Graphite ya kasu kashi-kashi na graphite na wucin gadi da graphite na halitta, tabbataccen tanadi na graphite na halitta a cikin kusan tan biliyan biyu.
Ana samun graphite na wucin gadi ta hanyar bazuwar da maganin zafi na kayan da ke ɗauke da carbon a ƙarƙashin matsa lamba na al'ada. Wannan canji yana buƙatar isasshen zafin jiki da kuzari a matsayin ƙarfin tuƙi, kuma tsarin da ba ya da kyau za a canza shi zuwa tsarin kristal graphite da aka ba da oda.
Graphitization ne a cikin widest ma'anar da carbonaceous abu ta hanyar sama 2000 ℃ high zafin jiki zafi magani carbon atom sake tsarawa, duk da haka wasu carbon kayan a cikin high zafin jiki sama da 3000 ℃ graphitization, irin wannan carbon kayan da aka sani da "hard gawayi", domin sauki graphitized carbon, da gargajiya high zafin jiki Hanyar sun hada da high graphitized sinadaran, da gargajiya high graphitization. hanyar shigar tururi, da sauransu.
Zane-zanen hoto hanya ce mai inganci ta ƙarin ƙimar amfani da kayan carbonaceous. Bayan bincike mai zurfi da zurfin bincike na masana, asali ya balaga a yanzu. Duk da haka, wasu abubuwan da ba su da kyau suna iyakance aikace-aikacen graphitization na gargajiya a cikin masana'antu, don haka yanayi ne da ba makawa don gano sababbin hanyoyin zane.
Narkakken gishiri electrolysis Hanyar tun karni na 19 ya fiye da karni na ci gaba, ta asali ka'idar da sababbin hanyoyin ne kullum bidi'a da ci gaba, yanzu ba a iyakance ga gargajiya metallurgical masana'antu, a farkon na 21st karni, da karfe a cikin narkakkar gishiri tsarin m oxide electrolytic rage shirye-shiryen na elemental karafa sun zama mayar da hankali a cikin mafi aiki.
Kwanan nan, wata sabuwar hanyar shirya kayan graphite ta narkakkar wutar lantarki ta gishiri ta ja hankali sosai.
Ta hanyar katodic polarization da electrodeposition, nau'i-nau'i daban-daban na kayan albarkatun carbon ana canza su zuwa kayan nano-graphite tare da ƙarin ƙima. Idan aka kwatanta da fasahar graphitization na gargajiya, sabuwar hanyar graphitization tana da fa'idodin ƙananan zafin jiki na graphitization da ilimin halittar jiki mai sarrafawa.
Wannan takarda tana nazarin ci gaban graphitization ta hanyar hanyar lantarki, gabatar da wannan sabuwar fasaha, tana nazarin fa'idodinta da rashin amfaninta, da kuma fatan yanayin ci gabanta na gaba.
Na farko, narkar da gishiri electrolytic cathode polarization hanya
1.1 albarkatun kasa
A halin yanzu, babban albarkatun kasa na wucin gadi graphite ne allura coke da farar coke na high graphitization digiri, wato ta mai saura da kwal kwal a matsayin albarkatun kasa don samar da wani high quality-carbon kayan, tare da low porosity, low sulfur, low ash abun ciki da kuma abũbuwan amfãni daga graphitization, bayan da shirye-shiryen a cikin graphite yana da kyau jure tasiri, high inji ƙarfi, low resistivity, low resistivity, high inji ƙarfi, low resistivity, low resistivity.
Sai dai, karancin man fetur da kuma hauhawar farashin man sun takaita ci gabansa, don haka neman sabbin albarkatun kasa ya zama matsala cikin gaggawa da za a magance.
Hanyoyin graphitization na gargajiya suna da iyakancewa, kuma hanyoyin graphitization daban-daban suna amfani da albarkatun ƙasa daban-daban. Ga carbon da ba a graphitized ba, hanyoyin gargajiya da kyar ba za su iya zayyana shi ba, yayin da tsarin sinadaran lantarki na narkakken gishirin lantarki ya karya ta iyakancewar albarkatun ƙasa, kuma ya dace da kusan dukkanin kayan carbon na gargajiya.
Kayayyakin carbon na gargajiya sun haɗa da carbon baƙin ƙarfe, carbon da aka kunna, kwal, da dai sauransu, daga cikinsu gawayi shine mafi alƙawari. Tawada mai tushen kwal yana ɗaukar gawayi azaman mafari kuma an shirya shi cikin samfuran graphite a babban zafin jiki bayan riga-kafi.
Kwanan nan, wannan takarda ya ba da shawarar sabon hanyoyin electrochemical, irin su Peng, ta zurfafan gishiri electrolysis ba shi yiwuwa a graphitized carbon baki a cikin babban crystallinity na graphite, da electrolysis na graphite samfurori dauke da petal siffar graphite nanometer kwakwalwan kwamfuta, yana da high takamaiman surface area, lokacin da ake amfani da lithium baturi cathode nuna kyau kwarai electrochemical yi fiye da na halitta graphite yi.
Zhu et al. sanya deashing bi da low quality-coal cikin CaCl2 narkakkar gishiri tsarin for electrolysis a 950 ℃, da kuma samu nasarar canza low quality-coal zuwa graphite tare da high crystallinity, wanda ya nuna mai kyau kudi yi da kuma dogon sake zagayowar rayuwa lokacin amfani da matsayin anode na lithium ion baturi.
Gwajin ya nuna cewa yana yiwuwa a canza nau'ikan kayan carbon na gargajiya daban-daban zuwa graphite ta hanyar narkakken gishirin lantarki, wanda ke buɗe wata sabuwar hanya don graphite roba a nan gaba.
1.2 tsarin
Hanyar electrolysis gishiri narke yana amfani da kayan carbon azaman cathode kuma yana canza shi zuwa graphite tare da babban crystallinity ta hanyar polarization na cathodic. A halin yanzu, wallafe-wallafen da ke akwai suna ambaton kau da iskar oxygen da kuma sake tsara nisa na atom na carbon a cikin yuwuwar tsarin jujjuyawar katodic polarization.
Kasancewar iskar oxygen a cikin kayan carbon zai hana graphitization zuwa wani matsayi. A cikin tsarin zane na gargajiya, za a cire oxygen a hankali lokacin da zafin jiki ya fi 1600K. Koyaya, yana da matukar dacewa don deoxidize ta hanyar polarization cathodic.
Peng, da dai sauransu a cikin gwaje-gwajen a karon farko sa gaba da narkakkar gishiri electrolysis cathodic polarization m inji, wato graphitization mafi wurin da za a fara shi ne da za a located in m carbon microspheres / electrolyte dubawa, na farko carbon microsphere form a kusa da wani asali guda diamita graphite harsashi, sa'an nan kuma taba barga anhydrous carbon carbon atoms yada zuwa mafi barga m waje, har sai gaba daya graphite flagraphite dubawa.
Tsarin graphitization yana tare da cire oxygen, wanda kuma an tabbatar da shi ta hanyar gwaje-gwaje.
Jin et al. Hakanan ya tabbatar da wannan ra'ayi ta hanyar gwaje-gwaje. Bayan carbonization na glucose, graphitization (17% oxygen abun ciki) da aka gudanar. Bayan graphitization, asali m carbon spheres (Fig. 1a da 1c) kafa porous harsashi hada da graphite nanosheets (Fig. 1b da 1d).
Ta hanyar electrolysis na carbon fibers (16% oxygen), za'a iya canza filayen carbon zuwa bututun graphite bayan graphitization bisa ga tsarin jujjuyawar da aka zayyana a cikin wallafe-wallafe.
An yi imani da cewa, da dogon nisa motsi ne a karkashin cathodic polarization na carbon atom da high crystal graphite zuwa amorphous carbon sake tsarawa dole ne aiwatar, roba graphite musamman petals siffar nanostructures amfana daga oxygen atom daga, amma musamman yadda za a tasiri graphite nanometer tsarin ba bayyananne, kamar oxygen daga carbon kwarangwal, da dai sauransu
A halin yanzu, bincike kan tsarin yana kan matakin farko, kuma ana buƙatar ƙarin bincike.
1.3 Halayen ilimin dabi'a na graphite na roba
Ana amfani da SEM don lura da yanayin yanayin yanayin graphite, ana amfani da TEM don lura da tsarin tsarin halittar ƙasa da 0.2 μm, XRD da Raman spectroscopy sune mafi yawan hanyoyin da ake amfani da su don siffanta ƙirar ƙirar graphite, ana amfani da XRD don siffata bayanan crystal na graphite, kuma ana amfani da siginar Raman don kwatanta hoto.
Akwai pores da yawa a cikin graphite wanda aka shirya ta hanyar cathode polarization na narkakken gishirin lantarki. Don albarkatun kasa daban-daban, irin su carbon black electrolysis, ana samun nanostructures mai kama da petal. Ana gudanar da bincike na bakan XRD da Raman akan baƙin carbon bayan electrolysis.
A 827 ℃, bayan an bi da shi tare da ƙarfin lantarki na 2.6V na 1h, hoton Raman na baƙar fata na carbon kusan iri ɗaya ne da na graphite na kasuwanci. Bayan an yi maganin baƙar carbon ɗin tare da yanayin zafi daban-daban, ana auna ƙimar sifa mai kaifi (002). Kololuwar rarrabuwar kawuna (002) tana wakiltar matakin daidaitawar Layer carbon aromatic a cikin graphite.
Da kaifi da carbon Layer ne, da karin daidaitacce shi ne.
Zhu ya yi amfani da kwal ɗin da aka tsarkake a matsayin cathode a cikin gwajin, kuma ƙirar ƙirar samfurin da aka zayyana an canza shi daga granular zuwa babban tsarin graphite, kuma an lura da madaidaicin faifan graphite a ƙarƙashin babban siginar lantarki mai saurin watsawa.
A cikin Raman Spectra, tare da canjin yanayin gwaji, ƙimar ID/Ig ita ma ta canza. Lokacin da zafin wutar lantarki ya kasance 950 ℃, lokacin electrolytic shine 6h, kuma ƙarfin lantarki shine 2.6V, ƙimar ID / Ig mafi ƙasƙanci shine 0.3, kuma D kololuwar ta kasance ƙasa da G ganiya. A lokaci guda, bayyanar kololuwar 2D shima yana wakiltar samuwar tsarin zane mai girma da aka ba da oda.
Kololuwa mai kaifi (002) a cikin hoton XRD kuma yana tabbatar da nasarar jujjuyawar ƙarancin gawayi zuwa graphite tare da babban crystallinity.
A cikin graphitization tsari, da karuwa da zafin jiki da kuma irin ƙarfin lantarki za su taka rawar inganta, amma ma high irin ƙarfin lantarki zai rage yawan amfanin ƙasa na graphite, kuma ma high zafin jiki ko kuma da yawa graphitization lokaci zai kai ga sharar gida da albarkatun, don haka ga daban-daban carbon kayan, yana da muhimmanci musamman don gano mafi dace electrolytic yanayi, shi ne kuma mayar da hankali da wahala.
Wannan petal-kamar flake nanostructure yana da kyawawan kaddarorin electrochemical. Yawancin pores suna ba da damar shigar da ions da sauri / sakawa, samar da kayan aikin cathode masu inganci don batura, da sauransu. Saboda haka, hanyar graphitization na electrochemical shine hanya mai yuwuwar graphitization.
Hanyar narkar da gishirin lantarki
2.1 Electrodeposition na carbon dioxide
A matsayin mafi mahimmancin iskar gas, CO2 shima ba mai guba bane, mara lahani, mai arha kuma mai sauƙin samun albarkatu. Koyaya, carbon a cikin CO2 yana cikin mafi girman yanayin iskar shaka, don haka CO2 yana da kwanciyar hankali mai ƙarfi, wanda ya sa ya zama da wahala a sake amfani da shi.
Binciken farko akan CO2 electrodeposition za a iya gano shi a shekarun 1960. Ingram et al. samu nasarar shirya carbon akan lantarki na gwal a cikin narkakken tsarin gishiri na Li2CO3-Na2CO3-K2CO3.
Van et al. ya nuna cewa foda na carbon da aka samu a hanyoyi daban-daban na raguwa suna da tsari daban-daban, ciki har da graphite, carbon amorphous da carbon nanofibers.
By narkakkar gishiri kama CO2 da shirye-shiryen hanyar carbon abu nasara, bayan dogon lokaci na bincike masana sun mayar da hankali a kan carbon jijiya samuwar inji da kuma sakamakon electrolysis yanayi a kan samfurin karshe, wanda ya hada da electrolytic zafin jiki, electrolytic irin ƙarfin lantarki da abun da ke ciki na narkakkar gishiri da lantarki, da dai sauransu, da shirye-shiryen high yi na graphite kayan ga electrodeposition na CO2 ya aza m tushe.
Ta hanyar canza electrolyte da amfani da tsarin gishiri na tushen CaCl2 tare da mafi girman ingancin kama CO2, Hu et al. samu nasarar shirya graphene tare da mafi girma graphitization digiri da carbon nanotubes da sauran nanographite Tsarin ta nazarin electrolytic yanayi kamar electrolysis zafin jiki, electrode abun da ke ciki da narkakkar gishiri abun da ke ciki.
Idan aka kwatanta da tsarin carbonate, CaCl2 yana da abũbuwan amfãni na arha da sauƙi don samun, high conductivity, mai sauƙi narke cikin ruwa, da kuma mafi girma solubility na oxygen ions, wanda samar da ka'idar yanayi don tuba na CO2 cikin graphite kayayyakin da high kara darajar.
2.2 Tsarin Canji
Shirye-shiryen abubuwan da aka ƙara darajar carbon ta hanyar electrodeposition na CO2 daga narkakken gishiri ya haɗa da kama CO2 da raguwa kai tsaye. An kammala kama CO2 ta O2- a cikin narkakken gishiri kyauta, kamar yadda aka nuna a cikin Equation (1):
CO2+O2-→CO3 2- (1)
A halin yanzu, an gabatar da hanyoyin rage kaikaice guda uku: amsa mataki ɗaya, amsa mataki biyu da tsarin rage ɗaukar ƙarfe.
Ingram ne ya fara gabatar da tsarin amsawa ta mataki ɗaya, kamar yadda aka nuna a cikin Equation (2):
CO3 2-+ 4E – →C+3O2- (2)
Borucka et al., ya gabatar da tsarin ɗaukar matakai biyu, kamar yadda aka nuna a cikin Equation (3-4):
CO3 2-+ 2E – →CO2 2-+O2- (3)
CO2 2-+ 2E - →C+2O2- (4)
Deanhardt et al ne ya gabatar da tsarin rage ƙarfin ƙarfe. Sun yi imanin cewa an fara rage ions ƙarfe zuwa ƙarfe a cikin cathode, sannan aka rage ƙarfe zuwa ions carbonate, kamar yadda aka nuna a cikin Equation (5 ~ 6):
M- + E – →M (5)
4 m + M2CO3 -> C + 3 m2o (6)
A halin yanzu, tsarin mayar da martani na mataki ɗaya gabaɗaya ana karɓa a cikin adabin da ke akwai.
Yin et al. yayi nazarin tsarin carbonate na Li-Na-K tare da nickel a matsayin cathode, tin dioxide a matsayin anode da waya ta azurfa a matsayin electrode na tunani, kuma ya sami adadi na gwajin voltammetry na cyclic a cikin Hoto 2 (nauyin bincike na 100 mV / s) a nickel cathode, kuma ya gano cewa akwai raguwa ɗaya kawai (a -2.0V) a cikin binciken mara kyau.
Sabili da haka, ana iya ƙaddamar da cewa amsa ɗaya kawai ya faru a lokacin raguwar carbonate.
Gao et al. samu irin wannan cyclic voltammetry a cikin wannan carbonate tsarin.
Ge et al. An yi amfani da anode inert da tungsten cathode don kama CO2 a cikin tsarin LiCl-Li2CO3 kuma sun sami irin wannan hotuna, kuma kawai raguwar ƙyalli na ƙwayar carbon ya bayyana a cikin mummunan binciken.
A cikin tsarin gishiri narkar da ƙarfe na alkaline, za a samar da ƙarfe na alkali da CO yayin da cathode ke ajiye carbon. Duk da haka, saboda yanayin yanayin zafin jiki na yanayin ajiyar carbon yana da ƙasa a ƙananan zafin jiki, kawai ragewar carbonate zuwa carbon za a iya ganowa a cikin gwaji.
2.3 CO2 kama ta gishiri narkakkar don shirya samfuran graphite
Za'a iya shirya manyan abubuwan da aka ƙara graphite nanomaterials kamar graphene da carbon nanotubes ta hanyar electrodeposition na CO2 daga narkakken gishiri ta hanyar sarrafa yanayin gwaji. Hu et al. an yi amfani da bakin karfe azaman cathode a cikin tsarin gishiri na CaCl2-NaCl-CaO da lantarki don 4h a ƙarƙashin yanayin 2.6V akai-akai a yanayin zafi daban-daban.
Godiya ga catalysis na baƙin ƙarfe da tasirin fashewar CO tsakanin graphite yadudduka, an sami graphene a saman cathode. Ana nuna tsarin shirye-shiryen graphene a cikin siffa 3.
Hoton
Daga baya karatu kara Li2SO4 a kan tushen CaCl2-NaClCaO narkar da gishiri tsarin, electrolysis zafin jiki ne 625 ℃, bayan 4h na electrolysis, a lokaci guda a cikin cathodic jijiya na carbon samu graphene da carbon nanotubes, binciken ya gano cewa Li + da SO4 2- don kawo sakamako mai kyau a kan graphitization.
Sulfur kuma an sami nasarar haɗa shi cikin jikin carbon, kuma ana iya samun zanen zanen hoto mai kauri da filamentous carbon ta hanyar sarrafa yanayin electrolytic.
Material irin su electrolytic zafin jiki na high da low ga samuwar graphene ne m, a lokacin da zafin jiki mafi girma fiye da 800 ℃ ne sauki don samar da CO maimakon carbon, kusan babu carbon shaida a lokacin da sama da 950 ℃, don haka zafin jiki iko ne musamman da muhimmanci ga samar da graphene da carbon nanotubes, da kuma mayar da bukatar carbon jijiya dauki CO da catgraphene don tabbatar da cewa bargarar carbon jijiya dauki.
Wadannan ayyuka suna ba da sabuwar hanya don shirye-shiryen samfuran nano-graphite ta CO2, wanda ke da mahimmanci ga maganin iskar gas da kuma shirye-shiryen graphene.
3. Summary da Outlook
Tare da saurin haɓaka sabbin masana'antar makamashi, graphite na halitta ya kasa biyan buƙatu na yanzu, kuma graphite na wucin gadi yana da mafi kyawun kaddarorin jiki da sinadarai fiye da graphite na halitta, don haka arha, inganci da graphitization abokantaka na muhalli shine burin dogon lokaci.
Electrochemical hanyoyin graphitization a cikin m da gaseous albarkatun kasa tare da Hanyar cathodic polarization da electrochemical jijiya aka samu nasarar fita daga cikin graphite kayan da high kara darajar, idan aka kwatanta da gargajiya hanyar graphitization, da electrochemical Hanyar ne na mafi girma yadda ya dace, ƙananan makamashi amfani, kore muhalli kariya, ga kananan iyaka da zažužžukan kayan a lokaci guda, bisa ga daban-daban electrolysis tsarin za a iya shirya a daban-daban electrolysis yanayin.
Yana ba da ingantacciyar hanya don kowane nau'in carbon amorphous da iskar gas don canza su zuwa kayan graphite mai ƙima mai mahimmanci na Nano kuma yana da kyakkyawan fata na aikace-aikacen.
A halin yanzu, wannan fasaha tana cikin ƙuruciyarta. Akwai ƴan karatu kan graphitization ta hanyar electrochemical, kuma har yanzu akwai matakai da yawa da ba a sani ba. Saboda haka, wajibi ne a fara daga albarkatun kasa da kuma gudanar da bincike mai zurfi da tsari akan nau'in carbon amorphous daban-daban, kuma a lokaci guda bincika ma'aunin thermodynamics da yanayin jujjuyawar graphite a cikin matakin zurfi.
Waɗannan suna da mahimmanci mai nisa don ci gaban masana'antar graphite na gaba.
Lokacin aikawa: Mayu-10-2021