Ua tsaug rau koj tuaj xyuas Nature.com. Cov version ntawm browser koj siv tau txwv CSS kev txhawb nqa. Txhawm rau kom tau txais txiaj ntsig zoo tshaj plaws, peb xav kom koj siv qhov tshiab ntawm koj tus browser (lossis lov tes taw Compatibility Hom hauv Internet Explorer). Nyob rau lub sijhawm no, txhawm rau ua kom muaj kev txhawb nqa tsis tu ncua, peb tab tom nthuav tawm lub xaib tsis muaj styling lossis JavaScript.
Nanoscale graphite films (NGFs) yog cov khoom siv nano muaj zog uas tuaj yeem tsim los ntawm cov tshuaj catalytic vapor deposition, tab sis cov lus nug tseem nyob ntawm lawv qhov yooj yim ntawm kev hloov mus thiab yuav ua li cas morphology saum npoo cuam tshuam rau lawv siv nyob rau hauv lwm tiam neeg. Ntawm no peb qhia txog kev loj hlob ntawm NGF ntawm ob sab ntawm polycrystalline npib tsib xee ntawv ci (thaj tsam 55 cm2, tuab txog 100 nm) thiab nws cov polymer-dawb hloov pauv (pem hauv ntej thiab nraub qaum, thaj tsam li 6 cm2). Vim lub morphology ntawm cov ntawv ci catalyst, ob daim ntawv carbon sib txawv ntawm lawv lub cev thiab lwm yam ntxwv (xws li nto roughness). Peb pom tau hais tias NGFs nrog ib tug rougher backside yog zoo haum rau NO2 nrhiav tau, thaum smoother thiab ntau conductive NGFs nyob rau hauv pem hauv ntej sab (2000 S / cm, daim ntawv tsis kam - 50 ohms / m2) yuav ua tau zoo conductors. channel lossis electrode ntawm lub hnub ci cell (vim nws kis tau 62% ntawm lub teeb pom kev). Zuag qhia tag nrho, cov txheej txheem kev loj hlob thiab kev thauj mus los tau piav qhia yuav pab kom paub txog NGF ua lwm yam khoom siv carbon rau kev siv thev naus laus zis uas graphene thiab micron-thick graphite films tsis haum.
Graphite yog cov khoom siv dav siv hauv kev lag luam. Tshwj xeeb, graphite muaj cov khoom ntawm cov hluav taws xob tsawg dua thiab muaj hluav taws xob siab, thiab muaj zog nyob rau hauv cov chaw ua phem thiab tshuaj ib puag ncig1,2. Flake graphite yog cov khoom siv paub zoo pib rau kev tshawb fawb graphene3. Thaum ua tiav rau hauv cov yeeb yaj kiab nyias, nws tuaj yeem siv rau ntau yam kev siv, suav nrog cov dab dej kub rau cov khoom siv hluav taws xob xws li smartphones4,5,6,7, ua cov khoom siv hauv sensors8,9,10 thiab tiv thaiv electromagnetic cuam tshuam11. 12 thiab cov yeeb yaj kiab rau lithography hauv ultraviolet 13,14, ua cov channel hauv hnub ci hlwb 15,16. Rau tag nrho cov ntawv thov no, nws yuav muaj txiaj ntsig zoo yog tias thaj chaw loj ntawm graphite films (NGFs) nrog cov thicknesses tswj hauv nanoscale <100 nm tuaj yeem tsim tau yooj yim thiab thauj.
Graphite films yog tsim los ntawm ntau txoj kev. Nyob rau hauv ib rooj plaub, embedding thiab expansion tom qab exfoliation tau siv los tsim graphene flakes10,11,17. Cov flakes yuav tsum tau ua tiav rau hauv cov yeeb yaj kiab ntawm qhov xav tau tuab, thiab nws feem ntau siv sijhawm ob peb hnub los tsim cov ntawv tuab graphite. Lwm txoj hauv kev yog pib nrog graphitable khoom precursors. Hauv kev lag luam, cov nplooj ntawv ntawm cov polymers yog carbonized (ntawm 1000-1500 ° C) thiab tom qab ntawd graphitized (ntawm 2800-3200 ° C) los tsim cov ntaub ntawv zoo txheej txheej. Txawm hais tias qhov zoo ntawm cov yeeb yaj kiab no yog siab, kev siv lub zog yog qhov tseem ceeb 1,18,19 thiab qhov tsawg kawg nkaus tuab yog txwv rau ob peb microns1,18,19,20.
Catalytic chemical vapor deposition (CVD) yog ib txoj kev paub zoo rau kev tsim cov graphene thiab ultrathin graphite films (<10 nm) nrog cov qauv zoo thiab tus nqi tsim nyog21,22,23,24,25,26,27. Txawm li cas los xij, piv nrog kev loj hlob ntawm graphene thiab ultrathin graphite films28, kev loj hlob ntawm cheeb tsam thiab / lossis daim ntawv thov NGF siv CVD yog qhov tsawg dua tshawb nrhiav 11,13,29,30,31,32,33.
CVD-loj graphene thiab graphite zaj duab xis feem ntau yuav tsum tau xa mus rau kev ua haujlwm substrates34. Cov kev hloov pauv ntawm cov yeeb yaj kiab nyias no suav nrog ob txoj hauv kev tseem ceeb35: (1) kev hloov pauv tsis-etch36,37 thiab (2) etch-raws li kev hloov tshuaj ntub dej (substrate txhawb nqa) 14,34,38. Txhua txoj kev muaj qee qhov zoo thiab qhov tsis zoo thiab yuav tsum tau xaiv nyob ntawm daim ntawv thov npaj, raws li tau piav qhia lwm qhov35,39. Rau graphene / graphite films zus nyob rau hauv catalytic substrates, hloov los ntawm cov txheej txheem tshuaj ntub dej (ntawm uas polymethyl methacrylate (PMMA) yog feem ntau siv cov txheej txheem txhawb nqa) tseem yog thawj qhov kev xaiv 13,30,34,38,40,41,42. Koj et al. Nws tau hais tias tsis muaj cov khoom siv polymer rau kev hloov pauv NGF (piv txwv li kwv yees li 4 cm2) 25,43, tab sis tsis muaj cov ntsiab lus hais txog kev ruaj ntseg ntawm cov qauv thiab / lossis kev tuav thaum hloov chaw; Cov txheej txheem ntub dej uas siv cov polymers muaj ob peb kauj ruam, nrog rau daim ntawv thov thiab tom qab tshem tawm ntawm cov txheej txheem polymer txheej 30,38,40,41,42. Cov txheej txheem no muaj qhov tsis zoo: piv txwv li, cov residues polymer tuaj yeem hloov pauv cov khoom ntawm cov qoob loo cog qoob loo38. Cov txheej txheem ntxiv tuaj yeem tshem tawm cov khoom seem ntawm cov polymer, tab sis cov kauj ruam ntxiv no nce tus nqi thiab lub sijhawm ntawm cov yeeb yaj kiab ntau lawm38,40. Thaum lub sij hawm CVD txoj kev loj hlob, ib txheej ntawm graphene yog tso tsis tau tsuas yog nyob rau sab pem hauv ntej ntawm lub catalyst foil (sab uas tig mus rau lub chav ntws), tab sis kuj nyob rau hauv nws sab nraub qaum. Txawm li cas los xij, tom kawg yog suav tias yog cov khoom pov tseg thiab tuaj yeem tshem tawm sai sai los ntawm cov ntshav plasma38,41. Kev rov ua dua cov yeeb yaj kiab no tuaj yeem pab ua kom tau txais txiaj ntsig zoo tshaj plaws, txawm tias nws yog qhov zoo dua li lub ntsej muag carbon film.
Ntawm no, peb qhia txog kev npaj ntawm wafer-scale bifacial loj hlob ntawm NGF nrog cov qauv zoo ntawm polycrystalline nickel ntawv ci los ntawm CVD. Nws tau soj ntsuam seb qhov roughness ntawm sab pem hauv ntej thiab nraub qaum ntawm cov ntawv ci cuam tshuam rau morphology thiab cov qauv ntawm NGF. Peb kuj ua kom pom tus nqi-zoo thiab ib puag ncig tus phooj ywg polymer-dawb hloov pauv ntawm NGF los ntawm ob sab ntawm cov ntawv nyiaj npib tsib xee mus rau ntau lub substrates thiab qhia seb cov yeeb yaj kiab pem hauv ntej thiab nraub qaum zoo li cas rau ntau yam kev siv.
Cov ntu hauv qab no sib tham txog qhov sib txawv graphite zaj duab xis thicknesses nyob ntawm tus naj npawb ntawm cov txheej graphene stacked: (i) ib txheej graphene (SLG, 1 txheej), (ii) ob peb txheej graphene (FLG, < 10 txheej), (iii) multilayer graphene ( MLG, 10-30 txheej) thiab (iv) NGF (~ 300 txheej). Cov tom kawg yog cov tuab tuab tshaj plaws qhia raws li feem pua ntawm cheeb tsam (kwv yees li 97% thaj tsam ntawm 100 µm2) 30. Tias yog vim li cas tag nrho zaj duab xis tsuas yog hu ua NGF.
Polycrystalline nickel foils siv rau kev sib txuas ntawm graphene thiab graphite zaj duab xis muaj qhov sib txawv ntawm qhov sib txawv ntawm lawv cov khoom siv thiab kev ua haujlwm tom qab. Peb nyuam qhuav tshaj tawm txoj kev tshawb fawb los txhim kho txoj kev loj hlob ntawm NGF30. Peb qhia tau hais tias cov txheej txheem tsis xws li lub sij hawm annealing thiab chamber siab thaum lub sij hawm kev loj hlob theem ua lub luag hauj lwm tseem ceeb nyob rau hauv tau txais NGFs ntawm uniform thickness. Ntawm no, peb tau tshawb xyuas ntxiv txog kev loj hlob ntawm NGF ntawm polished pem hauv ntej (FS) thiab unpolished rov qab (BS) nto ntawm nickel ntawv ci (Fig. 1a). Peb hom qauv FS thiab BS tau raug tshuaj xyuas, teev nyob rau hauv Table 1. Thaum kuaj pom, kev loj hlob zoo ntawm NGF ntawm ob sab ntawm cov ntawv nyiaj npib tsib xee (NiAG) tuaj yeem pom los ntawm cov xim hloov ntawm cov khoom Ni substrate los ntawm cov yam ntxwv ntawm cov xim hlau. grey mus rau matte grey xim (Fig. 1a); Kev ntsuas microscopic tau lees paub (Daim duab 1b, c). Ib tug raug Raman spectrum ntawm FS-NGF pom nyob rau hauv lub kaj cheeb tsam thiab qhia los ntawm liab, xiav thiab txiv kab ntxwv xub nyob rau hauv daim duab 1b yog qhia nyob rau hauv daim duab 1c. Cov yam ntxwv Raman peaks ntawm graphite G (1683 cm−1) thiab 2D (2696 cm−1) paub meej tias kev loj hlob ntawm crystalline NGF (Fig. 1c, Table SI1). Thoob plaws hauv zaj duab xis, qhov tseem ceeb ntawm Raman spectra nrog qhov sib piv (I2D / IG) ~ 0.3 tau pom, thaum Raman spectra nrog I2D / IG = 0.8 tsis tshua pom. Qhov tsis muaj qhov tsis xws luag (D = 1350 cm-1) nyob rau hauv tag nrho cov yeeb yaj kiab qhia txog kev loj hlob ntawm NGF zoo. Cov txiaj ntsig zoo xws li Raman tau txais ntawm BS-NGF qauv (Daim duab SI1 a thiab b, Table SI1).
Kev sib piv ntawm NiAG FS- thiab BS-NGF: (a) Daim duab ntawm ib qho piv txwv NGF (NiAG) uas qhia NGF kev loj hlob ntawm wafer nplai (55 cm2) thiab cov txiaj ntsig BS- thiab FS-Ni ntawv ci qauv, (b) FS-NGF Cov duab / Ni tau los ntawm lub tshuab ntsuas qhov muag, (c) raug Raman spectra kaw ntawm ntau txoj haujlwm hauv vaj huam sib luag b, (d, f) SEM cov duab ntawm qhov sib txawv ntawm FS-NGF/Ni, (e, g) SEM cov duab ntawm qhov sib txawv magnifications Teem BS -NGF/Ni. Cov xub xiav qhia txog thaj tsam FLG, lub xub xub txiv kab ntxwv qhia thaj tsam MLG (ze rau thaj tsam FLG), lub xub liab qhia txog thaj tsam NGF, thiab lub paj liab liab qhia txog qhov quav.
Txij li thaum txoj kev loj hlob nyob ntawm lub thickness ntawm thawj substrate, siv lead ua loj, kev taw qhia, thiab cov ciam teb ntawm grain, ua kom muaj kev tswj kom tsim nyog ntawm NGF thickness ntawm cov cheeb tsam loj tseem yog ib qho kev sib tw20,34,44. Txoj kev tshawb no siv cov ntsiab lus uas peb tau tshaj tawm yav dhau los 30. Cov txheej txheem no ua rau thaj tsam kaj ntawm 0.1 txog 3% ib 100 µm230. Hauv seem hauv qab no, peb nthuav tawm cov txiaj ntsig rau ob hom cheeb tsam. High magnification SEM cov duab qhia pom muaj ntau qhov sib txawv ntawm qhov sib txawv ntawm ob sab (Fig. 1f,g), qhia tias muaj FLG thiab MLG cheeb tsam 30,45. Qhov no kuj tau lees paub los ntawm Raman tawg (Daim duab 1c) thiab TEM cov txiaj ntsig (sib tham tom qab hauv ntu "FS-NGF: cov qauv thiab cov khoom"). Cov cheeb tsam FLG thiab MLG tau soj ntsuam ntawm FS- thiab BS-NGF/Ni cov qauv (pem hauv ntej thiab nraub qaum NGF cog rau Ni) tej zaum yuav loj hlob ntawm cov qoob loo loj Ni (111) thaum lub sij hawm ua ntej annealing22,30,45. Folding tau pom ntawm ob sab (Daim duab 1b, cim nrog cov xub ntshav). Cov folds no feem ntau pom nyob rau hauv CVD-loj graphene thiab graphite zaj duab xis vim qhov sib txawv loj hauv cov coefficient ntawm thermal expansion ntawm graphite thiab npib tsib xee substrate30,38.
Daim duab AFM tau lees paub tias tus qauv FS-NGF tau zoo dua li cov qauv BS-NGF (Daim duab SI1) (Daim duab SI2). Lub hauv paus txhais tau tias square (RMS) roughness qhov tseem ceeb ntawm FS-NGF/Ni (Fig. SI2c) thiab BS-NGF/Ni (Fig. SI2d) yog 82 thiab 200 nm, raws li (tseem nyob ib ncig ntawm 20 × 20 m2). Qhov kev ntxhib los mos siab dua tuaj yeem nkag siab raws li kev txheeb xyuas saum npoo ntawm nickel (NiAR) ntawv ci hauv lub xeev tau txais (Daim duab SI3). SEM dluab ntawm FS thiab BS-NiAR yog qhia nyob rau hauv daim duab SI3a-d, qhia txawv nto morphologies: polished FS-Ni ntawv ci muaj nano- thiab micron-loj spherical hais, thaum unpolished BS-Ni ntawv ci nthuav qhia ib tug ntau lawm ntaiv. raws li hais nrog siab zog. thiab poob. Tsawg thiab siab daws teeb meem dluab ntawm annealed npib tsib xee ntawv nyiaj (NiA) yog qhia nyob rau hauv daim duab SI3e–h. Nyob rau hauv cov duab no, peb tuaj yeem soj ntsuam qhov muaj ob peb micron-loj npib tsib xee ntawm ob sab ntawm cov ntawv nyiaj npib tsib xee (Fig. SI3e–h). Cov nplej loj tuaj yeem muaj Ni(111) kev taw qhia saum npoo, raws li tau tshaj tawm yav dhau los 30,46. Muaj qhov sib txawv tseem ceeb hauv nickel foil morphology ntawm FS-NiA thiab BS-NiA. Lub siab roughness ntawm BS-NGF / Ni yog vim lub unpolished nto ntawm BS-NiAR, qhov nto ntawm uas tseem ho ntxhib txawm tom qab annealing (Daim duab SI3). Hom txheej txheem saum npoo no ua ntej txoj kev loj hlob tso cai rau roughness ntawm graphene thiab graphite zaj duab xis los tswj. Nws yuav tsum tau muab sau tseg tias thawj substrate underwed ib co grain reorganization thaum lub sij hawm graphene txoj kev loj hlob, uas me ntsis txo lub grain loj thiab me ntsis nce qhov roughness ntawm lub substrate piv rau cov annealed ntawv ci thiab catalyst film22.
Fine-tuning lub substrate nto roughness, annealing lub sij hawm (grain loj) 30,47 thiab tso tawm control43 yuav pab txo tau lub regional NGF thickness uniformity mus rau lub µm2 thiab / los yog txawm nm2 nplai (ie, thickness variations ntawm ob peb nanometers). Txhawm rau tswj qhov roughness ntawm lub substrate, cov txheej txheem xws li electrolytic polishing ntawm cov ntawv nyiaj npib tsib xee tuaj yeem raug txiav txim siab 48. Cov ntawv ci nickel pretreated tuaj yeem muab tso rau ntawm qhov kub qis (< 900 ° C) 46 thiab lub sijhawm (< 5 min) kom tsis txhob muaj cov qoob loo loj Ni (111) (uas yog qhov zoo rau kev loj hlob FLG).
SLG thiab FLG graphene tsis tuaj yeem tiv taus qhov nro ntawm cov kua qaub thiab dej, xav tau cov txheej txheem kev txhawb nqa cov txheej txheem thaum ntub cov tshuaj hloov cov txheej txheem 22,34,38. Nyob rau hauv sib piv rau cov tshuaj ntub dej hloov ntawm polymer-txhawb ib txheej graphene38, peb pom tias ob sab ntawm NGF loj tuaj yeem hloov pauv yam tsis muaj kev txhawb nqa polymer, raws li qhia hauv daim duab 2a (saib daim duab SI4a kom paub meej ntxiv). Kev hloov ntawm NGF mus rau ib qho substrate pib nrog ntub etching ntawm lub hauv paus Ni30.49 zaj duab xis. Cov qoob loo NGF / Ni / NGF cov qauv tau muab tso rau hmo ntuj hauv 15 mL ntawm 70% HNO3 diluted nrog 600 mL ntawm deionized (DI) dej. Tom qab cov ntawv Ni yog yaj tag, FS-NGF tseem nyob tiaj tus thiab ntab rau saum cov kua dej, ib yam li cov qauv NGF/Ni/NGF, thaum BS-NGF yog immersed nyob rau hauv dej (Fig. 2a, b). Cov NGF cais tau raug xa mus los ntawm ib lub beaker uas muaj cov dej tshiab deionized mus rau lwm lub beaker thiab cov NGF cais tau raug ntxuav kom huv si, rov ua dua plaub mus rau rau lub sij hawm los ntawm lub khob iav. Thaum kawg, FS-NGF thiab BS-NGF tau muab tso rau ntawm qhov xav tau substrate (Fig. 2c).
Polymer-free wet chemical transfer process rau NGF zus ntawm nickel foil: (a) Cov txheej txheem ntws tawm (saib daim duab SI4 kom paub meej ntxiv), (b) Cov duab digital ntawm NGF sib cais tom qab Ni etching (2 qauv), (c) Piv txwv FS - thiab BS-NGF hloov mus rau SiO2 / Si substrate, (d) FS-NGF hloov mus rau opaque polymer substrate, (e) BS-NGF los ntawm tib tus qauv raws li vaj huam sib luag d ( faib ua ob ntu), hloov mus rau kub plated C ntawv thiab Nafion (hloov pob tshab substrate, npoo cim nrog cov ces kaum liab).
Nco ntsoov tias kev hloov pauv SLG tau ua los ntawm kev siv cov tshuaj ntub dej hloov pauv yuav tsum muaj sijhawm ua haujlwm tag nrho ntawm 20-24 teev 38. Nrog rau cov txheej txheem hloov pauv tsis muaj polymer tau pom ntawm no (Daim duab SI4a), tag nrho NGF hloov pauv lub sijhawm ua haujlwm tau txo qis (kwv yees li 15 teev). Cov txheej txheem muaj xws li: (Kaum 1) Npaj cov tshuaj etching thiab muab cov qauv tso rau hauv nws (~ 10 feeb), tom qab ntawd tos ib hmos rau Ni etching (~ 7200 feeb), (Kauj ruam 2) Yaug nrog dej deionized (Step - 3) . khaws cia hauv dej deionized lossis hloov mus rau lub hom phiaj substrate (20 min). Cov dej uas nyob nruab nrab ntawm NGF thiab cov matrix loj yog tshem tawm los ntawm kev ua haujlwm capillary (siv daim ntawv blotting) 38, tom qab ntawd cov dej ntws ntxiv raug tshem tawm los ntawm kev ziab (kwv yees li 30 min), thiab thaum kawg cov qauv yog qhuav rau 10 min. min nyob rau hauv lub tshuab nqus tsev qhov cub (10-1 mbar) ntawm 50-90 ° C (60 min) 38.
Graphite paub tias tiv taus cov dej thiab huab cua ntawm qhov kub siab (≥ 200 ° C) 50,51,52. Peb tau kuaj cov qauv siv Raman spectroscopy, SEM, thiab XRD tom qab tso rau hauv dej deionized ntawm chav tsev kub thiab hauv cov fwj kaw rau qhov twg los ntawm ob peb hnub mus rau ib xyoos (Daim duab SI4). Tsis muaj qhov pom kev degradation. Daim duab 2c qhia tias dawb-sawv FS-NGF thiab BS-NGF hauv dej deionized. Peb ntes lawv ntawm SiO2 (300 nm) / Si substrate, raws li pom nyob rau hauv qhov pib ntawm daim duab 2c. Tsis tas li ntawd, raws li pom nyob rau hauv daim duab 2d, e, nruam NGF tuaj yeem hloov mus rau ntau yam substrates xws li polymers (Thermabright polyamide los ntawm Nexolve thiab Nafion) thiab kub-coated carbon ntawv. Lub floating FS-NGF tau yooj yim muab tso rau ntawm lub hom phiaj substrate (Fig. 2c, d). Txawm li cas los xij, BS-NGF cov qauv loj dua 3 cm2 yog qhov nyuaj rau kev ua haujlwm thaum muab tso rau hauv dej. Feem ntau, thaum lawv pib dov hauv dej, vim kev tuav tsis zoo lawv qee zaum tawg ua ob lossis peb ntu (Fig. 2e). Zuag qhia tag nrho, peb muaj peev xwm ua tiav polymer-dawb hloov pauv ntawm PS- thiab BS-NGF (nruam seamless hloov pauv yam tsis muaj NGF / Ni / NGF kev loj hlob ntawm 6 cm2) rau cov qauv mus txog 6 thiab 3 cm2 hauv cheeb tsam, feem. Txhua daim loj lossis me me tuaj yeem ua tau (yooj yim pom hauv cov tshuaj etching lossis dej deionized) ntawm qhov xav tau substrate (~ 1 mm2, Daim duab SI4b, saib cov qauv xa mus rau daim phiaj tooj liab raws li hauv "FS-NGF: Cov Qauv thiab Cov Khoom (sib tham) nyob rau hauv "Structure and Properties") los yog cia rau yav tom ntej siv (Daim duab SI4). Raws li qhov kev ntsuas no, peb kwv yees tias NGF tuaj yeem rov qab los ntawm cov txiaj ntsig txog li 98-99% (tom qab kev loj hlob rau kev hloov pauv).
Hloov cov qauv uas tsis muaj polymer raug tshuaj xyuas kom meej. Surface morphological yam ntxwv tau txais ntawm FS- thiab BS-NGF/SiO2/Si (Fig. 2c) siv optical microscopy (OM) thiab SEM dluab (Fig. SI5 thiab Fig. 3) qhia tau hais tias cov qauv no tau pauv tsis muaj microscopy. Pom pom kev puas tsuaj xws li cov kab nrib pleb, qhov, lossis qhov chaw uas tsis muaj. Cov folds ntawm qhov loj hlob NGF (Fig. 3b, d, cim los ntawm cov xub liab doog) tseem nyob twj ywm tom qab hloov. Ob lub FS- thiab BS-NGFs yog tsim los ntawm FLG cheeb tsam (cov cheeb tsam kaj qhia los ntawm cov xub xiav hauv daim duab 3). Kuj ceeb tias, nyob rau hauv sib piv rau ob peb cheeb tsam uas puas lawm feem ntau pom thaum lub sij hawm hloov polymer ntawm ultrathin graphite films, ob peb micron-loj FLG thiab MLG cheeb tsam txuas mus rau NGF (cim los ntawm xiav xub hauv daim duab 3d) tau pauv tsis muaj kab nrib pleb lossis tawg (Daim duab 3d) . 3). . Mechanical kev ncaj ncees tau lees paub ntxiv tias siv TEM thiab SEM cov duab ntawm NGF pauv mus rau cov kab sib chaws-carbon tooj liab, raws li tau tham tom qab ("FS-NGF: Structure thiab Properties"). Qhov hloov BS-NGF / SiO2 / Si yog rougher dua FS-NGF / SiO2 / Si nrog rms qhov tseem ceeb ntawm 140 nm thiab 17 nm, raws li qhia hauv daim duab SI6a thiab b (20 × 20 μm2). Tus nqi RMS ntawm NGF pauv mus rau SiO2 / Si substrate (RMS < 2 nm) yog qhov qis dua (kwv yees 3 zaug) dua li ntawm NGF loj hlob ntawm Ni (Daim duab SI2), qhia tias qhov roughness ntxiv tuaj yeem sib haum rau Ni nto. Tsis tas li ntawd, AFM cov duab ua rau ntawm cov npoo ntawm FS- thiab BS-NGF/SiO2/Si cov qauv qhia NGF thicknesses ntawm 100 thiab 80 nm, raws li (Fig. SI7). Lub thickness me me ntawm BS-NGF tuaj yeem yog qhov tshwm sim ntawm qhov chaw tsis raug ncaj qha rau cov pa roj ua ntej.
Hloov NGF (NiAG) yam tsis muaj polymer ntawm SiO2 / Si wafer (saib daim duab 2c): (a, b) SEM cov duab pauv FS-NGF: qis thiab siab magnification (suav nrog lub txiv kab ntxwv square hauv vaj huam sib luag). Cov cheeb tsam uas raug) – a). (c, d) SEM dluab ntawm pauv BS-NGF: qis thiab siab magnification (suav nrog thaj chaw raug pom los ntawm lub txiv kab ntxwv square hauv vaj huam sib luag c). (e, f) AFM cov duab ntawm hloov FS- thiab BS-NGFs. Cov xub xiav sawv cev rau thaj av FLG - qhov sib txawv ci ntsa iab, cyan xub - dub MLG qhov sib piv, cov xub liab - qhov sib txawv dub sawv cev rau thaj tsam NGF, magenta xub sawv cev rau lub quav.
Cov tshuaj muaj pes tsawg leeg ntawm cov cog thiab pauv FS- thiab BS-NGFs tau txheeb xyuas los ntawm X-ray photoelectron spectroscopy (XPS) (Fig. 4). Lub ncov tsis muaj zog tau pom nyob rau hauv qhov ntsuas qhov ntsuas (Daim duab 4a, b), sib raug rau Ni substrate (850 eV) ntawm FS- thiab BS-NGFs (NiAG). Tsis muaj qhov siab tshaj plaws hauv qhov ntsuas qhov ntsuas ntawm qhov hloov pauv FS- thiab BS-NGF / SiO2 / Si (Daim duab 4c; cov txiaj ntsig zoo sib xws rau BS-NGF / SiO2 / Si tsis qhia), qhia tias tsis muaj qhov seem Ni paug tom qab hloov chaw. . Cov duab 4d-f qhia cov kev daws teeb meem siab ntawm C 1 s, O 1 s thiab Si 2p qib zog ntawm FS-NGF / SiO2 / Si. Lub zog khi ntawm C 1 s ntawm graphite yog 284.4 eV53.54. Lub linear duab ntawm graphite peaks feem ntau suav hais tias yog asymmetrical, raws li qhia hauv daim duab 4d54. Qhov kev daws teeb meem siab tshaj plaws-theem C 1 s spectrum (Fig. 4d) kuj tau lees paub kev hloov pauv ntshiab (piv txwv li, tsis muaj cov khoom siv polymer), uas zoo ib yam nrog cov kev tshawb fawb yav dhau los38. Cov kab dav dav ntawm C 1 s spectra ntawm cov qauv cog tshiab (NiAG) thiab tom qab hloov pauv yog 0.55 thiab 0.62 eV, feem. Cov nqi no siab dua cov SLG (0.49 eV rau SLG ntawm SiO2 substrate) 38. Txawm li cas los xij, cov txiaj ntsig no me dua li yav dhau los qhia linewidths rau cov qauv pyrolytic graphene siab heev (~ 0.75 eV) 53,54,55, qhia tias tsis muaj cov pa roj carbon tsis zoo hauv cov khoom siv tam sim no. C 1 s thiab O 1 s hauv av theem spectra kuj tsis muaj lub xub pwg nyom, tshem tawm qhov xav tau rau siab daws teeb meem ncov deconvolution54. Muaj π → π * satellite ncov nyob ib ncig ntawm 291.1 eV, uas feem ntau pom hauv cov qauv graphite. Lub 103 eV thiab 532.5 eV teeb liab nyob rau hauv Si 2p thiab O 1 s core theem spectra (saib daim duab 4e, f) raug ntaus nqi rau SiO2 56 substrate, feem. XPS yog cov txheej txheem nto-rhiab heev, yog li cov teeb liab sib raug rau Ni thiab SiO2 tau kuaj pom ua ntej thiab tom qab hloov NGF, raws li xav tau los ntawm thaj av FLG. Cov txiaj ntsig zoo sib xws tau raug soj ntsuam rau kev hloov pauv BS-NGF cov qauv (tsis pom).
NiAG XPS cov txiaj ntsig: (ac) Kev ntsuam xyuas qhov sib txawv ntawm qhov sib txawv ntawm cov atomic compositions ntawm zus FS-NGF/Ni, BS-NGF/Ni thiab pauv FS-NGF/SiO2/Si, feem. (d–f) Kev daws teeb meem siab ntawm cov tub ntxhais theem C 1 s, O 1s thiab Si 2p ntawm FS-NGF / SiO2 / Si qauv.
Tag nrho qhov zoo ntawm NGF crystals pauv tau raug soj ntsuam siv X-ray diffraction (XRD). Hom XRD qauv (Fig. SI8) ntawm pauv FS- thiab BS-NGF/SiO2/Si qhia lub xub ntiag ntawm diffraction peaks (0 0 0 2) thiab (0 0 0 4) ntawm 26.6 ° thiab 54.7 °, zoo ib yam li graphite. . Qhov no lees paub qhov siab crystalline zoo ntawm NGF thiab sib haum mus rau qhov kev ncua deb ntawm d = 0.335 nm, uas yog khaws cia tom qab cov kauj ruam hloov. Qhov kev siv ntawm lub ncov diffraction (0 0 0 2) yog kwv yees li 30 npaug ntawm qhov diffraction ncov (0 0 0 4), qhia tau hais tias NGF siv lead ua dav hlau zoo sib xws nrog cov qauv saum npoo.
Raws li cov txiaj ntsig ntawm SEM, Raman spectroscopy, XPS thiab XRD, qhov zoo ntawm BS-NGF / Ni tau pom tias zoo ib yam li FS-NGF / Ni, txawm hais tias nws rms roughness yog me ntsis siab dua (Figures SI2, SI5) thiab SI7).
SLGs nrog cov txheej txheem kev txhawb nqa polymer txog li 200 nm tuab tuaj yeem ntab saum dej. Qhov kev teeb tsa no feem ntau yog siv rau hauv cov txheej txheem ntawm cov tshuaj polymer-pab ntub dej 22,38. Graphene thiab graphite yog hydrophobic (ntub lub kaum sab xis 80-90 °) 57 . Lub peev xwm ntawm lub zog ntawm ob qho tib si graphene thiab FLG tau raug tshaj tawm tias yog tiaj tus, nrog lub zog tsis muaj zog (~ 1 kJ / mol) rau kev txav mus los ntawm dej ntawm qhov chaw58. Txawm li cas los xij, kev sib cuam tshuam ntawm cov dej nrog graphene thiab peb txheej ntawm graphene yog kwv yees li − 13 thiab − 15 kJ / mol, 58 feem, qhia tias kev sib cuam tshuam ntawm dej nrog NGF (txog 300 txheej) qis dua piv rau graphene. Qhov no tej zaum yuav yog ib qho ntawm cov laj thawj vim li cas qhov kev ywj pheej NGF tseem nyob tiaj tus ntawm cov dej, thaum lub graphene freestanding (uas ntab hauv dej) curls thiab tawg. Thaum NGF tag rau hauv dej (cov txiaj ntsig zoo ib yam rau cov ntxhib thiab tiaj tus NGF), nws cov npoo khoov (Daim duab SI4). Nyob rau hauv cov ntaub ntawv ntawm kev ua tiav immersion, nws xav tias NGF-dej sib cuam tshuam lub zog yuav luag ob npaug (piv rau ntab NGF) thiab cov npoo ntawm NGF quav kom muaj lub siab sib cuag (hydrophobicity). Peb ntseeg tias cov tswv yim tuaj yeem tsim kho kom tsis txhob curling ntawm cov npoo ntawm NGFs embedded. Ib txoj hauv kev yog siv cov kuab tshuaj sib xyaw los hloov cov tshuaj tiv thaiv ntub dej ntawm graphite zaj duab xis59.
Kev hloov pauv ntawm SLG mus rau ntau hom substrates los ntawm cov txheej txheem hloov cov tshuaj ntub dej tau raug tshaj tawm yav dhau los. Nws feem ntau lees paub tias tsis muaj zog van der Waals rog muaj nyob nruab nrab ntawm graphene / graphite films thiab substrates (xws li nws nruj substrates xws li SiO2 / Si38,41,46,60, SiC38, Au42, Si pillars22 thiab lacy carbon films30, 34 los yog hloov tau yooj yim substrates xws li polyimide 37). Ntawm no peb xav tias kev sib cuam tshuam ntawm tib hom predominate. Peb tsis tau soj ntsuam kev puas tsuaj los yog tev ntawm NGF rau ib qho ntawm cov substrates uas tau nthuav tawm no thaum lub sij hawm kho tshuab (thaum lub sij hawm ua tus cwj pwm nyob rau hauv lub tshuab nqus tsev thiab/los yog atmospheric tej yam kev mob los yog thaum lub sij hawm cia) (xws li, daim duab 2, SI7 thiab SI9). Tsis tas li ntawd, peb tsis tau soj ntsuam SiC ncov hauv XPS C 1 s spectrum ntawm theem tseem ceeb ntawm NGF/SiO2/Si qauv (Fig. 4). Cov txiaj ntsig no qhia tau tias tsis muaj tshuaj lom neeg ntawm NGF thiab lub hom phiaj substrate.
Hauv seem dhau los, "Polymer-free hloov ntawm FS- thiab BS-NGF," peb tau pom tias NGF tuaj yeem loj hlob thiab hloov mus rau ob sab ntawm cov ntawv nyiaj npib tsib xee. Cov FS-NGFs thiab BS-NGFs no tsis zoo ib yam nyob rau hauv cov nqe lus ntawm nto roughness, uas ua rau peb tshawb nrhiav cov ntawv thov uas haum rau txhua hom.
Xav txog cov pob tshab thiab smoother nto ntawm FS-NGF, peb tau kawm nws cov qauv hauv zos, kho qhov muag thiab cov khoom hluav taws xob kom ntxaws. Cov qauv thiab cov qauv ntawm FS-NGF yam tsis muaj kev hloov pauv ntawm polymer tau pom los ntawm kev sib kis ntawm electron microscopy (TEM) imaging thiab xaiv cheeb tsam electron diffraction (SAED) qauv tsom xam. Cov txiaj ntsig sib raug tau pom nyob rau hauv daim duab 5. Tsawg magnification planar TEM imaging qhia lub xub ntiag ntawm NGF thiab FLG cheeb tsam nrog txawv electron contrast yam ntxwv, piv txwv li tsaus nti thiab brighter cheeb tsam, raws li (Fig. 5a). Cov yeeb yaj kiab tag nrho qhia txog kev ua haujlwm zoo thiab kev ruaj ntseg ntawm thaj chaw sib txawv ntawm NGF thiab FLG, nrog kev sib tshooj zoo thiab tsis muaj kev puas tsuaj lossis tawg, uas kuj tau lees paub los ntawm SEM (Daim duab 3) thiab cov kev tshawb fawb loj TEM (Daim duab 5c-e). Tshwj xeeb, hauv daim duab 5d qhia txog tus choj qauv ntawm nws qhov loj tshaj plaws (txoj hauj lwm cim los ntawm cov xim dub dotted xub nyob rau hauv daim duab 5d), uas yog tus yam ntxwv ntawm daim duab peb sab thiab muaj ib tug graphene txheej nrog ib tug dav ntawm txog 51. Qhov sib xyaw ua ke nrog qhov sib txawv ntawm qhov sib txawv ntawm 0.33 ± 0.01 nm yog ntxiv txo mus rau ob peb txheej ntawm graphene hauv cheeb tsam nqaim (kawg ntawm cov khoom dub xub hauv daim duab 5 d).
Planar TEM duab ntawm ib tug polymer-free NiAG qauv ntawm ib tug carbon lacy tooj liab daim phiaj: (a, b) Tsawg magnification TEM cov duab nrog rau NGF thiab FLG cheeb tsam, (ce) High magnification dluab ntawm ntau lub cheeb tsam nyob rau hauv vaj huam sib luag-a thiab vaj huam sib luag-b yog cim xub ntawm tib xim. Cov xib xub ntsuab nyob rau hauv cov vaj huam sib luag a thiab c qhia cov cheeb tsam ntawm kev puas tsuaj thaum lub sij hawm sib dhos. (f–i) Hauv cov vaj huam sib luag a rau c, SAED cov qauv hauv thaj tsam sib txawv yog qhia los ntawm xiav, cyan, txiv kab ntxwv, thiab lub voj voog liab, feem.
Cov qauv ribbon nyob rau hauv daim duab 5c qhia (cim nrog liab xub) ntsug orientation ntawm lub graphite lattice dav hlau, uas tej zaum yuav yog vim tsim ntawm nanofolds raws cov zaj duab xis (inset nyob rau hauv daim duab 5c) vim overcompensated shear stress30,61,62 . Raws li kev daws teeb meem siab TEM, cov nanofolds 30 no nthuav tawm qhov sib txawv crystallographic orientation dua li ntawm thaj tsam NGF; cov dav hlau basal ntawm graphite lattice yog taw qhia yuav luag vertically, tsis yog kab rov tav zoo li tus so ntawm zaj duab xis (inset hauv daim duab 5c). Ib yam li ntawd, thaj tsam FLG qee zaus nthuav tawm cov kab thiab nqaim zoo li cov quav (cim los ntawm cov xub xiav), uas tshwm sim ntawm qhov qis thiab nruab nrab qhov loj hauv daim duab 5b, 5e, raws li. Lub inset nyob rau hauv daim duab 5e paub meej tias muaj ob- thiab peb-txheej graphene txheej nyob rau hauv lub FLG sector (interplanar nrug 0.33 ± 0.01 nm), uas yog nyob rau hauv kev pom zoo nrog peb yav dhau los 30. Tsis tas li ntawd, kaw SEM dluab ntawm polymer-dawb NGF pauv mus rau daim phiaj tooj liab nrog lacy carbon films (tom qab ua qhov kev ntsuas saum toj kawg nkaus TEM) tau qhia hauv daim duab SI9. Qhov zoo raug tshem tawm FLG cheeb tsam (cim nrog xiav xub) thiab thaj tsam tawg hauv daim duab SI9f. Cov xub xiav (ntawm ntug ntawm qhov hloov NGF) yog txhob txwm tshaj tawm los qhia tias thaj tsam FLG tuaj yeem tiv thaiv cov txheej txheem hloov pauv yam tsis muaj polymer. Hauv cov ntsiab lus, cov duab no tau lees paub tias qee qhov raug tshem tawm NGF (xws li FLG cheeb tsam) tswj xyuas kev ncaj ncees txawm tias tom qab tuav nruj thiab raug rau lub tshuab nqus tsev siab thaum ntsuas TEM thiab SEM (Daim duab SI9).
Vim qhov zoo tshaj plaws flatness ntawm NGF (saib daim duab 5a), nws tsis yooj yim rau taw qhia cov flakes raws [0001] domain axis los soj ntsuam cov qauv SAED. Nyob ntawm seb qhov tuab ntawm cov yeeb yaj kiab hauv zos thiab nws qhov chaw nyob, ntau thaj tsam ntawm kev txaus siab (12 cov ntsiab lus) tau txheeb xyuas rau cov kev tshawb fawb electron diffraction. Nyob rau hauv daim duab 5a–c, plaub ntawm cov cheeb tsam raug pom thiab cim nrog lub voj voog xim (xiav, cyan, txiv kab ntxwv, thiab xim liab). Daim duab 2 thiab 3 rau SAED hom. Cov duab 5f thiab g tau txais los ntawm FLG cheeb tsam uas muaj nyob rau hauv daim duab 5 thiab 5. Raws li pom nyob rau hauv daim duab 5b thiab c, feem. Lawv muaj cov qauv hexagonal zoo ib yam li twisted graphene63. Tshwj xeeb, Daim duab 5f qhia peb tus qauv superimposed nrog tib qhov kev taw qhia ntawm [0001] cheeb tsam axis, tig los ntawm 10 ° thiab 20 °, raws li pov thawj los ntawm lub kaum sab xis tsis sib haum ntawm peb khub ntawm (10-10) kev xav. Ib yam li ntawd, daim duab 5g qhia ob lub superimposed hexagonal qauv tig los ntawm 20 °. Ob lossis peb pawg ntawm cov qauv hexagonal nyob rau hauv cheeb tsam FLG tuaj yeem tshwm sim los ntawm peb lub dav hlau los yog tawm ntawm lub dav hlau graphene txheej 33 rotated txheeb ze rau ib leeg. Nyob rau hauv sib piv, cov qauv electron diffraction nyob rau hauv daim duab 5h, i (xws li NGF cheeb tsam nyob rau hauv daim duab 5a) qhia ib tug [0001] qauv nrog ib tug tag nrho ntau dua point diffraction siv, sib xws rau ntau dua cov ntaub ntawv thickness. Cov qauv SAED no sib haum mus rau cov qauv graphitic tuab thiab kev taw qhia nruab nrab ntawm FLG, raws li kev txiav txim siab los ntawm qhov ntsuas 64. Cov yam ntxwv ntawm cov khoom siv crystalline ntawm NGF qhia txog kev sib koom ua ke ntawm ob lossis peb lub superimposed graphite (lossis graphene) crystallites. Dab tsi yog qhov tshwj xeeb tshaj yog nyob rau hauv cheeb tsam FLG yog tias cov crystallites muaj qee qhov kev sib tw hauv dav hlau lossis tawm ntawm lub dav hlau tsis zoo. Graphite particles/layers with in-plane rotations angles of 17°, 22° and 25° tau yav tas los tau tshaj tawm rau NGF zus rau Ni 64 zaj duab xis. Qhov kev sib hloov lub kaum sab xis tau pom nyob rau hauv txoj kev tshawb no yog ua raws li yav tas los soj ntsuam kev sib hloov lub kaum sab xis (± 1 °) rau twisted BLG63 graphene.
Cov khoom hluav taws xob ntawm NGF / SiO2 / Si tau ntsuas ntawm 300 K tshaj thaj tsam ntawm 10 × 3 mm2. Qhov tseem ceeb ntawm electron carrier concentration, txav thiab conductivity yog 1.6 × 1020 cm-3, 220 cm2 V-1 C-1 thiab 2000 S-cm-1, feem. Qhov kev txav mus los thiab kev ua tau zoo ntawm peb cov NGF zoo ib yam li ntuj graphite2 thiab siab dua li cov khoom lag luam muaj ntau yam kev taw qhia pyrolytic graphite (tsim ntawm 3000 ° C) 29. Cov kev soj ntsuam electron carrier concentration qhov tseem ceeb yog ob qhov kev txiav txim siab ntau dua li cov uas nyuam qhuav tshaj tawm (7.25 × 10 cm-3) rau micron-thick graphite films npaj siv high-temperature (3200 ° C) polyimide nplooj 20 .
Peb kuj tau ua UV-pom kev ntsuas ntsuas ntawm FS-NGF hloov mus rau quartz substrates (Daim duab 6). Qhov tshwm sim spectrum qhia tau hais tias yuav luag tas li ntawm 62% nyob rau hauv thaj tsam 350-800 nm, qhia tias NGF yog translucent rau pom lub teeb. Qhov tseeb, lub npe "KAUST" tuaj yeem pom hauv cov duab digital ntawm cov qauv hauv daim duab 6b. Txawm hais tias tus qauv nanocrystalline ntawm NGF txawv ntawm SLG, tus naj npawb ntawm cov khaubncaws sab nraud povtseg tuaj yeem kwv yees kwv yees siv txoj cai ntawm 2.3% kev sib kis poob rau ib txheej ntxiv 65. Raws li qhov kev sib raug zoo no, tus naj npawb ntawm graphene txheej nrog 38% kev sib kis tsis tau yog 21. Cov NGF loj hlob feem ntau muaj 300 graphene txheej, piv txwv li txog 100 nm tuab (Fig. 1, SI5 thiab SI7). Yog li ntawd, peb xav tias qhov pom qhov pom kev pom zoo sib xws rau thaj tsam FLG thiab MLG, txij li lawv tau faib thoob plaws hauv zaj duab xis (Daim duab 1, 3, 5 thiab 6c). Ntxiv rau cov ntaub ntawv saum toj no, conductivity thiab transparency kuj paub meej tias lub siab crystalline zoo ntawm hloov NGF.
(a) UV-pom kev ntsuas ntsuas, (b) raug NGF hloov pauv ntawm quartz siv tus qauv sawv cev. (c) Schematic ntawm NGF (dub lub thawv) nrog cov sib npaug ntawm FLG thiab MLG cheeb tsam cim raws li grey random duab thoob plaws hauv cov qauv (saib daim duab 1) (kwv yees li 0.1–3% thaj tsam ntawm 100 μm2). Cov duab random thiab lawv qhov ntau thiab tsawg hauv daim duab yog rau kev piav qhia nkaus xwb thiab tsis sib haum rau thaj chaw tiag tiag.
Translucent NGF zus los ntawm CVD yav dhau los tau raug xa mus rau liab qab silicon nto thiab siv nyob rau hauv lub hnub ci hlwb 15,16. Cov txiaj ntsig kev hloov pauv hluav taws xob (PCE) yog 1.5%. Cov NGFs no ua haujlwm ntau yam xws li cov txheej txheem sib xyaw ua ke, them nqi thauj mus los, thiab pob tshab electrodes15,16. Txawm li cas los xij, graphite zaj duab xis tsis zoo ib yam. Kev ua kom zoo ntxiv yog qhov tsim nyog los ntawm kev ua tib zoo tswj cov ntawv tsis kam thiab kho qhov muag ntawm cov graphite electrode, vim tias ob lub zog no ua lub luag haujlwm tseem ceeb hauv kev txiav txim siab PCE tus nqi ntawm lub hnub ci cell15,16. Feem ntau, graphene films yog 97.7% pob tshab rau pom lub teeb, tab sis muaj ib daim ntawv tsis kam ntawm 200-3000 ohms / sq.16. Qhov kev tiv thaiv nto ntawm graphene zaj duab xis tuaj yeem raug txo los ntawm kev nce cov txheej (ntau hloov ntawm graphene txheej) thiab doping nrog HNO3 (~ 30 Ohm / sq.) 66. Txawm li cas los xij, cov txheej txheem no yuav siv sijhawm ntev thiab cov txheej txheem hloov pauv sib txawv tsis tas yuav muaj kev sib cuag zoo. Peb sab pem hauv ntej NGF muaj cov khoom xws li conductivity 2000 S / cm, zaj duab xis tsis kam 50 ohm / sq. thiab 62% pob tshab, ua rau nws muaj txiaj ntsig zoo rau cov kab hluav taws xob hluav taws xob lossis cov txee hluav taws xob hauv cov hnub ci hnub ci 15,16.
Txawm hais tias tus qauv thiab chemistry ntawm BS-NGF zoo ib yam li FS-NGF, nws qhov roughness txawv ("Growth of FS- thiab BS-NGF"). Yav dhau los, peb siv ultra-nyias zaj duab xis graphite22 raws li ib tug roj sensor. Yog li, peb tau sim qhov ua tau ntawm kev siv BS-NGF rau kev ua haujlwm ntawm cov pa roj (Daim duab SI10). Ua ntej, mm2-qhov loj me ntawm BS-NGF raug xa mus rau qhov sib txawv electrode sensor nti (Daim duab SI10a-c). Kev tsim cov ntsiab lus ntawm cov nti tau tshaj tawm yav dhau los; nws lub active rhiab cheeb tsam yog 9 mm267. Hauv SEM dluab (Daim duab SI10b thiab c), lub hauv paus kub electrode yog pom meej los ntawm NGF. Ntxiv dua thiab, nws tuaj yeem pom tau tias cov txheej txheem nti tau ua tiav rau txhua qhov qauv. Gas sensor ntsuas ntawm ntau yam gases tau sau tseg (Fig. SI10d) (Daim duab. SI11) thiab qhov tshwm sim cov nqi teb yog qhia nyob rau hauv daim duab. SIB 10 g. Zoo li lwm yam kev cuam tshuam cov pa roj xws li SO2 (200 ppm), H2 (2%), CH4 (200 ppm), CO2 (2%), H2S (200 ppm) thiab NH3 (200 ppm). Ib qho ua tau yog NO2. electrophilic xwm ntawm gas22,68. Thaum adsorbed rau saum npoo ntawm graphene, nws txo qhov nqus tam sim no ntawm electrons los ntawm lub cev. Kev sib piv ntawm cov ntaub ntawv lub sij hawm teb ntawm BS-NGF sensor nrog cov ntawv luam tawm yav dhau los tau nthuav tawm hauv Table SI2. Cov txheej txheem rau reactivating NGF sensors siv UV plasma, O3 plasma los yog thermal (50-150 ° C) kev kho mob ntawm cov qauv raug tau mus tas li, lub hom phiaj ua raws li kev siv ntawm embedded systems69.
Thaum lub sij hawm CVD txheej txheem, graphene kev loj hlob tshwm sim ntawm ob sab ntawm lub catalyst substrate41. Txawm li cas los xij, BS-graphene feem ntau yog ejected thaum lub sij hawm hloov cov txheej txheem41. Hauv txoj kev tshawb no, peb pom tau hais tias kev loj hlob zoo NGF thiab polymer-dawb NGF hloov pauv tuaj yeem ua tiav ntawm ob sab ntawm kev txhawb nqa catalyst. BS-NGF yog thinner (~ 80 nm) dua FS-NGF (~ 100 nm), thiab qhov sib txawv no tau piav qhia los ntawm qhov tseeb tias BS-Ni tsis raug ncaj qha rau cov pa roj ua ntej. Peb kuj pom tias qhov roughness ntawm NiAR substrate cuam tshuam qhov roughness ntawm NGF. Cov txiaj ntsig no qhia tau hais tias cov cog qoob loo FS-NGF tuaj yeem siv los ua cov khoom siv ua ntej rau graphene (los ntawm exfoliation method70) los yog raws li cov kab hluav taws xob hauv cov hnub ci hnub ci15,16. Hauv qhov sib piv, BS-NGF yuav raug siv rau kev tshawb nrhiav roj (Daim duab SI9) thiab tejzaum nws rau lub zog cia tshuab71,72 qhov twg nws qhov roughness yuav siv tau.
Xav txog cov saum toj no, nws yog qhov tsim nyog los ua ke cov haujlwm tam sim no nrog yav dhau los luam tawm graphite zaj duab xis loj hlob los ntawm CVD thiab siv cov ntawv nyiaj npib tsib xee. Raws li tuaj yeem pom nyob rau hauv Table 2, qhov siab dua peb siv luv luv lub sij hawm cov tshuaj tiv thaiv (kev loj hlob theem) txawm nyob rau ntawm qhov kub thiab txias (nyob rau hauv thaj tsam ntawm 850-1300 ° C). Peb kuj ua tiav kev loj hlob ntau dua li niaj zaus, qhia tias muaj peev xwm nthuav dav. Muaj lwm yam los xav txog, qee qhov peb tau suav nrog hauv lub rooj.
Ob chav sided high-zoo NGF tau loj hlob ntawm nickel ntawv ci los ntawm catalytic CVD. Los ntawm kev tshem tawm cov tsoos polymer substrates (xws li cov siv hauv CVD graphene), peb ua tiav cov dej huv thiab tsis muaj qhov tsis zoo-dawb hloov pauv ntawm NGF (loj nyob rau sab nraub qaum thiab sab pem hauv ntej ntawm cov ntawv nyiaj npib tsib xee) rau ntau yam txheej txheem-tseem ceeb substrates. Qhov tseem ceeb, NGF suav nrog FLG thiab MLG cheeb tsam (feem ntau yog 0.1% mus rau 3% ib 100 µm2) uas yog structurally zoo integrated rau hauv lub thicker zaj duab xis. Planar TEM qhia tau hais tias cov cheeb tsam no yog tsim los ntawm cov pawg ntawm ob mus rau peb graphite / graphene hais (crystals los yog txheej, raws li), ib co ntawm uas muaj ib tug rotational mismatch ntawm 10-20 °. Cov cheeb tsam FLG thiab MLG yog lub luag haujlwm rau qhov pom tseeb ntawm FS-NGF kom pom lub teeb pom kev. Raws li rau cov nplooj ntawv nram qab, lawv tuaj yeem nqa mus rau hauv cov nplooj ntawv pem hauv ntej thiab, raws li qhia, tuaj yeem muaj lub hom phiaj ua haujlwm (piv txwv li, txhawm rau txhawm rau ntsuas roj). Cov kev tshawb fawb no muaj txiaj ntsig zoo rau kev txo cov khoom pov tseg thiab cov nqi hauv cov txheej txheem CVD.
Feem ntau, qhov nruab nrab thickness ntawm CVD NGF nyob ntawm (tsawg- thiab ntau txheej) graphene thiab industrial (micrometer) graphite nplooj ntawv. Qhov ntau ntawm lawv cov khoom nthuav dav, ua ke nrog cov txheej txheem yooj yim uas peb tau tsim rau lawv cov khoom tsim thiab thauj, ua rau cov yeeb yaj kiab no tshwj xeeb tshaj yog tsim rau cov ntawv thov uas xav tau cov lus teb ua haujlwm ntawm graphite, tsis tas siv cov khoom siv hluav taws xob ntau lawm tam sim no.
A 25-μm-thick nickel foil (99.5% purity, Goodfellow) tau teeb tsa hauv kev lag luam CVD reactor (Aixtron 4-nti BMPro). Lub kaw lus tau purged nrog argon thiab khiav tawm mus rau lub hauv paus siab ntawm 10-3 mbar. Tom qab ntawd nickel ntawv ci tau muab tso rau. nyob rau hauv Ar / H2 (Tom qab pre-annealing lub Ni foil rau 5 min, cov ntawv ci tau raug mus rau ib tug siab ntawm 500 mbar ntawm 900 ° C. NGF tau tso rau hauv ib tug ntws ntawm CH4 / H2 (100 cm3 txhua) rau 5 min. Tom qab ntawd cov qauv tau txias rau qhov kub qis dua 700 ° C siv Ar flow (4000 cm3) ntawm 40 ° C / min Cov ntsiab lus ntawm kev ua kom zoo ntawm cov txheej txheem NGF tau piav qhia lwm qhov30.
Qhov chaw morphology ntawm tus qauv tau pom los ntawm SEM siv Zeiss Merlin microscope (1 kV, 50 pA). Cov qauv nto roughness thiab NGF thickness tau ntsuas siv AFM (Dimension Icon SPM, Bruker). TEM thiab SAED kev ntsuas tau ua tiav siv FEI Titan 80-300 Cubed microscope nruab nrog lub siab ci ntsa iab emission phom (300 kV), FEI Wien hom monochromator thiab CEOS lens spherical aberration corrector kom tau txais cov txiaj ntsig kawg. spatial daws teeb meem 0.09 nm. NGF cov qauv raug xa mus rau carbon lacy coated copper daim phiaj rau tiaj tus TEM duab thiab SAED qauv tsom xam. Yog li, feem ntau ntawm cov qauv flocs raug tshem tawm nyob rau hauv lub qhov hws ntawm kev txhawb nqa daim nyias nyias. Hloov NGF cov qauv raug tshuaj xyuas los ntawm XRD. X-ray diffraction qauv tau txais siv cov hmoov diffractometer (Brucker, D2 theem shifter nrog Cu Kα qhov chaw, 1.5418 Å thiab LYNXEYE detector) siv lub Cu hluav taws xob qhov chaw nrog lub beam chaw txoj kab uas hla ntawm 3 hli.
Ob peb Raman taw tes ntsuas tau raug kaw siv ib qho kev sib koom ua ke ntawm lub tshuab tsom iav (Alpha 300 RA, WITEC). Lub 532 nm laser nrog qis excitation zog (25%) tau siv los tiv thaiv thermally induced los. X-ray photoelectron spectroscopy (XPS) tau ua nyob rau ntawm Kratos Axis Ultra spectrometer hla thaj tsam ntawm 300 × 700 μm2 siv monochromatic Al Kα hluav taws xob (hν = 1486.6 eV) ntawm lub zog ntawm 150 W. Resolution spectra tau txais ntawm Kev xa tawm hluav taws xob ntawm 160 eV thiab 20 eV, feem. NGF cov qauv pauv mus rau SiO2 raug txiav rau hauv daim (3 × 10 mm2 txhua) siv PLS6MW (1.06 μm) ytterbium fiber ntau laser ntawm 30 W. Copper wire contacts (50 μm tuab) tau tsim los siv nyiaj paste nyob rau hauv lub tshuab ntsuas qhov muag. Kev thauj khoom hluav taws xob thiab Hall effect thwmsim tau ua tiav ntawm cov qauv no ntawm 300 K thiab qhov sib nqus teb sib txawv ntawm ± 9 Tesla hauv kev ntsuas lub cev (PPMS EverCool-II, Quantum Design, USA). Kev xa tawm UV-vis spectra tau sau tseg siv Lambda 950 UV-vis spectrophotometer nyob rau hauv 350-800 nm NGF ntau pauv mus rau quartz substrates thiab quartz siv cov qauv.
Cov tshuaj tiv thaiv kab mob (interdigitated electrode nti) tau xaim mus rau lub rooj tsav xwm kev cai luam tawm 73 thiab qhov kev tiv thaiv tau muab rho tawm ib ntus. Lub rooj tsav xwm luam tawm uas lub cuab yeej nyob rau hauv kev sib txuas nrog cov chaw sib txuas thiab muab tso rau hauv cov pa ntsuas hluav taws xob 74. Kev ntsuas kev tiv thaiv tau raug coj los ntawm qhov hluav taws xob ntawm 1 V nrog kev soj ntsuam tas li los ntawm kev tshem tawm mus rau cov pa roj thiab tom qab ntawd tshem tawm dua. Lub chamber yog thawj zaug ntxuav los ntawm purging nrog nitrogen ntawm 200 cm3 rau 1 teev kom tshem tawm tag nrho lwm yam analytes nyob rau hauv lub chamber, nrog rau cov dej noo. Tus neeg soj ntsuam tau maj mam tso tawm mus rau hauv lub chamber ntawm tib qhov ntws ntawm 200 cm3 los ntawm kev kaw N2 lub tog raj kheej.
Ib qho kev hloov kho tshiab ntawm tsab xov xwm no tau raug luam tawm thiab tuaj yeem nkag mus tau los ntawm qhov txuas rau sab saum toj ntawm tsab xov xwm.
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Post lub sij hawm: Aug-23-2024