Kev loj hlob ntawm cov zaj duab xis graphite translucent ntawm Ni thiab nws txoj kev hloov pauv polymer-free ob txoj kev

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Cov yeeb yaj kiab graphite nanoscale (NGFs) yog cov khoom siv nano uas muaj zog uas tuaj yeem tsim los ntawm kev tso cov pa tshuaj catalytic, tab sis cov lus nug tseem nyob txog lawv qhov yooj yim ntawm kev hloov pauv thiab qhov morphology ntawm qhov chaw cuam tshuam li cas rau lawv siv hauv cov khoom siv tiam tom ntej. Ntawm no peb tshaj tawm kev loj hlob ntawm NGF ntawm ob sab ntawm cov ntawv ci polycrystalline nickel (cheeb tsam 55 cm2, tuab txog 100 nm) thiab nws txoj kev hloov pauv tsis muaj polymer (pem hauv ntej thiab nraub qaum, thaj tsam txog 6 cm2). Vim yog qhov morphology ntawm cov ntawv ci catalyst, ob zaj duab xis carbon sib txawv hauv lawv cov khoom siv lub cev thiab lwm yam ntxwv (xws li qhov roughness ntawm qhov chaw). Peb qhia tau tias NGFs nrog lub nraub qaum rougher zoo rau kev kuaj NO2, thaum du thiab conductive NGFs ntawm sab pem hauv ntej (2000 S/cm2, daim ntawv tsis kam - 50 ohms/m2) tuaj yeem ua cov neeg coj ua tau. channel lossis electrode ntawm lub hnub ci cell (txij li nws xa 62% ntawm lub teeb pom kev). Zuag qhia tag nrho, cov txheej txheem kev loj hlob thiab kev thauj mus los uas tau piav qhia yuav pab ua kom NGF ua lwm yam khoom siv carbon rau cov ntawv thov thev naus laus zis uas cov yeeb yaj kiab graphene thiab micron-tuab tsis haum.
Graphite yog ib yam khoom siv hauv kev lag luam uas siv dav dav. Qhov tseem ceeb, graphite muaj cov yam ntxwv ntawm qhov ceev ntawm qhov hnyav tsawg thiab muaj kev ua haujlwm kub thiab hluav taws xob siab hauv lub dav hlau, thiab ruaj khov heev hauv cov chaw kub thiab tshuaj lom neeg hnyav1,2. Flake graphite yog ib yam khoom pib paub zoo 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 nquag hauv cov sensors8,9,10 thiab rau kev tiv thaiv kev cuam tshuam hluav taws xob11.12 thiab cov yeeb yaj kiab rau lithography hauv ultraviolet heev13,14, kev coj cov channel hauv cov hlwb hnub ci15,16. Rau tag nrho cov ntawv thov no, nws yuav yog qhov zoo dua yog tias thaj chaw loj ntawm cov yeeb yaj kiab graphite (NGFs) nrog cov tuab tswj hwm hauv nanoscale <100 nm tuaj yeem tsim thiab thauj tau yooj yim.
Cov yeeb yaj kiab graphite raug tsim los ntawm ntau txoj kev. Hauv ib qho xwm txheej, kev ntxig thiab nthuav dav ua raws li kev exfoliation tau siv los tsim cov graphene flakes10,11,17. Cov flakes yuav tsum tau ua tiav ntxiv rau hauv cov yeeb yaj kiab ntawm qhov tuab uas xav tau, thiab nws feem ntau siv sijhawm ob peb hnub los tsim cov ntawv graphite ntom ntom. Lwm txoj hauv kev yog pib nrog cov khoom siv graphitable solid precursors. Hauv kev lag luam, cov ntawv polymers raug 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 siab, kev siv zog yog qhov tseem ceeb1,18,19 thiab qhov tuab tsawg kawg nkaus yog txwv rau ob peb microns1,18,19,20.
Kev siv tshuaj lom neeg catalytic vapor deposition (CVD) yog ib txoj kev paub zoo rau kev tsim cov yeeb yaj kiab graphene thiab ultrathin graphite (<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 zaj duab xis28, kev loj hlob hauv thaj chaw loj thiab/lossis daim ntawv thov ntawm NGF siv CVD tseem tsawg dua11,13,29,30,31,32,33.
Cov yeeb yaj kiab graphene thiab graphite uas cog los ntawm CVD feem ntau yuav tsum tau hloov mus rau cov khoom siv ua haujlwm 34. Cov kev hloov pauv zaj duab xis nyias no muaj ob txoj hauv kev tseem ceeb 35: (1) kev hloov pauv tsis yog etch 36,37 thiab (2) kev hloov pauv tshuaj ntub raws li etch (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 uas xav tau, raws li tau piav qhia rau lwm qhov 35,39. Rau cov yeeb yaj kiab graphene / graphite uas cog rau ntawm cov khoom siv catalytic, kev hloov pauv ntawm cov txheej txheem tshuaj ntub (uas polymethyl methacrylate (PMMA) yog cov txheej txheem txhawb nqa feem ntau siv) tseem yog thawj qhov kev xaiv 13,30,34,38,40,41,42. Koj et al. Nws tau hais tias tsis muaj polymer siv rau kev hloov pauv NGF (qauv loj kwv yees li 4 cm2) 25,43, tab sis tsis muaj cov ntsiab lus tau muab txog kev ruaj khov ntawm cov qauv thiab / lossis kev tuav thaum lub sijhawm hloov pauv; Cov txheej txheem tshuaj lom neeg ntub dej siv cov polymers muaj ntau kauj ruam, suav nrog daim ntawv thov thiab tom qab ntawd tshem tawm ntawm cov txheej polymer sacrificial30,38,40,41,42. Cov txheej txheem no muaj qhov tsis zoo: piv txwv li, cov polymer residues tuaj yeem hloov cov khoom ntawm cov zaj duab xis loj hlob38. Kev ua ntxiv tuaj yeem tshem tawm cov polymer seem, tab sis cov kauj ruam ntxiv no ua rau tus nqi thiab lub sijhawm ntawm kev tsim zaj duab xis nce ntxiv38,40. Thaum lub sijhawm CVD loj hlob, ib txheej ntawm graphene tsis yog tsuas yog tso rau sab pem hauv ntej ntawm cov ntawv ci catalyst (sab ntsib cov pa dej ntws), tab sis kuj nyob rau sab nraub qaum. Txawm li cas los xij, qhov kawg yog suav tias yog cov khoom pov tseg thiab tuaj yeem tshem tawm sai sai los ntawm cov plasma mos38,41. Kev siv cov zaj duab xis no tuaj yeem pab ua kom muaj txiaj ntsig zoo tshaj plaws, txawm tias nws tsis zoo dua li cov zaj duab xis carbon.
Ntawm no, peb tshaj tawm txog kev npaj ntawm wafer-scale bifacial kev loj hlob ntawm NGF nrog cov qauv zoo ntawm polycrystalline nickel ntawv ci los ntawm CVD. Nws tau soj ntsuam seb qhov roughness ntawm pem hauv ntej thiab nraub qaum ntawm cov ntawv ci cuam tshuam li cas rau morphology thiab cov qauv ntawm NGF. Peb kuj qhia txog kev hloov pauv polymer-dawb ntawm NGF los ntawm ob sab ntawm nickel ntawv ci mus rau ntau yam substrates thiab qhia tias cov yeeb yaj kiab pem hauv ntej thiab nraub qaum haum rau ntau yam kev siv.
Cov ntu hauv qab no tham txog cov tuab ntawm cov zaj duab xis graphite sib txawv nyob ntawm seb muaj pes tsawg txheej graphene sib dhos: (i) ib txheej graphene (SLG, 1 txheej), (ii) ob peb txheej graphene (FLG, < 10 txheej), (iii) ntau txheej graphene (MLG, 10-30 txheej) thiab (iv) NGF (~ 300 txheej). Qhov kawg yog qhov tuab tshaj plaws uas qhia ua feem pua ​​ntawm thaj chaw (kwv yees li 97% thaj chaw ib 100 µm2)30. Yog vim li cas tag nrho zaj duab xis thiaj li hu ua NGF.
Cov ntawv ci polycrystalline nickel siv rau kev tsim cov graphene thiab graphite zaj duab xis muaj cov qauv sib txawv vim yog lawv txoj kev tsim khoom thiab kev ua tiav tom qab. Tsis ntev los no peb tau tshaj tawm ib txoj kev tshawb fawb los ua kom zoo dua cov txheej txheem kev loj hlob ntawm NGF30. Peb qhia tias cov txheej txheem xws li lub sijhawm annealing thiab lub siab hauv chav tsev thaum lub sijhawm loj hlob ua lub luag haujlwm tseem ceeb hauv kev tau txais NGFs ntawm cov tuab sib xws. Ntawm no, peb tau tshawb xyuas ntxiv txog kev loj hlob ntawm NGF ntawm cov nplaim polished (FS) thiab cov nplaim rov qab tsis polished (BS) ntawm cov ntawv ci nickel (Daim Duab 1a). Peb hom qauv FS thiab BS tau raug tshuaj xyuas, teev nyob rau hauv Rooj 1. Thaum kuaj xyuas pom, kev loj hlob sib xws ntawm NGF ntawm ob sab ntawm cov ntawv ci nickel (NiAG) tuaj yeem pom los ntawm kev hloov xim ntawm cov khoom loj Ni substrate los ntawm cov xim grey nyiaj mus rau xim grey matte (Daim Duab 1a); kev ntsuas microscopic tau lees paub (Daim Duab 1b, c). Ib qho Raman spectrum ntawm FS-NGF pom nyob rau hauv thaj chaw ci thiab qhia los ntawm cov xub liab, xiav thiab txiv kab ntxwv hauv Daim Duab 1b tau pom hauv Daim Duab 1c. Cov Raman peaks tshwj xeeb ntawm graphite G (1683 cm−1) thiab 2D (2696 cm−1) lees paub qhov kev loj hlob ntawm NGF crystalline heev (Daim duab 1c, Rooj SI1). Thoob plaws hauv zaj duab xis, qhov tseem ceeb ntawm Raman spectra nrog qhov sib piv ntawm qhov muaj zog (I2D/IG) ~0.3 tau pom, thaum Raman spectra nrog I2D/IG = 0.8 tsis tshua pom. Qhov tsis muaj cov peaks tsis zoo (D = 1350 cm-1) hauv tag nrho zaj duab xis qhia txog qhov zoo ntawm NGF kev loj hlob. Cov txiaj ntsig Raman zoo sib xws tau txais ntawm BS-NGF qauv (Daim duab SI1 a thiab b, Rooj SI1).
Kev Sib Piv ntawm NiAG FS- thiab BS-NGF: (a) Duab ntawm cov qauv NGF (NiAG) uas qhia txog kev loj hlob ntawm NGF ntawm qhov ntsuas wafer (55 cm2) thiab cov qauv ntawv ci BS- thiab FS-Ni, (b) Cov Duab FS-NGF/ Ni tau los ntawm lub tshuab tsom iav, (c) cov qauv Raman uas tau kaw tseg ntawm ntau qhov chaw hauv vaj huam sib luag b, (d, f) Cov duab SEM ntawm ntau qhov loj ntawm FS-NGF/Ni, (e, g) Cov duab SEM ntawm ntau qhov loj ntawm Sets BS -NGF/Ni. Tus xub xiav qhia txog thaj tsam FLG, tus xub txiv kab ntxwv qhia txog thaj tsam MLG (nyob ze thaj tsam FLG), tus xub liab qhia txog thaj tsam NGF, thiab tus xub magenta qhia txog qhov quav.
Vim tias kev loj hlob nyob ntawm qhov tuab ntawm cov substrate pib, qhov loj me ntawm cov siv lead ua, kev taw qhia, thiab cov ciam teb ntawm cov noob, kev ua tiav kev tswj hwm qhov tuab ntawm NGF hla thaj chaw loj tseem yog qhov nyuaj20,34,44. Txoj kev tshawb fawb no siv cov ntsiab lus uas peb tau luam tawm ua ntej30. Cov txheej txheem no tsim cov cheeb tsam ci ntsa iab ntawm 0.1 txog 3% ib 100 µm230. Hauv cov ntu hauv qab no, peb nthuav qhia cov txiaj ntsig rau ob hom cheeb tsam. Cov duab SEM loj loj qhia txog qhov muaj ntau thaj chaw sib piv ci ntsa iab ntawm ob sab (Daim duab 1f, g), qhia txog qhov muaj FLG thiab MLG cheeb tsam30,45. Qhov no kuj tau lees paub los ntawm Raman scattering (Daim duab 1c) thiab TEM cov txiaj ntsig (tham txog tom qab hauv ntu "FS-NGF: cov qauv thiab cov khoom"). Cov cheeb tsam FLG thiab MLG pom ntawm FS- thiab BS-NGF / Ni cov qauv (pem hauv ntej thiab nraub qaum NGF loj hlob ntawm Ni) tej zaum yuav tau loj hlob ntawm cov noob loj Ni (111) tsim thaum lub sijhawm ua ntej-annealing22,30,45. Kev quav tau pom ntawm ob sab (Daim Duab 1b, cim nrog cov xub liab). Cov quav no feem ntau pom muaj nyob rau hauv CVD-grown graphene thiab graphite zaj duab xis vim qhov sib txawv loj hauv cov coefficient ntawm thermal expansion ntawm graphite thiab nickel substrate30,38.
Daim duab AFM tau lees paub tias cov qauv FS-NGF yog qhov tiaj dua li cov qauv BS-NGF (Daim Duab SI1) (Daim Duab SI2). Cov nqi roughness ntawm FS-NGF/Ni (Daim Duab SI2c) thiab BS-NGF/Ni (Daim Duab SI2d) yog 82 thiab 200 nm, feem (ntsuas hla thaj tsam ntawm 20 × 20 μm2). Qhov roughness siab dua tuaj yeem nkag siab raws li kev tshuaj xyuas qhov chaw ntawm cov ntawv ci nickel (NiAR) hauv lub xeev tau txais (Daim Duab SI3). Cov duab SEM ntawm FS thiab BS-NiAR tau pom hauv Daim Duab SI3a-d, qhia txog cov qauv sib txawv ntawm qhov chaw: cov ntawv ci FS-Ni uas tau ci tiav lawm muaj cov khoom me me uas muaj qhov loj me me thiab me me, thaum cov ntawv ci BS-Ni uas tsis tau ci tiav lawm qhia txog cov ntaiv tsim khoom. ua cov khoom me me uas muaj zog siab. thiab poob qis. Cov duab qis thiab siab daws teeb meem ntawm cov ntawv ci nickel annealed (NiA) tau pom hauv Daim Duab SI3e-h. Hauv cov duab no, peb tuaj yeem pom qhov muaj ntau lub micron-sized nickel me me ntawm ob sab ntawm cov ntawv ci nickel (Daim Duab SI3e-h). Cov noob loj yuav muaj Ni (111) qhov chaw, raws li tau tshaj tawm ua ntej30,46. Muaj qhov sib txawv tseem ceeb hauv cov ntawv ci nickel ntawm FS-NiA thiab BS-NiA. Qhov roughness siab dua ntawm BS-NGF / Ni yog vim qhov chaw tsis tau polished ntawm BS-NiAR, qhov chaw uas tseem nyob ntxhib txawm tias tom qab annealing (Daim Duab SI3). Hom kev piav qhia ntawm qhov chaw ua ntej txoj kev loj hlob no tso cai rau qhov roughness ntawm graphene thiab graphite zaj duab xis kom tswj tau. Nws yuav tsum tau sau tseg tias cov substrate thawj zaug tau dhau los ua qee qhov kev hloov pauv noob thaum lub sijhawm loj hlob graphene, uas me ntsis txo qhov loj me ntawm cov noob thiab me ntsis ua rau qhov roughness ntawm qhov chaw piv rau cov ntawv ci annealed thiab catalyst zaj duab xis22.
Kev kho kom zoo dua qhov roughness ntawm qhov chaw substrate, lub sijhawm annealing (qhov loj ntawm cov noob)30,47 thiab kev tswj kev tso tawm43 yuav pab txo qhov tuab ntawm NGF hauv cheeb tsam mus rau µm2 thiab/lossis txawm tias nm2 nplai (piv txwv li, qhov sib txawv ntawm ob peb nanometers). Txhawm rau tswj qhov roughness ntawm qhov chaw substrate, cov txheej txheem xws li electrolytic polishing ntawm cov ntawv ci nickel uas tau tshwm sim tuaj yeem txiav txim siab48. Cov ntawv ci nickel uas tau kho ua ntej tuaj yeem raug annealed ntawm qhov kub qis dua (< 900 °C)46 thiab lub sijhawm (< 5 feeb) kom tsis txhob muaj cov noob Ni (111) loj (uas yog qhov zoo rau FLG kev loj hlob).
SLG thiab FLG graphene tsis tuaj yeem tiv taus qhov nro ntawm cov kua qaub thiab dej, xav tau cov txheej txheem txhawb nqa thaum lub sijhawm hloov pauv tshuaj ntub22,34,38. Sib piv rau kev hloov pauv tshuaj ntub ntawm polymer-txhawb nqa ib txheej graphene38, peb pom tias ob sab ntawm NGF uas loj hlob tuaj yeem hloov pauv yam tsis muaj kev txhawb nqa polymer, raws li pom hauv Daim Duab 2a (saib Daim Duab SI4a kom paub ntau ntxiv). Kev hloov pauv ntawm NGF mus rau ib qho substrate pib nrog kev etching ntub ntawm zaj duab xis Ni30.49 hauv qab. Cov qauv NGF/Ni/NGF uas loj hlob tau muab tso rau hauv 15 mL ntawm 70% HNO3 diluted nrog 600 mL ntawm dej deionized (DI). Tom qab Ni ntawv ci yaj tag, FS-NGF tseem tiaj tus thiab ntab rau ntawm qhov chaw ntawm cov kua, ib yam li cov qauv NGF/Ni/NGF, thaum BS-NGF raug raus rau hauv dej (Daim Duab 2a, b). Tom qab ntawd, NGF uas raug cais tawm tau raug xa mus los ntawm ib lub beaker uas muaj dej tshiab deionized mus rau lwm lub beaker thiab NGF uas raug cais tawm tau raug ntxuav kom huv si, rov ua plaub mus rau rau zaug los ntawm lub tais iav concave. Thaum kawg, FS-NGF thiab BS-NGF tau muab tso rau ntawm lub substrate xav tau (Daim duab 2c).
Cov txheej txheem hloov pauv tshuaj ntub dej tsis muaj polymer rau NGF cog rau ntawm cov ntawv ci nickel: (a) Daim duab qhia txog cov txheej txheem (saib Daim Duab SI4 kom paub meej ntxiv), (b) Daim 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 cov qauv li vaj huam sib luag d (muab faib ua ob ntu), hloov mus rau daim ntawv C kub plated thiab Nafion (flexible transparent substrate, cov npoo cim nrog cov ces kaum liab).
Nco ntsoov tias kev hloov SLG ua tiav siv cov txheej txheem hloov tshuaj ntub dej yuav tsum muaj lub sijhawm ua tiav tag nrho ntawm 20-24 teev 38. Nrog rau cov txheej txheem hloov pauv polymer-free uas tau qhia ntawm no (Daim Duab SI4a), lub sijhawm ua tiav NGF hloov pauv tag nrho raug txo qis heev (kwv yees li 15 teev). Cov txheej txheem muaj: (Kauj Ruam 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 (Kauj Ruam - 3). khaws cia rau hauv dej deionized lossis hloov mus rau lub hom phiaj substrate (20 feeb). Cov dej uas raug kaw ntawm NGF thiab cov matrix loj raug tshem tawm los ntawm kev ua capillary (siv daim ntawv blotting) 38, tom qab ntawd cov dej tshuav seem raug tshem tawm los ntawm kev ziab ntuj (kwv yees li 30 feeb), thiab thaum kawg cov qauv raug ziab rau 10 feeb. feeb hauv lub qhov cub nqus tsev (10-1 mbar) ntawm 50-90 ° C (60 feeb) 38.
Graphite paub tias yuav tiv taus dej thiab cua ntawm qhov kub siab heev (≥ 200 °C) 50, 51, 52. Peb tau sim cov qauv siv Raman spectroscopy, SEM, thiab XRD tom qab khaws cia rau hauv dej deionized ntawm chav tsev kub thiab hauv lub raj mis kaw rau txhua qhov chaw txij li ob peb hnub mus txog ib xyoos (Daim Duab SI4). Tsis muaj kev puas tsuaj pom tseeb. Daim Duab 2c qhia txog FS-NGF thiab BS-NGF sawv ntsug hauv dej deionized. Peb ntes lawv ntawm SiO2 (300 nm) / Si substrate, raws li pom thaum pib ntawm Daim Duab 2c. Tsis tas li ntawd, raws li pom hauv Daim Duab 2d, e, NGF txuas ntxiv tuaj yeem hloov mus rau ntau yam substrates xws li polymers (Thermabright polyamide los ntawm Nexolve thiab Nafion) thiab daim ntawv carbon kub-coated. Lub FS-NGF ntab tau yooj yim tso rau ntawm lub hom phiaj substrate (Daim Duab 2c, d). Txawm li cas los xij, BS-NGF cov qauv loj dua 3 cm2 nyuaj rau kev tuav thaum muab tso rau hauv dej tag nrho. Feem ntau, thaum lawv pib dov hauv dej, vim yog kev tuav tsis zoo lawv qee zaum tawg ua ob lossis peb ntu (Daim Duab 2e). Zuag qhia tag nrho, peb tau ua tiav kev hloov pauv tsis muaj polymer ntawm PS- thiab BS-NGF (kev hloov pauv tsis tu ncua yam tsis muaj NGF / Ni / NGF kev loj hlob ntawm 6 cm2) rau cov qauv txog li 6 thiab 3 cm2 hauv thaj chaw, raws li. Txhua daim loj lossis me me uas tseem tshuav tuaj yeem (pom yooj yim hauv cov tshuaj etching lossis dej deionized) ntawm cov substrate xav tau (~ 1 mm2, Daim Duab SI4b, saib cov qauv hloov mus rau tooj liab grid zoo li hauv "FS-NGF: Cov Qauv thiab Cov Khoom (tham txog) hauv qab "Cov Qauv thiab Cov Khoom") lossis khaws cia rau yav tom ntej siv (Daim Duab SI4). Raws li cov qauv no, peb kwv yees tias NGF tuaj yeem rov qab tau hauv cov txiaj ntsig txog li 98-99% (tom qab kev loj hlob rau kev hloov pauv).
Cov qauv hloov pauv uas tsis muaj polymer tau raug tshuaj xyuas kom meej. Cov yam ntxwv ntawm qhov chaw tau txais ntawm FS- thiab BS-NGF/SiO2/Si (Daim Duab 2c) siv lub tshuab tsom iav (OM) thiab SEM duab (Daim Duab SI5 thiab Daim Duab 3) qhia tau tias cov qauv no tau raug hloov pauv yam tsis muaj lub tshuab tsom iav. Kev puas tsuaj ntawm cov qauv pom xws li cov kab nrib pleb, qhov, lossis thaj chaw tsis tau dov. Cov quav ntawm NGF uas loj hlob (Daim Duab 3b, d, cim los ntawm cov xub xiav) tseem nyob ruaj khov tom qab hloov pauv. Ob qho tib si FS- thiab BS-NGFs yog tsim los ntawm thaj chaw FLG (thaj chaw ci qhia los ntawm cov xub xiav hauv Daim Duab 3). Qhov xav tsis thoob, sib piv rau ob peb thaj chaw puas tsuaj uas feem ntau pom thaum lub sijhawm hloov pauv polymer ntawm cov yeeb yaj kiab graphite ultrathin, ntau thaj chaw FLG thiab MLG uas loj me me uas txuas rau NGF (cim los ntawm cov xub xiav hauv Daim Duab 3d) tau raug hloov pauv yam tsis muaj kab nrib pleb lossis tawg (Daim Duab 3d). 3). . Kev ua haujlwm ntawm lub tshuab tau lees paub ntxiv siv cov duab TEM thiab SEM ntawm NGF hloov mus rau ntawm cov kab sib txuas ntawm cov hlau nplaum-carbon, raws li tau tham tom qab ("FS-NGF: Cov Qauv thiab Cov Khoom"). BS-NGF/SiO2/Si uas tau hloov mus yog qhov ntxhib dua li FS-NGF/SiO2/Si nrog cov nqi rms ntawm 140 nm thiab 17 nm, raws li pom hauv Daim Duab SI6a thiab b (20 × 20 μm2). Tus nqi RMS ntawm NGF hloov mus rau ntawm SiO2/Si substrate (RMS < 2 nm) yog qhov qis dua (kwv yees li 3 zaug) dua li ntawm NGF loj hlob ntawm Ni (Daim Duab SI2), qhia tias qhov roughness ntxiv yuav sib xws rau Ni nto. Tsis tas li ntawd, cov duab AFM ua rau ntawm ntug ntawm FS- thiab BS-NGF/SiO2/Si cov qauv qhia txog NGF thicknesses ntawm 100 thiab 80 nm, raws li (Daim Duab SI7). Qhov tuab me dua ntawm BS-NGF yuav yog qhov tshwm sim ntawm qhov chaw tsis raug ncaj qha rau cov roj ua ntej.
NGF (NiAG) uas tau hloov pauv yam tsis muaj polymer ntawm SiO2/Si wafer (saib Daim Duab 2c): (a,b) Cov duab SEM ntawm FS-NGF uas tau hloov pauv: qhov loj me qis thiab siab (sib raug rau lub xwmfab txiv kab ntxwv hauv vaj huam sib luag). Cov cheeb tsam ib txwm muaj) - a). (c,d) Cov duab SEM ntawm BS-NGF uas tau hloov pauv: qhov loj me qis thiab siab (sib raug rau thaj chaw ib txwm muaj uas tau qhia los ntawm lub xwmfab txiv kab ntxwv hauv vaj huam sib luag c). (e, f) Cov duab AFM ntawm FS- thiab BS-NGF uas tau hloov pauv. Xub xiav sawv cev rau thaj tsam FLG - qhov sib piv ci ntsa iab, xub xiav - qhov sib piv dub MLG, xub liab - qhov sib piv dub sawv cev rau thaj tsam NGF, xub magenta sawv cev rau qhov quav.
Cov tshuaj lom neeg sib xyaw ntawm cov FS- thiab BS-NGFs uas loj hlob thiab hloov pauv tau raug tshuaj xyuas los ntawm X-ray photoelectron spectroscopy (XPS) (Daim Duab 4). Ib qho peak tsis muaj zog tau pom nyob rau hauv cov spectra ntsuas (Daim Duab 4a, b), sib raug rau Ni substrate (850 eV) ntawm cov FS- thiab BS-NGFs uas loj hlob (NiAG). Tsis muaj peaks nyob rau hauv cov spectra ntsuas ntawm FS- thiab BS-NGF/SiO2/Si uas tau hloov pauv (Daim Duab 4c; cov txiaj ntsig zoo sib xws rau BS-NGF/SiO2/Si tsis tau pom), qhia tias tsis muaj Ni seem tom qab hloov pauv. Cov duab 4d-f qhia cov spectra siab daws teeb meem ntawm C 1 s, O 1 s thiab Si 2p zog ntawm FS-NGF/SiO2/Si. Lub zog khi ntawm C 1 s ntawm graphite yog 284.4 eV53.54. Cov duab kab ntawm cov graphite peaks feem ntau suav tias yog asymmetrical, raws li pom hauv Daim Duab 4d54. Lub spectrum C1s core-level siab (Daim Duab 4d) kuj tau lees paub qhov kev hloov pauv ntshiab (piv txwv li, tsis muaj polymer residues), uas yog sib xws nrog cov kev tshawb fawb yav dhau los38. Cov kab dav ntawm C1s spectra ntawm cov qauv tshiab cog (NiAG) thiab tom qab hloov pauv yog 0.55 thiab 0.62 eV, feem. Cov nqi no siab dua li cov ntawm SLG (0.49 eV rau SLG ntawm SiO2 substrate)38. Txawm li cas los xij, cov nqi no me dua li cov kab dav uas tau tshaj tawm yav dhau los rau cov qauv pyrolytic graphene siab heev (~ 0.75 eV)53,54,55, qhia txog qhov tsis muaj cov chaw carbon tsis zoo hauv cov khoom siv tam sim no. C1s thiab O1s av theem spectra kuj tsis muaj xub pwg nyom, tshem tawm qhov xav tau rau qhov kev daws teeb meem siab deconvolution54. Muaj ib qho π → π * satellite peak nyob ib ncig ntawm 291.1 eV, uas feem ntau pom hauv cov qauv graphite. Cov teeb liab 103 eV thiab 532.5 eV hauv Si 2p thiab O 1 s core level spectra (saib daim duab 4e, f) yog muab rau SiO2 56 substrate, feem. XPS yog ib txoj kev siv surface-sensitive, yog li cov teeb liab sib xws rau Ni thiab SiO2 pom ua ntej thiab tom qab NGF hloov, feem, xav tias yog los ntawm thaj tsam FLG. Cov txiaj ntsig zoo sib xws tau pom rau cov qauv BS-NGF hloov (tsis tau qhia).
Cov txiaj ntsig ntawm NiAG XPS: (ac) Cov spectra soj ntsuam ntawm cov khoom sib txawv ntawm cov atomic compositions ntawm FS-NGF/Ni, BS-NGF/Ni thiab hloov FS-NGF/SiO2/Si, raws li. (d–f) Cov spectra siab daws teeb meem ntawm cov theem tseem ceeb C 1 s, O 1s thiab Si 2p ntawm FS-NGF/SiO2/Si qauv.
Qhov zoo tag nrho ntawm cov NGF siv lead ua hloov pauv tau raug soj ntsuam siv X-ray diffraction (XRD). Cov qauv XRD ib txwm muaj (Daim duab SI8) ntawm FS- thiab BS-NGF/SiO2/Si hloov pauv qhia txog qhov muaj cov 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 zoo ntawm crystalline ntawm NGF thiab sib raug rau qhov deb ntawm d = 0.335 nm, uas tau tswj hwm tom qab kauj ruam hloov pauv. Qhov muaj zog ntawm diffraction peak (0 0 0 2) yog kwv yees li 30 npaug ntawm diffraction peak (0 0 0 4), qhia tias NGF siv lead ua dav hlau tau sib phim zoo nrog qhov chaw ntawm cov qauv.
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 qhov rms roughness siab dua me ntsis (Daim duab SI2, SI5) thiab SI7).
SLGs nrog cov txheej txheem txhawb nqa polymer txog li 200 nm tuab tuaj yeem ntab saum dej. Qhov kev teeb tsa no feem ntau siv rau hauv cov txheej txheem hloov pauv tshuaj ntub dej uas muaj polymer pab22,38. Graphene thiab graphite yog hydrophobic (lub kaum ntub dej 80–90 °) 57. Cov nplaim hluav taws xob muaj peev xwm ntawm ob qho tib si graphene thiab FLG tau tshaj tawm tias tiaj tus, nrog lub zog muaj peev xwm qis (~ 1 kJ / mol) rau kev txav mus los ntawm sab ntawm dej ntawm qhov chaw58. Txawm li cas los xij, lub zog sib cuam tshuam ntawm 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 (kwv yees li 300 txheej) qis dua piv rau graphene. Qhov no yuav yog ib qho ntawm cov laj thawj vim li cas freestanding NGF tseem tiaj tus ntawm qhov chaw ntawm dej, thaum freestanding graphene (uas ntab hauv dej) curls thiab tawg. Thaum NGF raug raus tag nrho hauv dej (cov txiaj ntsig zoo ib yam rau cov ntxhib thiab tiaj tus NGF), nws cov npoo khoov (Daim Duab SI4). Yog tias muaj kev sib xyaw ua ke tag nrho, nws xav tias lub zog sib cuam tshuam ntawm NGF-dej yuav luag ob npaug (piv rau NGF ntab) thiab tias cov npoo ntawm NGF quav kom tswj tau lub kaum sab xis siab (hydrophobicity). Peb ntseeg tias cov tswv yim tuaj yeem tsim tau kom tsis txhob nkhaus ntawm cov npoo ntawm cov NGFs uas tau muab tso rau hauv. Ib txoj hauv kev yog siv cov kuab tshuaj sib xyaw los hloov kho qhov kev cuam tshuam ntawm cov yeeb yaj kiab graphite59.
Kev hloov pauv ntawm SLG mus rau ntau hom substrates ntawm cov txheej txheem hloov pauv tshuaj ntub tau tshaj tawm ua ntej. Feem ntau lees txais tias lub zog van der Waals tsis muaj zog muaj nyob nruab nrab ntawm cov yeeb yaj kiab graphene / graphite thiab cov substrates (yog nws cov substrates tawv xws li SiO2 / Si38,41,46,60, SiC38, Au42, Si pillars22 thiab lacy carbon films30, 34 lossis cov substrates yooj ywm xws li polyimide 37). Ntawm no peb xav tias kev sib cuam tshuam ntawm tib hom predominate. Peb tsis tau pom ib qho kev puas tsuaj lossis tev tawm ntawm NGF rau ib qho ntawm cov substrates uas tau nthuav tawm ntawm no thaum lub sijhawm tuav tshuab (thaum lub sijhawm ua cim hauv qab lub tshuab nqus tsev thiab / lossis huab cua lossis thaum lub sijhawm khaws cia) (piv txwv li, Daim Duab 2, SI7 thiab SI9). Tsis tas li ntawd, peb tsis tau pom SiC ncov hauv XPS C 1 s spectrum ntawm qib tseem ceeb ntawm NGF / SiO2 / Si qauv (Daim Duab 4). Cov txiaj ntsig no qhia tau tias tsis muaj kev sib txuas tshuaj lom neeg ntawm NGF thiab lub hom phiaj substrate.
Hauv ntu dhau los, "Kev hloov pauv FS- thiab BS-NGF uas tsis muaj Polymer," peb tau ua pov thawj tias NGF tuaj yeem loj hlob thiab hloov pauv ntawm ob sab ntawm cov ntawv ci nickel. Cov FS-NGFs thiab BS-NGFs no tsis zoo ib yam li qhov roughness ntawm qhov chaw, uas ua rau peb tshawb nrhiav cov ntawv thov tsim nyog tshaj plaws rau txhua hom.
Xav txog qhov pom tseeb thiab du ntawm FS-NGF, peb tau kawm txog nws cov qauv hauv zos, cov khoom siv kho qhov muag thiab hluav taws xob kom ntxaws ntxiv. Cov qauv thiab cov qauv ntawm FS-NGF tsis muaj polymer hloov pauv tau piav qhia los ntawm kev siv tshuab hluav taws xob xa hluav taws xob (TEM) thiab kev tshuaj xyuas cov qauv xaiv cheeb tsam hluav taws xob diffraction (SAED). Cov txiaj ntsig sib xws tau pom hauv Daim Duab 5. Kev ntsuas qis planar TEM imaging qhia tau tias muaj NGF thiab FLG thaj chaw nrog cov yam ntxwv sib txawv ntawm electron, piv txwv li thaj chaw tsaus ntuj thiab ci dua, feem (Daim Duab 5a). Zaj duab xis tag nrho qhia txog kev ua haujlwm zoo thiab kev ruaj khov ntawm thaj chaw sib txawv ntawm NGF thiab FLG, nrog kev sib tshooj zoo thiab tsis muaj kev puas tsuaj lossis kev rhuav tshem, uas kuj tau lees paub los ntawm SEM (Daim Duab 3) thiab kev tshawb fawb TEM siab (Daim Duab 5c-e). Tshwj xeeb, hauv Daim Duab 5d qhia txog cov qauv choj ntawm nws qhov loj tshaj plaws (qhov chaw cim los ntawm tus xub dub hauv Daim Duab 5d), uas yog tus cwj pwm los ntawm lub duab peb ceg thiab muaj cov txheej graphene nrog qhov dav txog li 51. Cov khoom sib xyaw nrog qhov sib nrug ntawm 0.33 ± 0.01 nm raug txo kom ntau txheej ntawm graphene hauv thaj chaw nqaim tshaj plaws (qhov kawg ntawm tus xub dub khov kho hauv Daim Duab 5 d).
Daim duab TEM ntawm cov qauv NiAG uas tsis muaj polymer ntawm daim phiaj tooj liab carbon lacy: (a, b) Cov duab TEM uas tsis tshua muaj magnification suav nrog thaj tsam NGF thiab FLG, (ce) Cov duab magnification siab ntawm ntau thaj tsam hauv vaj huam sib luag-a thiab vaj huam sib luag-b yog cov xub cim ntawm tib xim. Cov xub ntsuab hauv vaj huam sib luag a thiab c qhia txog thaj chaw puag ncig ntawm kev puas tsuaj thaum lub sijhawm teeb tsa beam. (f-i) Hauv vaj huam sib luag a txog c, cov qauv SAED hauv thaj chaw sib txawv yog qhia los ntawm xiav, xiav ntsuab, txiv kab ntxwv, thiab liab voj voog, raws li.
Cov qauv ribbon hauv Daim Duab 5c qhia (cim nrog xub liab) qhov kev taw qhia ntsug ntawm cov graphite lattice dav hlau, uas tej zaum yuav yog vim muaj kev tsim cov nanofolds raws li zaj duab xis (inset hauv Daim Duab 5c) vim muaj kev ntxhov siab ntau dhau uncompensated shear 30,61,62. Hauv qab high-resolution TEM, cov nanofolds no 30 qhia txog kev taw qhia crystallographic sib txawv dua li lwm qhov ntawm thaj tsam NGF; cov dav hlau basal ntawm graphite lattice yog taw qhia yuav luag ntsug, es tsis yog kab rov tav zoo li lwm qhov ntawm zaj duab xis (inset hauv Daim Duab 5c). Ib yam li ntawd, thaj tsam FLG qee zaum qhia txog cov kab ncaj thiab nqaim zoo li cov kab (cim los ntawm xub xiav), uas tshwm sim ntawm qhov qis thiab nruab nrab magnification hauv Daim Duab 5b, 5e, feem. Daim inset hauv Daim Duab 5e lees paub qhov muaj ob- thiab peb-txheej graphene txheej hauv FLG sector (interplanar nrug 0.33 ± 0.01 nm), uas yog qhov zoo sib xws nrog peb cov txiaj ntsig yav dhau los 30. Tsis tas li ntawd xwb, cov duab SEM kaw tseg ntawm cov NGF uas tsis muaj polymer uas tau hloov mus rau ntawm cov phiaj tooj liab nrog cov yeeb yaj kiab carbon lacy (tom qab ua qhov ntsuas TEM saib sab saud) tau pom hauv Daim Duab SI9. Thaj chaw FLG uas dai zoo (cim nrog tus xub xiav) thiab thaj chaw tawg hauv Daim Duab SI9f. Tus xub xiav (ntawm ntug ntawm NGF uas tau hloov mus) tau raug nthuav tawm los qhia tias thaj chaw FLG tuaj yeem tiv taus cov txheej txheem hloov mus yam tsis muaj polymer. Hauv kev xaus, cov duab no lees paub tias NGF uas dai ib nrab (suav nrog thaj chaw FLG) tseem muaj kev ruaj khov txawm tias tom qab kev tuav thiab raug rau lub tshuab nqus tsev siab thaum lub sijhawm ntsuas TEM thiab SEM (Daim Duab SI9).
Vim yog qhov zoo heev ntawm NGF (saib Daim Duab 5a), nws tsis nyuaj rau kev taw qhia cov flakes raws li [0001] domain axis los tshuaj xyuas cov qauv SAED. Nyob ntawm qhov tuab ntawm zaj duab xis thiab nws qhov chaw, ntau thaj chaw txaus siab (12 cov ntsiab lus) tau txheeb xyuas rau kev tshawb fawb electron diffraction. Hauv Daim Duab 5a-c, plaub ntawm cov cheeb tsam ib txwm muaj no tau pom thiab cim nrog cov voj voog xim (xiav, cyan, txiv kab ntxwv, thiab liab coded). Daim Duab 2 thiab 3 rau SAED hom. Daim Duab 5f thiab g tau txais los ntawm thaj chaw FLG qhia hauv Daim Duab 5 thiab 5. Raws li tau pom hauv Daim Duab 5b thiab c, feem. Lawv muaj cov qauv hexagonal zoo ib yam li twisted graphene63. Hauv kev tshwj xeeb, Daim Duab 5f qhia peb cov qauv superimposed nrog tib qho kev taw qhia ntawm [0001] cheeb tsam axis, tig los ntawm 10 ° thiab 20 °, raws li pov thawj los ntawm qhov tsis sib xws ntawm peb khub ntawm (10-10) reflections. Ib yam li ntawd, Daim Duab 5g qhia ob lub qauv hexagonal uas tig los ntawm 20 °. Ob lossis peb pawg ntawm cov qauv hexagonal hauv thaj tsam FLG tuaj yeem tshwm sim los ntawm peb txheej graphene hauv-dav hlau lossis tawm ntawm-dav hlau 33 tig piv rau ib leeg. Qhov sib txawv, cov qauv diffraction electron hauv Daim Duab 5h, i (sib raug rau thaj tsam NGF qhia hauv Daim Duab 5a) qhia ib qho qauv [0001] nrog qhov siab dua ntawm qhov taw qhia diffraction, sib raug rau cov khoom tuab dua. Cov qauv SAED no sib raug rau cov qauv graphitic tuab dua thiab kev taw qhia nruab nrab dua li FLG, raws li tau txiav txim siab los ntawm cov ntsuas 64. Kev piav qhia ntawm cov khoom crystalline ntawm NGF tau qhia txog kev sib koom ua ke ntawm ob lossis peb lub graphite (lossis graphene) crystallites. Qhov tshwj xeeb tshaj yog qhov tseem ceeb hauv thaj tsam FLG yog tias cov crystallites muaj qee qib ntawm kev tsis sib haum xeeb hauv-dav hlau lossis tawm ntawm-dav hlau. Cov khoom me me / txheej graphite nrog lub kaum sab xis tig hauv dav hlau ntawm 17 °, 22 ° thiab 25 ° tau tshaj tawm yav dhau los rau NGF loj hlob ntawm Ni 64 zaj duab xis. Cov nqi kaum sab xis tig uas tau pom hauv txoj kev tshawb fawb no yog sib xws nrog cov kaum sab xis tig uas tau pom yav dhau los (± 1 °) rau BLG63 graphene ntswj.
Cov khoom siv hluav taws xob ntawm NGF / SiO2 / Si tau ntsuas ntawm 300 K hla thaj tsam ntawm 10 × 3 mm2. Cov nqi ntawm electron carrier concentration, mobility thiab conductivity yog 1.6 × 1020 cm-3, 220 cm2 V-1 C-1 thiab 2000 S-cm-1, feem. Cov nqi txav mus los thiab conductivity ntawm peb NGF zoo ib yam li graphite ntuj2 thiab siab dua li cov khoom lag luam pyrolytic graphite uas muaj kev taw qhia siab (tsim ntawm 3000 ° C)29. Cov nqi electron carrier concentration uas tau pom yog ob qho kev txiav txim siab siab dua li cov uas tau tshaj tawm tsis ntev los no (7.25 × 10 cm-3) rau cov yeeb yaj kiab graphite micron-tuab uas tau npaj siv cov ntawv polyimide kub siab (3200 ° C) 20.
Peb kuj tau ua qhov kev ntsuas UV-pom kev xa mus rau FS-NGF hloov mus rau cov khoom siv quartz (Daim Duab 6). Cov spectrum tshwm sim qhia txog kev xa mus tas li ntawm 62% hauv qhov ntau ntawm 350–800 nm, qhia tias NGF yog translucent rau lub teeb pom kev zoo. Qhov tseeb, lub npe "KAUST" tuaj yeem pom hauv daim duab digital ntawm cov qauv hauv Daim Duab 6b. Txawm hais tias cov qauv nanocrystalline ntawm NGF txawv ntawm SLG, tus lej ntawm cov khaubncaws sab nraud povtseg tuaj yeem kwv yees siv txoj cai ntawm 2.3% kev poob kis ib txheej ntxiv 65. Raws li kev sib raug zoo no, tus lej ntawm cov khaubncaws sab nraud povtseg graphene nrog 38% kev poob kis yog 21. Cov NGF loj hlob feem ntau muaj 300 txheej graphene, piv txwv li txog 100 nm tuab (Daim Duab 1, SI5 thiab SI7). Yog li ntawd, peb xav tias qhov pom kev pom tseeb sib raug rau thaj tsam FLG thiab MLG, txij li thaum lawv tau faib thoob plaws hauv zaj duab xis (Daim Duab 1, 3, 5 thiab 6c). Ntxiv rau cov ntaub ntawv qauv saum toj no, kev coj ua thiab pob tshab kuj lees paub qhov zoo ntawm cov NGF hloov pauv.
(a) Kev ntsuas qhov pom kev xa tawm UV, (b) kev hloov pauv NGF ib txwm muaj ntawm quartz siv cov qauv sawv cev. (c) Daim duab qhia txog NGF (lub thawv tsaus nti) nrog cov cheeb tsam FLG thiab MLG faib sib npaug zos uas cim ua cov duab grey random thoob plaws hauv cov qauv (saib Daim Duab 1) (kwv yees li 0.1–3% thaj tsam ib 100 μm2). Cov duab random thiab lawv qhov loj me hauv daim duab yog rau kev piav qhia xwb thiab tsis sib xws rau thaj chaw tiag tiag.
Cov NGF uas pom tseeb uas CVD cog tau yav dhau los tau raug xa mus rau cov nplaim silicon liab qab thiab siv rau hauv cov hlwb hnub ci15,16. Qhov ua tau zoo ntawm kev hloov pauv hluav taws xob (PCE) yog 1.5%. Cov NGF no ua ntau yam haujlwm xws li cov txheej sib xyaw ua ke, txoj kev thauj mus los them, thiab cov hluav taws xob pob tshab15,16. Txawm li cas los xij, zaj duab xis graphite tsis sib xws. Kev ua kom zoo dua yog qhov tsim nyog los ntawm kev tswj hwm qhov tsis kam ntawm daim ntawv thiab kev xa tawm ntawm lub teeb ntawm cov hluav taws xob graphite, vim tias ob yam khoom no ua lub luag haujlwm tseem ceeb hauv kev txiav txim siab tus nqi PCE ntawm lub hlwb hnub ci15,16. Feem ntau, cov yeeb yaj kiab graphene yog 97.7% pob tshab rau lub teeb pom kev, tab sis muaj qhov tsis kam ntawm daim ntawv ntawm 200–3000 ohms / sq.16. Qhov tsis kam ntawm qhov chaw ntawm cov yeeb yaj kiab graphene tuaj yeem txo qis los ntawm kev nce tus lej ntawm cov txheej (kev hloov pauv ntau ntawm cov txheej graphene) thiab doping nrog HNO3 (~ 30 Ohm / sq.)66. Txawm li cas los xij, cov txheej txheem no siv sijhawm ntev thiab cov txheej hloov pauv sib txawv tsis ib txwm tswj 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 yog lwm txoj hauv kev zoo rau cov channel conductive lossis counter electrodes hauv lub hnub ci cell15,16.
Txawm hais tias cov qauv thiab cov tshuaj lom neeg ntawm BS-NGF zoo ib yam li FS-NGF, nws qhov roughness txawv ("Kev Loj Hlob ntawm FS- thiab BS-NGF"). Yav dhau los, peb tau siv ultra-thin film graphite22 ua lub sensor roj. Yog li ntawd, peb tau sim qhov ua tau ntawm kev siv BS-NGF rau cov haujlwm sensing roj (Daim Duab SI10). Ua ntej, mm2-qhov loj ntawm BS-NGF tau hloov mus rau ntawm lub interdigitating electrode sensor chip (Daim Duab SI10a-c). Cov ntsiab lus tsim khoom ntawm lub chip tau tshaj tawm ua ntej; nws thaj chaw rhiab heev yog 9 mm267. Hauv cov duab SEM (Daim Duab SI10b thiab c), lub electrode kub hauv qab pom tseeb los ntawm NGF. Dua li, nws tuaj yeem pom tias kev npog chip sib xws tau ua tiav rau txhua qhov qauv. Kev ntsuas roj sensor ntawm ntau yam roj tau sau tseg (Daim Duab SI10d) (Daim Duab SI11) thiab cov nqi teb tau pom hauv Figs. SI10g. Tej zaum yuav muaj lwm cov pa roj cuam tshuam xws li SO2 (200 ppm), H2 (2%), CH4 (200 ppm), CO2 (2%), H2S (200 ppm) thiab NH3 (200 ppm). Ib qho ua rau muaj yog NO2. qhov xwm txheej electrophilic ntawm cov pa roj22,68. Thaum adsorbed rau ntawm qhov chaw ntawm graphene, nws txo qhov kev nqus tam sim no ntawm cov electrons los ntawm lub kaw lus. Kev sib piv ntawm cov ntaub ntawv teb ntawm BS-NGF sensor nrog cov sensors luam tawm yav dhau los tau nthuav tawm hauv Rooj SI2. Lub tshuab rau kev rov ua dua NGF sensors siv UV plasma, O3 plasma lossis thermal (50–150 ° C) kev kho mob ntawm cov qauv raug tab tom ua mus, qhov zoo tshaj plaws ua raws li kev siv cov kab ke embedded69.
Thaum lub sijhawm CVD, kev loj hlob ntawm graphene tshwm sim rau ob sab ntawm cov khoom siv catalyst41. Txawm li cas los xij, BS-graphene feem ntau raug tshem tawm thaum lub sijhawm hloov pauv41. Hauv kev tshawb fawb no, peb qhia tau tias kev loj hlob zoo ntawm NGF thiab kev hloov pauv NGF tsis muaj polymer tuaj yeem ua tiav rau ob sab ntawm kev txhawb nqa catalyst. BS-NGF nyias dua (~ 80 nm) dua li FS-NGF (~ 100 nm), thiab qhov sib txawv no 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 rau qhov roughness ntawm NGF. Cov txiaj ntsig no qhia tau tias cov planar FS-NGF uas loj hlob tuaj yeem siv ua cov khoom siv ua ntej rau graphene (los ntawm exfoliation method70) lossis ua cov channel conductive hauv cov hlwb hnub ci15,16. Qhov sib piv, BS-NGF yuav siv rau kev kuaj pom roj (Daim duab SI9) thiab tej zaum rau cov tshuab khaws cia hluav taws xob71,72 qhov twg nws qhov roughness ntawm qhov chaw yuav pab tau.
Xav txog qhov saum toj no, nws yog ib qho muaj txiaj ntsig los muab cov haujlwm tam sim no ua ke nrog cov yeeb yaj kiab graphite uas tau luam tawm yav dhau los uas cog los ntawm CVD thiab siv cov ntawv ci nickel. Raws li pom tau hauv Rooj 2, qhov siab dua uas peb siv tau ua rau lub sijhawm teb (theem kev loj hlob) luv dua txawm tias nyob rau qhov kub qis dua (hauv qhov ntau ntawm 850–1300 ° C). Peb kuj tau ua tiav kev loj hlob ntau dua li niaj zaus, qhia txog lub peev xwm rau kev nthuav dav. Muaj lwm yam uas yuav tsum xav txog, qee qhov uas peb tau suav nrog hauv rooj.
Cov NGF zoo ob sab tau loj hlob ntawm cov ntawv ci nickel los ntawm catalytic CVD. Los ntawm kev tshem tawm cov polymer substrates ib txwm muaj (xws li cov uas siv hauv CVD graphene), peb ua tiav kev hloov pauv ntub dej huv thiab tsis muaj qhov tsis zoo ntawm NGF (loj hlob ntawm sab nraub qaum thiab sab pem hauv ntej ntawm cov ntawv ci nickel) mus rau ntau yam substrates tseem ceeb rau cov txheej txheem. Qhov tseem ceeb, NGF suav nrog thaj tsam FLG thiab MLG (feem ntau 0.1% txog 3% ib 100 µm2) uas tau sib xyaw ua ke zoo rau hauv zaj duab xis tuab dua. Planar TEM qhia tau hais tias cov cheeb tsam no yog tsim los ntawm cov pawg ntawm ob mus rau peb lub graphite/graphene me me (siv lead ua lossis txheej, feem), qee qhov muaj qhov sib txawv ntawm 10-20 °. Thaj tsam FLG thiab MLG yog lub luag haujlwm rau qhov pom tseeb ntawm FS-NGF rau lub teeb pom kev zoo. Raws li rau cov ntawv tom qab, lawv tuaj yeem nqa mus rau pem hauv ntej thiab, raws li tau pom, tuaj yeem muaj lub hom phiaj ua haujlwm (piv txwv li, rau kev kuaj pom roj). Cov kev tshawb fawb no muaj txiaj ntsig zoo rau kev txo cov khib nyiab thiab cov nqi hauv cov txheej txheem CVD hauv kev lag luam.
Feem ntau, qhov nruab nrab tuab ntawm CVD NGF nyob nruab nrab ntawm (qis- thiab ntau txheej) graphene thiab kev lag luam (micrometer) graphite ntawv. Qhov ntau ntawm lawv cov khoom nthuav, ua ke nrog txoj kev yooj yim uas peb tau tsim rau lawv cov khoom tsim thiab kev thauj mus los, ua rau cov yeeb yaj kiab no tshwj xeeb tshaj yog rau cov ntawv thov uas xav tau cov lus teb ua haujlwm ntawm graphite, tsis muaj tus nqi ntawm cov txheej txheem tsim khoom siv hluav taws xob uas siv tam sim no.
Ib daim ntawv ci nickel tuab 25-μm (99.5% purity, Goodfellow) tau teeb tsa rau hauv lub tshuab hluav taws xob CVD (Aixtron 4-nti BMPro). Lub kaw lus tau purged nrog argon thiab evacuated mus rau lub hauv paus siab ntawm 10-3 mbar. Tom qab ntawd nickel ntawv ci tau muab tso rau hauv Ar/H2 (Tom qab pre-annealing lub ntawv ci Ni rau 5 feeb, lub ntawv ci tau raug rau lub siab ntawm 500 mbar ntawm 900 ° C. NGF tau tso rau hauv qhov ntws ntawm CH4/H2 (100 cm3 txhua) rau 5 feeb. Cov qauv tau txias rau qhov kub hauv qab 700 ° C siv Ar ntws (4000 cm3) ntawm 40 ° C / feeb. Cov ntsiab lus ntawm kev ua kom zoo dua ntawm cov txheej txheem loj hlob NGF tau piav qhia rau lwm qhov 30.
Cov qauv ntawm qhov chaw tau pom los ntawm SEM siv lub tshuab tsom iav Zeiss Merlin (1 kV, 50 pA). Qhov roughness ntawm qhov chaw ntawm cov qauv thiab NGF thickness tau ntsuas los ntawm AFM (Dimension Icon SPM, Bruker). Kev ntsuas TEM thiab SAED tau ua tiav los ntawm kev siv lub tshuab tsom iav FEI Titan 80–300 Cubed uas muaj rab phom tua hluav taws xob siab (300 kV), lub tshuab FEI Wien hom monochromator thiab lub tshuab kho qhov tsis zoo ntawm CEOS lens kom tau txais cov txiaj ntsig kawg. kev daws teeb meem ntawm qhov chaw 0.09 nm. Cov qauv NGF tau hloov mus rau cov hlau nplaum uas muaj carbon lacy coated rau kev thaij duab TEM tiaj tiaj thiab kev tshuaj xyuas cov qauv SAED. Yog li, feem ntau ntawm cov qauv flocs tau dai rau hauv cov qhov hws ntawm daim nyias nyias txhawb nqa. Cov qauv NGF hloov pauv tau tshuaj xyuas los ntawm XRD. Cov qauv X-ray diffraction tau txais los ntawm kev siv lub tshuab diffractometer hmoov (Brucker, D2 theem hloov pauv nrog Cu Kα qhov chaw, 1.5418 Å thiab LYNXEYE ntes) siv lub tshuab hluav taws xob Cu nrog lub qhov chaw beam ntawm 3 hli.
Muaj ntau qhov kev ntsuas Raman point tau kaw cia siv lub tshuab microscope confocal (Alpha 300 RA, WITeC). Lub laser 532 nm nrog lub zog qis excitation (25%) tau siv los zam kev cuam tshuam thermally. X-ray photoelectron spectroscopy (XPS) tau ua tiav ntawm Kratos Axis Ultra spectrometer hla thaj chaw kuaj ntawm 300 × 700 μm2 siv monochromatic Al Kα hluav taws xob (hν = 1486.6 eV) ntawm lub zog ntawm 150 W. Cov spectra daws teeb meem tau txais ntawm lub zog kis ntawm 160 eV thiab 20 eV, feem. Cov qauv NGF hloov mus rau SiO2 tau txiav ua tej daim (3 × 10 mm2 txhua) siv PLS6MW (1.06 μm) ytterbium fiber laser ntawm 30 W. Cov xov tooj liab hlau sib cuag (50 μm tuab) tau tsim los siv cov nyiaj muab tshuaj txhuam hauv qab lub tshuab microscope kho qhov muag. Kev sim thauj hluav taws xob thiab Hall effect tau ua tiav rau cov qauv no ntawm 300 K thiab qhov sib txawv ntawm lub zog sib nqus ntawm ± 9 Tesla hauv lub cev ntsuas lub cev (PPMS EverCool-II, Quantum Design, USA). Cov spectra UV-vis uas kis tau raug kaw cia siv Lambda 950 UV-vis spectrophotometer hauv 350–800 nm NGF ntau yam hloov mus rau cov khoom siv quartz thiab cov qauv siv quartz.
Lub ntsuas tshuaj tiv thaiv (interdigitated electrode chip) tau txuas rau lub rooj tsavxwm luam tawm tshwj xeeb 73 thiab qhov tiv thaiv tau rho tawm ib ntus. Lub rooj tsavxwm luam tawm uas lub cuab yeej nyob ntawd txuas nrog cov chaw sib cuag thiab muab tso rau hauv lub chamber ntsuas roj 74. Kev ntsuas tiv thaiv tau ua ntawm qhov hluav taws xob ntawm 1 V nrog kev luam theej tas mus li los ntawm kev ntxuav mus rau kev raug roj thiab tom qab ntawd ntxuav dua. Lub chamber tau ntxuav thawj zaug los ntawm kev ntxuav nrog nitrogen ntawm 200 cm3 rau 1 teev kom ntseeg tau tias tshem tawm tag nrho lwm cov analytes uas muaj nyob hauv lub chamber, suav nrog cov dej noo. Cov analytes ib leeg tau maj mam tso tawm rau hauv lub chamber ntawm tib qhov ntws ntawm 200 cm3 los ntawm kev kaw lub tog raj kheej N2.
Ib tsab xov xwm kho dua tshiab tau muab luam tawm lawm thiab koj tuaj yeem nkag mus saib tau los ntawm qhov txuas saum toj ntawm tsab xov xwm.
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