40) amasonyeza kuti Integrated elekitironi kachulukidwe 4-NS amaunjikana pambuyo adsorption ake padziko RuNi SAA (111).Kuonjezera apo, -NO2 kachulukidwe kawo kachulukidwe kanachulukira kwambiri poyerekeza ndi gulu la vinilu mu 4-NS chifukwa cha kusamutsidwa kwa ma elekitironi pa mawonekedwe a Ru-Ni, kuwonetsa kutsegulira kwapadera kwa NO bond mu gulu la nitro.
Mu situ FT-IR chinachitika kuwunika chothandizira ndondomeko ya 4-NS hydrogenation anachita pa chothandizira zitsanzo (mkuyu. 6).Kwa chothandizira choyamba cha nickel (mkuyu 6a), kuchepa pang'ono kokha kwa kachulukidwe ka nitro (1520 ndi 1351 cm-1) ndi C = C (1595 cm-1) magulu adawonedwa pamene akudutsa H2 kwa 12 min, yomwe. zikuwonetsa kuti - activation NO2 ndi C=C ndizofooka.Pamaso pa monometallic Ru (Mkuyu 6b), gulu la ν(C=C) (pa 1591 cm–1) limacheperachepera mkati mwa mphindi 0-12, pomwe magulu a νs(NO2) ndi νas(NO2) amachepetsedwa kwambiri. .Pang'onopang'ono Izi zikuwonetsa kuyatsa kwabwino kwa gulu la vinilu la hydrogenation, zomwe zimapangitsa kupanga 4-nitroethylbenzene (4-NE).Pankhani ya 0,4 wt.% RuNi (SAA) (Mkuyu 6c), gulu la νs(NO2) (1347 cm–1) lizimiririka mofulumira ndi kuchuluka kwa haidrojeni, limodzi ndi kuwola kwapang’onopang’ono kwa ν(N=O );gulu latsopano lomwe limakhala pa 1629 cm-1 lidawonedwanso, chifukwa cha kugwedezeka kwa NH.Kuphatikiza apo, gulu la ν(C=C) (1596 cm–1) limangowonetsa kuchepa pang'ono pakatha mphindi 12.Kusintha kwamphamvu kumeneku kumatsimikizira polarization ndi hydrogenation ya -NO2 mpaka -NH2 ndi 0.4 wt% RuNi (SAA) yochokera ku chemoselectivity yapadera ku 4-aminostyrene.Kwa chitsanzo cha 2 wt.% RuNi (mkuyu 6d), kuwonjezera pa kuwonekera kwa gulu latsopano pa 1628 cm-1 lotchedwa δ (NH), gulu la ν(C = C) makamaka limachepetsa ndikuzimiririka ndi kuwonjezeka kwa gulu la nitro (1514). ndi 1348cm-1).Izi zikusonyeza kuti C = C ndi -NO2 imayendetsedwa bwino chifukwa cha kupezeka kwa Ru-Ru ndi Ru-Ni interfacial centers, motero, zomwe zimagwirizana ndi mapangidwe a 4-NE ndi 4-AE pa 2 wt.% RuNi chothandizira.
Mu situ FT-IR mawonekedwe a 4-NS hydrogenation pamaso pa monometallic Ni, b monometallic Ru, c 0.4 wt% RuNi SAA, ndi d 2 wt% RuNi mu H2 ikuyenda pa 1700-1240 cm- Range 1 inalembedwa ngati gasi amachitira pambuyo 0, 3, 6, 9 ndi 12 mphindi, motero."au" amatanthauza mayunitsi osagwirizana.Kugawa mphamvu zomwe zingatheke komanso zida zofananirako za C=C hydrogenation ndi NO scission mu 4-NS pa e Ni(111) ndi f RuNi SAA(111) pamalo.Ru - violet, Ni - wobiriwira, C - lalanje, O - wofiira, N - buluu, H - woyera."zotsatsa", "IS", "TS", ndi "FS" zimayimira chikhalidwe cha adsorption, chikhalidwe choyambirira, chikhalidwe cha kusintha, ndi chikhalidwe chomaliza, motsatira.
Njira zomwe zingatheke za kusintha kwa 4-NS kukhala Ni(111) ndi RuNi SAA(111), kuphatikizapo C=C hydrogenation ndi NO bond cleavage, anafufuzidwa ndi kuwerengetsera kwa DFT kuti adziwe bwino ntchito yovuta ya 4-NS.Magawo a mawonekedwe a Ru-Ni popanga zolinga za 4-AS.Kwa Ni (111) pamwamba (mkuyu 6e), zotchinga mphamvu NO scission ndi hydrogenation wa vinilu magulu mu gawo loyamba ndi 0,74 ndi 0.72 eV, motero, zomwe zikusonyeza kuti chemoselective hydrogenation wa nitro magulu 4-HC ndi. zosasangalatsa.kwa monometallic faifi tambala pamwamba.M'malo mwake, chotchinga mphamvu kwa NO dissociation ndi 0.46 eV okha apamwamba kuposa RuNi SAA (111), amene ali otsika kwambiri kuposa C = C chomangira hydrogenation (0.76 eV) (Fig. 6f).Izi zimatsimikizira momveka bwino kuti malo a Ru-Ni interfacial amachepetsa mphamvu yotchinga mphamvu ya NO scission m'magulu a nitro, zomwe zimapangitsa kuti magulu a nitro athermodynamically achepetse poyerekeza ndi magulu a C = C pamtunda wa surfactant wa RuNi, womwe umagwirizana ndi zotsatira zoyesera.
Zomwe zimapangidwira ndi ma curve amphamvu owerengera a 4-NS hydrogenation pa RuNi SAA adafufuzidwa potengera mawerengedwe a DFT (mkuyu 7), ndipo kusinthidwa kwatsatanetsatane kwa masitepe akuluakulu kukuwonetsedwa mu Supplementary Fig. 41. Kuti muwonjezere pulogalamu yowerengera, zopinga zopangira mphamvu za mamolekyu amadzi sizinaphatikizidwe ku mawerengedwe.mbale zitsanzo9,17.Monga momwe tawonetsera mkuyu.7, mamolekyu a 4-NS amayamba kutengeka mofanana pa surfactant ya RuNi, ndipo ma atomu awiri a O mu gulu la nitro amamangiriridwa kumalo osakanikirana a Ru-Ni (S0; sitepe I).Pambuyo pake, mgwirizano wa NO womwe umagwirizanitsidwa ndi malo a Ru wathyoka, womwe umaphatikizidwa ndi mapangidwe a nitroso intermediate (C8H7NO *) pa malo a mawonekedwe a Ru-Ni ndi O * pamalo opanda kanthu a Ni (S0 → S1 kudzera pa TS1; mphamvu chotchinga: 0.46 eV, sitepe yachiwiri).O* ma radicals amapangidwa ndi hydrogenated ndi ma atomu a H kuti apange mamolekyu a H2O okhala ndi exotherm ya 0.99 eV (S1 → S2).Zolepheretsa mphamvu za hydrogenation wa C8H7NO* wapakatikati (Zowonjezera 42 ndi 43) zikuwonetsa kuti maatomu a H ochokera ku malo opanda kanthu a Ru-Ni amakonda kuukira maatomu a O kuposa ma atomu a N, zomwe zimapangitsa C8H7NOH* (S2 → S4; chotchinga mphamvu TS2: 0.84) eV, sitepe III).Ma atomu a N mu C8H7NOH* adapangidwa ndi hydrogenated kuti apange C8H7NHOH* atadutsa chotchinga cha 1.03 eV (S4→S6; sitepe IV), chomwe ndi sitepe yodziwika bwino ya zomwe zimachitika.Kenako, chomangira cha N-OH mu C8H7NHOH* chinasweka pa mawonekedwe a Ru-Ni (S6 → S7; chotchinga mphamvu: 0.59 eV; siteji V), pambuyo pake OH* idapangidwa ndi hydrogenated ku HO (S7 → S8; exotherm: 0.31 eV ) Pambuyo pake, ma atomu a N a malo apakati a Ru-Ni ku C8H7NH * adapangidwanso ndi hydrogenated kuti apange C8H7NH2 * (4-AS) ndi chotchinga mphamvu cha 0.69 eV (S8 → S10; sitepe VI).Pomaliza, mamolekyu a 4-AS ndi HO adachotsedwa pamtunda wa RuNi-PAA, ndipo chothandizira chinabwerera ku chikhalidwe chake choyambirira (sitepe VII).Kapangidwe kapadera kameneka pakati pa ma atomu amodzi a Ru ndi magawo a Ni, omwe amatsagana ndi mphamvu yolumikizana ndi doping mu RuNi SAA, zimabweretsa ntchito yopambana komanso chemoselectivity ya 4-NS hydrogenation.
Mpunga.4. Chithunzi chojambula cha njira ya hydrogenation reaction ya NS ku 4-AS pa RuNi PAA pamwamba.Ru - violet, Ni - wobiriwira, C - lalanje, O - wofiira, N - buluu, H - woyera.Chigawochi chikuwonetsa kugawidwa kwa mphamvu zomwe zingatheke za 4-NS hydrogenation pamtunda wa RuNi SAA (111), wowerengedwa pamaziko a DFT."S0" imayimira malo oyamba, ndipo "S1-S10" imayimira maiko angapo otsatsa."TS" imayimira kusintha kwa nyengo.Manambala omwe ali m'mabokosi amaimira zolepheretsa mphamvu zamasitepe akuluakulu, ndipo manambala otsalawo amaimira mphamvu zotsatsa zapakati zomwe zimagwirizana.
Choncho, zothandizira za RuNi SAA zinapezedwa pogwiritsa ntchito electrosubstitution reactions pakati pa RuCl3 ndi Ni NPs zotengedwa kuchokera ku LDH precursors.Poyerekeza ndi zomwe zidanenedwa kale za monometallic Ru, Ni ndi zothandizira zina zosasinthika, RuNi SAA yotsatira idawonetsa bwino kwambiri 4-NS chemoselective hydrogenation (4-AS zokolola:> 99%; mtengo wa TOF: 4293 h-1).Makhalidwe ophatikizana kuphatikiza AC-HAADF-STEM, in situ CO-DRIFTS, ndi XAFS adatsimikizira kuti ma atomu a Ru anali osasunthika pa Ni NPs pamlingo wa atomu imodzi kudzera pa ma bond a Ru-Ni, omwe adatsagana ndi kusamutsidwa kwa ma elekitironi kuchokera ku Ni kupita ku Ru.Mu situ XAFS, kuyesa kwa FT-IR, ndi kuwerengera kwa DFT kunasonyeza kuti malo owonetserako a Ru-Ni amagwira ntchito ngati malo omwe akugwira nawo ntchito kuti athandizidwe ndi NO bond mu gulu la nitro;synergism pakati pa Ru ndi malo oyandikana nawo Ni amathandizira kutsegula kwapakatikati ndi hydrogenation, potero kumapangitsa kuti ntchito zitheke.Ntchitoyi imapereka chidziwitso pa ubale pakati pa malo omwe amagwira ntchito kawiri ndi machitidwe othandizira a SAA pamlingo wa atomiki, ndikutsegulira njira yopangira zopangira zina zanjira ziwiri zomwe zimasankhidwa.
Ma analytical reagents omwe amagwiritsidwa ntchito poyesera adagulidwa kuchokera ku Sigma Aldrich: Al2(SO4)3 18H2O, sodium tartrate, CO (NH2)2, NH4NO3, Ni(NO3)2 6H2O, RuCl3, ethanol, 4-nitrostyrene (4- NS) , 4-aminostyrene, 4-nitroethylbenzene, 4-aminoethylbenzene ndi nitrostyrene.Madzi oyeretsedwa adagwiritsidwa ntchito pazoyesera zonse.
Ma Hierarchical NiAl LDHs adapangidwa ngati ma precursors ndi in situ kukula.Choyamba, urea (3.36 g), Al2 (SO4) 3 · 18H2O (9.33 g) ndi sodium tartrate (0.32 g) adasungunuka m'madzi osungunuka (140 ml).Njira yothetsera vutoli idasamutsidwa ku autoclave yokhala ndi Teflon ndikutenthedwa mpaka 170 ° C kwa 3 h.Chotsatiracho chinatsukidwa ndi madzi osungunuka ndikuwumitsa bwino, pambuyo pake chinali calcined pa 500 ° C (2 ° C min-1; 4 h) kuti apeze amorphous Al2O3.Ndiye Al2O3 (0.2 g), Ni(NO3)2 6H2O (5.8 g) ndi NH4NO3 (9.6 g) anabalalitsidwa m'madzi oyeretsedwa (200 ml) ndi pH inasinthidwa ~ 6.5 powonjezera 1 mol l -1 ammonia madzi..Kuyimitsidwa kudasamutsidwa mu botolo ndikusungidwa pa 90 ° C kwa 48 h kuti mupeze NiAl-LDH.Kenako NiAl-LDH ufa (0.3 g) unachepetsedwa mumtsinje wa H2/N2 (10/90, v/v; 35 ml min–1) pa 500 ° C kwa 4 h (kutentha kwa 2 ° C min -1 ).Kukonzekera zitsanzo za faifi tambala monometallic (Ni/Al2O3) waikamo pa amorphous Al2O3.Zitsanzo za bimetallic za RuNi zidapangidwa ndi njira ya electrodisplacement.Kawirikawiri, chitsanzo chatsopano cha Ni/Al2O3 (0.2 g) chinamwazikana mu 30 ml ya madzi oyera, ndiye yankho la RuCl3 (0.07 mmol l-1) linawonjezeredwa pang'onopang'ono ndikugwedezeka mwamphamvu kwa mphindi 60 pansi pa chitetezo cha mpweya wa N2. .The chifukwa precipitate anali centrifuged, kutsukidwa ndi madzi oyera, ndi zouma mu uvuni zingalowe pa 50 ° C kwa 24 h, kupeza chitsanzo munali 0.1% RuNi.Kuwunika kothandizira kusanachitike, zitsanzo zongopangidwa kumene zidachepetsedwa poyambira mukuyenda kwa H2/N2 (10/90, v/v) pa 300 ° C (kutentha kwa 2 ° C min-1) kwa 1 h, kenako kutenthedwa. N2 Kuzizira mpaka kutentha.Kufotokozera: zitsanzo zokhala ndi Ru/Al2O3 zomwe zili ndi 0.4% ndi 2% mwa misa, zokhala ndi Ru zenizeni za 0.36% ndi misa ndi 2.3% ndi misa, zidakonzedwa ndi mvula ndi mvula ndikutenthetsa pa 300 ° C (kugwiritsa ntchito H2 / N2 : 10/90, v/v, kutentha kwa 2 °C min–1) kwa maola atatu.
Kuyesera kwa X-ray diffraction (XRD) kunachitika pa Bruker DAVINCI D8 ADVANCE diffractometer yokhala ndi gwero la radiation la Cu Kα (40 kV ndi 40 mA).Shimadzu ICPS-7500 Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) idagwiritsidwa ntchito kudziwa kuchuluka kwenikweni kwa zinthu m'zitsanzo zosiyanasiyana.Zithunzi za scanning electron microscopy (SEM) zinajambulidwa pogwiritsa ntchito maikulosikopu ya Zeiss Supra 55 electron.Kuyesera kwa N2 adsorption-desorption kunachitika pa chipangizo cha Micromeritics ASAP 2020 ndipo malo enieni adawerengedwa pogwiritsa ntchito njira ya Brunauer-Emmett-Teller (BET) multipoint.Mawonekedwe a ma electron microscopy (TEM) adachitidwa pa maikulosikopu ya JEOL JEM-2010 yotalikirapo kwambiri.High Angle Aberration Corrected Scanning Transmission Electron Microscope Dark Field (AC-HAADF) - STEM yokhala ndi FEI Titan Cube Themis G2 300 yokhala ndi spherical aberration corrector ndi Energy Dispersive X-ray Spectroscopy (EDS) ndi JEOL JEM-ARM200F miyeso) ndi zida zamapu za EDS .Kapangidwe kabwino ka X-ray mayamwidwe spectroscopy (XAFS) in situ K-m'mphepete mwa Ru ndi Ni K-m'mphepete anayesedwa pa njira 1W1B ndi 1W2B wa Beijing Synchrotron Radiation Facility (BSRF) wa Institute of High Energy Physics (IHEP), China .Academy of Sciences (KAN).Kuyesa kwa pulsed CO chemisorption ndi kutentha-programmed hydrogen desorption (H2-TPD) kunachitika pa chida cha Micromeritics Autochem II 2920 pogwiritsa ntchito chowunikira chowongolera matenthedwe (TCD).Zoyeserera za in situ DRIFTS ndi FT-IR zidachitika pa Bruker TENSOR II infrared spectrometer yokhala ndi cell yosinthidwa mu situ reaction komanso chowunikira champhamvu cha MCT.Njira zofotokozera zatsatanetsatane zafotokozedwa mu Supplementary Information.
Choyamba, gawo lapansi (4-NS, 1 mmol), zosungunulira (ethanol, 8 ml) ndi chothandizira (0.02 g) zidawonjezeredwa mosamala ku autoclave ya 25 ml yachitsulo chosapanga dzimbiri.Makinawo adatsukidwa kwathunthu ndi 2.0 MPa (> 99.999%) haidrojeni nthawi 5, kenako amakakamizidwa ndikusindikizidwa ku 1.0 MPa ndi H2.Zomwezo zidachitika pa 60 ° C pa liwiro lokhazikika la 700 rpm.Pambuyo pazimenezi, zotsatira zake zidadziwika ndi GC-MS ndikuwunikidwa mochulukira pogwiritsa ntchito Shimadzu GC-2014C gas chromatography system yokhala ndi GSBP-INOWAX capillary column (30 m×0.25 mm×0.25 mm) ndi chowunikira cha FID.Kutembenuka kwa 4-nitrostyrene ndi kusankha kwazinthu kunatsimikiziridwa motere:
Ma frequency a Turnover (TOF) adawerengedwa ngati mol 4-NS otembenuzidwa pa malo azitsulo a mol pa ola limodzi (mol4-NS mol-1 h-1) kutengera kutembenuka kwa 4-NS (~ 15%).Ponena za kuchuluka kwa ma Ru-node, ma Ru-Ni mawonekedwe amtundu ndi kuchuluka kwa maatomu achitsulo pamwamba.Pakuti recyclability mayeso, chothandizira anasonkhanitsidwa ndi centrifugation pambuyo anachita, kutsukidwa katatu ndi Mowa, ndiyeno kachiwiri anayambitsa mu autoclave kwa mkombero chothandizira lotsatira.
Kuwerengera konse kwa density functional theory (DFT) kunachitika pogwiritsa ntchito phukusi la Vienna ab initio simulation (VASP 5.4.1).Ntchito ya Generalized Gradient Approximation (GGA) PBE imagwiritsidwa ntchito pofotokoza kusinthana kwa ma elekitironi ndi mikhalidwe yolumikizana.Njira ya Projector Augmented Wave (PAW) imagwiritsidwa ntchito pofotokoza kuyanjana pakati pa ma nuclei a atomiki ndi ma electron.Njira ya Grimm DFT-D3 imalongosola zotsatira za van der Waals kuyanjana pakati pa gawo lapansi ndi mawonekedwe.Kuwerengera Zolepheretsa Mphamvu ndi Kukwera Mabandi Okhazikika okhala ndi Image Boost (CI-NEB) ndi Njira za Dimer.Kusanthula pafupipafupi kwa ma oscillations kunkachitika, kutsimikizira kukhalapo kwafupipafupi komwe kumangoganizira pakusintha kulikonse (Zowonjezera Zowonjezera 44-51).Kuwerengera mwatsatanetsatane kumafotokozedwa muzowonjezera zowonjezera.
Deta yayikulu yomwe imathandizira ziwembu zomwe zili m'nkhaniyi zimaperekedwa m'mafayilo a data source.Zina zomwe zikugwirizana ndi kafukufukuyu zikupezeka kuchokera kwa olemba omwe afunsidwa ngati afunsidwa.Nkhaniyi imapereka deta yoyambirira.
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