Kukula filimu yowala ya graphite pa Ni ndi kusamutsa kwake kopanda polymer m'njira ziwiri

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Mafilimu a Nanoscale graphite (NGFs) ndi zinthu zolimba zomwe zimatha kupangidwa ndi catalytic chemical vapor deposition, koma mafunso akadali okhudza kusamutsa kwawo mosavuta komanso momwe mawonekedwe a pamwamba amakhudzira kugwiritsa ntchito kwawo muzipangizo zam'badwo wotsatira. Pano tikunena za kukula kwa NGF mbali zonse ziwiri za polycrystalline nickel foil (dera la 55 cm2, makulidwe pafupifupi 100 nm) ndi kusamutsa kwake kopanda polymer (kutsogolo ndi kumbuyo, dera mpaka 6 cm2). Chifukwa cha mawonekedwe a catalyst foil, mafilimu awiri a carbon amasiyana mu mawonekedwe awo akuthupi ndi makhalidwe ena (monga kuuma kwa pamwamba). Tikuwonetsa kuti NGFs zokhala ndi kumbuyo kolimba ndizoyenera kuzindikira NO2, pomwe NGFs zosalala komanso zoyendetsa bwino mbali yakutsogolo (2000 S/cm, kukana kwa pepala - 50 ohms/m2) zitha kukhala zowongolera zogwira ntchito. njira kapena electrode ya solar cell (popeza imatumiza 62% ya kuwala kowoneka). Ponseponse, njira zomwe zafotokozedwa za kukula ndi mayendedwe zingathandize kupanga NGF ngati chinthu china chogwiritsa ntchito kaboni pogwiritsira ntchito ukadaulo pomwe mafilimu a graphene ndi graphite wandiweyani wa micron sali oyenera.
Graphite ndi chinthu chomwe chimagwiritsidwa ntchito kwambiri m'mafakitale. Chofunika kwambiri, graphite ili ndi mphamvu zochepa zolemera komanso kutentha kwambiri komanso magetsi, ndipo imakhala yokhazikika m'malo otentha komanso a mankhwala1,2. Flake graphite ndi chinthu chodziwika bwino choyambira kafukufuku wa graphene3. Ikakonzedwa kukhala mafilimu opyapyala, ingagwiritsidwe ntchito m'njira zosiyanasiyana, kuphatikizapo zotenthetsera zamagetsi monga mafoni a m'manja4,5,6,7, ngati chinthu chogwira ntchito mu masensa8,9,10 komanso kuteteza kusokoneza kwa maginito11.12 ndi mafilimu a lithography mu ultraviolet yoopsa13,14, kuyendetsa njira mu maselo a dzuwa15,16. Pa ntchito zonsezi, zingakhale zabwino kwambiri ngati madera akuluakulu a mafilimu a graphite (NGFs) okhala ndi makulidwe olamulidwa mu nanoscale <100 nm angapangidwe mosavuta ndikunyamulidwa.
Makanema a graphite amapangidwa m'njira zosiyanasiyana. Nthawi ina, kuyika ndi kukulitsa kutsatiridwa ndi exfoliation kunagwiritsidwa ntchito popanga ma graphene flakes10,11,17. Ma flakes ayenera kukonzedwanso kukhala mafilimu a makulidwe ofunikira, ndipo nthawi zambiri zimatenga masiku angapo kuti apange mapepala okhuthala a graphite. Njira ina ndikuyamba ndi ma graphite solid precursors. Mu mafakitale, mapepala a ma polima amasinthidwa kukhala carbon (pa 1000–1500 °C) kenako amasinthidwa kukhala graphit (pa 2800–3200 °C) kuti apange zinthu zomangidwa bwino. Ngakhale kuti mafilimu awa ndi apamwamba, mphamvu zomwe zimagwiritsidwa ntchito ndi zofunika kwambiri1,18,19 ndipo makulidwe ochepa amakhala ochepa ma microns1,18,19,20.
Kuyika mpweya wa graphene (CVD) ndi njira yodziwika bwino yopangira mafilimu a graphene ndi ultrathin graphite (<10 nm) okhala ndi kapangidwe kake kapamwamba komanso mtengo wake ndi wokwanira21,22,23,24,25,26,27. Komabe, poyerekeza ndi kukula kwa mafilimu a graphene ndi ultrathin graphite28, kukula ndi/kapena kugwiritsa ntchito NGF pogwiritsa ntchito CVD sikunafufuzidwe kwambiri11,13,29,30,31,32,33.
Mafilimu a graphene ndi graphite omwe amakula m'ma CVD nthawi zambiri amafunika kusamutsidwa kupita ku ma substrates ogwira ntchito34. Kusamutsa filimu yopyapyala kumeneku kumaphatikizapo njira ziwiri zazikulu35: (1) kusamutsa kosadulidwa36,37 ndi (2) kusamutsa mankhwala onyowa pogwiritsa ntchito etch (substrate yothandizidwa)14,34,38. Njira iliyonse ili ndi zabwino ndi zoyipa zina ndipo iyenera kusankhidwa kutengera momwe ikugwiritsidwira ntchito, monga tafotokozera kwina35,39. Pa mafilimu a graphene/graphite omwe amakula pa ma catalytic substrates, kusamutsa kudzera mu njira zonyowa za mankhwala (zomwe polymethyl methacrylate (PMMA) ndiye gawo lothandizira lomwe limagwiritsidwa ntchito kwambiri) kumakhalabe chisankho choyamba13,30,34,38,40,41,42. Inu ndi ena. Zinanenedwa kuti palibe polima yomwe idagwiritsidwa ntchito posamutsa NGF (kukula kwa chitsanzo pafupifupi 4 cm2)25,43, koma palibe tsatanetsatane womwe unaperekedwa wokhudza kukhazikika kwa chitsanzo ndi/kapena kusamalira panthawi yosamutsa; Njira zonyowa za chemistry pogwiritsa ntchito ma polima zimakhala ndi masitepe angapo, kuphatikizapo kugwiritsa ntchito ndi kuchotsa pambuyo pake gawo la polymer loperekedwa nsembe30,38,40,41,42. Njirayi ili ndi zovuta: mwachitsanzo, zotsalira za polymer zimatha kusintha mawonekedwe a filimu yomwe yakula38. Kukonza kwina kumatha kuchotsa polima yotsala, koma masitepe owonjezerawa amawonjezera mtengo ndi nthawi yopanga filimu38,40. Pakukula kwa CVD, wosanjikiza wa graphene umayikidwa osati kutsogolo kwa chojambula chothandizira (mbali yomwe ikuyang'anizana ndi kuyenda kwa nthunzi), komanso kumbuyo kwake. Komabe, yomalizayi imaonedwa ngati chinthu chotayira ndipo imatha kuchotsedwa mwachangu ndi plasma38,41 yofewa. Kubwezeretsanso filimuyi kungathandize kukulitsa phindu, ngakhale itakhala yotsika kuposa filimu ya kaboni.
Apa, tikunena za kukonzekera kwa kukula kwa NGF kwa wafer-scale bifacial yokhala ndi kapangidwe kapamwamba pa polycrystalline nickel foil ndi CVD. Zinawunikidwa momwe kukhwima kwa kutsogolo ndi kumbuyo kwa foil kumakhudzira mawonekedwe ndi kapangidwe ka NGF. Tikuwonetsanso kusamutsa kwa NGF kotsika mtengo komanso kopanda chilengedwe kuchokera mbali zonse ziwiri za nickel foil kupita kuzinthu zambiri ndikuwonetsa momwe mafilimu akutsogolo ndi akumbuyo alili oyenera kugwiritsidwa ntchito mosiyanasiyana.
Magawo otsatirawa akufotokoza makulidwe osiyanasiyana a filimu ya graphite kutengera kuchuluka kwa zigawo za graphene zoyikidwa: (i) graphene imodzi (SLG, gawo limodzi), (ii) graphene yochepa (FLG, < zigawo 10), (iii) graphene yambiri (MLG, zigawo 10-30) ndi (iv) NGF (~ zigawo 300). Yotsirizirayi ndi makulidwe ofala kwambiri omwe amafotokozedwa ngati peresenti ya dera (pafupifupi 97% dera pa 100 µm2)30. Ndicho chifukwa chake filimu yonseyi imatchedwa NGF.
Ma polycrystalline nickel foil omwe amagwiritsidwa ntchito popanga mafilimu a graphene ndi graphite ali ndi mawonekedwe osiyanasiyana chifukwa cha kupanga kwawo ndi kukonza kwawo. Posachedwapa tapereka lipoti la kafukufuku wokonza njira yokulira ya NGF30. Tikuwonetsa kuti magawo a njira monga nthawi yonyowa ndi kupanikizika kwa chipinda panthawi ya kukula amachita gawo lofunikira kwambiri pakupeza ma NGF okhala ndi makulidwe ofanana. Pano, tafufuzanso kukula kwa NGF pamalo opukutidwa kutsogolo (FS) ndi kumbuyo kosapukutidwa (BS) kwa pepala la nickel (Chithunzi 1a). Mitundu itatu ya zitsanzo za FS ndi BS idawunikidwa, zomwe zalembedwa mu Gome 1. Pakuwunika kowoneka bwino, kukula kofanana kwa NGF mbali zonse ziwiri za pepala la nickel (NiAG) kumatha kuwoneka ndi kusintha kwa mtundu wa gawo la bulk Ni kuchokera ku imvi yachitsulo yachitsulo kupita ku imvi yopepuka (Chithunzi 1a); miyeso yaying'ono idatsimikiziridwa (Chithunzi 1b, c). Raman spectrum ya FS-NGF yodziwika bwino yomwe imawoneka m'dera lowala ndipo ikuwonetsedwa ndi mivi yofiira, yabuluu ndi lalanje mu Chithunzi 1b ikuwonetsedwa mu Chithunzi 1c. Ma Raman peaks odziwika bwino a graphite G (1683 cm−1) ndi 2D (2696 cm−1) amatsimikizira kukula kwa NGF yonyezimira kwambiri (Chithunzi 1c, Table SI1). Mu filimu yonseyi, kuchuluka kwa ma Raman spectra okhala ndi mphamvu (I2D/IG) ~0.3 kunawonedwa, pomwe ma Raman spectra okhala ndi I2D/IG = 0.8 sanawonekere kawirikawiri. Kusakhalapo kwa ma peaks olakwika (D = 1350 cm-1) mu filimu yonseyi kumasonyeza kukula kwa NGF. Zotsatira zofanana za Raman zinapezeka pa chitsanzo cha BS-NGF (Chithunzi SI1 a ndi b, Table SI1).
Kuyerekeza kwa NiAG FS- ndi BS-NGF: (a) Chithunzi cha chitsanzo cha NGF (NiAG) chosonyeza kukula kwa NGF pa sikelo ya wafer (55 cm2) ndi zitsanzo za BS- ndi FS-Ni zomwe zapezeka, (b) Zithunzi za FS-NGF/ Ni zomwe zapezedwa ndi maikulosikopu yowala, (c) ma spectra a Raman omwe amalembedwa m'malo osiyanasiyana mu panel b, (d, f) Zithunzi za SEM pa kukula kosiyanasiyana pa FS-NGF/Ni, (e, g) Zithunzi za SEM pa kukula kosiyanasiyana. Amakhazikitsa BS -NGF/Ni. Muvi wabuluu umasonyeza chigawo cha FLG, muvi wa lalanje umasonyeza chigawo cha MLG (pafupi ndi chigawo cha FLG), muvi wofiira umasonyeza chigawo cha NGF, ndipo muvi wa magenta umasonyeza kupindika.
Popeza kukula kumadalira makulidwe a gawo loyambirira, kukula kwa kristalo, malo ozungulira, ndi malire a tirigu, kukwaniritsa kuwongolera koyenera kwa makulidwe a NGF m'malo akuluakulu kumakhalabe vuto20,34,44. Kafukufukuyu adagwiritsa ntchito zomwe tidasindikiza kale30. Njirayi imapanga dera lowala la 0.1 mpaka 3% pa ​​100 µm230. M'magawo otsatirawa, tikuwonetsa zotsatira za mitundu yonse iwiri ya madera. Zithunzi za SEM zokulitsa kwambiri zikuwonetsa kukhalapo kwa madera angapo owala osiyana mbali zonse ziwiri (Chithunzi 1f, g), kusonyeza kukhalapo kwa madera a FLG ndi MLG30,45. Izi zidatsimikiziridwanso ndi Raman scattering (Chithunzi 1c) ndi zotsatira za TEM (zomwe zidakambidwa pambuyo pake mu gawo la "FS-NGF: kapangidwe ndi katundu"). Madera a FLG ndi MLG omwe adawonedwa pa zitsanzo za FS- ndi BS-NGF/Ni (kutsogolo ndi kumbuyo kwa NGF komwe kudakulira pa Ni) mwina kudakulira pa tirigu waukulu wa Ni(111) womwe udapangidwa panthawi ya pre-annealing22,30,45. Kupindika kunawonedwa mbali zonse ziwiri (Chithunzi 1b, cholembedwa ndi mivi yofiirira). Mapindika awa nthawi zambiri amapezeka mu mafilimu a graphene ndi graphite omwe amakula mu CVD chifukwa cha kusiyana kwakukulu kwa coefficient of thermal expansion pakati pa graphite ndi nickel substrate30,38.
Chithunzi cha AFM chinatsimikizira kuti chitsanzo cha FS-NGF chinali chosalala kuposa chitsanzo cha BS-NGF (Chithunzi SI1) (Chithunzi SI2). Ma root mean square (RMS) roughness values ​​​​a FS-NGF/Ni (Chithunzi SI2c) ndi BS-NGF/Ni (Chithunzi SI2d) ndi 82 ndi 200 nm, motsatana (kuyesedwa pa dera la 20 × 20 μm2). roughness yapamwamba imatha kumvedwa kutengera kusanthula kwa pamwamba pa nickel (NiAR) foil mu mkhalidwe wolandiridwa (Chithunzi SI3). Zithunzi za SEM za FS ndi BS-NiAR zikuwonetsedwa mu Zithunzi SI3a–d, zomwe zikuwonetsa mawonekedwe osiyanasiyana a pamwamba: foil yopukutidwa ya FS-Ni ili ndi tinthu tating'onoting'ono tozungulira tokhala ndi nano- ndi micron, pomwe foil yosapukutidwa ya BS-Ni ikuwonetsa makwerero opanga ngati tinthu tamphamvu kwambiri. ndi kuchepa. Zithunzi zotsika komanso zapamwamba za foil ya nickel (NiA) yonyowa zikuwonetsedwa mu Chithunzi SI3e–h. Muzithunzi izi, titha kuwona kukhalapo kwa tinthu tating'onoting'ono ta nickel tomwe tili ndi micron mbali zonse ziwiri za nickel foil (Chithunzi SI3e–h). Mbewu zazikulu zitha kukhala ndi mawonekedwe a Ni(111) pamwamba, monga momwe zanenedwera kale30,46. Pali kusiyana kwakukulu mu mawonekedwe a nickel foil pakati pa FS-NiA ndi BS-NiA. Kukhwima kwakukulu kwa BS-NGF/Ni kumachitika chifukwa cha pamwamba pa BS-NiAR yosapukutidwa, yomwe pamwamba pake imakhalabe yolimba ngakhale itatha kupukutidwa (Chithunzi SI3). Mtundu uwu wa mawonekedwe a pamwamba usanayambe kukula umalola kukhwima kwa mafilimu a graphene ndi graphite kuti azilamuliridwa. Tiyenera kudziwa kuti gawo loyambirira linasinthidwanso pang'ono panthawi ya kukula kwa graphene, zomwe zinachepetsa pang'ono kukula kwa tirigu ndikuwonjezera pang'ono kukhwima kwa pamwamba pa substrate poyerekeza ndi foil yopukutidwa ndi catalyst film22.
Kukonza bwino kuuma kwa pamwamba pa substrate, nthawi yothira (kukula kwa tirigu) 30,47 ndi kulamulira kumasula 43 kudzathandiza kuchepetsa kufanana kwa makulidwe a NGF m'deralo kufika pa sikelo ya µm2 ndi/kapena nm2 (mwachitsanzo, kusiyana kwa makulidwe a nanometers ochepa). Kuti muwongolere kuuma kwa pamwamba pa substrate, njira monga kupukuta kwa electrolytic kwa nickel foil yomwe yatuluka ikhoza kuganiziridwa 48. Nickel foil yokonzedwa kale ikhoza kumatiridwa pa kutentha kotsika (< 900 °C) 46 ndi nthawi (< 5 min) kuti mupewe kupanga timbewu ta Ni(111) tating'onoting'ono (zomwe zimathandiza kukula kwa FLG).
Graphene ya SLG ndi FLG singathe kupirira kupsinjika kwa pamwamba pa asidi ndi madzi, zomwe zimafuna zigawo zothandizira makina panthawi yonyowa mankhwala22,34,38. Mosiyana ndi kusamutsa mankhwala konyowa kwa graphene imodzi yothandizidwa ndi polymer38, tapeza kuti mbali zonse ziwiri za NGF zomwe zakula zimatha kusamutsidwa popanda thandizo la polymer, monga momwe zasonyezedwera pa Chithunzi 2a (onani Chithunzi SI4a kuti mudziwe zambiri). Kusamutsa NGF kupita ku substrate yoperekedwa kumayamba ndi kunyowa kwa filimu ya Ni30.49 yomwe ili pansi pake. Zitsanzo za NGF/Ni/NGF zomwe zakula zidayikidwa usiku wonse mu 15 mL ya 70% HNO3 yochepetsedwa ndi 600 mL ya madzi a deionized (DI). Pambuyo poti Ni foil yasungunuka kwathunthu, FS-NGF imakhalabe yathyathyathya ndikuyandama pamwamba pa madzi, monga chitsanzo cha NGF/Ni/NGF, pomwe BS-NGF imamizidwa m'madzi (Chithunzi 2a,b). Kenako NGF yopatulidwayo inasamutsidwa kuchokera ku beaker imodzi yokhala ndi madzi atsopano osasungunuka kupita ku beaker ina ndipo NGF yopatulidwayo inatsukidwa bwino, kubwerezabwereza kanayi kapena kasanu ndi kamodzi kudzera mu mbale yagalasi yopindika. Pomaliza, FS-NGF ndi BS-NGF zinayikidwa pa substrate yomwe mukufuna (Chithunzi 2c).
Njira yosamutsira mankhwala onyowa opanda polima ya NGF yomwe imamera pa nickel foil: (a) Chithunzi cha kayendedwe ka njira (onani Chithunzi SI4 kuti mudziwe zambiri), (b) Chithunzi cha digito cha NGF yolekanitsidwa pambuyo pa Ni etching (zitsanzo 2), (c) Chitsanzo cha kusamutsa FS - ndi BS-NGF kupita ku substrate ya SiO2/Si, (d) kusamutsa FS-NGF kupita ku substrate ya polymer yosawoneka bwino, (e) BS-NGF kuchokera ku chitsanzo chomwecho ndi panel d (yogawidwa m'magawo awiri), kusamutsidwa kupita ku pepala la C lopakidwa golide ndi Nafion (substrate yowonekera yosinthasintha, m'mbali mwake muli zizindikiro za ngodya zofiira).
Dziwani kuti kusamutsa kwa SLG komwe kumachitika pogwiritsa ntchito njira zonyowa zotumizira mankhwala kumafuna nthawi yonse yokonza ya maola 20-24. Ndi njira yosamutsira yopanda polymer yomwe yawonetsedwa pano (Chithunzi SI4a), nthawi yonse yogwiritsira ntchito kusamutsa kwa NGF imachepetsedwa kwambiri (pafupifupi maola 15). Njirayi imakhala ndi: (Gawo 1) Konzani yankho lopaka ndikuyika chitsanzocho (~ mphindi 10), kenako dikirani usiku wonse kuti Ni etching (~ mphindi 7200), (Gawo 2) Tsukani ndi madzi osungunuka (Gawo - 3). sungani m'madzi osungunuka kapena tumizani ku substrate yolunjika (mphindi 20). Madzi otsekedwa pakati pa NGF ndi bulk matrix amachotsedwa ndi capillary action (pogwiritsa ntchito pepala lofukula)38, kenako madontho otsala amadzi amachotsedwa powumitsa mwachilengedwe (pafupifupi mphindi 30), ndipo pomaliza chitsanzocho chimauma kwa mphindi 10 mu uvuni wa vacuum (10-1 mbar) pa 50-90 °C (mphindi 60)38.
Graphite imadziwika kuti imatha kupirira madzi ndi mpweya kutentha kwambiri (≥ 200 °C)50,51,52. Tinayesa zitsanzo pogwiritsa ntchito Raman spectroscopy, SEM, ndi XRD titasunga m'madzi oyeretsedwa kutentha kwa chipinda komanso m'mabotolo otsekedwa kwa masiku angapo mpaka chaka chimodzi (Chithunzi SI4). Palibe kuwonongeka kooneka. Chithunzi 2c chikuwonetsa FS-NGF ndi BS-NGF zokhazikika m'madzi oyeretsedwa. Tinazijambula pa SiO2 (300 nm)/Si substrate, monga momwe zasonyezedwera kumayambiriro kwa Chithunzi 2c. Kuphatikiza apo, monga momwe zasonyezedwera pa Chithunzi 2d,e, NGF yopitilira ikhoza kusamutsidwa ku substrate zosiyanasiyana monga ma polima (Thermabright polyamide ochokera ku Nexolve ndi Nafion) ndi pepala la carbon lopakidwa golide. FS-NGF yoyandama inayikidwa mosavuta pa substrate yomwe yafunidwa (Chithunzi 2c, d). Komabe, zitsanzo za BS-NGF zazikulu kuposa 3 cm2 zinali zovuta kuzigwira zikamizidwa kwathunthu m'madzi. Kawirikawiri, akayamba kugubuduzika m'madzi, chifukwa chosasamalira bwino nthawi zina amasweka m'magawo awiri kapena atatu (Chithunzi 2e). Ponseponse, tinatha kupeza kusamutsa kopanda polima kwa PS- ndi BS-NGF (kusamutsa kosalekeza kopanda kukula kwa NGF/Ni/NGF pa 6 cm2) kwa zitsanzo mpaka 6 ndi 3 cm2 m'dera, motsatana. Zidutswa zilizonse zazikulu kapena zazing'ono zotsala zitha (kuwoneka mosavuta mu yankho lopaka kapena madzi oyeretsedwa) pa substrate yomwe mukufuna (~1 mm2, Chithunzi SI4b, onani chitsanzo chosamutsidwira ku gridi ya mkuwa monga mu “FS-NGF: Kapangidwe ndi Katundu (kakambidwa) pansi pa “Kapangidwe ndi Katundu”) kapena kusungidwa kuti zigwiritsidwe ntchito mtsogolo (Chithunzi SI4). Kutengera ndi muyezo uwu, tikuyerekeza kuti NGF ikhoza kubwezedwa mu zokolola zofika 98-99% (mutatha kukula kuti isamutsidwe).
Zitsanzo zosamutsa popanda polima zinasanthulidwa mwatsatanetsatane. Makhalidwe a mawonekedwe a pamwamba omwe adapezeka pa FS- ndi BS-NGF/SiO2/Si (Chithunzi 2c) pogwiritsa ntchito maikulosikopu owoneka (OM) ndi zithunzi za SEM (Chithunzi SI5 ndi Chithunzi 3) adawonetsa kuti zitsanzozi zidasamutsidwa popanda maikulosikopu. Kuwonongeka kooneka kwa kapangidwe monga ming'alu, mabowo, kapena madera otseguka. Makuponi pa NGF yomwe ikukula (Chithunzi 3b, d, yolembedwa ndi mivi yofiirira) adakhalabe momwemo pambuyo posamutsidwa. Ma FS- ndi BS-NGF onsewa amapangidwa ndi madera a FLG (madera owala omwe akuwonetsedwa ndi mivi yabuluu pa Chithunzi 3). Chodabwitsa n'chakuti, mosiyana ndi madera ochepa owonongeka omwe nthawi zambiri amawonedwa panthawi yosamutsa ma polima a mafilimu owonda kwambiri a graphite, madera angapo a FLG ndi MLG okhala ndi micron-size olumikizana ndi NGF (olembedwa ndi mivi yabuluu pa Chithunzi 3d) adasamutsidwa popanda ming'alu kapena kusweka (Chithunzi 3d). 3). Kukhulupirika kwa makina kunatsimikiziridwanso pogwiritsa ntchito zithunzi za TEM ndi SEM za NGF zomwe zasamutsidwa pa ma gridi amkuwa a lace-carbon, monga momwe tafotokozera pambuyo pake (“FS-NGF: Kapangidwe ndi Katundu”). BS-NGF/SiO2/Si yomwe yasamutsidwa ndi yolimba kuposa FS-NGF/SiO2/Si yokhala ndi ma rms values ​​​​a 140 nm ndi 17 nm, motsatana, monga momwe zasonyezedwera pa Chithunzi SI6a ndi b (20 × 20 μm2). Mtengo wa RMS wa NGF womwe wasamutsidwa pa SiO2/Si substrate (RMS < 2 nm) ndi wotsika kwambiri (pafupifupi nthawi zitatu) kuposa wa NGF womwe wakula pa Ni (Chithunzi SI2), zomwe zikusonyeza kuti kukhwima kowonjezera kungafanane ndi pamwamba pa Ni. Kuphatikiza apo, zithunzi za AFM zomwe zachitika m'mphepete mwa zitsanzo za FS- ndi BS-NGF/SiO2/Si zinawonetsa makulidwe a NGF a 100 ndi 80 nm, motsatana (Chithunzi SI7). Kukhuthala kochepa kwa BS-NGF kungakhale chifukwa chakuti pamwamba sipanawonekere mwachindunji ku mpweya woyambira.
NGF (NiAG) yosinthidwa popanda polima pa SiO2/Si wafer (onani Chithunzi 2c): (a,b) Zithunzi za SEM za FS-NGF yosinthidwa: kukula kochepa komanso kwakukulu (kofanana ndi sikweya lalanje mu panelo). Malo wamba) - a). (c,d) Zithunzi za SEM za BS-NGF yosinthidwa: kukula kochepa komanso kwakukulu (kofanana ndi malo wamba omwe akuwonetsedwa ndi sikweya lalanje mu panelo c). (e, f) Zithunzi za AFM za FS- ndi BS-NGF zosinthidwa. Muvi wabuluu ukuyimira chigawo cha FLG - kusiyana kowala, muvi wa cyan - kusiyana kwakuda kwa MLG, muvi wofiira - kusiyana kwakuda kukuyimira chigawo cha NGF, muvi wa magenta ukuyimira kupindika.
Kapangidwe ka mankhwala a ma FS- ndi BS-NGF omwe adakula ndi kusamutsidwa adawunikidwa ndi X-ray photoelectron spectroscopy (XPS) (Chithunzi 4). Nsonga yofooka idawonedwa mu ma spectra omwe adayesedwa (Chithunzi 4a, b), yofanana ndi substrate ya Ni (850 eV) ya ma FS- ndi BS-NGF omwe adakula (NiAG). Palibe nsonga mu ma spectra omwe adayesedwa a ma FS- ndi BS-NGF/SiO2/Si (Chithunzi 4c; zotsatira zofanana za BS-NGF/SiO2/Si sizikuwonetsedwa), zomwe zikusonyeza kuti palibe kuipitsidwa kwa Ni komwe kwatsala pambuyo pa kusamutsidwa. Zithunzi 4d–f zikuwonetsa ma spectra apamwamba a C1 s, O1 s ndi Si 2p energy levels a FS-NGF/SiO2/Si. Mphamvu yomangirira ya C1 s ya graphite ndi 284.4 eV53.54. Mawonekedwe a mzere wa nsonga za graphite nthawi zambiri amaonedwa kuti ndi osafanana, monga momwe zasonyezedwera pa Chithunzi 4d54. Sipekitiramu ya C1 s yokhazikika kwambiri (Chithunzi 4d) idatsimikiziranso kusamutsa koyera (mwachitsanzo, palibe zotsalira za polymer), zomwe zikugwirizana ndi maphunziro am'mbuyomu38. Mizere ya mzere wa C1 s spectra ya chitsanzo chatsopano (NiAG) ndi kusamutsa pambuyo pake ndi 0.55 ndi 0.62 eV, motsatana. Mitengo iyi ndi yokwera kuposa ya SLG (0.49 eV ya SLG pa substrate ya SiO2)38. Komabe, mitengo iyi ndi yaying'ono kuposa mizere ya mzere yomwe idanenedwa kale ya zitsanzo za pyrolytic graphene (~0.75 eV)53,54,55, zomwe zikusonyeza kuti palibe malo olakwika a kaboni muzinthu zomwe zilipo. Sipekitiramu ya C1 s ndi O1 s yokhazikika pansi ilibe mapewa, zomwe zimachotsa kufunikira kwa deconvolution ya peak yapamwamba54. Pali satellite peak ya π → π* yozungulira 291.1 eV, yomwe nthawi zambiri imapezeka mu zitsanzo za graphite. Zizindikiro za 103 eV ndi 532.5 eV mu Si 2p ndi O1 s core level spectra (onani Chithunzi 4e, f) zimagwirizanitsidwa ndi SiO2 56 substrate, motsatana. XPS ndi njira yodziwira pamwamba, kotero zizindikiro zofanana ndi Ni ndi SiO2 zomwe zapezeka NGF isanatumizidwe komanso itatha, motsatana, zimaganiziridwa kuti zimachokera ku dera la FLG. Zotsatira zofananazo zidawonedwa pa zitsanzo za BS-NGF zomwe zasamutsidwa (sizinawonetsedwe).
Zotsatira za NiAG XPS: (ac) Kufufuza ma spectra a ma elemental atomic compositions osiyanasiyana a FS-NGF/Ni, BS-NGF/Ni ndi kusamutsidwa kwa FS-NGF/SiO2/Si, motsatana. (d–f) Ma spectra apamwamba kwambiri a core levels C 1 s, O 1s ndi Si 2p ya FS-NGF/SiO2/Si sample.
Ubwino wonse wa makristalo a NGF osunthidwa unayesedwa pogwiritsa ntchito X-ray diffraction (XRD). Mawonekedwe wamba a XRD (Chithunzi SI8) a FS- ndi BS-NGF/SiO2/Si osunthidwa amasonyeza kukhalapo kwa ma diffraction peaks (0 0 0 2) ndi (0 0 0 4) pa 26.6° ndi 54.7°, ofanana ndi graphite. . Izi zimatsimikizira kuti NGF ndi yapamwamba kwambiri ndipo ikugwirizana ndi mtunda wa pakati pa d = 0.335 nm, womwe umasungidwa pambuyo pa sitepe yosamutsira. Mphamvu ya diffraction peak (0 0 0 2) ndi pafupifupi nthawi 30 kuposa ya diffraction peak (0 0 0 4), zomwe zikusonyeza kuti NGF crystal plane ikugwirizana bwino ndi pamwamba pa chitsanzo.
Malinga ndi zotsatira za SEM, Raman spectroscopy, XPS ndi XRD, mtundu wa BS-NGF/Ni unapezeka kuti ndi wofanana ndi wa FS-NGF/Ni, ngakhale kuti kuuma kwake kwa rms kunali kwakukulu pang'ono (Zithunzi SI2, SI5) ndi SI7).
Ma SLG okhala ndi zigawo zothandizira polima mpaka 200 nm wandiweyani amatha kuyandama pamadzi. Kapangidwe kameneka kamagwiritsidwa ntchito kwambiri mu njira zotumizira mankhwala onyowa zothandizidwa ndi polima22,38. Graphene ndi graphite ndi hydrophobic (ngodya yonyowa 80–90°) 57. Malo amphamvu omwe graphene ndi FLG onse anenedwa kuti ndi athyathyathya, okhala ndi mphamvu zochepa (~1 kJ/mol) zoyendetsera madzi mbali ina58. Komabe, mphamvu zowerengera zolumikizirana za madzi ndi graphene ndi zigawo zitatu za graphene ndi pafupifupi −13 ndi −15 kJ/mol,58 motsatana, zomwe zikusonyeza kuti kuyanjana kwa madzi ndi NGF (pafupifupi zigawo 300) ndikotsika poyerekeza ndi graphene. Ichi chikhoza kukhala chimodzi mwa zifukwa zomwe NGF yokhazikika imakhalabe yathyathyathya pamwamba pa madzi, pomwe graphene yokhazikika (yomwe imayandama m'madzi) imapindika ndikusweka. Pamene NGF yamizidwa kwathunthu m'madzi (zotsatira zake zimakhala zofanana ndi NGF yosalala komanso yosalala), m'mphepete mwake mumapindika (Chithunzi SI4). Pankhani yomiza kwathunthu, zikuyembekezeka kuti mphamvu yolumikizirana ndi madzi a NGF imawirikiza kawiri (poyerekeza ndi NGF yoyandama) ndipo m'mphepete mwa NGF zimapindika kuti zikhalebe ndi ngodya yolumikizana kwambiri (hydrophobicity). Tikukhulupirira kuti njira zitha kupangidwa kuti tipewe kupindika m'mphepete mwa ma NGF ophatikizidwa. Njira imodzi ndikugwiritsa ntchito zosungunulira zosakaniza kuti zisinthe momwe filimu ya graphite imanyowetsera.
Kusamutsa kwa SLG ku mitundu yosiyanasiyana ya ma substrate kudzera mu njira zotumizira mankhwala onyowa kwanenedwa kale. Kawirikawiri anthu ambiri amavomereza kuti mphamvu zofooka za van der Waals zilipo pakati pa mafilimu a graphene/graphite ndi ma substrate (kaya ndi ma substrate olimba monga SiO2/Si38,41,46,60, SiC38, Au42, Si pillars22 ndi ma lacy carbon films30, 34 kapena ma substrate osinthasintha monga polyimide 37). Apa tikuganiza kuti kuyanjana kwa mtundu womwewo kumalamulira. Sitinaone kuwonongeka kulikonse kapena kuchotsedwa kwa NGF pa ma substrate aliwonse omwe aperekedwa pano panthawi yogwiritsira ntchito makina (panthawi yowunikira pansi pa vacuum ndi/kapena nyengo kapena panthawi yosungira) (mwachitsanzo, Chithunzi 2, SI7 ndi SI9). Kuphatikiza apo, sitinawone SiC peak mu XPS C1 s spectrum ya core level ya NGF/SiO2/Si sample (Chithunzi 4). Zotsatirazi zikusonyeza kuti palibe mgwirizano wa mankhwala pakati pa NGF ndi substrate yomwe ikufunidwa.
Mu gawo lapitalo, "Kusamutsa kwa FS- ndi BS-NGF popanda polima," tawonetsa kuti NGF imatha kukula ndikusamutsa mbali zonse ziwiri za nickel foil. Ma FS-NGF ndi BS-NGF awa safanana pankhani ya kuuma kwa pamwamba, zomwe zidatipangitsa kufufuza ntchito zoyenera kwambiri pamtundu uliwonse.
Poganizira za kuwonekera bwino komanso pamwamba pake posalala, tinaphunzira mwatsatanetsatane kapangidwe kake, mawonekedwe ake ndi mphamvu zake zamagetsi. Kapangidwe ndi kapangidwe ka FS-NGF popanda kusuntha kwa polymer kunadziwika ndi kujambula kwa ma electron microscopy (TEM) ndi kusanthula kwa mawonekedwe a electron diffraction (SAED) area. Zotsatira zofanana zikuwonetsedwa mu Chithunzi 5. Kujambula kwa TEM kotsika kwa kukula kunawonetsa kukhalapo kwa madera a NGF ndi FLG okhala ndi mawonekedwe osiyanasiyana a electron contrast, mwachitsanzo madera amdima komanso owala, motsatana (Chithunzi 5a). Filimu yonseyi ikuwonetsa umphumphu wabwino wamakina ndi kukhazikika pakati pa madera osiyanasiyana a NGF ndi FLG, ndi kulumikizana bwino komanso popanda kuwonongeka kapena kung'ambika, komwe kunatsimikiziridwanso ndi SEM (Chithunzi 3) ndi maphunziro a TEM okwera kwambiri (Chithunzi 5c-e). Makamaka, mu Chithunzi 5d ikuwonetsa kapangidwe ka mlatho pamalo ake akuluakulu (malo olembedwa ndi muvi wakuda womwe uli mu Chithunzi 5d), womwe umadziwika ndi mawonekedwe a triangular ndipo uli ndi graphene layer yokhala ndi m'lifupi wa pafupifupi 51. Kapangidwe kake kamene kali ndi mtunda wa pakati pa 0.33 ± 0.01 nm kamachepetsedwanso kukhala zigawo zingapo za graphene m'dera lopapatiza kwambiri (kumapeto kwa muvi wakuda wolimba mu Chithunzi 5 d).
Chithunzi cha Planar TEM cha chitsanzo cha NiAG chopanda polymer pa gridi ya mkuwa ya lacy ya kaboni: (a, b) Zithunzi za TEM zokulitsa zochepa kuphatikiza madera a NGF ndi FLG, (ce) Zithunzi zokulitsa kwambiri za madera osiyanasiyana mu panel-a ndi panel-b ndi mivi yolembedwa yamtundu womwewo. Mivi yobiriwira m'mapanelo a ndi c imasonyeza madera ozungulira omwe awonongeka panthawi yolinganiza beam. (f–i) M'mapanelo a mpaka c, mapangidwe a SAED m'madera osiyanasiyana amawonetsedwa ndi mabwalo abuluu, cyan, lalanje, ndi ofiira, motsatana.
Kapangidwe ka riboni mu Chithunzi 5c kakuwonetsa (kolembedwa ndi muvi wofiira) mawonekedwe owongoka a mapulaneti a graphite lattice, omwe angakhale chifukwa cha kupangika kwa ma nanofolds motsatira filimu (mkati mwa Chithunzi 5c) chifukwa cha kupsinjika kwakukulu kwa shear stress30,61,62. Pansi pa TEM yapamwamba kwambiri, ma nanofolds awa 30 amawonetsa mawonekedwe osiyana a crystallographic kuposa madera ena onse a NGF; mapulaneti oyambira a graphite lattice amalunjika molunjika, m'malo molunjika ngati filimu yonse (mkati mwa Chithunzi 5c). Mofananamo, chigawo cha FLG nthawi zina chimawonetsa ma folds olunjika komanso opapatiza ngati band (olembedwa ndi mivi yabuluu), omwe amawoneka pakukula kochepa komanso kwapakati mu Zithunzi 5b, 5e, motsatana. Ma inset mu Chithunzi 5e amatsimikizira kukhalapo kwa zigawo ziwiri ndi zitatu za graphene mu gawo la FLG (mtunda wolumikizana 0.33 ± 0.01 nm), zomwe zikugwirizana bwino ndi zotsatira zathu zam'mbuyomu30. Kuphatikiza apo, zithunzi za SEM zojambulidwa za NGF yopanda polymer zomwe zasamutsidwa pa gridi zamkuwa ndi mafilimu a lacy carbon (atachita kuyeza TEM pamwamba) zikuwonetsedwa mu Chithunzi SI9. Dera la FLG lopachikidwa bwino (lolembedwa ndi muvi wabuluu) ndi dera losweka mu Chithunzi SI9f. Muvi wabuluu (m'mphepete mwa NGF yosamutsidwa) waperekedwa mwadala kuti awonetse kuti dera la FLG lingathe kukana njira yosamutsira popanda polymer. Mwachidule, zithunzi izi zikutsimikizira kuti NGF yopachikidwa pang'ono (kuphatikiza dera la FLG) imasunga umphumphu wamakina ngakhale itatha kugwiridwa mwamphamvu komanso kuwonetsedwa ku vacuum yayikulu panthawi ya kuyeza kwa TEM ndi SEM (Chithunzi SI9).
Chifukwa cha kusalala bwino kwa NGF (onani Chithunzi 5a), sikovuta kulunjika ma flakes motsatira mzere wa [0001] kuti mufufuze kapangidwe ka SAED. Kutengera ndi makulidwe am'deralo a filimuyo ndi malo ake, madera angapo ofunikira (mfundo 12) adadziwika kuti aphunzire za diffraction ya ma electron. Mu Zithunzi 5a–c, madera anayi mwa awa akuwonetsedwa ndipo amalembedwa ndi mabwalo amitundu (buluu, cyan, lalanje, ndi ofiira). Zithunzi 2 ndi 3 za SAED mode. Zithunzi 5f ndi g zidapezeka kuchokera kudera la FLG lomwe lawonetsedwa mu Zithunzi 5 ndi 5. Monga momwe zasonyezedwera mu Zithunzi 5b ndi c, motsatana. Ali ndi kapangidwe ka hexagonal kofanana ndi graphene yopotoka63. Makamaka, Chithunzi 5f chikuwonetsa mapatani atatu okhala ndi mawonekedwe ofanana a mzere wa [0001] zone, ozunguliridwa ndi 10° ndi 20°, monga momwe zasonyezedwera ndi kusiyana kwa angular kwa mawiri atatu a (10-10) reflections. Mofananamo, Chithunzi 5g chikuwonetsa mapangidwe awiri a hexagonal ozungulira ndi 20°. Magulu awiri kapena atatu a mapangidwe a hexagonal m'chigawo cha FLG amatha kuchokera ku zigawo zitatu za graphene mkati kapena kunja kwa ndege 33 zozungulirana. Mosiyana ndi zimenezi, mapangidwe a diffraction a electron mu Chithunzi 5h, i (yofanana ndi dera la NGF lomwe lawonetsedwa mu Chithunzi 5a) akuwonetsa kapangidwe kamodzi [0001] kokhala ndi mphamvu yayikulu ya diffraction, kofanana ndi makulidwe akuluakulu a zinthu. Ma Model a SAED awa akugwirizana ndi kapangidwe kokhuthala ka graphite ndi mawonekedwe apakati kuposa FLG, monga momwe zafotokozedwera kuchokera ku index 64. Kufotokozera kwa mawonekedwe a crystalline a NGF kwawonetsa kukhalapo kwa ma crystallites awiri kapena atatu a superimposed graphite (kapena graphene). Chodziwika kwambiri m'chigawo cha FLG ndichakuti ma crystallites ali ndi kusokonekera kwina kwa mkati kapena kunja kwa ndege. Tinthu ta grafiti/zigawo zomwe zili ndi ngodya zozungulira za 17°, 22° ndi 25° zanenedwa kale za NGF zomwe zalimidwa pa mafilimu a Ni 64. Ma angle ozungulira omwe awonedwa mu kafukufukuyu akugwirizana ndi ngodya zozungulira zomwe zawonedwa kale (±1°) za BLG63 graphene yopotoka.
Mphamvu zamagetsi za NGF/SiO2/Si zinayesedwa pa 300 K pamalo a 10×3 mm2. Miyezo ya kuchuluka kwa ma elekitironi, kuyenda, ndi mphamvu yamagetsi ndi 1.6 × 1020 cm-3, 220 cm2 V-1 C-1 ndi 2000 S-cm-1, motsatana. Miyezo ya kuyenda ndi mphamvu yamagetsi ya NGF yathu ndi yofanana ndi graphite2 yachilengedwe ndipo ndi yapamwamba kuposa graphite ya pyrolytic yopezeka m'masitolo (yopangidwa pa 3000 °C)29. Miyezo ya kuchuluka kwa ma elekitironi yonyamulira magetsi ndi yapamwamba kwambiri kuposa yomwe yanenedwa posachedwapa (7.25 × 10 cm-3) ya mafilimu a graphite okhuthala a micron okonzedwa pogwiritsa ntchito mapepala a polyimide otentha kwambiri (3200 °C) 20.
Tinayesanso kuyeza kwa ma transmittance owoneka ndi UV pa FS-NGF yomwe yasamutsidwa ku ma substrates a quartz (Chithunzi 6). Ma spectrum omwe amachokera akuwonetsa kufalikira kwa 62% pakati pa 350–800 nm, zomwe zikusonyeza kuti NGF imawala kwambiri. Ndipotu, dzina lakuti "KAUST" likhoza kuwoneka pachithunzi cha digito cha chitsanzo chomwe chili pa Chithunzi 6b. Ngakhale kapangidwe ka nanocrystalline ka NGF ndi kosiyana ndi ka SLG, chiwerengero cha zigawo chikhoza kuyerekezeredwa pogwiritsa ntchito lamulo la kutayika kwa 2.3% pa ​​gawo lililonse lowonjezera65. Malinga ndi ubalewu, chiwerengero cha zigawo za graphene zomwe zili ndi kutayika kwa 38% ndi 21. NGF yomwe yakula imakhala ndi zigawo 300 za graphene, mwachitsanzo pafupifupi 100 nm wandiweyani (Chithunzi 1, SI5 ndi SI7). Chifukwa chake, tikuganiza kuti kuwonekera kwa kuwala komwe kwawonedwa kukugwirizana ndi madera a FLG ndi MLG, popeza amagawidwa mufilimu yonse (Zithunzi 1, 3, 5 ndi 6c). Kuwonjezera pa deta ya kapangidwe kamene kali pamwambapa, kuyendetsa bwino magetsi ndi kuwonekera bwino zimatsimikiziranso khalidwe lapamwamba la kristalo la NGF yosamutsidwa.
(a) Muyeso wa kufalikira kwa UV, (b) kusuntha kwa NGF kwachizolowezi pa quartz pogwiritsa ntchito chitsanzo choyimira. (c) Chidule cha NGF (bokosi lakuda) ndi madera a FLG ndi MLG omwe amagawidwa mofanana omwe amalembedwa ngati mawonekedwe a imvi osasinthika mu chitsanzo chonse (onani Chithunzi 1) (pafupifupi 0.1–3% dera lililonse pa 100 μm2). Mawonekedwe osasinthika ndi kukula kwawo pachithunzichi ndi ongowonetsera chabe ndipo sakugwirizana ndi madera enieni.
NGF yowala yomwe imakula ndi CVD idasamutsidwira kale kumalo opanda silicon ndipo imagwiritsidwa ntchito m'maselo a dzuwa15,16. Mphamvu yosinthira mphamvu (PCE) yomwe imachitika chifukwa cha izi ndi 1.5%. Ma NGF awa amagwira ntchito zosiyanasiyana monga zigawo zogwira ntchito, njira zoyendera magetsi, ndi ma electrode owonekera15,16. Komabe, filimu ya graphite si yofanana. Kukonzanso kwina ndikofunikira poyang'anira mosamala kukana kwa pepala ndi kutumiza kwa kuwala kwa graphite electrode, popeza zinthu ziwirizi zimagwira ntchito yofunika kwambiri pakuzindikira mtengo wa PCE wa selo la dzuwa15,16. Kawirikawiri, mafilimu a graphene amakhala owonekera 97.7% ku kuwala kowoneka, koma ali ndi kukana kwa pepala kwa 200–3000 ohms/sq.16. Kukana kwa pamwamba pa mafilimu a graphene kungachepe powonjezera kuchuluka kwa zigawo (kutumiza zingapo za zigawo za graphene) ndikuyika HNO3 (~30 Ohm/sq.)66. Komabe, njirayi imatenga nthawi yayitali ndipo zigawo zosiyanasiyana zosinthira sizimalumikizana bwino nthawi zonse. Mbali yathu yakutsogolo ya NGF ili ndi zinthu monga conductivity ya 2000 S/cm, kukana kwa pepala la filimu ya 50 ohm/sq. ndi kuwonekera bwino kwa 62%, zomwe zimapangitsa kuti ikhale njira ina yabwino yogwiritsira ntchito njira zoyendetsera magetsi kapena ma counter electrodes m'maselo a dzuwa15,16.
Ngakhale kapangidwe kake ndi kapangidwe kake ka pamwamba pa BS-NGF ndizofanana ndi FS-NGF, kuuma kwake n'kosiyana ("Kukula kwa FS- ndi BS-NGF"). Kale, tinkagwiritsa ntchito graphite22 yopyapyala kwambiri ngati sensa ya gasi. Chifukwa chake, tinayesa kuthekera kogwiritsa ntchito BS-NGF pa ntchito zowunikira gasi (Chithunzi SI10). Choyamba, magawo a BS-NGF a kukula kwa mm2 adasamutsidwira ku chip ya sensor ya electrode (Chithunzi SI10a-c). Tsatanetsatane wa kupanga kwa chip udanenedwa kale; malo ake okhudzidwa ndi 9 mm267. Mu zithunzi za SEM (Chithunzi SI10b ndi c), electrode yagolide yomwe ili pansi pake ikuwoneka bwino kudzera mu NGF. Apanso, zitha kuwoneka kuti kuphimba kwa chip kofanana kudakwaniritsidwa pa zitsanzo zonse. Kuyeza kwa sensa ya gasi ya mpweya wosiyanasiyana kudalembedwa (Chithunzi SI10d) (Chithunzi SI11) ndipo kuchuluka kwa mayankho komwe kumabwera chifukwa chake kwawonetsedwa mu Zithunzi SI10g. Mwina ndi mpweya wina wosokoneza kuphatikizapo SO2 (200 ppm), H2 (2%), CH4 (200 ppm), CO2 (2%), H2S (200 ppm) ndi NH3 (200 ppm). Chimodzi mwa zifukwa zomwe zingachitike ndi NO2. mpweyawu umakhala ndi mphamvu zamagetsi. Ukalowetsedwa pamwamba pa graphene, umachepetsa kuyamwa kwa ma elekitironi ndi dongosolo. Kuyerekeza deta ya nthawi yoyankhira ya sensa ya BS-NGF ndi masensa omwe adasindikizidwa kale kwawonetsedwa mu Table SI2. Njira yoyambitsiranso masensa a NGF pogwiritsa ntchito plasma ya UV, plasma ya O3 kapena kutentha (50–150°C) kwa zitsanzo zomwe zawonekera ikupitilira, makamaka kutsatiridwa ndi kukhazikitsa machitidwe ophatikizidwa69.
Pa nthawi ya CVD, kukula kwa graphene kumachitika mbali zonse ziwiri za catalyst substrate41. Komabe, BS-graphene nthawi zambiri imatulutsidwa panthawi yosinthira41. Mu kafukufukuyu, tikuwonetsa kuti kukula kwa NGF kwapamwamba komanso kusamutsa NGF yopanda polymer kumatha kuchitika mbali zonse ziwiri za catalyst support. BS-NGF ndi yopyapyala (~80 nm) kuposa FS-NGF (~100 nm), ndipo kusiyana kumeneku kukufotokozedwa ndi mfundo yakuti BS-Ni siiwonekera mwachindunji ku kayendedwe ka mpweya woyambira. Tapezanso kuti kuuma kwa substrate ya NiAR kumakhudza kuuma kwa NGF. Zotsatirazi zikusonyeza kuti FS-NGF yokhazikika yomwe yakula ingagwiritsidwe ntchito ngati zinthu zoyambira za graphene (mwa njira yochotsera fumbi70) kapena ngati njira yoyendetsera ma solar cell15,16. Mosiyana ndi zimenezi, BS-NGF idzagwiritsidwa ntchito pozindikira mpweya (Chithunzi SI9) komanso mwina pamakina osungira mphamvu71,72 komwe kuuma kwake pamwamba kudzakhala kothandiza.
Poganizira zomwe zili pamwambapa, ndikofunikira kuphatikiza ntchito yomwe ilipo pano ndi mafilimu a graphite omwe adasindikizidwa kale omwe adalimidwa ndi CVD ndikugwiritsa ntchito nickel foil. Monga momwe tikuonera mu Table 2, kupsinjika kwakukulu komwe tidagwiritsa ntchito kunafupikitsa nthawi yochitira (gawo la kukula) ngakhale kutentha kochepa (pakati pa 850–1300 °C). Tinapezanso kukula kwakukulu kuposa masiku onse, zomwe zikusonyeza kuthekera kwa kukula. Pali zinthu zina zoti tiganizire, zina mwa zomwe taziphatikiza patebulo.
NGF yapamwamba kwambiri ya mbali ziwiri idakulitsidwa pa nickel foil pogwiritsa ntchito CVD yothandiza. Mwa kuchotsa ma polymer substrates achikhalidwe (monga omwe amagwiritsidwa ntchito mu CVD graphene), timapeza kusamutsa konyowa kwa NGF (komwe kumakula kumbuyo ndi kutsogolo kwa nickel foil) kupita ku ma substrates osiyanasiyana ofunikira kwambiri. Chodziwika bwino n'chakuti, NGF imaphatikizapo madera a FLG ndi MLG (nthawi zambiri 0.1% mpaka 3% pa ​​100 µm2) omwe amaphatikizidwa bwino mu filimu yokhuthala. Planar TEM ikuwonetsa kuti madera awa amapangidwa ndi tinthu tating'onoting'ono ta graphite/graphene tating'ono ...
Kawirikawiri, makulidwe apakati a CVD NGF ali pakati pa mapepala a graphene (otsika komanso ambiri) ndi mapepala a graphite a mafakitale (micrometer). Mitundu yosiyanasiyana ya zinthu zawo zosangalatsa, kuphatikiza njira yosavuta yomwe tapanga popanga ndi kunyamula, zimapangitsa mafilimu awa kukhala oyenera kwambiri kugwiritsa ntchito graphite, popanda kugwiritsa ntchito njira zopangira mafakitale zomwe zimagwiritsidwa ntchito pakali pano.
Chipepala cha nickel chokhuthala cha 25 μm (99.5% pureness, Goodfellow) chinayikidwa mu reactor yamalonda ya CVD (Aixtron 4-inch BMPro). Dongosololi linatsukidwa ndi argon ndikuchotsedwa ku base pressure ya 10-3 mbar. Kenako chipepala cha nickel chinayikidwa mu Ar/H2 (Pambuyo poyika chipepala cha Ni kwa mphindi 5, chipepalacho chinayikidwa ku pressure ya 500 mbar pa 900 °C. NGF inayikidwa mu flow ya CH4/H2 (100 cm3 iliyonse) kwa mphindi 5. Kenako chitsanzocho chinazizidwa mpaka kutentha kotsika kuposa 700 °C pogwiritsa ntchito Ar flow (4000 cm3) pa 40 °C/min. Tsatanetsatane wa kukonza njira yokulira ya NGF wafotokozedwa kwina.
Kapangidwe ka pamwamba pa chitsanzocho kanawonetsedwa ndi SEM pogwiritsa ntchito maikulosikopu ya Zeiss Merlin (1 kV, 50 pA). Kukhwima kwa chitsanzocho ndi makulidwe a NGF kunayesedwa pogwiritsa ntchito AFM (Dimension Icon SPM, Bruker). Kuyeza kwa TEM ndi SAED kunachitika pogwiritsa ntchito maikulosikopu ya FEI Titan 80–300 Cubed yokhala ndi mfuti yotulutsa mpweya wowala kwambiri (300 kV), monochromator ya FEI Wien ndi chowongolera cha lens ya CEOS spherical aberration kuti mupeze zotsatira zomaliza. spatial resolution 0.09 nm. Zitsanzo za NGF zinasamutsidwa ku carbon lacy coated copper grids kuti ziwonetsedwe bwino ndi kusanthula kapangidwe ka SAED. Chifukwa chake, zitsanzo zambiri za flocs zimayimitsidwa m'mabowo a nembanemba yothandizira. Zitsanzo za NGF zosamutsidwa zinasanthulidwa ndi XRD. Mawonekedwe a diffraction a X-ray adapezeka pogwiritsa ntchito ufa wa diffractometer (Brucker, D2 phase shifter yokhala ndi Cu Kα source, 1.5418 Å ndi LYNXEYE detector) pogwiritsa ntchito Cu radiation source yokhala ndi beam spot diameter ya 3 mm.
Kuyeza mfundo zingapo za Raman kunajambulidwa pogwiritsa ntchito maikulosikopu yolumikizirana (Alpha 300 RA, WITeC). Laser ya 532 nm yokhala ndi mphamvu yotsika yotulutsa (25%) idagwiritsidwa ntchito kupewa zotsatira zomwe zimayambitsidwa ndi kutentha. X-ray photoelectron spectroscopy (XPS) idachitidwa pa Kratos Axis Ultra spectrometer pamwamba pa dera la 300 × 700 μm2 pogwiritsa ntchito monochromatic Al Kα radiation (hν = 1486.6 eV) pa mphamvu ya 150 W. Ma spectra otsimikiza adapezeka pa mphamvu zotumizira za 160 eV ndi 20 eV, motsatana. Zitsanzo za NGF zomwe zidasamutsidwa ku SiO2 zidadulidwa mzidutswa (3 × 10 mm2 chilichonse) pogwiritsa ntchito PLS6MW (1.06 μm) ytterbium fiber laser pa 30 W. Ma waya olumikizirana ndi mkuwa (50 μm makulidwe) adapangidwa pogwiritsa ntchito siliva paste pansi pa maikulosikopu yowala. Kuyesa kwa magetsi ndi zotsatira za Hall kunachitika pa zitsanzo izi pa 300 K ndi kusintha kwa mphamvu ya maginito ya ± 9 Tesla mu dongosolo loyezera katundu (PPMS EverCool-II, Quantum Design, USA). Ma spectra a UV-vis otumizidwa adajambulidwa pogwiritsa ntchito spectrophotometer ya Lambda 950 UV-vis mu range ya 350-800 nm NGF yosamutsidwa ku substrates za quartz ndi zitsanzo zosonyeza quartz.
Chojambulira cha mankhwala chokana (chip cha electrode chosakanikirana) chinalumikizidwa ku bolodi la circuit losindikizidwa mwapadera 73 ndipo chokanacho chinachotsedwa kwakanthawi. Bodi la circuit losindikizidwa lomwe chipangizocho chilipo limalumikizidwa ku malo olumikizirana ndipo limayikidwa mkati mwa chipinda chowonera mpweya 74. Miyeso ya kukana idatengedwa pa voteji ya 1 V ndi kusanthula kosalekeza kuyambira pakutsuka mpaka kuwonetsa mpweya kenako ndikutsukanso. Poyamba chipindacho chinatsukidwa pochotsa nayitrogeni pa 200 cm3 kwa ola limodzi kuti zitsimikizire kuti ma analyte ena onse omwe ali mchipindamo achotsedwa, kuphatikiza chinyezi. Kenako ma analyte onse adatulutsidwa pang'onopang'ono mchipindacho pamlingo womwewo wa 200 cm3 potseka silinda ya N2.
Nkhaniyi yasinthidwanso ndipo ikupezeka kudzera pa ulalo womwe uli pamwamba pa nkhaniyi.
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