An raba Graphite zuwa graphite na wucin gadi da graphite na halitta, wanda shine adadin graphite na halitta da aka tabbatar a duniya, wanda ya kai kimanin tan biliyan 2.
Ana samun graphite na wucin gadi ta hanyar rugujewa da kuma maganin zafi na kayan da ke ɗauke da carbon a ƙarƙashin matsin lamba na yau da kullun. Wannan canjin yana buƙatar isasshen zafin jiki da kuzari a matsayin ƙarfin tuƙi, kuma tsarin da ba shi da tsari zai canza zuwa tsarin lu'ulu'u na graphite mai tsari.
Graphitization a cikin ma'anar mafi faɗi na kayan carbonaceous ta hanyar sake fasalin ƙwayoyin carbon a cikin zafin jiki sama da 2000 ℃, duk da haka, wasu kayan carbon a cikin zafin jiki sama da 3000 ℃ graphitization, irin wannan kayan carbon an san shi da "gawayi mai tauri", don kayan carbon masu sauƙin graphitization, hanyar graphitization ta gargajiya ta haɗa da hanyar zafi mai yawa da matsin lamba mai yawa, graphitization na catalytic, hanyar adana tururin sinadarai, da sauransu.
Grafitization hanya ce mai inganci ta amfani da kayan carbonaceous masu yawa. Bayan bincike mai zurfi da zurfi daga masana, yanzu ya girma. Duk da haka, wasu abubuwa marasa kyau suna iyakance amfani da graphitization na gargajiya a masana'antu, don haka ba makawa ne a binciko sabbin hanyoyin graphitization.
Hanyar electrolysis na gishirin da aka narke tun ƙarni na 19 ta kasance fiye da ƙarni na ci gaba, ka'idar asali da sabbin hanyoyinta koyaushe sabbin abubuwa ne da haɓakawa, yanzu ba ta iyakance ga masana'antar ƙarfe ta gargajiya ba, a farkon ƙarni na 21, ƙarfe a cikin tsarin gishirin da aka narke mai ƙarfi na oxide mai rage electrolytic shirye-shiryen ƙarfe na elemental sun zama abin da aka fi mayar da hankali a cikin mafi yawan aiki,
Kwanan nan, wata sabuwar hanyar shirya kayan graphite ta hanyar amfani da narkakken gishirin electrolysis ta jawo hankali sosai.
Ta hanyar amfani da cathodic polarization da electrodeposition, nau'ikan kayan carbon guda biyu daban-daban ana canza su zuwa kayan nano-graphite tare da ƙarin ƙima mai yawa. Idan aka kwatanta da fasahar graphitization ta gargajiya, sabuwar hanyar graphitization tana da fa'idodin ƙarancin zafin graphitization da yanayin da za a iya sarrafawa.
Wannan takarda ta yi bitar ci gaban graphitization ta hanyar amfani da hanyar lantarki, ta gabatar da wannan sabuwar fasaha, ta yi nazari kan fa'idodi da rashin amfanin ta, sannan ta yi hasashen yanayin ci gabanta a nan gaba.
Da farko, hanyar polarization ta gishirin narke electrolytic cathode
1.1 kayan asali
A halin yanzu, babban kayan da ake amfani da shi wajen yin graphite na wucin gadi shine allurar coke da pitch coke mai girman digiri, wato ta hanyar ragowar mai da kwal a matsayin kayan da ake amfani da su wajen samar da kayan carbon masu inganci, tare da ƙarancin porosity, ƙarancin sulfur, ƙarancin toka da fa'idodin graphitization, bayan an shirya shi zuwa graphite yana da kyakkyawan juriya ga tasiri, ƙarfin injina, ƙarancin juriya,
Duk da haka, ƙarancin man fetur da kuma canjin farashin mai sun takaita ci gabansa, don haka neman sabbin kayan masarufi ya zama matsala ta gaggawa da za a magance.
Hanyoyin graphitization na gargajiya suna da iyaka, kuma hanyoyin graphitization daban-daban suna amfani da kayan aiki daban-daban. Ga carbon mara graphitized, hanyoyin gargajiya ba za su iya graphitizing shi ba, yayin da dabarar electrochemical ta gishirin narke electrolysis ta karya iyakokin kayan aiki, kuma ya dace da kusan dukkan kayan carbon na gargajiya.
Kayan da aka yi amfani da su wajen samar da carbon sun haɗa da baƙin carbon, carbon mai aiki, kwal, da sauransu, waɗanda daga cikinsu kwal shine mafi kyau. Tawada mai amfani da kwal tana ɗaukar kwal a matsayin abin da zai fara aiki kuma ana shirya ta don yin samfuran graphite a zafin jiki mai yawa bayan an yi mata magani kafin a yi mata magani.
Kwanan nan, wannan takarda ta gabatar da sabbin hanyoyin lantarki, kamar Peng, ta hanyar amfani da gishirin da aka narke, ba zai yiwu a yi amfani da electrolysis na gishirin da aka narke ba, wanda zai iya sanya carbon baki ya zama babban lu'ulu'u na graphite, electrolysis na samfuran graphite waɗanda ke ɗauke da guntun nanometer na siffar fure, yana da babban yanki na musamman, lokacin da aka yi amfani da shi don cathode na batirin lithium ya nuna kyakkyawan aikin lantarki fiye da graphite na halitta.
Zhu da abokan aikinsa sun sanya kwal mai ƙarancin inganci da aka yi wa deashing a cikin tsarin gishirin CaCl2 don electrolysis a zafin 950 ℃, kuma sun yi nasarar canza kwal mai ƙarancin inganci zuwa graphite tare da babban lu'ulu'u, wanda ya nuna kyakkyawan aiki da tsawon lokacin zagayowar lokacin da aka yi amfani da shi azaman anode na batirin lithium ion.
Gwajin ya nuna cewa yana yiwuwa a canza nau'ikan kayan carbon na gargajiya daban-daban zuwa graphite ta hanyar amfani da narkakken gishirin electrolysis, wanda ke buɗe sabuwar hanya don graphite na roba na gaba.
1.2 tsarin
Hanyar electrolysis na gishirin da aka narke tana amfani da kayan carbon a matsayin cathode kuma tana mayar da shi zuwa graphite tare da babban lu'ulu'u ta hanyar polarization na cathodic. A halin yanzu, wallafe-wallafen da ake da su sun ambaci cire iskar oxygen da sake tsara atom na carbon a cikin yuwuwar canza polarization na cathodic.
Kasancewar iskar oxygen a cikin kayan carbon zai hana graphitization zuwa wani mataki. A cikin tsarin graphitization na gargajiya, za a cire iskar oxygen a hankali lokacin da zafin ya fi 1600K. Duk da haka, yana da matuƙar dacewa a cire iskar oxygen ta hanyar rarraba cathodic.
Peng, da sauransu a cikin gwaje-gwajen a karon farko sun gabatar da tsarin yuwuwar electrolysis na gishirin da aka narke, wato graphitization mafi yawan wuraren da za a fara shine a sanya shi a cikin microspheres na carbon mai ƙarfi/hanyar sadarwa ta electrolyte, da farko siffar carbon microsphere a kusa da harsashin graphite mai diamita ɗaya, sannan kuma ba za a taɓa samun ƙwayoyin carbon carbon mai ƙarfi waɗanda suka bazu zuwa flake na graphite na waje mai ƙarfi ba, har sai an yi masa graphitization gaba ɗaya.
Tsarin graphitization yana tare da cire iskar oxygen, wanda kuma gwaje-gwaje suka tabbatar.
Jin da abokan aikinsa sun kuma tabbatar da wannan ra'ayi ta hanyar gwaje-gwaje. Bayan an yi amfani da sinadarin carbon a cikin glucose, an gudanar da graphitization (kashi 17% na iskar oxygen). Bayan an yi graphitization, asalin ƙwayoyin carbon masu ƙarfi (Hoto na 1a da 1c) sun samar da harsashi mai ramuka wanda aka yi da zanen graphite (Hoto na 1b da 1d).
Ta hanyar electrolysis na zaruruwan carbon (16% oxygen), za a iya canza zaruruwan carbon zuwa bututun graphite bayan an yi graphitization bisa ga tsarin juyawa da aka yi hasashe a cikin wallafe-wallafen.
An yi imani da cewa, motsi mai nisa yana ƙarƙashin rarrabuwar ƙwayoyin carbon ta hanyar amfani da tsarin graphite mai girma zuwa amorphous carbon, tsarin nanostructures na musamman na graphite na roba wanda aka amfana daga ƙwayoyin oxygen daga gare su, amma takamaiman yadda ake tasiri tsarin nanometer na graphite ba a bayyane yake ba, kamar iskar oxygen daga kwarangwal na carbon bayan yadda ake amsawar cathode, da sauransu.
A halin yanzu, binciken da aka yi kan wannan tsari har yanzu yana matakin farko, kuma ana buƙatar ƙarin bincike.
1.3 Siffar siffofi na graphite na roba
Ana amfani da SEM don lura da yanayin saman graphite mai ƙananan ƙwayoyin cuta, ana amfani da TEM don lura da yanayin tsarin ƙasa da 0.2 μm, XRD da Raman spectroscopy sune hanyoyin da aka fi amfani da su don kwatanta tsarin graphite mai ƙananan ƙwayoyin cuta, ana amfani da XRD don bayyana bayanan lu'ulu'u na graphite, kuma ana amfani da Raman spectroscopy don bayyana lahani da matakin tsari na graphite.
Akwai ramuka da yawa a cikin graphite wanda cathode polarization na gishirin da aka narkar da shi. Don kayan aiki daban-daban, kamar carbon black electrolysis, ana samun nanostructures masu ramuka masu kama da fure. Ana gudanar da nazarin XRD da Raman spectrum akan carbon black bayan electrolysis.
A zafin 827 ℃, bayan an yi masa magani da ƙarfin lantarki na 2.6V na tsawon awa 1, hoton baƙar carbon na Raman kusan iri ɗaya ne da na graphite na kasuwanci. Bayan an yi wa baƙin carbon magani da yanayin zafi daban-daban, ana auna kololuwar halayyar graphite mai kaifi (002). Kololuwar diffraction (002) tana wakiltar matakin daidaitawar layin carbon mai ƙamshi a cikin graphite.
Mafi kaifi da kaifi na carbon, haka nan kuma mafi daidaito yake.
Zhu ya yi amfani da kwal mai tsabta a matsayin cathode a cikin gwajin, kuma an canza tsarin samfurin da aka zana daga granular zuwa babban tsarin graphite, kuma an lura da matsewar layin graphite a ƙarƙashin na'urar hangen nesa ta lantarki mai saurin watsawa.
A cikin yanayin Raman, tare da canjin yanayin gwaji, ƙimar ID/Ig ta canza. Lokacin da zafin lantarki ya kasance 950 ℃, lokacin lantarki shine awanni 6, kuma ƙarfin lantarki shine 2.6V, mafi ƙarancin ƙimar ID/Ig shine 0.3, kuma mafi girman D ya yi ƙasa da kololuwar G. A lokaci guda, bayyanar kololuwar 2D kuma yana wakiltar samuwar tsarin graphite mai tsari sosai.
Kololuwar diffraction mai kaifi (002) a cikin hoton XRD kuma ya tabbatar da nasarar canza ƙasan kwal zuwa graphite tare da babban lu'ulu'u.
A cikin tsarin graphitization, ƙaruwar zafin jiki da ƙarfin lantarki za su taka rawa wajen haɓaka aiki, amma ƙarfin lantarki mai yawa zai rage yawan amfanin graphite, kuma yawan zafin jiki ko lokacin graphitization mai tsawo zai haifar da ɓatar da albarkatu, don haka ga kayan carbon daban-daban, yana da mahimmanci musamman a bincika yanayin electrolytic mafi dacewa, kuma shine abin da aka fi mayar da hankali da wahala.
Wannan tsarin nanostructure mai kama da fure yana da kyawawan halaye na lantarki. Yawan ramukan da ke cikin ramin suna ba da damar saka ions cikin sauri/duba su, suna samar da kayan cathode masu inganci don batura, da sauransu. Saboda haka, hanyar electrochemical graphitization hanya ce mai yuwuwar yin graphitization.
Hanyar sanya wutar lantarki a cikin gishirin da aka narkar
2.1 Lalacewar iskar carbon dioxide
A matsayinsa na mafi mahimmancin iskar gas mai dumama yanayi, CO2 kuma ba shi da guba, marar lahani, mai araha kuma mai sauƙin samuwa. Duk da haka, carbon da ke cikin CO2 yana cikin mafi girman yanayin iskar shaka, don haka CO2 yana da kwanciyar hankali mai ƙarfi na thermodynamic, wanda ke sa ya zama da wahala a sake amfani da shi.
Binciken farko kan matsayin lantarki na CO2 za a iya gano shi tun daga shekarun 1960. Ingram da abokan aikinsa sun yi nasarar shirya carbon akan lantarki na zinariya a cikin tsarin gishirin da aka narkar na Li2CO3-Na2CO3-K2CO3.
Van da abokan aikinsa sun nuna cewa foda na carbon da aka samu a wurare daban-daban na rage yawan iskar oxygen yana da tsari daban-daban, ciki har da graphite, amorphous carbon da carbon nanofibers.
Ta hanyar gishirin da aka narke don kama CO2 da kuma hanyar shirya nasarar kayan carbon, bayan dogon lokaci na masana bincike sun mayar da hankali kan tsarin samar da sinadarin carbon da tasirin yanayin electrolysis akan samfurin ƙarshe, wanda ya haɗa da zafin lantarki, ƙarfin lantarki na electrolytic da kuma abun da ke cikin gishirin da aka narke da electrodes, da sauransu, shirya kayan graphite masu ƙarfi don daidaita CO2 ya sanya harsashi mai ƙarfi.
Ta hanyar canza electrolyte da amfani da tsarin gishirin da aka narkar da shi bisa CaCl2 tare da ingantaccen kama CO2, Hu et al. sun yi nasarar shirya graphene tare da babban matakin graphitization da carbon nanotubes da sauran tsarin nanographite ta hanyar nazarin yanayin electrolytic kamar zafin electrolysis, abun da ke cikin electrode da abun da ke cikin gishirin da aka narkar.
Idan aka kwatanta da tsarin carbonate, CaCl2 yana da fa'idodi na arha da sauƙin samu, yawan watsawa, sauƙin narkewa a cikin ruwa, da kuma yawan narkewar ions na iskar oxygen, waɗanda ke ba da yanayi na ka'ida don canza CO2 zuwa samfuran graphite tare da ƙarin ƙima mai yawa.
2.2 Tsarin Sauyi
Shirye-shiryen kayan carbon masu ƙima ta hanyar amfani da wutar lantarki na CO2 daga gishirin da aka narke galibi ya haɗa da kama CO2 da rage shi kai tsaye. Ana kammala kama CO2 ta hanyar gishirin da aka narke kyauta na O2, kamar yadda aka nuna a cikin Lissafi (1):
CO2+O2-→CO3 2- (1)
A halin yanzu, an gabatar da hanyoyi guda uku na rage tasirin sakamako kai tsaye: martanin mataki ɗaya, martanin mataki biyu da kuma tsarin rage tasirin sakamako na ƙarfe.
Ingram ne ya fara gabatar da tsarin amsawar mataki ɗaya, kamar yadda aka nuna a cikin Lissafi (2):
CO3 2-+ 4E – →C+3O2- (2)
Borucka et al. ne suka gabatar da tsarin martani mai matakai biyu, kamar yadda aka nuna a cikin Lissafi (3-4):
CO3 2-+ 2E – →CO2 2-+O2- (3)
CO2 2-+ 2E – →C+2O2- (4)
Deanhardt da abokan aikinsa ne suka gabatar da tsarin rage karfin ƙarfe. Sun yi imanin cewa da farko an rage ions na ƙarfe zuwa ƙarfe a cikin cathode, sannan aka rage ƙarfe zuwa ions na carbonate, kamar yadda aka nuna a cikin Lissafi (5~6):
M- + E – →M (5)
4 m + M2CO3 – > C + 3 m2o (6)
A halin yanzu, tsarin martani na mataki ɗaya gabaɗaya ana karɓarsa a cikin wallafe-wallafen da ake da su.
Yin da abokan aikinsa sun yi nazarin tsarin carbonate na Li-Na-K tare da nickel a matsayin cathode, tin dioxide a matsayin anode da waya ta azurfa a matsayin lantarki mai tunani, kuma sun sami adadi na gwajin voltammetry na cyclic a cikin Hoto na 2 (ƙimar dubawa ta 100 mV/s) a cathode na nickel, kuma sun gano cewa akwai kololuwar raguwa ɗaya kawai (a -2.0V) a cikin hoton da ba shi da kyau.
Saboda haka, za a iya kammala da cewa abu ɗaya ne kawai ya faru yayin rage sinadarin carbonate.
Gao da abokan aikinsa sun sami irin wannan ƙarfin lantarki na cyclic voltammetry a cikin tsarin carbonate iri ɗaya.
Ge et al. sun yi amfani da anode mara aiki da tungsten cathode don kama CO2 a cikin tsarin LiCl-Li2CO3 kuma sun sami hotuna iri ɗaya, kuma raguwar kololuwar ajiyar carbon ne kawai ya bayyana a cikin hoton da ba shi da kyau.
A cikin tsarin gishirin ƙarfe mai narkewa, za a samar da karafan alkali da CO2 yayin da cathode ke ajiye carbon. Duk da haka, saboda yanayin thermodynamic na amsawar ajiyar carbon yana ƙasa da ƙasa a ƙaramin zafin jiki, kawai za a iya gano raguwar carbon zuwa carbon a cikin gwajin.
2.3 Gishirin da aka narke a cikin gishirin CO2 don shirya samfuran graphite
Ana iya shirya kayan aikin graphite masu ƙima kamar graphene da na'urorin carbon ta hanyar amfani da na'urar lantarki ta CO2 daga gishirin da aka narke ta hanyar sarrafa yanayin gwaji. Hu da abokan aikinsa sun yi amfani da bakin ƙarfe a matsayin cathode a cikin tsarin gishirin da aka narke na CaCl2-NaCl-CaO kuma an yi amfani da na'urar lantarki na tsawon awanni 4 a ƙarƙashin yanayin ƙarfin lantarki mai 2.6V a yanayin zafi daban-daban.
Godiya ga tasirin ƙarfe da tasirin fashewar CO tsakanin layukan graphite, an sami graphene a saman cathode. An nuna tsarin shirya graphene a cikin Hoto na 3.
Hoton
Daga baya binciken ya ƙara Li2SO4 bisa tsarin gishirin CaCl2-NaClCaO2, zafin electrolysis ya kasance 625 ℃, bayan awanni 4 na electrolysis, a lokaci guda a cikin ajiyar cathodic na carbon da aka samu graphene da nanotubes na carbon, binciken ya gano cewa Li+ da SO4 2- suna kawo tasiri mai kyau akan graphitization.
Haka kuma an haɗa sulfur cikin jikin carbon cikin nasara, kuma ana iya samun zanen graphite mai siriri da carbon mai filamentous ta hanyar sarrafa yanayin electrolytic.
Kayan aiki kamar zafin jiki na electrolytic mai girma da ƙasa don ƙirƙirar graphene yana da mahimmanci, lokacin da zafin jiki sama da 800 ℃ ya fi sauƙi don samar da CO2 maimakon carbon, kusan babu ajiyar carbon lokacin da ya fi 950 ℃, don haka sarrafa zafin jiki yana da matuƙar mahimmanci don samar da graphene da nanotubes na carbon, da kuma dawo da buƙatar haɗin gwiwar ajiyar carbon don tabbatar da cewa cathode don samar da graphene mai karko.
Waɗannan ayyukan suna samar da sabuwar hanya don shirya samfuran nano-graphite ta hanyar CO2, wanda ke da matuƙar muhimmanci ga maganin iskar gas mai dumama yanayi da kuma shirya graphene.
3. Takaitawa da hangen nesa
Tare da saurin ci gaban sabbin masana'antun makamashi, graphite na halitta bai iya biyan buƙatun da ake da su a yanzu ba, kuma graphite na wucin gadi yana da kyawawan halaye na zahiri da na sinadarai fiye da graphite na halitta, don haka graphitization mai araha, inganci da kuma mara wa muhalli baya babban buri ne na dogon lokaci.
Hanyoyin lantarki graphitization a cikin kayan albarkatun ƙasa masu ƙarfi da iskar gas tare da hanyar cathodic polarization da electrochemical deposition an yi nasarar fitar da kayan graphite tare da ƙarin ƙima, idan aka kwatanta da hanyar gargajiya ta graphitization, hanyar electrochemical tana da inganci mafi girma, ƙarancin amfani da makamashi, kare muhalli kore, don ƙaramin iyaka ta kayan zaɓe a lokaci guda, bisa ga yanayin electrolysis daban-daban za a iya shirya su a yanayin siffa daban-daban na tsarin graphite,
Yana samar da hanya mai inganci don canza dukkan nau'ikan iskar gas mai amorphous da greenhouse zuwa kayan graphite masu mahimmanci masu tsari na nano kuma yana da kyakkyawan damar amfani.
A halin yanzu, wannan fasaha tana cikin ƙuruciya. Akwai ƙananan bincike kan graphitization ta hanyar electrochemical, kuma har yanzu akwai hanyoyi da yawa da ba a sani ba. Saboda haka, ya zama dole a fara daga kayan aiki da kuma gudanar da cikakken bincike mai tsari kan nau'ikan carbons marasa tsari, sannan a lokaci guda a binciki thermodynamics da dynamics na canza graphite a cikin zurfi.
Waɗannan suna da matuƙar muhimmanci ga ci gaban masana'antar graphite nan gaba.
Lokacin Saƙo: Mayu-10-2021