Graphite lagawidwa yokumba graphite ndi chilengedwe graphite, dziko kutsimikiziridwa nkhokwe zachilengedwe graphite pafupifupi 2 biliyoni matani.
Graphite yochita kupanga imapezeka mwa kuwonongeka ndi kutentha kwa zinthu zomwe zimakhala ndi carbon pansi pa kupanikizika kwabwino.Kusintha kumeneku kumafuna kutentha ndi mphamvu zokwanira monga mphamvu yoyendetsera galimoto, ndipo dongosolo losokonezeka lidzasinthidwa kukhala dongosolo la graphite crystal.
Graphitization ndi m'lingaliro yotakata ya zinthu carbonaceous kupyolera pamwamba 2000 ℃ kutentha kutentha mankhwala mpweya maatomu rearrangement, Komabe ena zipangizo mpweya mu kutentha pamwamba 3000 ℃ graphitization, mtundu wa zipangizo mpweya ankadziwika kuti "makala olimba", chifukwa zosavuta graphitized mpweya zipangizo, chikhalidwe graphitization njira monga kutentha ndi kuthamanga kwambiri njira, catalytic graphitization, mankhwala nthunzi deposition njira, etc.
Graphitization ndi njira yabwino yowonjezeretsa kugwiritsa ntchito zinthu za carbonaceous.Pambuyo pofufuza mozama komanso mozama ndi akatswiri, ndi okhwima tsopano.Komabe, zinthu zina zoyipa zimachepetsa kugwiritsa ntchito graphitization yachikhalidwe m'makampani, chifukwa chake ndizochitika zosapeŵeka kufufuza njira zatsopano za graphitization.
Kusungunula mchere electrolysis njira kuyambira zaka za m'ma 19 anali oposa zaka za chitukuko, chiphunzitso chake chachikulu ndi njira zatsopano nthawi zonse luso ndi chitukuko, tsopano salinso okha makampani chikhalidwe zitsulo, kumayambiriro kwa zaka za m'ma 21, zitsulo mu dongosolo la mchere wosungunuka wa solid oxide electrolytic kuchepetsa kukonza zitsulo zoyambira zakhala zikuyang'ana kwambiri pakuchita bwino,
Posachedwapa, njira yatsopano yopangira zida za graphite ndi electrolysis yosungunuka yamchere yakopa chidwi kwambiri.
Pogwiritsa ntchito cathodic polarization ndi electrodeposition, mitundu iwiri yosiyana ya carbon yaiwisi imasinthidwa kukhala zipangizo za nano-graphite zomwe zili ndi mtengo wowonjezera.Poyerekeza ndi luso lamakono la graphitization, njira yatsopano yojambula zithunzi ili ndi ubwino wa kutentha kochepa kwa graphitization ndi morphology yosinthika.
Pepalali likuwunika momwe graphitization ikuyendera pogwiritsa ntchito njira ya electrochemical, imayambitsa ukadaulo watsopanowu, kusanthula zabwino ndi zoyipa zake, ndikuyembekeza zomwe zidzachitike m'tsogolo.
Choyamba, wosungunuka mchere electrolytic cathode polarization njira
1.1 zinthu zopangira
Pakali pano, waukulu zopangira wa yokumba graphite ndi singano coke ndi phula coke mkulu graphitization digiri, ndicho ndi zotsalira mafuta ndi malasha phula monga zopangira kupanga apamwamba mpweya zipangizo, ndi otsika porosity, otsika sulfure, otsika phulusa. zomwe zili ndi ubwino wa graphitization, itatha kukonzekera mu graphite ili ndi kukana bwino kukhudzidwa, mphamvu zamakina apamwamba, kutsika kwa resistivity,
Komabe, nkhokwe zocheperako zamafuta ndi kusinthasintha kwamitengo yamafuta kwalepheretsa kukula kwake, kotero kufunafuna zida zatsopano zakhala vuto lachangu lomwe liyenera kuthetsedwa.
Njira zachikhalidwe za graphitization zili ndi malire, ndipo njira zosiyanasiyana za graphitization zimagwiritsa ntchito zida zosiyanasiyana.Pakuti mpweya sanali graphitized, njira zachikhalidwe sangathe graphitize izo, pamene electrochemical chilinganizo cha wosungunuka mchere electrolysis imaswa malire a zopangira, ndi oyenera pafupifupi onse chikhalidwe carbon zipangizo.
Zida zachikhalidwe za carbon zimaphatikizapo mpweya wakuda, activated carbon, malasha, ndi zina zotero, zomwe malasha ndi omwe amalonjeza kwambiri.Inki yopangidwa ndi malasha imatenga malasha ngati kalambulabwalo ndipo imakonzedwa kukhala zinthu za graphite pa kutentha kwakukulu mutatha kuthandizidwa kale.
Posachedwapa, pepalali akufunsira njira zatsopano electrochemical, monga Peng, ndi wosungunuka mchere electrolysis ndi chodziwikiratu kuti graphitized mpweya wakuda mu mkulu crystallinity wa graphite, ndi electrolysis wa zitsanzo graphite munali petal mawonekedwe graphite nanometer tchipisi, ali mkulu enieni pamwamba m'dera. pamene ntchito lifiyamu batire cathode anasonyeza kwambiri electrochemical ntchito kuposa masoka graphite.
Zhu ndi al.kuika deashing ankachitira otsika khalidwe malasha mu CaCl2 wosungunuka mchere dongosolo electrolysis pa 950 ℃, ndi bwinobwino kusandulika malasha otsika mu graphite ndi mkulu crystallinity, amene anasonyeza bwino mlingo ntchito ndi moyo wautali mkombero pamene ntchito monga anode wa lithiamu ion batire. .
Kuyeseraku kukuwonetsa kuti ndizotheka kutembenuza mitundu yosiyanasiyana ya zinthu zakale za kaboni kukhala graphite pogwiritsa ntchito electrolysis yamchere yosungunuka, yomwe imatsegula njira yatsopano yopangira graphite yamtsogolo.
1.2 ndondomeko ya
Njira yosungunuka yamchere ya electrolysis imagwiritsa ntchito mpweya wa carbon ngati cathode ndikuisintha kukhala graphite yokhala ndi crystallinity yapamwamba pogwiritsa ntchito cathodic polarization.Pakalipano, mabuku omwe alipo kale amatchula kuchotsedwa kwa mpweya ndi kukonzanso mtunda wautali wa maatomu a carbon mu njira yosinthika ya cathodic polarization.
Kukhalapo kwa mpweya muzinthu za carbon kudzalepheretsa graphitization kumlingo wina.Mwachikhalidwe cha graphitization, mpweya udzachotsedwa pang'onopang'ono pamene kutentha kuli pamwamba kuposa 1600K.Komabe, ndikosavuta kwambiri kutulutsa mpweya kudzera mu cathodic polarization.
Peng, etc mu zoyeserera kwa nthawi yoyamba anapereka wosungunuka mchere electrolysis cathodic polarization angathe limagwirira, ndicho graphitization kwambiri malo kuyamba ndi kukhala olimba mpweya microspheres/electrolyte mawonekedwe, woyamba mpweya microsphere mawonekedwe mozungulira maziko awiri awiri ofanana. graphite chipolopolo, ndiyeno osakhala khola anhydrous mpweya mpweya maatomu kufalikira ku khola kunja graphite flake, mpaka kwathunthu graphitized,
Njira ya graphitization imatsagana ndi kuchotsedwa kwa okosijeni, yomwe imatsimikiziridwanso ndi zoyesera.
Jin et al.adatsimikiziranso malingaliro awa kudzera muzoyesera.Pambuyo pa carbonization ya shuga, graphitization (17% ya okosijeni) inachitika.Pambuyo graphitization, choyambirira olimba mpweya mabwalo (mkuyu. 1a ndi 1c) anapanga porous chipolopolo wapangidwa graphite nanosheets (mkuyu. 1b ndi 1d).
Pogwiritsa ntchito electrolysis ya carbon fibers (16% oxygen), mpweya wa carbon ukhoza kusinthidwa kukhala machubu a graphite pambuyo pa graphitization malinga ndi njira yosinthira yomwe ikufotokozedwa m'mabuku.
Amakhulupirira kuti, kuyenda mtunda wautali ndi pansi cathodic polarization wa maatomu mpweya mkulu galasi graphite kuti amorphous mpweya Yalani ayenera pokonza, kupanga graphite wapadera pamakhala mawonekedwe nanostructures kupindula maatomu mpweya ku, koma yeniyeni mmene kukopa graphite nanometer dongosolo si bwino, monga mpweya wochokera ku mafupa a carbon pambuyo pa momwe cathode reaction, etc.,
Pakalipano, kafukufuku wokhudza makinawo akadali pachiyambi, ndipo kufufuza kwina kumafunika.
1.3 Maonekedwe a morphological a graphite yopanga
SEM ntchito kuona yaying'ono padziko morphology wa graphite, TEM ntchito kuona structural morphology zosakwana 0,2 μm, XRD ndi Raman spectroscopy ndi ambiri ntchito njira yodziwika ndi microstructure wa graphite, XRD ntchito yosonyeza kristalo. zambiri za graphite, ndi Raman spectroscopy ntchito yosonyeza zolakwika ndi dongosolo digiri ya graphite.
Pali pores ambiri mu graphite wokonzedwa ndi cathode polarization wa wosungunuka mchere electrolysis.Pazinthu zosiyanasiyana zopangira, monga carbon black electrolysis, petal-ngati porous nanostructures amapezeka.XRD ndi Raman spectrum kusanthula kumachitika pa carbon wakuda pambuyo electrolysis.
Pa 827 ℃, atathandizidwa ndi 2.6V voteji kwa 1h, chithunzi cha Raman chowoneka bwino cha kaboni wakuda chimakhala chofanana ndi cha graphite yamalonda.Pambuyo pa kaboni wakuda ndi kutentha kosiyana, nsonga yakuthwa ya graphite (002) imayesedwa.Pachimake cha diffraction (002) chikuyimira kupendekera kwa gawo la mpweya wonunkhira mu graphite.
Pamene mpweya wosanjikiza wa kaboni umakhala wakuthwa kwambiri, umakhala wolunjika kwambiri.
Zhu anagwiritsa ntchito malasha oyeretsedwa otsika ngati cathode mu kuyesera, ndi microstructure ya mankhwala graphitized anasandulika ku granular kuti lalikulu graphite dongosolo, ndi zolimba graphite wosanjikiza ankaonanso pansi pa mlingo mkulu kufala elekitironi maikulosikopu.
Mu mawonekedwe a Raman, ndikusintha kwa zoyeserera, mtengo wa ID/Ig unasinthanso.Pamene kutentha kwa electrolytic kunali 950 ℃, nthawi ya electrolytic inali 6h, ndipo magetsi a electrolytic anali 2.6V, mtengo wotsika kwambiri wa ID / Ig unali 0.3, ndipo D nsonga inali yotsika kwambiri kuposa G peak.Nthawi yomweyo, mawonekedwe a 2D pachimake adayimiranso kupangidwa kwadongosolo kwambiri la graphite.
Pachimake chakuthwa (002) cha diffraction pachithunzi cha XRD chimatsimikiziranso kusinthika kopambana kwa malasha otsika kukhala graphite yokhala ndi crystallinity yayikulu.
Mu ndondomeko graphitization, kuwonjezeka kwa kutentha ndi voteji adzakhala ndi udindo kulimbikitsa, koma mkulu voteji kuchepetsa zokolola za graphite, ndi kutentha kwambiri kapena nthawi yaitali graphitization zingachititse kuwononga chuma, kotero kwa zinthu zosiyanasiyana mpweya. , ndikofunikira kwambiri kuti mufufuze mikhalidwe yoyenera kwambiri ya electrolytic, ndikuyang'ananso komanso zovuta.
Izi petal-ngati flake nanostructure ali kwambiri electrochemical katundu.Ma pores ambiri amalola kuti ma ion alowetsedwe / kulowetsedwa mwachangu, kupereka zida zapamwamba za cathode zamabatire, etc. Choncho, njira ya electrochemical graphitization ndi njira yotheka kwambiri ya graphitization.
Njira yosungunuka yamchere ya electrodeposition
2.1 Electrodeposition ya carbon dioxide
Monga mpweya wofunikira kwambiri wowonjezera kutentha, CO2 ndiyopanda poizoni, yopanda vuto, yotsika mtengo komanso yopezeka mosavuta.Komabe, mpweya wa CO2 uli pamalo okwera kwambiri oxidation, kotero CO2 imakhala ndi kukhazikika kwa thermodynamic, zomwe zimapangitsa kuti zikhale zovuta kugwiritsanso ntchito.
Kafukufuku wakale kwambiri pa CO2 electrodeposition atha kuyambika m'ma 1960s.Ingram et al.okonzeka bwino mpweya pa golide elekitirodi mu wosungunuka mchere dongosolo Li2CO3-Na2CO3-K2CO3.
Van et al.adanenanso kuti ufa wa kaboni womwe umapezeka pakuchepetsa kosiyanasiyana umakhala ndi mawonekedwe osiyanasiyana, kuphatikiza ma graphite, amorphous carbon ndi carbon nanofibers.
Ndi mchere wosungunuka kuti agwire CO2 ndi njira yokonzekera bwino zakuthupi za carbon, patapita nthawi yaitali ya akatswiri ofufuza akhala akuyang'ana pakupanga mapangidwe a carbon ndi zotsatira za electrolysis pa chinthu chomaliza, chomwe chimaphatikizapo kutentha kwa electrolytic, electrolytic voltage ndi mapangidwe a magetsi. mchere wosungunuka ndi maelekitirodi, etc., kukonzekera mkulu ntchito graphite zipangizo electrodeposition wa CO2 wayala maziko olimba.
Posintha ma electrolyte ndikugwiritsa ntchito mchere wopangidwa ndi CaCl2 wokhala ndi mpweya wokwanira wa CO2, Hu et al.Kukonzekera bwino graphene yokhala ndi digirii yapamwamba ya graphitization ndi ma carbon nanotubes ndi zida zina za nanographite powerenga zinthu za electrolytic monga kutentha kwa electrolysis, kapangidwe ka electrode ndi kapangidwe ka mchere wosungunuka.
Poyerekeza ndi dongosolo carbonate, CaCl2 ali ubwino wotchipa ndi zosavuta kupeza, madutsidwe mkulu, zosavuta kupasuka m'madzi, ndi apamwamba solubility ayoni mpweya, amene amapereka mikhalidwe ongoyerekeza kutembenuka kwa CO2 mu mankhwala graphite ndi mkulu anawonjezera mtengo.
2.2 Njira Yosinthira
Kukonzekera kwa zida za carbon zowonjezeredwa ndi electrodeposition ya CO2 kuchokera ku mchere wosungunula makamaka kumaphatikizapo kugwidwa kwa CO2 ndi kuchepetsa kwachindunji.Kujambula kwa CO2 kumatsirizidwa ndi O2- mumchere wosungunula waulere, monga momwe zikusonyezedwera mu Equation (1) :
CO2+O2-→CO3 2- (1)
Pakalipano, njira zitatu zochepetsera zowonongeka zaperekedwa: njira imodzi, njira ziwiri komanso njira yochepetsera zitsulo.
Njira yochitira gawo limodzi idaperekedwa koyamba ndi Ingram, monga zikuwonetsedwa mu Equation (2):
CO3 2-+ 4E – →C+3O2- (2)
Njira yochitira magawo awiri idaperekedwa ndi Borucka et al., monga zikuwonetsedwa mu Equation (3-4):
CO3 2-+ 2E – →CO2 2-+O2- (3)
CO2 2-+ 2E – →C+2O2- (4)
Njira yochepetsera zitsulo idapangidwa ndi Deanhardt et al.Iwo ankakhulupirira kuti ayoni zitsulo poyamba anasanduka chitsulo mu cathode, ndiyeno zitsulo anasanduka carbonate ayoni, monga momwe Equation (5~6):
M- + E – →M (5)
4 m + M2CO3 – > C + 3 m2o (6)
Pakali pano, njira imodzi yochitira zinthu imavomerezedwa m'mabuku omwe alipo.
Yin et al.adaphunzira za Li-Na-K carbonate system yokhala ndi faifi tambala ngati cathode, tini dioxide ngati anode ndi waya wa siliva ngati ma elekitirodi, ndipo adapeza chiwonetsero cha cyclic voltammetry mu Chithunzi 2 (kujambula kwa 100 mV/s) pa faifi tambala cathode, ndipo anapeza. kuti panali nsonga imodzi yokha yochepetsera (pa -2.0V) pakusanthula koyipa.
Choncho, tinganene kuti chinthu chimodzi chokha chinachitika panthawi yochepetsera carbonate.
Gao et al.adapezanso cyclic voltammetry munjira yomweyo ya carbonate.
Pa et al.adagwiritsa ntchito anode ya inert ndi tungsten cathode kuti agwire CO2 mu dongosolo la LiCl-Li2CO3 ndikupeza zithunzi zofananira, ndipo nsonga yochepetsera yokha ya carbon deposition idawonekera pakuwunika koyipa.
Mu dongosolo la mchere wosungunuka wa zitsulo zamchere, zitsulo za alkali ndi CO zidzapangidwa pamene mpweya umayikidwa ndi cathode.Komabe, chifukwa thermodynamic mikhalidwe ya carbon deposition reaction ndi yotsika pa kutentha kochepa, kuchepetsa kokha kwa carbonate kukhala carbon kungadziwike pakuyesa.
2.3 CO2 kugwidwa ndi mchere wosungunula kukonzekera mankhwala a graphite
Ma graphite nanomaterials apamwamba kwambiri monga graphene ndi carbon nanotubes akhoza kukonzedwa ndi electrodeposition ya CO2 kuchokera ku mchere wosungunuka poyang'anira zinthu zoyesera.Hu et al.ntchito zitsulo zosapanga dzimbiri monga cathode mu CaCl2-NaCl-CaO wosungunuka mchere dongosolo ndi electrolyzed kwa 4h pansi pa chikhalidwe cha 2.6V zonse voteji pa kutentha osiyana.
Chifukwa cha catalysis ya chitsulo ndi kuphulika kwa CO pakati pa zigawo za graphite, graphene inapezeka pamwamba pa cathode.Kukonzekera kwa graphene kukuwonetsedwa mkuyu 3.
Chithunzi
Kenako maphunziro anawonjezera Li2SO4 pamaziko a CaCl2-NaClCaO wosungunuka mchere dongosolo, electrolysis kutentha anali 625 ℃, pambuyo 4h wa electrolysis, pa nthawi yomweyo mu cathodic mafunsidwe mpweya anapeza graphene ndi mpweya nanotubes, kafukufuku anapeza kuti Li + ndi SO4 2 - kubweretsa zotsatira zabwino pa graphitization.
Sulfure imaphatikizidwanso bwino mu thupi la kaboni, ndipo mapepala owonjezera-woonda kwambiri a graphite ndi mpweya wa filamentous angapezeke poyang'anira zinthu za electrolytic.
Zinthu monga electrolytic kutentha kwa mkulu ndi otsika mapangidwe graphene n'kofunika kwambiri, pamene kutentha kuposa 800 ℃ n'kosavuta kupanga CO m'malo carbon, pafupifupi palibe mpweya mafunsidwe pamene apamwamba kuposa 950 ℃, kotero kulamulira kutentha n'kofunika kwambiri. kupanga graphene ndi mpweya nanotubes, ndi kubwezeretsa kufunika mpweya mafunsidwe anachita CO anachita synergy kuonetsetsa kuti cathode kupanga khola graphene.
Ntchitozi zimapereka njira yatsopano yokonzekera mankhwala a nano-graphite ndi CO2, yomwe ili yofunikira kwambiri yothetsera mpweya wowonjezera kutentha ndi kukonzekera graphene.
3. Chidule ndi Outlook
Ndi chitukuko chofulumira cha makampani opanga mphamvu zatsopano, graphite yachilengedwe yalephera kukwaniritsa zomwe zikuchitika panopa, ndipo graphite yochita kupanga imakhala ndi thupi labwino komanso lamankhwala kuposa graphite yachilengedwe, kotero kuti graphitization yotsika mtengo, yothandiza komanso yosamalira zachilengedwe ndi cholinga cha nthawi yaitali.
Electrochemical njira graphitization mu zipangizo olimba ndi mpweya zopangira ndi njira cathodic polarization ndi electrochemical mafunsidwe anali bwinobwino kunja kwa zipangizo graphite ndi mkulu anawonjezera mtengo, poyerekeza ndi chikhalidwe njira graphitization, njira electrochemical ndi Mwachangu kwambiri, mowa wotsika mphamvu, chitetezo chilengedwe chobiriwira, kwa ang'onoang'ono malire ndi zipangizo kusankha pa nthawi yomweyo, malinga ndi zinthu zosiyanasiyana electrolysis akhoza kukonzekera pa morphology osiyana kapangidwe graphite,
Zimapereka njira yothandiza kuti mitundu yonse ya mpweya wa amorphous ndi wowonjezera kutentha usanduke kukhala zida zamtengo wapatali za nano-structured graphite ndipo zimakhala ndi chiyembekezo chabwino chogwiritsira ntchito.
Pakali pano, luso limeneli lili pa chiyambi.Pali maphunziro ochepa okhudza graphitization ndi electrochemical njira, ndipo pali njira zambiri zosadziwika.Choncho, m'pofunika kuti tiyambe kuchokera ku zipangizo zopangira ndikuchita kafukufuku wambiri komanso mwadongosolo pamagulu osiyanasiyana a carbon amorphous, ndipo nthawi yomweyo kufufuza za thermodynamics ndi mphamvu za kutembenuka kwa graphite mozama.
Izi zili ndi tanthauzo lalikulu pakukula kwamakampani a graphite.
Nthawi yotumiza: May-10-2021