Graphite amagawidwa mu 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 kwakukulu 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 "malala 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 ndi njira yosapeŵeka yofufuza njira zatsopano za graphitization.
Wosungunula 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 wosungunula solid oxide electrolytic kuchepetsa kukonza zitsulo zoyambira kwakhala cholinga chachikulu chogwira ntchito,
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 graphitization chikhalidwe, njira yatsopano graphitization ali ubwino kutsika kutentha graphitization ndi morphology controllable.
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 kukhala graphite ili ndi kukana bwino, mphamvu zamakina, mphamvu zochepa,
Komabe, kuchepa kwa mafuta osungira mafuta komanso 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 sanali graphitized mpweya, 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 pambuyo pochiritsidwa 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 padziko 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
Kusungunuka mchere electrolysis njira amagwiritsa carbon zinthu monga cathode ndi kuwasandutsa graphite ndi mkulu crystallinity kudzera 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 okosijeni muzinthu za kaboni kudzalepheretsa graphitization kumlingo wina. Mwachikhalidwe cha graphitization, mpweya udzachotsedwa pang'onopang'ono pamene kutentha kuli pamwamba kuposa 1600K. Komabe, ndikosavuta kwambiri kutulutsa deoxidize 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, choyamba mpweya microsphere mawonekedwe mozungulira maziko awiri awiri ofanana. chipolopolo cha graphite, ndiyeno osakhazikika maatomu a carbon anhydrous carbon kufalikira ku khola lakunja la graphite flake, mpaka graphitized kwathunthu,
Njira ya graphitization imatsagana ndi kuchotsedwa kwa okosijeni, komwe kumatsimikiziridwa ndi kuyesa.
Jin et al. adatsimikiziranso mfundo iyi 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 Yalaninso 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 kusanthula sipekitiramu ikuchitika pa mpweya wakuda pambuyo electrolysis.
Pa 827 ℃, atathandizidwa ndi 2.6V voteji kwa 1h, chithunzi cha Raman chakuda cha kaboni wakuda chimakhala chofanana ndi cha graphite yamalonda. Pambuyo pa kaboni wakuda ndi kutentha kosiyanasiyana, nsonga yakuthwa ya graphite (002) imayesedwa. Chisomo 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 mapangidwe a graphite olamulidwa kwambiri.
Pachimake chakuthwa (002) cha diffraction pachithunzi cha XRD chimatsimikiziranso kusinthika kopambana kwa malasha otsika kukhala graphite yokhala ndi crystallinity yayikulu.
Mu ndondomeko graphitization, kuwonjezeka kutentha ndi voteji adzakhala ndi udindo kulimbikitsa, koma mkulu voteji kuchepetsa zokolola za graphite, ndi kutentha kwambiri kapena nthawi yaitali graphitization kungachititse kuti kuwononga chuma, kotero kwa zipangizo zosiyanasiyana mpweya. , ndikofunikira kwambiri kuti mufufuze mikhalidwe yoyenera kwambiri ya electrolytic, ndikuyang'ananso ndizovuta.
Izi petal-ngati flake nanostructure ali kwambiri electrochemical katundu. Ma pores ambiri amalola ma ions kuti alowetsedwe / kulowetsedwa mwamsanga, kupereka zipangizo zamakono 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 ndiwopanda poizoni, wopanda vuto, wotchipa komanso wopezeka 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 akhoza kutsatiridwa mpaka zaka za m'ma 1960. 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 mosiyanasiyana pakuchepetsa umakhala ndi mawonekedwe osiyanasiyana, kuphatikiza ma graphite, amorphous carbon ndi carbon nanofibers.
Mwa mchere wosungunula kuti agwire CO2 ndi kukonzekera njira ya kupambana carbon chuma, patapita nthawi yaitali kafukufuku akatswiri amayang'ana pa mpweya mafunsidwe mapangidwe limagwirira ndi zotsatira za zinthu electrolysis pa chomaliza mankhwala, monga electrolytic kutentha, electrolytic voteji ndi zikuchokera 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 ma elekitirodi 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 yongopeka kwa 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 zikuwonetsedwera 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, tin dioxide ngati anode ndi waya wa siliva monga ma elekitirodi, ndipo adapeza chiwonetsero cha cyclic voltammetry mu Chithunzi 2 (chiwerengero cha 100 mV/s) pa nickel cathode, ndipo adapeza. kuti panali nsonga imodzi yokha yochepetsera (pa -2.0V) pakusanthula koyipa.
Choncho, tinganene kuti chinthu chimodzi chokha chinachitika panthawi yochepetsera carbonate.
Gao et al. adapeza cyclic voltammetry yomweyo mu dongosolo lomwelo la 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 kaboni idawonekera pakusanthula koyipa.
Mu dongosolo la mchere wosungunula wazitsulo 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 zochitika za electrolytic.
Zinthu monga electrolytic kutentha kwa mkulu ndi otsika mapangidwe graphene n'kofunika, 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, ndipo graphite yochita kupanga imakhala ndi zinthu zabwino zakuthupi ndi zamankhwala kuposa ma graphite achilengedwe, kotero kuti graphitization yotsika mtengo, yothandiza komanso yosamalira zachilengedwe ndi cholinga chanthawi yayitali.
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 ya dzuwa kwambiri, mowa wotsika mphamvu, chitetezo chilengedwe chobiriwira, kwa ang'onoang'ono malire ndi kusankha zipangizo 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 pamitundu yosiyanasiyana ya 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