Graphite tau muab faib ua graphite dag thiab ntuj graphite, lub ntiaj teb pov thawj reserves ntawm ntuj graphite nyob rau hauv txog 2 billion tons.
Artificial graphite yog tau los ntawm decomposition thiab kev kho cua sov ntawm cov ntaub ntawv uas muaj carbon nyob rau hauv ib txwm siab.Qhov kev hloov pauv no yuav tsum muaj qhov kub txaus thiab lub zog txaus raws li lub zog tsav, thiab cov qauv tsis sib haum yuav raug hloov mus rau hauv cov qauv graphite crystal.
Graphitization yog nyob rau hauv qhov dav tshaj plaws ntawm cov khoom siv carbonaceous los ntawm saum toj no 2000 ℃ kub kub kho carbon atoms rearrangement, tab sis qee cov ntaub ntawv carbon nyob rau hauv qhov kub siab tshaj 3000 ℃ graphitization, hom carbon cov ntaub ntawv no hu ua "hard charcoal", rau yooj yim graphitized carbon cov ntaub ntawv, cov tsoos graphitization txoj kev muaj xws li kub thiab kub siab txoj kev, catalytic graphitization, tshuaj vapor deposition txoj kev, thiab lwm yam.
Graphitization yog ib qho txiaj ntsig zoo ntawm kev siv cov khoom siv carbonaceous ntau ntxiv.Tom qab kev tshawb fawb dav thiab tob los ntawm cov kws tshawb fawb, nws yog qhov pib paub tab tam sim no.Txawm li cas los xij, qee yam tsis zoo txwv tsis pub siv cov graphitization ib txwm nyob hauv kev lag luam, yog li nws yog ib qho kev tsis pom zoo los tshawb txog cov txheej txheem graphitization tshiab.
Molten ntsev electrolysis txoj kev txij li thaum xyoo pua 19th yog ntau tshaj li ib puas xyoo ntawm txoj kev loj hlob, nws cov kev tshawb xav thiab cov txheej txheem tshiab yog tas li innovation thiab kev loj hlob, tam sim no tsis txwv rau cov tsoos metallurgical kev lag luam, thaum pib ntawm lub xyoo pua 21st, cov hlau nyob rau hauv. molten ntsev system khoom oxide electrolytic txo qhov kev npaj ntawm cov hlau hlau tau dhau los ua qhov tseem ceeb hauv kev ua haujlwm ntau dua,
Tsis ntev los no, ib txoj kev tshiab rau kev npaj graphite cov ntaub ntawv los ntawm molten ntsev electrolysis tau nyiam heev.
Los ntawm txoj kev cathodic polarization thiab electrodeposition, ob hom kev sib txawv ntawm cov ntaub ntawv carbon yog hloov mus rau hauv cov ntaub ntawv nano-graphite nrog cov nqi ntxiv.Piv nrog rau cov cuab yeej siv graphitization ib txwm muaj, txoj kev graphitization tshiab muaj qhov zoo ntawm qhov kub thiab txias graphitization thiab tswj tau morphology.
Daim ntawv no tshuaj xyuas qhov kev nce qib ntawm graphitization los ntawm txoj kev electrochemical, qhia txog cov cuab yeej tshiab no, tshuaj xyuas nws qhov zoo thiab qhov tsis zoo, thiab kev cia siab rau nws txoj kev loj hlob yav tom ntej.
Ua ntej, molten ntsev electrolytic cathode polarization txoj kev
1.1 raw khoom
Tam sim no, cov khoom siv tseem ceeb ntawm cov khoom siv graphite yog rab koob coke thiab pitch coke ntawm high graphitization degree, uas yog los ntawm cov roj residue thiab thee tar ua raw khoom los tsim cov khoom siv roj carbon zoo, tsis muaj porosity, tsis tshua muaj sulfur, tsawg tshauv. Cov ntsiab lus thiab qhov zoo ntawm graphitization, tom qab nws qhov kev npaj rau hauv graphite muaj kev tiv thaiv zoo rau kev cuam tshuam, siab mechanical zog, tsis tshua muaj zog,
Txawm li cas los xij, txwv cov roj cia thiab cov nqi roj hloov pauv tau txwv nws txoj kev txhim kho, yog li nrhiav cov khoom siv tshiab tau dhau los ua qhov teeb meem ceev uas yuav tsum tau daws.
Cov txheej txheem graphitization ib txwm muaj kev txwv, thiab cov txheej txheem graphitization sib txawv siv cov khoom sib txawv.Rau cov uas tsis yog-graphitized carbon, cov kev cai ib txwm muaj peev xwm tsis graphitize nws, thaum lub electrochemical formula ntawm molten ntsev electrolysis tawg los ntawm kev txwv ntawm raw cov ntaub ntawv, thiab yog haum rau yuav luag tag nrho cov tsoos carbon cov ntaub ntawv.
Cov khoom siv niaj hnub muaj xws li cov pa roj carbon dub, cov pa roj carbon activated, thee, thiab lwm yam, ntawm cov thee yog qhov zoo tshaj plaws.Cov thee-raws li tus cwj mem siv cov thee ua ntej thiab tau npaj rau hauv cov khoom graphite ntawm qhov kub siab tom qab kev kho mob ua ntej.
Tsis ntev los no, daim ntawv no qhia txog cov txheej txheem electrochemical tshiab, xws li Peng, los ntawm molten ntsev electrolysis yog tsis zoo li graphitized carbon dub rau hauv siab crystallinity ntawm graphite, cov electrolysis ntawm graphite cov qauv uas muaj cov petal puab graphite nanometer chips, muaj siab tshwj xeeb deg cheeb tsam, Thaum siv rau lithium roj teeb cathode pom zoo electrochemical kev ua tau zoo tshaj li ntuj graphite.
Zhu et al.muab cov deashing kho cov thee tsis zoo rau hauv CaCl2 molten ntsev system rau electrolysis ntawm 950 ℃, thiab ua tiav cov thee tsis zoo rau hauv graphite nrog siab crystallinity, uas qhia tau hais tias zoo npaum li cas thiab lub neej voj voog ntev thaum siv los ua anode ntawm lithium ion roj teeb. .
Qhov kev sim qhia tau hais tias nws muaj peev xwm hloov ntau yam ntawm cov khoom siv roj carbon monoxide rau hauv graphite los ntawm kev siv ntsev ntsev electrolysis, uas qhib txoj hauv kev tshiab rau yav tom ntej hluavtaws graphite.
1.2 lub mechanism
Molten ntsev electrolysis txoj kev siv cov khoom siv carbon li cathode thiab hloov mus rau hauv graphite nrog siab crystallinity los ntawm cathodic polarization.Tam sim no, cov ntaub ntawv uas twb muaj lawm hais txog kev tshem tawm cov pa oxygen thiab kev ncua deb ntawm cov pa roj carbon atoms hauv cov txheej txheem hloov pauv ntawm cathodic polarization.
Lub xub ntiag ntawm cov pa oxygen hauv cov ntaub ntawv carbon yuav cuam tshuam graphitization rau qee qhov.Hauv cov txheej txheem graphitization ib txwm, cov pa oxygen yuav maj mam tshem tawm thaum qhov kub siab tshaj 1600K.Txawm li cas los xij, nws yooj yim heev rau deoxidize los ntawm cathodic polarization.
Peng, thiab lwm yam hauv qhov kev sim thawj zaug muab tso rau pem hauv ntej molten ntsev electrolysis cathodic polarization muaj peev xwm mechanism, uas yog lub graphitization feem ntau qhov chaw pib yog nyob rau hauv cov khoom carbon microspheres / electrolyte interface, thawj carbon microsphere daim ntawv nyob ib ncig ntawm ib tug yooj yim txoj kab uas hla. graphite plhaub, thiab ces yeej tsis ruaj khov anhydrous carbon atoms kis mus rau ntau ruaj khov txheej graphite flake, kom txog rau thaum tag nrho graphitized,
Cov txheej txheem graphitization yog nrog los ntawm kev tshem tawm cov pa oxygen, uas kuj tau lees paub los ntawm kev sim.
Jin et al.kuj tau ua pov thawj qhov kev xav no los ntawm kev sim.Tom qab carbonization ntawm qabzib, graphitization (17% oxygen cov ntsiab lus) tau ua.Tom qab graphitization, thawj cov khoom carbon spheres (Fig. 1a thiab 1c) tsim ib lub plhaub ntxeem tau tsim los ntawm graphite nanosheets (Fig. 1b thiab 1d).
Los ntawm electrolysis ntawm carbon fibers (16% oxygen), cov pa roj carbon fibers yuav hloov mus rau hauv graphite hlab tom qab graphitization raws li kev hloov dua siab tshiab mechanism speculated nyob rau hauv cov ntaub ntawv.
Ntseeg tias, kev txav mus los ntev yog nyob rau hauv cathodic polarization ntawm carbon atoms lub siab siv lead ua graphite rau amorphous carbon rearrange yuav tsum tau ua, hluavtaws graphite cim petals zoo li nanostructures tau txais txiaj ntsig los ntawm oxygen atoms los ntawm, tab sis qhov tshwj xeeb yuav ua li cas cuam tshuam graphite nanometer qauv tsis meej, xws li oxygen los ntawm cov pob txha pob txha tom qab yuav ua li cas ntawm cov tshuaj tiv thaiv cathode, thiab lwm yam.
Tam sim no, kev tshawb fawb ntawm lub tshuab tseem nyob rau theem pib, thiab xav tau kev tshawb fawb ntxiv.
1.3 Morphological characterization ntawm hluavtaws graphite
SEM yog siv los soj ntsuam lub microscopic nto morphology ntawm graphite, TEM yog siv los soj ntsuam cov qauv morphology ntawm tsawg dua 0.2 μm, XRD thiab Raman spectroscopy yog cov feem ntau siv txhais tau tias kom characterize lub microstructure ntawm graphite, XRD yog siv los characterize lub siv lead ua. Cov ntaub ntawv ntawm graphite, thiab Raman spectroscopy yog siv los qhia qhov tsis xws luag thiab txiav txim siab qib ntawm graphite.
Muaj ntau qhov pores hauv graphite npaj los ntawm cathode polarization ntawm molten ntsev electrolysis.Rau cov ntaub ntawv sib txawv, xws li carbon dub electrolysis, petal-like porous nanostructures tau txais.XRD thiab Raman spectrum tsom xam yog nqa tawm ntawm cov pa roj carbon dub tom qab electrolysis.
Ntawm 827 ℃, tom qab tau kho nrog 2.6V voltage rau 1h, Raman spectral duab ntawm carbon dub yuav luag tib yam li cov lag luam graphite.Tom qab cov pa roj carbon dub tau kho nrog qhov kub sib txawv, qhov ntse graphite yam ntxwv ncov (002) yog ntsuas.Lub diffraction ncov (002) sawv cev rau qib ntawm kev taw qhia ntawm cov pa roj carbon monoxide hauv graphite.
Lub sharper txheej carbon yog, qhov ntau oriented nws yog.
Zhu siv cov purified inferior thee raws li cathode nyob rau hauv qhov kev sim, thiab cov microstructure ntawm cov khoom graphitized tau hloov los ntawm granular mus rau loj graphite qauv, thiab nruj graphite txheej kuj tau soj ntsuam nyob rau hauv tus nqi siab kis tau tus mob electron microscope.
Hauv Raman spectra, nrog kev hloov pauv ntawm kev sim, tus nqi ID / Ig kuj hloov.Thaum lub electrolytic kub yog 950 ℃, lub sij hawm electrolytic yog 6h, thiab cov electrolytic voltage yog 2.6V, qhov qis tshaj ID / Ig tus nqi yog 0.3, thiab lub ncov D yog ntau qis dua G ncov.Nyob rau tib lub sijhawm, cov tsos ntawm 2D ncov kuj sawv cev rau kev tsim cov qauv graphite heev.
Qhov ntse (002) diffraction ncov hauv daim duab XRD kuj lees paub qhov kev hloov pauv ntawm cov thee tsis zoo rau hauv graphite nrog siab crystallinity.
Nyob rau hauv cov txheej txheem graphitization, qhov nce ntawm qhov kub thiab qhov hluav taws xob yuav ua lub luag haujlwm txhawb nqa, tab sis qhov hluav taws xob siab dhau yuav txo cov txiaj ntsig ntawm graphite, thiab kub siab dhau los yog lub sij hawm graphitization ntev dhau lawm yuav ua rau cov khoom pov tseg, yog li rau cov khoom siv sib txawv carbon. , nws yog ib qho tseem ceeb tshwj xeeb rau kev tshawb nrhiav qhov tsim nyog tshaj plaws electrolytic tej yam kev mob, kuj yog lub hom phiaj thiab qhov nyuaj.
Qhov no petal-zoo li flake nanostructure muaj zoo heev electrochemical zog.Ntau qhov pores tso cai rau ions kom nrawm nrawm nrawm, muab cov khoom zoo cathode rau cov roj teeb, thiab lwm yam. Yog li ntawd, cov txheej txheem electrochemical graphitization yog ib txoj kev graphitization muaj peev xwm heev.
Molten ntsev electrodeposition txoj kev
2.1 Electrodeposition ntawm carbon dioxide
Raws li lub tsev cog khoom tseem ceeb tshaj plaws, CO2 kuj yog cov tsis muaj tshuaj lom, tsis muaj mob, pheej yig thiab yooj yim muaj peev xwm txuas ntxiv mus.Txawm li cas los xij, carbon nyob rau hauv CO2 yog nyob rau hauv lub siab tshaj plaws oxidation lub xeev, yog li CO2 muaj siab thermal stability, uas ua rau nws nyuaj rau rov siv dua.
Cov kev tshawb fawb ntxov tshaj plaws ntawm CO2 electrodeposition tuaj yeem taug qab rov qab mus rau xyoo 1960s.Ingram et al.ua tiav cov pa roj carbon ntawm cov electrode kub hauv cov ntsev ntsev ntawm Li2CO3-Na2CO3-K2CO3.
Van et al.taw qhia tias cov pa roj carbon monoxide tau txais ntawm qhov sib txawv txo qhov peev xwm muaj cov qauv sib txawv, suav nrog graphite, amorphous carbon thiab carbon nanofibers.
Los ntawm molten ntsev kom ntes CO2 thiab kev npaj ntawm cov khoom siv roj carbon zoo, tom qab lub sijhawm ntev ntawm cov kws tshawb fawb tshawb fawb tau tsom mus rau carbon deposition tsim mechanism thiab cov nyhuv ntawm electrolysis tej yam kev mob ntawm cov khoom kawg, uas muaj xws li electrolytic kub, electrolytic voltage thiab muaj pes tsawg leeg ntawm electrolysis. molten ntsev thiab electrodes, thiab lwm yam., kev npaj ntawm kev ua tau zoo ntawm graphite cov ntaub ntawv rau electrodeposition ntawm CO2 tau nteg lub hauv paus ruaj khov.
Los ntawm kev hloov cov electrolyte thiab siv CaCl2-raws li molten ntsev system nrog ntau dua CO2 capture efficiency, Hu li al.Ua tiav kev npaj graphene nrog ntau dua graphitization degree thiab carbon nanotubes thiab lwm yam nanographite qauv los ntawm kev kawm electrolytic tej yam kev mob xws li electrolysis kub, electrode muaj pes tsawg leeg thiab molten ntsev muaj pes tsawg leeg.
Piv nrog rau carbonate system, CaCl2 muaj qhov zoo ntawm pheej yig thiab yooj yim kom tau, siab conductivity, yooj yim rau yaj hauv dej, thiab ntau dua solubility ntawm oxygen ions, uas muab theoretical tej yam kev mob rau hloov dua siab tshiab ntawm CO2 rau hauv graphite cov khoom uas muaj nqi ntxiv.
2.2 Kev hloov pauv tshuab
Kev npaj cov khoom muaj nqis ntxiv cov pa roj carbon monoxide los ntawm electrodeposition ntawm CO2 los ntawm molten ntsev feem ntau suav nrog CO2 capture thiab indirect txo.Kev ntes ntawm CO2 yog ua tiav los ntawm O2 dawb hauv molten ntsev, raws li qhia nyob rau hauv Equation (1):
CO2 + O2 - → CO 3 2 - (1)
Tam sim no, peb txoj kev txo qis cov tshuaj tiv thaiv ncaj qha tau raug npaj: ib-kauj ruam cov tshuaj tiv thaiv, ob-kauj ruam cov tshuaj tiv thaiv thiab hlau txo cov tshuaj tiv thaiv mechanism.
Ib kauj ruam cov tshuaj tiv thaiv yog thawj zaug los ntawm Ingram, raws li qhia nyob rau hauv Equation (2):
CO3 2-+ 4E → C + 3O2- (2)
Ob-kauj ruam cov tshuaj tiv thaiv mechanism yog npaj los ntawm Borucka li al., raws li qhia nyob rau hauv Equation (3-4):
CO3 2-+ 2E → CO2 2-+O2- (3)
CO2 2-+ 2E → C + 2O2- (4)
Lub tshuab ntawm hlau txo cov tshuaj tiv thaiv yog npaj los ntawm Deanhardt li al.Lawv ntseeg tias cov hlau ions tau raug txo qis rau cov hlau hauv cathode, thiab tom qab ntawd cov hlau raug txo mus rau carbonate ions, raws li qhia nyob rau hauv Equation (5 ~ 6):
M- + E → M (5)
4 m + M2CO3 -> C + 3 m2o (6)
Tam sim no, ib kauj ruam cov tshuaj tiv thaiv feem ntau tau txais nyob rau hauv cov ntaub ntawv uas twb muaj lawm.
Yin et al.kawm txog Li-Na-K carbonate system nrog npib tsib xee li cathode, tin dioxide li anode thiab nyiaj hlau raws li siv electrode, thiab tau txais lub voj voog voltammetry test daim duab hauv daim duab 2 (scanning npaum li cas ntawm 100 mV / s) ntawm nickel cathode, thiab pom. tias tsuas muaj ib qho kev txo qis (ntawm -2.0V) hauv qhov tsis zoo scanning.
Yog li ntawd, nws tuaj yeem xaus lus tias tsuas yog ib qho kev tshwm sim tshwm sim thaum lub sij hawm txo cov carbonate.
Gao et al.tau tib yam cyclic voltammetry nyob rau hauv tib lub carbonate system.
Ge et al.siv inert anode thiab tungsten cathode los ntes CO2 hauv LiCl-Li2CO3 system thiab tau txais cov duab zoo sib xws, thiab tsuas yog txo qis ntawm cov pa roj carbon deposition tshwm sim hauv qhov tsis zoo scanning.
Nyob rau hauv alkaline hlau molten ntsev system, alkali hlau thiab CO yuav raug generated thaum carbon yog deposited los ntawm cathode.Txawm li cas los xij, vim hais tias cov thermodynamic tej yam kev mob ntawm cov pa roj carbon deposition cov tshuaj tiv thaiv yog qis dua nyob rau hauv ib tug qis kub, tsuas yog txo cov carbonate rau carbon thiaj li pom nyob rau hauv qhov kev sim.
2.3 CO2 ntes los ntawm molten ntsev los npaj cov khoom graphite
High-nqi-ntxiv graphite nanomaterials xws li graphene thiab carbon nanotubes tuaj yeem npaj los ntawm electrodeposition ntawm CO2 los ntawm molten ntsev los ntawm kev tswj cov kev sim.Hu et al.siv stainless hlau li cathode nyob rau hauv lub CaCl2-NaCl-CaO molten ntsev system thiab electrolyzed rau 4h nyob rau hauv tus mob ntawm 2.6V tsis tu ncua voltage ntawm txawv kub.
Ua tsaug rau cov catalysis ntawm hlau thiab cov nyhuv tawg ntawm CO ntawm graphite txheej, graphene tau pom nyob rau saum npoo ntawm cathode.Cov txheej txheem npaj ntawm graphene muaj nyob rau hauv daim duab 3.
Daim duab
Tom qab cov kev tshawb fawb ntxiv Li2SO4 los ntawm lub hauv paus ntawm CaCl2-NaClCaO molten ntsev system, electrolysis kub yog 625 ℃, tom qab 4h ntawm electrolysis, tib lub sij hawm nyob rau hauv lub cathodic deposition ntawm carbon pom graphene thiab carbon nanotubes, txoj kev tshawb no pom tias Li + thiab SO4 2. - kom coj tau qhov zoo ntawm graphitization.
Sulfur kuj tau ua tiav zoo rau hauv lub cev carbon, thiab ultra-thin graphite nplooj ntawv thiab filamentous carbon tuaj yeem tau los ntawm kev tswj cov kab mob electrolytic.
Cov khoom siv xws li electrolytic kub ntawm qhov siab thiab qis rau kev tsim cov graphene yog qhov tseem ceeb, thaum qhov kub siab tshaj 800 ℃ yog yooj yim los tsim CO es tsis txhob carbon, yuav luag tsis muaj carbon deposition thaum siab tshaj 950 ℃, yog li kev tswj kub yog qhov tseem ceeb heev. los tsim graphene thiab carbon nanotubes, thiab rov qab xav tau cov pa roj carbon deposition tshuaj tiv thaiv CO cov tshuaj tiv thaiv synergy los xyuas kom meej tias cov cathode los tsim graphene ruaj khov.
Cov hauj lwm no muab ib txoj hauv kev tshiab rau kev npaj cov khoom siv nano-graphite los ntawm CO2, uas yog qhov tseem ceeb rau kev daws teeb meem ntawm tsev cog khoom gases thiab kev npaj ntawm graphene.
3. Cov ntsiab lus thiab Outlook
Nrog rau kev loj hlob sai ntawm kev lag luam hluav taws xob tshiab, ntuj graphite tsis tuaj yeem ua tau raws li qhov xav tau tam sim no, thiab cov khoom siv graphite muaj lub cev zoo thiab cov khoom siv tshuaj zoo dua li cov graphite, yog li pheej yig, zoo thiab ib puag ncig tus phooj ywg graphitization yog lub hom phiaj mus sij hawm ntev.
Electrochemical txoj kev graphitization nyob rau hauv cov khoom thiab gaseous raw cov ntaub ntawv nrog cov txheej txheem ntawm cathodic polarization thiab electrochemical deposition tau ntse tawm ntawm graphite cov ntaub ntawv nrog siab ntxiv tus nqi, piv nrog rau cov tsoos txoj kev ntawm graphitization, electrochemical txoj kev yog ntau dua efficiency, tsawg zog noj, ntsuab kev tiv thaiv ib puag ncig, rau me me txwv los ntawm cov khoom siv tib lub sijhawm, raws li qhov sib txawv electrolysis tuaj yeem npaj tau ntawm cov qauv sib txawv ntawm cov qauv graphite,
Nws muab txoj hauv kev zoo rau txhua yam ntawm amorphous carbon thiab tsev cog khoom gases kom hloov mus rau hauv cov khoom muaj txiaj ntsig nano-structured graphite thiab muaj kev cia siab rau daim ntawv thov.
Tam sim no, cov cuab yeej no yog nyob rau hauv nws cov me nyuam mos.Muaj ob peb txoj kev tshawb fawb txog graphitization los ntawm txoj kev electrochemical, thiab tseem muaj ntau yam tsis paub txog.Yog li ntawd, nws yog ib qho tsim nyog yuav tau pib los ntawm cov ntaub ntawv raw thiab ua ib qho kev kawm tiav thiab kev kawm ntawm ntau yam amorphous carbons, thiab tib lub sij hawm tshawb nrhiav cov thermodynamics thiab dynamics ntawm graphite hloov dua siab tshiab nyob rau hauv ib tug sib sib zog nqus theem.
Cov no muaj qhov tseem ceeb tshaj plaws rau kev txhim kho yav tom ntej ntawm kev lag luam graphite.
Post lub sij hawm: May-10-2021