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Ƙirƙirar ƙira da haɓaka manyan abubuwan haɓaka aiki sun sami kulawa sosai a cikin zaɓin halayen hydrogenation amma ya kasance babban ƙalubale.Anan mun bayar da rahoton wani guntun RuNi na monotomic (SAA) wanda a cikinsa guda ɗaya Ru atom ɗin ke dawwama a saman Ni nanoparticles ta hanyar haɗin gwiwar Ru-Ni, wanda ke tare da canja wurin lantarki daga ƙarƙashin Ni zuwa Ru.Don iliminmu, mafi kyawun mai haɓaka 0.4% RuNi SAA lokaci guda ya nuna babban aiki (darajar TOF: 4293 h-1) da chemoselectivity don zaɓin hydrogenation na 4-nitrostyrene zuwa 4-aminostyrene (samar:> 99%), matakin mafi girma ta hanyar idan aka kwatanta da sananne iri-iri masu kara kuzari.A cikin gwaje-gwajen yanayi da ƙididdige ƙididdiga sun nuna cewa rukunin yanar gizo na Ru-Ni, a matsayin rukunin yanar gizo masu aiki, suna haɓaka fifikon karya NO shaidu tare da ƙaramin shingen makamashi na 0.28 eV.Bugu da kari, Ru-Ni catalysis synergistic yana goyon bayan samuwar tsaka-tsaki (C8H7NO* da C8H7NOH*) kuma yana haɓaka matakin ƙayyadaddun ƙimar (hydrogenation na C8H7NOH*).
Amines masu ƙanshi masu aiki, mahimman tubalan ginin sinadarai masu kyau, suna da mahimman aikace-aikacen masana'antu a cikin samar da magunguna, agrochemicals, pigments da polymers1,2,3.Halin hydrogenation na katalytic na mahadi na nitroaromatic da ke samuwa a kan abubuwan haɓakawa daban-daban ya jawo hankali sosai a matsayin hanyar da za ta dace da muhalli da kuma sake yin fa'ida don haɗar amines tare da ƙarin darajar4,5,6,7.Koyaya, raguwar chemoselective na ƙungiyoyin -NO2 yayin da ake riƙe sauran ƙungiyoyin da za a iya ragewa kamar alkenes, alkynes, halogens, ko ketones abu ne mai matuƙar kyawawa amma aiki mai wahala8,9,10,11.Sabili da haka, amfani da hankali na abubuwan haɓakawa daban-daban don ƙayyadaddun raguwa na ƙungiyoyin -NO2 ba tare da shafar sauran haɗin da za a iya ragewa ba yana da kyawawa12,13,14.An bincika yawancin abubuwan da ba su da ƙarfe masu daraja don haɓaka hydrogenation na nitroarenes, amma yanayin ɗaukar zafi ya hana aikace-aikacen su mai fa'ida15,16.Ko da yake masu haɓaka ƙarfe masu daraja (kamar Ru17, Pt18, 19, 20 ko Pd21, 22, 23) suna aiki a ƙarƙashin yanayi mai sauƙi, yawanci suna fama da tsada mai tsada, zaɓi mai ƙima, da ƙarancin amfani da zarra.Don haka, samun madaidaicin ma'auni da kemikal ta hanyar ƙira mai kyau da kuma daidaita kyakkyawan tsari ya kasance babban ƙalubale24,25,26.
Monatomic Alloy (SAA) masu haɓakawa suna da matsakaicin ingancin ƙarfe mai daraja, tsarin lissafi na musamman da tsarin lantarki, suna ba da wuraren aiki na musamman, da kuma samar da fitaccen aikin ƙara kuzari ta hanyar ƙetare halayen sikelin sikeli27,28,29,30,31.Doped guda atom da rundunan ƙarfe na ƙarfe a cikin SAA na iya zama wuraren aiki biyu masu aiki, sauƙaƙe kunna abubuwa masu yawa ko ƙyale matakan martani daban-daban don faruwa a shafuka daban-daban32,33,34.Bugu da ƙari, ƙungiyoyin heterometallic tsakanin keɓaɓɓen zarra na ƙarfe na ƙazanta da ƙarfe masu masaukin baki na iya haifar da tasirin haɗin gwiwa na idiosyncratic, kodayake fahimtar irin waɗannan tasirin synergistic tsakanin saiti biyu na rukunin ƙarfe a matakin atomic ya kasance mai kawo rigima35,36,37,38.Don hydrogenation na nitroarenes mai aiki, dole ne a tsara tsarin lantarki da na geometric na wuraren aiki ta yadda za a hanzarta kunna ƙungiyoyin nitro na keɓancewar.A matsayinka na mai mulki, ƙungiyoyin nitro da ke da ƙarancin lantarki galibi suna tallata su a cikin yankuna na nucleophilic na farfajiyar mai kara kuzari, yayin da a cikin hanyar hydrogenation ta gaba, haɓakar haɗin gwiwar wuraren aiki na makwabta za su taka muhimmiyar rawa wajen sarrafa reactivity da chemoselectivity4,25.Wannan ya sa mu bincika abubuwan haɓakawa na SAA a matsayin ɗan takara mai ban sha'awa don haɓaka haɓakar haɓakar haɓakar haɓakar haɓakar hydrogenation na mahaɗan nitroaromatic, da kuma ƙara haɓaka alaƙar da ke tsakanin tsarin rukunin aiki da aikin sikelin atomic.
Anan, an shirya abubuwan da suka danganci monotomic RuNi alloys bisa tsarin haɗin gwiwa na matakai biyu, gami da canjin tsari-topological na Layered Double hydroxide (LDH) wanda ke biye da maganin ƙaura.RuNi SAA yana nuna ingantaccen haɓaka mai haɓakawa (> 99% yawan amfanin ƙasa) don chemoselective hydrogenation na 4-nitrostyrene zuwa 4-aminostyrene tare da mitar juyawa (TOF) har zuwa ~ 4300 mol-mol Ru-1 h-1, wanda shine mafi girma. matakin tsakanin iri-iri masu kara kuzari da aka yi rajista a ƙarƙashin yanayi masu kama da juna.Electron microscopy da spectroscopic hali ya nuna cewa keɓantattun rukunan Ru suna tarwatsewa a saman Ni nanoparticles (~ 8 nm), suna samar da daidaituwar Ru-Ni, wanda ya haifar da ruɗaɗɗen Ru shafukan (Ruδ-) saboda canja wurin lantarki daga ƙarƙashin Ni zuwa Ru. .A cikin FT-IR, nazarin XAFS da ƙididdige ka'idar aiki mai yawa (DFT) sun tabbatar da cewa shafukan yanar gizo a Ru-Ni interface kamar yadda wuraren aiki na ciki ke sauƙaƙe nitro.Tallace-tallacen da aka kunna (0.46 eV) ya bambanta da na mai kara kuzari na nickel monometallic.(0.74v).Bugu da kari, hydrogen dissociation faruwa a makwabta Ni matsayi, bi hydrogenation na matsakaici (C8H7NO * da C8H7NOH *) a Ruδ matsayi.Tasirin haɗin gwiwa na tallafin doping a cikin RuNi SAA mai haɓakawa yana haifar da fitattun ayyukan hydrogenation na nitroarenes da zaɓin zaɓi, wanda za'a iya ƙarawa zuwa wasu abubuwan haɓaka ƙarfe masu ƙarancin ƙarfi waɗanda aka yi amfani da su a cikin halayen halayen tsari.
Dangane da jujjuyawar tsarin topology na masu haɓakawa biyu na Layered Double hydroxide (LDH), mun shirya monometallic Ni wanda aka ajiye akan madaidaicin Al2O3.Bayan haka, saitin samfuran bimetallic na RuNi / Al2O3 tare da nau'in abun ciki daban-daban na Ru (0.1-2 wt%) an haɗa shi daidai ta hanyar rarrabawar lantarki don saka atom ɗin Ru a saman Ni nanoparticles (NPs) (Fig. 1a).Haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-haɗe-tsayi-ma'auni na plasma atomic atomic spectrometry (ICP-AES) sun ba da a sarari abun da ke ciki na Ru da Ni a cikin waɗannan samfuran (Ƙarin Tebu na 1), wanda ke kusa da lodin ka'idar ciyarwa.Hotunan SEM (Ƙarin Hoto 1) da sakamakon BET (Ƙarin Figures 2-9 da Ƙarin Table 1) sun nuna a fili cewa tsarin ilimin halittar jiki da takamaiman yanki na samfuran RuNi / Al2O3 ba sa samun canje-canje a bayyane yayin jiyya na electrochemical.– tsarin motsi.Tsarin X-ray (Fig. 1b) yana nuna jerin halayen halayen halayen a 2θ 44.3 °, 51.6 °, da 76.1 °, yana nuna matakai (111), (200), da (220) na al'ada Ni (JCPDS 004-0850). ).Musamman, samfuran RuNi ba sa nuna alamun ƙarfe ko oxidized Ru, yana nuna babban tarwatsa nau'ikan Ru.Ma'auni na microscopy na watsawa (TEM) na monometallic Ni da samfurori na RuNi (Fig. 1c1-c8) sun nuna cewa nickel nanoparticles suna da kyau tarwatsa kuma ba su iya motsawa a kan goyon bayan Al2O3 na amorphous tare da nau'i mai kama da nau'i (7.7-8.3 nm).Hotunan HRTEM (Figs. 1d1-d8) suna nuna daidaitaccen lokacin lattice na kusan 0.203 nm a cikin samfuran Ni da RuNi, daidai da jiragen Ni (111), duk da haka, gefuna na lattice na rukunan Ru ba su nan.Wannan yana nuna cewa Ru atom ɗin sun tarwatse sosai akan saman samfurin kuma baya shafar lokacin Ni lattice.A halin yanzu, 2 wt% Ru / Al2O3 an haɗa shi ta hanyar hanyar ajiya-deposition a matsayin mai sarrafawa, wanda aka rarraba rukunonin Ru a kan farfajiyar Al2O3 substrate (Ƙarin Hotuna. 10-12).
Tsarin hanyar haɗin gwiwa don samfuran RuNi/Al2O3, b X-ray diffraction alamu na Ni/Al2O3 da samfuran RuNi/Al2O3 daban-daban.c1-c8 TEM da d1-d8 HRTEM hotuna grating tare da rabe-raben girman barbashi na monometallic Ni, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0, 8% wt., 1 wt.Hoton tsige.% da 2 wt.% RuNi."au" yana nufin raka'a na sabani.
An yi nazarin ayyukan catalytic na samfuran RuNi ta hanyar chemoselective hydrogenation na 4-nitrostyrene (4-NS) zuwa 4-aminostyrene (4-AS).Juyin 4-NS akan madaidaicin Al2O3 shine kawai 0.6% bayan sa'o'i 3 (Ƙarin Teburin 2), yana nuna ƙaramin tasirin Al2O3.Kamar yadda aka nuna a cikin fig.2a, asali na nickel mai haɓakawa ya nuna ƙarancin aiki mai ƙarancin kuzari tare da jujjuyawar 4-NS na 7.1% bayan sa'o'i 3, yayin da 100% juzu'i za a iya samu a gaban monometallic Ru catalyst a ƙarƙashin yanayi iri ɗaya.Duk masu haɓakawa na RuNi sun nuna haɓakar haɓakar haɓakar haɓakar hydrogenation (canzawa: ~ 100%, 3 h) idan aka kwatanta da samfuran monometallic, kuma ƙimar amsawa tana da alaƙa da alaƙa da abun ciki na Ru.Wannan yana nufin cewa barbashi Ru suna taka muhimmiyar rawa a cikin tsarin hydrogenation.Abin sha'awa, zaɓin samfur (Fig. 2b) ya bambanta sosai dangane da mai haɓakawa.Ga mafi ƙarancin aiki mai ƙara kuzari na nickel, babban samfurin shine 4-nitroethylbenzene (4-NE) (zaɓi: 83.6%) kuma zaɓi na 4-AC shine 11.3%.A cikin yanayin monometallic Ru, haɗin C = C a cikin 4-NS ya fi dacewa da hydrogenation fiye da -NO2, yana haifar da samuwar 4-nitroethylbenzene (4-NE) ko 4-aminoethylbenzene (4-AE);Zaɓin na 4-AC ya kasance kawai 15.7%.Abin mamaki, RuNi masu haɓakawa tare da ƙananan abun ciki na Ru (0.1-0.4 wt%) sun nuna kyakkyawan zaɓi (> 99%) zuwa 4-aminostyrene (4-AS), yana nuna cewa NO2 ne kuma ba vinyl ba, yana da chemoselective na musamman.Lokacin da abun ciki na Ru ya wuce 0.6 wt.%, zaɓi na 4-AS ya ragu sosai tare da ƙara yawan nauyin Ru, yayin da zaɓi na 4-AE ya karu maimakon.Ga mai kara kuzari mai ɗauke da 2 wt% RuNi, duka ƙungiyoyin nitro da vinyl an yi su da hydrogenated sosai tare da babban zaɓi zuwa 4-AE na 98%.Don nazarin sakamakon Ru watsawa jihar a kan catalytic dauki, 0.4 wt% Ru / Al2O3 samfurori da aka shirya (Karin Figures 10, 13 da kuma 14) a cikin abin da Ru barbashi aka yawa tarwatsa kamar yadda mutum kwayoyin zarra bi da 'yan Ru gungu.(quasi-atomic Ru).Ayyukan catalytic (Ƙarin Teburin 2) yana nuna cewa 0.4 wt% Ru / Al2O3 yana inganta zaɓin 4-AS (67.5%) idan aka kwatanta da samfurin 2 wt% Ru / Al2O3, amma aikin yana da ƙasa sosai (canzawa: 12.9).%;3 hours).Dangane da jimlar adadin wuraren ƙarfe a saman da aka ƙayyade ta CO pulsed chemisorption ma'auni, an sami mitar juyawa (TOFmetal) na mai kara kuzari na RuNi a ƙaramin juzu'in 4-NS (Ƙarin Hoto 15), wanda ya nuna yanayin farko don haɓakawa. sa'an nan kuma don ragewa tare da ƙara karuwa a cikin loading Ru (Ƙarin Hoto 16).Wannan yana nuna cewa ba duk rukunin ƙarfe na saman ke aiki azaman rukunin yanar gizo masu aiki don abubuwan RuNi ba.Bugu da ƙari, an ƙididdige TOF na RuNi mai haɓakawa daga rufukan Ru don ƙara bayyana ayyukan haɓakawa na ciki (Fig. 2c).Kamar yadda abun ciki na Ru ya karu daga 0.1 wt.% zuwa 0.4 wt.% RuNi catalysts sun nuna kusan ƙimar TOF akai-akai (4271-4293 h-1), wanda ke nuna ƙayyadaddun ƙwayoyin ru a cikin watsawar atomatik (wataƙila tare da samuwar RuNi SAA).) kuma yana aiki azaman babban wurin aiki.Duk da haka, tare da ƙarin karuwa a cikin loading na Ru (a cikin 0.6-2 wt%), ƙimar TOF ta ragu sosai, wanda ke nuna canji a cikin tsarin da ke cikin cibiyar aiki (daga watsawa ta atomatik zuwa Ru nanoclusters).Bugu da ƙari, ga iliminmu, TOF na 0.4 wt% RuNi (SAA) mai haɓakawa yana cikin matsayi mafi girma a tsakanin masu haɓaka ƙarfe da aka ruwaito a baya a ƙarƙashin irin yanayin amsawa (Ƙarin Table 3), yana ƙara nuna cewa monoatomic RuNi alloys yana samar da kyawawan kaddarorin haɓaka.abin kallo.Ƙarin Hoto na 17 yana nuna aikin ƙara kuzari na 0.4 wt% RuNi (SAA) mai haɓakawa a matsi daban-daban da yanayin zafi na H2, inda aka yi amfani da matsi na H2 na 1 MPa da zafin jiki na 60 °C azaman mafi kyawun sigogin amsawa.samfurin dauke da RuNi 0.4 wt.% (Siffa 2d), kuma ba a sami raguwar aiki da yawan amfanin ƙasa sama da zagaye biyar a jere ba.Hotunan X-ray da TEM na 0.4 wt% RuNi mai haɓakawa da aka yi amfani da su bayan zagayowar 5 (Ƙarin Figures 18 da 19) ba su nuna wani gagarumin canje-canje a cikin tsarin crystal ba, yana nuna babban kwanciyar hankali na zaɓin halayen hydrogenation.Bugu da ƙari, 0.4 wt% RuNi (SAA) mai haɓakawa kuma yana ba da kyakkyawan sakamako na amines don chemoselective hydrogenation na sauran mahadi na nitroaromatic da ke dauke da halogens, aldehydes, da ƙungiyoyin hydroxyl (Ƙarin Table 4), yana nuna kyakkyawan amfani.
Canjin Catalytic da b rarraba samfuran hydrogenation na 4-nitrostyrene a gaban monometallic Ni, Ru, da RuNi masu haɓakawa tare da abun ciki daban-daban na Ru (0.1-2 wt%), c a cikin kewayon haɓaka mai ƙarfi, Mitar juyawa (TOF) akan RuNi masu kara kuzari c dangane da Ru da tawadar Allah.d Gwaji don yuwuwar sake amfani da 0.4 wt.% RuNi mai kara kuzari don zagayowar kuzari guda biyar a jere.ln (C0 / C) yana dogara ne akan lokacin amsawar hydrogenation na e-nitrobenzene da f-styrene tare da cakuda nitrobenzene da styrene (1: 1).Yanayin amsawa: 1 mmol reagent, 8 ml sauran ƙarfi (ethanol), 0.02 g mai kara kuzari, 1 MPa H2, 60 ° C, 3 hours.An bayyana sandunan kurakurai azaman madaidaicin sabani na maimaitawa uku.
Don ci gaba da bincika babban bambancin chemoselective, hydrogenation na cakuda styrene da nitrobenzene (1: 1) an kuma aiwatar da su a gaban abubuwan haɓakar monometallic Ni, Ru, 0.4 wt% RuNi, da 2 wt% RuNi, bi da bi (Ƙarin Fig. 20).Ko da yake chemoselectivity na halayen hydrogenation na ƙungiyoyi masu aiki daidai ne, hakika akwai wasu bambance-bambance a cikin zaɓi na intramolecular da intermolecular hydrogenation saboda tasirin allosteric.Kamar yadda aka nuna a cikin fig.2e,f, lanƙwasa ln (C0/C) tare da lokacin amsawa yana ba da madaidaiciyar layi daga asalin, yana nuna cewa duka nitrobenzene da styrene sune halayen tsari na farko-farko.Monometallic nickel catalysts sun nuna ƙarancin ƙarancin adadin hydrogenation na p-nitrobenzene (0.03 h-1) da styrene (0.05 h-1).Musamman ma, aikin da aka fi so na styrene hydrogenation (ƙididdigar ƙima: 0.89 h-1) an samu a kan Ru monometallic catalyst, wanda ya fi girma fiye da aikin hydrogenation na nitrobenzene (ƙididdigar ƙimar: 0.18 h-1).A cikin yanayin mai kara kuzari mai dauke da RuNi(SAA) 0.4 wt.% nitrobenzene hydrogenation yana da ƙarfi sosai fiye da styrene hydrogenation (ƙididdigar ƙimar: 1.90 h-1 vs. 0.04 h-1), yana nuna fifiko ga ƙungiyar -NO2.sama da C hydrogenation = bond C. Don mai kara kuzari tare da 2 wt.% RuNi, yawan adadin hydrogenation na nitrobenzene (1.65 h-1) ya ragu idan aka kwatanta da 0.4 wt.% RuNi (amma har yanzu ya fi na mono-metal catalyst), yayin da adadin hydrogenation na styrene ya karu sosai (ƙididdigar ƙima: 0.68).h-1).Wannan kuma yana nuna cewa tare da tasirin haɗin gwiwa tsakanin Ni da Ru, ayyukan catalytic da chemoselectivity zuwa ƙungiyoyin -NO2 suna ƙaruwa sosai idan aka kwatanta da RuNi SAA.
Don gani ƙayyadaddun tarwatsa jihohin Ru da Ni mahadi, an yi amfani da hanyar yin hoto ta amfani da babban kusurwar zoben duhu mai ɗaukar hoto na lantarki tare da gyaran gyare-gyare (AC-HAADF-STEM) da taswirar abubuwan taswirar makamashi mai watsawa (EDS).Taswirar farko na EMF na samfurin tare da 0.4 wt% RuNi abun ciki (Fig. 3a, b) yana nuna cewa Ru yana tarwatse sosai a kan nanoparticles na nickel, amma ba akan ma'aunin Al2O3 ba, hoton AC-HAADF-STEM mai dacewa (Fig. 3c) ya nuna, Ana iya ganin cewa saman Ni NPs yana ƙunshe da wurare masu haske da yawa na girman atomic na Ru atom (alama da kibiyoyi masu launin shuɗi), yayin da ba a lura da gungu ko Ru nanoparticles ba.Hoto na 3d), yana nuna samuwar monatomic RuNi gami.Don samfurin da ke ɗauke da RuNi 0.6 wt.% (Fig. 3e), Ru guda Ru atom da ƙananan adadin ruɗaɗɗen ruɗaɗɗen ruɓi an lura dasu akan Ni NPs, wanda ke nuna ƙaramin adadin ruɗaɗɗen ruɗaɗɗen ruɗi saboda ƙarar kaya.A cikin yanayin samfurin tare da 2 wt% RuNi abun ciki, yawancin manyan rukunin Ru a kan Ni NPs an samo su a cikin hoton HAADF-STEM (Fig. 3f) da kuma EDS na farko taswira (Ƙarin Hoto 21), yana nuna babban tarin Ru. .
Hoton HAADF-STEM, b madaidaicin hoton taswirar EDS, c babban ƙuduri AC-HAADF-STEM Hoton, d girman siffar STEM da daidaitaccen ƙarfin rarraba samfurin 0.4 wt% RuNi.(e, f) Hotunan AC-HAADF-STEM na samfurori masu ɗauke da 0.6 wt.% RuNi da 2 wt.% RuNi, bi da bi.
Idan aka kwatanta da samfurori na Ni / Al2O3 da Ru / Al2O3, DRIFTS spectra na CO adsorption a wurin da aka yi (Fig. 4a) don kara nazarin bayanan tsarin samfurori da ke dauke da 0.4 wt.%, 0.6 wt.% da 2 wt.% RuNi.CO adsorption akan samfurin Ru/Al2O3 yana ba da babban kololuwa a 2060 cm-1 da kuma wani tsayin tsayi mai tsayi a 1849 cm-1 wanda aka danganta shi da tallan CO na layi akan Ru da daidaitawa akan ƙwayoyin ru guda biyu maƙwabta, bi da bi CO39,40.Don samfurin Ni monometallic, ana lura da tsayi mai ƙarfi kawai a 2057 cm-1, wanda aka danganta da CO41,42 na layi a cikin yankin nickel.Don samfurin RuNi, ban da babban kololuwa a 2056 cm-1, akwai wata kafaɗa ta musamman wacce ke tsakiya a ~ 2030 cm-1.An yi amfani da hanyar dacewa mafi girma na Gaussian don ƙaddamar da rarraba samfuran RuNi a cikin kewayon 2000-2100 cm-1 da rarraba CO a cikin yankin Ni (2056 cm-1) da yankin Ru (2031-2039 cm).An ƙaddamar da kololuwa biyu a layi - 1) (Fig. 4b).Abin sha'awa shine, daga samfuran Ru / Al2O3 (2060 cm-1) zuwa samfuran RuNi (2031-2039 cm-1), ƙimar CO mai alaƙa da layi a cikin yankin Ru yana fuskantar jajayen ja kuma yana ƙaruwa tare da haɓaka abun ciki na Ru.Wannan yana nuna ƙarar electronegativity na ruɓaɓɓen ƙwayoyin RuNi a cikin samfurin RuNi, wanda shine sakamakon canja wurin lantarki daga Ni zuwa Ru, yana haɓaka ra'ayin d-π electron daga Ru zuwa madaidaicin CO 2π* orbital.Bugu da kari, don samfurin da ke dauke da 0.4 mass% RuNi, ba a ga kololuwar tallan tallace-tallace ba, wanda ke nuna cewa rukunan Ru sun kasance a matsayin keɓaɓɓen Ni atoms (SAA).A cikin yanayin samfurori tare da 0.6 wt.% RuNi da 2 wt.% RuNi, kasancewar haɗin gwiwar CO yana tabbatar da kasancewar Ru multimers ko clusters, wanda ke cikin kyakkyawar yarjejeniya tare da sakamakon AC-HAADF-STEM.
a Situ CO-DRIFTS spectra na Ni / Al2O3, Ru / Al2O3 da 0.4 wt.%, 0.6 wt.%, 2 wt.% RuNi samfurori tare da iskar gas na helium a cikin kewayon 2100-1500 cm-1 don 20 min.b Scaled da Gaussian-fitted bakan na samfurin RuNi/Al2O3 tare da kafaffen matsayi mafi tsayi da FWHM.c A cikin yanayin Ru K-gefen XANES da EXAFS Fourier suna canza bakan samfura daban-daban.Canjin igiyar igiyar ruwa mai nauyin K2 na siginar XAFS K-geki Ru dangane da raƙuman ruwa na Morlet don samfuran e Ru daga e Ru foil, f 0.4 wt% RuNi da g RuO2."au" yana nufin raka'a na sabani.
An daidaita shi a cikin situ tsarin sha na X-ray X-ray (XANES) bakan da aka yi don nazarin tsarin lantarki da tsarin lissafi na samfuran RuNi tare da samfuran Ru foil da samfuran RuO2.Kamar yadda aka nuna a cikin fig.4c, yayin da nauyin Ru ya ragu, ƙarfin farin layin a hankali yana raguwa daga samfuran Ru/Al2O3 zuwa samfuran RuNi.A halin yanzu, tsananin farin layin XANES bakan a K-gefen Ni yana nuna ɗan ƙara kaɗan daga samfurin Ni na asali zuwa samfurin RuNi (Ƙarin Hoton 22).Wannan yana nuna canji a cikin ƙarancin lantarki da yanayin daidaitawar mahaɗan Ru.Kamar yadda aka nuna a cikin X-ray photoelectron spectroscopy (XPS) spectra (Ƙarin Hoto 23), kololuwar Ru0 na samfurin RuNi ya canza zuwa ƙaramin ƙarfin ɗauri kuma tsayin Ni0 ya matsa zuwa mafi girman ƙarfin ɗauri idan aka kwatanta da monometallic Ru da Ni., wanda kuma ke nuna canja wurin lantarki daga Ni atom zuwa ru atom a RuNi SAA.Binciken cajin Bader na saman RuNi SAA (111) ya nuna cewa keɓantaccen atom ɗin Ru suna ɗauke da caji mara kyau (Ruδ-) da aka canjawa wuri daga ƙananan atom ɗin Ni (Ƙarin Hoto 24), wanda ya yi daidai da sakamakon DRIFTS da XPS.Don yin nazarin cikakken tsarin daidaitawa na Ru (Fig. 4d), mun yi tsawaita shayarwa ta X-ray mai kyan gani mai kyau (EXAFS) a cikin canjin Fourier.Samfurin da ke ɗauke da RuNi 0.4 wt.% yana da ƙaƙƙarfan kololuwa a ~ 2.1 Å, wanda yake a cikin yanki tsakanin rukunin Ru-O (1.5 Å) da ru-Ru (2.4 Å), wanda za'a iya danganta shi da haɗin gwiwar Ru-Ni44, 45. Sakamakon dacewa bayanai EXAFS (Ƙarin Teburin 5 da Ƙarin Bayanai 25-28) sun nuna cewa hanyar Ru-Ni tana da lambar daidaitawa (CN) na 5.4, yayin da babu haɗin Ru-Ru da Ru-O a 0.4 wt.% RuNi samfurin.Wannan yana tabbatar da cewa manyan rukunan zarra suna tarwatsa su ta atomatik kuma Ni sun kewaye su, suna samar da gami da monoatomic.Ya kamata a lura cewa babban ƙarfin (~ 2.4 Å) na haɗin gwiwar Ru-Ru ya bayyana a cikin samfurin 0.6 wt.% RuNi kuma an inganta shi a cikin samfurin ta 2 wt.% RuNi.Musamman, EXAFS mai lankwasa fitting ya nuna cewa lambobin daidaitawar Ru-Ru sun ƙaru sosai daga 0 (0.4 wt.% RuNi) zuwa 2.2 (0.6 wt.% RuNi) kuma ya ƙara zuwa 6.7 (2 wt.% .% RuNi), bi da bi. , wanda ke nuni da cewa yayin da nauyin Ru ya ƙaru, Ru atom ɗin suna haɗuwa a hankali.An ƙara yin amfani da siginar Ru K-gefen XAFS mai nauyin nauyin K2 don nazarin yanayin daidaitawa na nau'in Ru.Kamar yadda aka nuna a cikin fig.4e, Ru foil lobes a 2.3 Å, 9.7 Å-1 koma ga gudunmawar Ru-Ru.A cikin samfurin da ke ɗauke da RuNi 0.4 wt.% (Fig. 4f) babu lobes a k = 9.7 Å-1 da 5.3 Å-1, sai dai na tsakiya na Ru tare da ru atom da O atoms (Fig. 4g);Ana lura da Ru-Ni a 2.1 Å, 7.1 Å-1, wanda ke tabbatar da samuwar SAA.Bugu da ƙari, ƙirar EXAFS a K-gefen Ni don samfurori daban-daban ba su nuna wani bambance-bambance ba (Ƙarin Hoto 29), yana nuna cewa tsarin daidaitawa na Ni ba shi da rinjaye ta hanyar rukunan rukunan.A takaice, sakamakon AC-HAADF-STEM, a situ CO-DRIFTS, da kuma a wurin gwaje-gwajen XAFS sun tabbatar da nasarar shirye-shiryen RuNi SAA catalysts da juyin halittar Ru a kan Ni NPs daga atom guda zuwa ru multimers ta hanyar haɓaka Ku load.Bugu da ƙari, Hotunan HAADF-STEM (Ƙarin Hoto 30) da EXAFS spectra (Ƙarin Hotuna 31) na RuNi SAA masu haɓakawa da aka yi amfani da su sun nuna cewa yanayin watsawa da tsarin daidaitawa na Ru atom ba su canza sosai ba bayan 5 hawan keke, yana tabbatar da cewa ba su canza ba. cewa barga RuNi SAA mai kara kuzari.
An yi amfani da ma'auni na H2-TPD don nazarin ƙaddamar da ƙaddamarwa na hydrogen a kan nau'i-nau'i daban-daban kuma sakamakon ya nuna cewa duk waɗannan masu haɓakawa suna da ƙarfin haɗin H2 mai ƙarfi tare da ƙarancin lalacewa a ~ 100 ° C (Ƙarin Fig. 32).Sakamakon ƙididdigar ƙididdiga (Ƙarin Hoto 33) bai nuna madaidaicin madaidaiciyar daidaitawa tsakanin sake kunnawa da adadin ƙarancin hydrogen ba.Bugu da ƙari, mun yi gwaje-gwaje tare da D2 isotopes kuma mun sami tasirin isotope na kinetic (KIE) darajar 1.31 (TOFH / TOFD) (Ƙarin Hoton 34), yana nuna cewa kunnawa da rarrabawar H2 suna da mahimmanci amma ba matakan iyakancewa ba.An yi lissafin DFT don ƙarin bincike game da haɓakawa da haɓaka halayen hydrogen akan RuNi SAA da ƙarfe Ni kaɗai (Ƙarin Hoto 35).Don samfuran RuNi SAA, ƙwayoyin H2 sun fi son chemisorb sama da rukunan ru guda ɗaya tare da ƙarfin tallan -0.76 eV.Daga baya, hydrogen ya rabu zuwa nau'ikan nau'ikan H guda biyu masu aiki akan rukunin ru-Ni RuNi SAA, suna shawo kan shingen makamashi na 0.02 eV.Baya ga rukunan Ru, ana iya sanya kwayoyin H2 a saman manyan rukunan Ni a kusa da Ru (makamashi talla: -0.38 eV) sannan a raba su zuwa Hs biyu a wuraren ru-Ni da Ni-Ni.Katangar atomatik 0.06 eV.Sabanin haka, shingen makamashi don haɓakawa da rarraba kwayoyin H2 akan Ni (111) surface sune -0.40 eV da 0.09 eV, bi da bi.Ƙarƙashin shingen makamashi mai ƙarancin ƙarfi da bambance-bambancen da ba su da mahimmanci suna nuna cewa H2 cikin sauƙi yana rarrabuwa a saman Ni da RuNi surfactants (Ni-site ko Ru-site), wanda ba shine mahimmin abin da ke shafar ayyukan sa ba.
Kunna adsorption na wasu ƙungiyoyin aiki yana da mahimmanci don zaɓin hydrogenation na kayan aiki.Saboda haka, mun yi lissafin DFT don bincika yiwuwar jeri na 4-NS adsorption da wuraren aiki a kan RuNi SAA (111), kuma an nuna sakamakon ingantawa a Ƙarin Hoto. 36e), wanda N atom ɗin ke cikin rukunin ru-Ni mara kyau kuma O atom guda biyu suna haɗin haɗin haɗin Ru-Ni yana nuna mafi ƙarancin ƙarfin talla (-3.14 eV).Wannan yana nuna tsarin tsarin adsorption mafi kyawun yanayin zafi idan aka kwatanta da na tsaye da sauran jeri na layi daya (Ƙarin Hoto 36a-d).Bugu da ƙari, bayan ƙaddamar da 4-HC akan RuNi SAA (111), tsayin N-O1 (L (N-O1)) a cikin rukunin nitro ya karu zuwa 1.330 Å (Fig. 5a), wanda yake da yawa. ya fi tsayi fiye da tsawon gaseous 4- NS (1.244 Å) (Ƙarin Hoton 37), har ma da wuce L (N-O1) (1.315 Å) akan Ni (111).Wannan yana nuna cewa an inganta tallan tallace-tallacen N-O1 a saman RuNi PAA idan aka kwatanta da farkon Ni(111).
Saitunan Adsorption na 4-HC akan Ni (111) da RuNi SAA (111) (Eads) saman (gefe da manyan ra'ayoyi).Ru - violet, Ni - kore, C - orange, O - ja, N - blue, H - fari.b A cikin yanayin FT-IR na gaseous da chemisorbed 4-HC akan monometallic surfactants Ni, Ru, RuNi (0.4 wt.%) da 2 wt.% RuNi, bi da bi.c An daidaita shi a wurin XANES da d-phase-gyara Fourier EXAFS a Ru K-gefen 0.4 wt % RuNi PAA yayin tallan 4-NS (RuNi SAA-4NS) da matakan hydrogenation (RuNi SAA-4NS-H2) .Transformation Spectra ;…e Hasashen yawa na jihohi (PDOS) na farkon saman RuNi SAA (111), N-O1 a cikin gas mai 4-NS kuma an tallata 4-NS akan RuNi SAA (111)."au" yana nufin raka'a na sabani.
Don ƙarin gwada halayen adsorption na 4-NS, a cikin wurin FT-IR an yi ma'auni akan Ni monometallic, Ru monometallic, 0.4 wt% RuNi (SAA), da 2 wt% RuNi catalysts (Fig. 5b).Bakan FT-IR na gaseous 4-NS ya nuna halayen halayen guda uku a 1603, 1528, da 1356 cm-1, waɗanda aka sanya su zuwa ν (C = C), νas (NO2), da νs (NO2) 46,47, 48.A gaban monometallic Ni, ana lura da jajayen nau'ikan nau'ikan nau'ikan guda uku: v(C=C) (1595 cm–1), νas (NO2) (1520 cm–1), da νs (NO2) (1351 cm–1) ., wanda ke nuna chemisorption na C = C da -NO2 kungiyoyin a kan Ni surface (mafi yiwuwa, a cikin daidaitawa na layi daya adsorption).Don samfurin monometallic Ru, an sami jajayen nau'ikan nau'ikan nau'ikan nau'ikan guda uku (1591, 1514, da 1348 cm-1, bi da bi) dangane da monometallic Ni, wanda ke nuna haɓakar haɓakar ƙungiyoyin nitro da С=C bond akan Ru.A cikin yanayin 0.4 wt.% RuNi (SAA), ƙungiyar ν (C = C) tana a tsakiya a 1596 cm–1, wanda ke kusa da rukunin Ni na monometallic (1595 cm–1), yana nuna cewa ƙungiyoyin vinyl suna son ƙara Ni akan RuNi. Shafukan SAA.Bugu da ƙari, ya bambanta da mai haɓaka monometallic, ƙarfin dangi na νs (NO2) band (1347 cm-1) ya fi rauni fiye da νas (NO2) band (1512 cm-1) akan 0.4 wt.% RuNi (SAA) ) , wanda ke da alaƙa da raguwar NO bond zuwa -NO2 don samar da tsaka-tsakin nitroso bisa ga binciken da ya gabata49,50.An kuma lura da irin wannan sabon abu a cikin samfurin tare da abun ciki na RuNi na 2 wt.%.Sakamakon da ke sama ya tabbatar da cewa tasirin haɗin gwiwar cibiyoyin bimetallic a cikin PAA RuNi yana inganta haɓakar polarization da rarraba ƙungiyoyin nitro, wanda ke da kyakkyawar yarjejeniya tare da ingantaccen tsarin adsorption da aka samu ta hanyar lissafin DFT.
A wurin XAFS spectroscopy an gudanar da binciken don nazarin juyin halitta mai ƙarfi na tsarin lantarki da yanayin daidaitawa na RuNi SAA yayin tallan 4-NS da halayen catalytic.Kamar yadda ake iya gani daga K-gefen XANES bakan na Ru (Fig. 5c), bayan tallan 4-HC, 0.4 wt.% RuNi PAA, gefen sha yana canzawa sosai zuwa mafi girman kuzari, wanda ke tare da karuwa a cikin tsananin farin layin, wanda ke nuna cewa nau'in Ru na iya faruwa saboda canjin lantarki daga Ru zuwa 4-NS.Bugu da ƙari, gyare-gyaren da aka gyara na Fourier ya canza fasalin EXAFS na adsorbed 4-NS RuNi SAA (Fig. 5d) yana nuna ingantaccen haɓakar sigina a ~ 1.7 Å da ~ 3.2 Å, wanda ke hade da haɗin gwiwar Ru-O.Siffar XANES da EXAFS na 0.4 wt% RuNi SAA sun koma asalin asalinsu bayan allurar iskar hydrogen na mintuna 30.Waɗannan al'amuran suna nuna cewa ana tallata ƙungiyoyin nitro akan rukunin Ru-O ta hanyar haɗin gwiwar Ru-O dangane da hulɗar lantarki.Dangane da yanayin XAFS na gefen Ni-K a wurin (Ƙarin Hoto 38), ba a sami canje-canje a bayyane ba, wanda zai iya kasancewa saboda tasirin dilution na Ni atom a cikin babban lokaci akan ɓangarorin Ni.Yawan da aka annabta na jihohi (PDOS) na RuNi SAA (Fig. 5e) ya nuna cewa yanayin rukunin nitro da ke sama da matakin Femi yana faɗaɗa kuma yana motsawa ƙasa da matakin Femi a cikin jihar da aka haɗa, wanda kuma yana nuna cewa electrons daga d- jihar RuNi SAA ta sauya sheka zuwa jihar da ba kowa a cikin -NO2.Bambancin nauyin cajin (Ƙarin Hoto 39) da bincike na cajin Bader (Ƙarin hoto na 40) ya nuna cewa haɗaɗɗen ƙwayar lantarki na 4-NS yana tarawa bayan tallan sa a saman RuNi SAA (111).Bugu da ƙari, ƙimar cajin -NO2 ya ƙaru sosai idan aka kwatanta da ƙungiyar vinyl a cikin 4-NS saboda canja wurin lantarki a cikin Ru-Ni interface, yana nuna takamaiman kunnawa na NO bond a cikin ƙungiyar nitro.
A cikin wurin FT-IR an yi shi don saka idanu akan tsarin haɓakawa na 4-NS hydrogenation dauki akan samfurori masu haɓakawa (Fig. 6).Don mai haɓaka nickel na farko (Fig. 6a), an sami raguwa kaɗan a cikin nitro (1520 da 1351 cm-1) da C = C (1595 cm-1) bandeji lokacin wucewa H2 don 12 min, wanda. yana nuna cewa - Kunna NO2 da C=C sun fi rauni.A gaban monometallic Ru (Fig. 6b), ν (C = C) band (a 1591 cm-1) da sauri ya ragu a cikin 0-12 min, yayin da νs (NO2) da νas (NO2) bandeji suna raguwa sosai. .Slow Wannan yana nuna fifikon kunna ƙungiyar vinyl don hydrogenation, wanda ke haifar da samuwar 4-nitroethylbenzene (4-NE).A cikin yanayin 0.4 wt.%.An kuma lura da wani sabon band a tsakiya a 1629 cm-1, dangana ga lankwasa vibrations na NH.Bugu da ƙari, ƙungiyar don ν (C = C) (1596 cm-1) yana nuna raguwa kaɗan kaɗan bayan 12 min.Wannan canji mai ƙarfi yana tabbatar da polarization da hydrogenation na -NO2 zuwa -NH2 ta 0.4 wt% RuNi (SAA) dangane da keɓantaccen chemoselectivity zuwa 4-aminostyrene.Don samfurin 2 wt.% RuNi (Fig. 6d), ban da bayyanar sabon band a 1628 cm-1 wanda aka danganta ga δ (NH), ν (C = C) band ya ragu kuma ya ɓace tare da ƙara yawan rukunin nitro (1514). kuma 1348 cm-1).Wannan yana nuna cewa C=C da -NO2 suna aiki yadda ya kamata saboda kasancewar cibiyoyin ru-Ru da Ru-Ni, bi da bi, wanda yayi daidai da samuwar 4-NE da 4-AE akan 2 wt.% RuNi catalyst.
A cikin yanayin FT-IR na 4-NS hydrogenation a gaban monometallic Ni, b monometallic Ru, c 0.4 wt% RuNi SAA, da d 2 wt% RuNi a cikin kwararar H2 a 1700-1240 cm - Range 1 an rubuta shi azaman amsa gas bayan 0, 3, 6, 9 da 12 mintuna, bi da bi."au" yana nufin raka'a na sabani.Rarraba makamashi mai yuwuwa da ingantattun ingantattun sifofi don C=C hydrogenation da NO scission zuwa 4-NS akan e Ni(111) da f RuNi SAA(111) saman.Ru - violet, Ni - kore, C - orange, O - ja, N - blue, H - fari.“ads”, “IS”, “TS”, da “FS” suna wakiltar jihar adsorption, yanayin farko, yanayin miƙa mulki, da jiha ta ƙarshe, bi da bi.
Hanyoyi masu yiwuwa don 4-NS canzawa zuwa Ni (111) da RuNi SAA (111), ciki har da C = C hydrogenation da NO bond cleavage, an bincikar su ta hanyar lissafin DFT don ƙara bayyana mahimmancin rawar 4-NS.Sassan haɗin Ru-Ni don samar da maƙasudin 4-AS.Domin Ni (111) surface (Fig. 6e), da makamashi shinge ga NO scission da hydrogenation na vinyl kungiyoyin a farkon mataki ne 0.74 da 0.72 eV, bi da bi, wanda ya nuna cewa chemoselective hydrogenation na nitro kungiyoyin a 4-HC ne. m.domin monometallic nickel saman.Sabanin haka, shingen makamashi don NO dissociation shine kawai 0.46 eV sama da na RuNi SAA (111), wanda ya fi ƙasa da na C = C bond hydrogenation (0.76 eV) (Fig. 6f).Wannan ba shakka yana tabbatar da cewa cibiyoyin haɗin gwiwar Ru-Ni suna rage shingen makamashi don NO scission a cikin ƙungiyoyin nitro, wanda ke haifar da raguwar yanayin zafi da aka fi so na ƙungiyoyin nitro idan aka kwatanta da ƙungiyoyin C=C akan saman RuNi surfactant, wanda ya yarda da sakamakon gwaji.
An bincika tsarin amsawa da ƙididdige ƙididdiga na makamashi na 4-NS hydrogenation akan RuNi SAA bisa la'akari da lissafin DFT (Fig. 7), kuma an nuna cikakken tsarin tallan tallace-tallace na manyan matakai a Ƙarin Hoto 41. Don inganta tsarin lissafin, An cire shingen samar da makamashi na kwayoyin ruwa daga lissafin.farantin karfe 9,17.Kamar yadda aka nuna a cikin fig.7, kwayoyin 4-NS an fara tsotse su a layi daya akan RuNi surfactant, kuma O atom guda biyu a cikin rukunin nitro an ɗaure su zuwa cibiyoyin ru-Ni (S0; mataki na I).Daga baya, NO bond ɗin da ke haɗe zuwa rukunin Ru ya karye, wanda ke tare da samuwar nitroso matsakaici (C8H7NO*) a rukunin yanar gizon Ru-Ni da O * a rukunin Ni na wofi (S0 → S1 ta hanyar TS1; makamashi shamaki: 0.46 eV, mataki na biyu).O* radicals suna hydrogenated ta H atoms masu aiki don samar da kwayoyin H2O tare da exotherm na 0.99 eV (S1 → S2).Shingayen makamashi don hydrogenation na matsakaicin C8H7NO* (Ƙarin Figures 42 da 43) sun nuna cewa masu amsawa na H atom daga rukunin ru-Ni mara kyau sun fi kaiwa hari akan O atom akan N atom, wanda ya haifar da C8H7NOH* (S2 → S4; shingen makamashi TS2: 0.84 eV, mataki III).N atom ɗin C8H7NOH* daga nan aka sanya hydrogenated don samar da C8H7NHOH* bayan haye shingen 1.03 eV (S4→S6; mataki IV), wanda shine ma'anar matakin gaba ɗaya.Na gaba, haɗin N-OH a cikin C8H7NHOH * ya karye a Ru-Ni interface (S6 → S7; shingen makamashi: 0.59 eV; mataki V), bayan haka OH * ya kasance hydrogenated zuwa HO (S7 → S8; exotherm: 0.31 eV). ) Bayan haka, N atom na ru-Ni hollow sites a cikin C8H7NH * an kuma sanya hydrogenated don samar da C8H7NH2* (4-AS) tare da shingen makamashi na 0.69 eV (S8 → S10; mataki VI).A ƙarshe, an lalata ƙwayoyin 4-AS da HO daga saman RuNi-PAA, kuma mai haɓakawa ya koma matsayinsa na asali (mataki VII).Wannan tsari na musamman na tsaka-tsakin tsaka-tsaki tsakanin rututun Ru guda ɗaya da abubuwan Ni, tare da tasirin haɗin gwiwar rundunonin doping a cikin RuNi SAA, yana haifar da ƙwararren aiki da chemoselectivity na 4-NS hydrogenation.
Shinkafa4. Tsarin tsari na tsarin aikin hydrogenation na NS zuwa 4-AS akan RuNi PAA surface.Ru - violet, Ni - kore, C - orange, O - ja, N - blue, H - fari.Wurin shiga yana nuna rarraba yuwuwar makamashi na 4-NS hydrogenation akan RuNi SAA (111), wanda aka lasafta akan tushen DFT."S0" yana wakiltar yanayin farko, kuma "S1-S10" yana wakiltar jerin jihohin talla."TS" yana nufin yanayin canji.Lambobin da ke cikin ɓangarorin suna wakiltar shingen makamashi na manyan matakai, sauran lambobi kuma suna wakiltar ƙarfin tallan madaidaicin madaidaicin.
Don haka, RuNi SAA masu haɓakawa an samo su ta amfani da halayen maye gurbin lantarki tsakanin RuCl3 da Ni NPs waɗanda aka samu daga magabatan LDH.Idan aka kwatanta da a baya rahoton monometallic Ru, Ni da sauran nau'ikan masu haɓakawa daban-daban, sakamakon RuNi SAA ya nuna ingantaccen ƙarfin kuzari don 4-NS chemoselective hydrogenation (4-AS yawan amfanin ƙasa:> 99%; darajar TOF: 4293 h-1).Haɗaɗɗen halayen da suka haɗa da AC-HAADF-STEM, a cikin CO-DRIFTS, da XAFS sun tabbatar da cewa Ru atoms sun kasance marasa motsi akan Ni NPs a matakin zarra ɗaya ta hanyar haɗin Ru-Ni, wanda ke tare da canja wurin lantarki daga Ni zuwa Ru.A cikin XAFS, gwaje-gwajen FT-IR, da ƙididdigar DFT sun nuna cewa rukunin yanar gizon Ru-Ni yana aiki azaman wurin aiki na ciki don fifita kunna NO bond a cikin ƙungiyar nitro;Haɗin kai tsakanin rukunin Ru da maƙwabtan Ni yana sauƙaƙe kunna tsaka-tsaki da hydrogenation, ta haka yana haɓaka haɓakar haɓakawa sosai.Wannan aikin yana ba da haske game da alaƙar da ke tsakanin rukunin yanar gizo masu aiki na bifunctional da halayen catalytic na SAA a matakin atomic, yana buɗe hanya don ƙirar ma'ana ta sauran masu haɓaka hanyoyin biyu tare da zaɓin da ake so.
An siyi masu binciken da aka yi amfani da su a cikin gwajin daga 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 da nitrostyrene.An yi amfani da ruwa mai tsafta a duk gwaje-gwaje.
NiAl LDHs an haɗa su azaman mafari ta haɓakar yanayi.Na farko, urea (3.36 g), Al2 (SO4) 3 · 18H2O (9.33 g) da sodium tartrate (0.32 g) an narkar da su a cikin ruwa mai tsabta (140 ml).An canza sakamakon da aka samu zuwa autoclave mai rufi na Teflon kuma ya yi zafi zuwa 170 ° C na 3 h.Sakamakon da aka samu an wanke shi da ruwa mai tsabta kuma an bushe shi sosai, bayan haka an yi shi a 500 ° C (2 ° C min-1; 4 h) don samun Al2O3 amorphous.Sa'an nan Al2O3 (0.2 g), Ni (NO3)2 6H2O (5.8 g) da NH4NO3 (9.6 g) an tarwatsa a cikin ruwa mai tsabta (200 ml) kuma an daidaita pH zuwa ~ 6.5 ta ƙara 1 mol l -1 ammonia ruwa..An mayar da dakatarwar a cikin flask kuma an ajiye shi a 90°C na awa 48 don samun NiAl-LDH.Sa'an nan kuma NiAl-LDH foda (0.3 g) an rage a cikin rafi na H2/N2 (10/90, v / v; 35 ml min-1) a 500 ° C na 4 h (yawan zafi: 2 ° C min -1). ).Shirye-shiryen samfurori na nickel monometallic (Ni/Al2O3) da aka ajiye akan Al2O3.Samfurori bimetallic da aka ajiye na RuNi an haɗa su ta hanyar hanyar canja wurin lantarki.Yawanci, an tarwatsa sabon samfurin Ni/Al2O3 (0.2 g) a cikin 30 ml na ruwa mai tsafta, sannan an ƙara wani bayani na RuCl3 (0.07 mmol l-1) a hankali kuma yana motsawa da ƙarfi na mintuna 60 ƙarƙashin kariya daga yanayin N2. .Sakamakon hazo an wanke shi da ruwa mai tsafta, sannan a bushe a cikin tanda a zafin jiki na 50 ° C na sa'o'i 24, ana samun samfurin mai 0.1% RuNi.Kafin kimar catalytic, sabbin samfuran da aka haɗa an rage su da farko a cikin kwararar H2 / N2 (10/90, v / v) a 300 ° C (yawan zafi: 2 ° C min-1) na 1 h, sannan mai zafi a cikin N2 Sanyi zuwa zafin daki.Don tunani: samfurori tare da abun ciki na Ru / Al2O3 na 0.4% da 2% ta taro, tare da ainihin abun ciki na Ru na 0.36% ta taro da 2.3% ta taro, an shirya su ta hanyar hazo ta hazo da mai tsanani a 300 ° C (ci abinci H2 / N2: 10/90, v/v, yawan dumama: 2 °C min-1) na 3 hours.
An gudanar da gwaje-gwajen diffraction X-ray (XRD) akan Bruker DAVINCI D8 ADVANCE diffractometer tare da tushen hasken Cu Kα (40 kV da 40 mA).An yi amfani da Shimadzu ICPS-7500 Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) don tantance ainihin yawan abubuwa a cikin samfurori daban-daban.An zana hotunan hotunan na'urar lantarki (SEM) ta amfani da na'urar ganimar lantarki ta Zeiss Supra 55.N2 adsorption-desorption gwaje-gwaje an yi a kan na'urar Micromeritics ASAP 2020 kuma an ƙididdige takamaiman yanki ta amfani da hanyar Brunauer-Emmett-Teller (BET).An yi sifofin watsawa na lantarki (TEM) akan JEOL JEM-2010 babban ma'aunin watsawa na lantarki.Babban Aberration Daidaita Canjin Canjin Electron Microscope Dark Field (AC-HAADF) - STEM tare da FEI Titan Cube Themis G2 300 tare da madaidaicin aberration mai daidaitawa da Tsarin Rarraba X-ray Spectroscopy (EDS) da JEOL JEM-ARM200F kayan aiki) da ma'aunin taswirar EDS .Kyakkyawan tsarin X-ray absorption spectroscopy (XAFS) a wurin K-gefen Ru da Ni K-gefen an auna su akan tashoshi 1W1B da 1W2B na Cibiyar Radiation ta Beijing Synchrotron (BSRF) na Cibiyar Babban Makamashi Physics (IHEP), China .Kwalejin Kimiyya (KAN).Pulsed CO chemisorption da zafin jiki-tsara hydrogen desorption (H2-TPD) gwaje-gwaje an yi a kan Micromeritics Autochem II 2920 kayan aiki ta amfani da thermal conductivity detector (TCD).An gudanar da gwaje-gwajen DRIFTS na cikin wurin da FT-IR akan na'urar infrared spectrometer Bruker TENSOR II sanye take da gyaggyarawa a cikin tantanin halitta da kuma na'urar gano MCT sosai.An bayyana cikakkun hanyoyin siffantawa a cikin Ƙarin Bayani.
Na farko, da substrate (4-NS, 1 mmol), sauran ƙarfi (ethanol, 8 ml) da mai kara kuzari (0.02 g) an sanya su a hankali a cikin 25 ml bakin karfe autoclave.Daga nan aka wanke reactor gaba daya tare da 2.0 MPa (> 99.999%) hydrogen sau 5, sa'an nan kuma aka matsa kuma an rufe shi zuwa 1.0 MPa tare da H2.An gudanar da aikin a 60 ° C a akai-akai mai saurin motsawa na 700 rpm.Bayan amsawa, an gano samfuran da aka samo ta GC-MS kuma an ƙididdige su ta hanyar ƙididdigewa ta amfani da tsarin chromatography na Shimadzu GC-2014C wanda aka sanye da ginshiƙin capillary GSBP-INOWAX (30 m × 0.25 mm × 0.25 mm) da mai gano FID.An ƙaddara fassarar 4-nitrostyrene da zaɓin samfur kamar haka:
An ƙididdige ƙimar juzu'i (TOF) azaman mol 4-NS da aka canza ta kowane rukunin ƙarfe na mol a kowace awa (mol4-NS mol-1 h-1) dangane da ƙaramin juzu'in 4-NS (~ 15%).Amma ga yawan Ru nodes, Ru-Ni interface nodes da jimlar adadin saman karfe atom.Don gwajin sake yin amfani da shi, an tattara mai haɓakawa ta hanyar centrifugation bayan amsawa, an wanke shi sau uku tare da ethanol, sannan a sake shigar da shi cikin autoclave don sake zagayowar catalytic na gaba.
An yi duk lissafin aikin aikin density (DFT) ta amfani da fakitin kwaikwayo na Vienna ab initio (VASP 5.4.1).Ana amfani da aikin PBE na Gabaɗaya Gradient Approximation (GGA) don kwatanta musayar lantarki da yanayin daidaitawa.Ana amfani da hanyar Projector Augmented Wave (PAW) don kwatanta hulɗar tsakanin kwayoyin atomic da electrons.Hanyar Grimm DFT-D3 ta bayyana tasirin hulɗar van der Waals tsakanin ma'auni da mai dubawa.Ƙididdigar Ƙarfafa Makamashi ta hanyar Hawan Ƙaƙwalwar Ƙwaƙwalwa tare da Ƙarfafa Hoto (CI-NEB) da Hanyoyin Dimer.An gudanar da nazarin mita na oscillations, yana tabbatar da kasancewar mitar hasashe guda ɗaya kawai a cikin kowace yanayin canji (Ƙarin Figures 44-51).An kwatanta ƙarin ƙididdiga a cikin ƙarin bayani.
Babban bayanan da ke goyan bayan makircin a cikin wannan labarin an bayar da su a cikin fayilolin bayanan tushen.Ana samun wasu bayanan da suka dace da wannan binciken daga marubutan bisa ga buƙatu mai ma'ana.Wannan labarin yana ba da bayanan asali.
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