Supporting Information

Transcription

1 Supporting Information Direct Chemical Vapor Deposition-Derived Graphene Glasses Targeting Wide Ranged Applications Jingyu Sun, Yubin Chen, Manish Kr. Priydarshi, Zhang Chen, Alicja Bachmatiuk,, Zhiyu Zou, Zhaolong Chen, Xiuju Song, Yanfeng Gao, Mark H. Rümmeli,,ǁ,# Yanfeng Zhang,*,, Zhongfan Liu*, Center for Nanochemistry (CNC), Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing , P. R. China Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing , P. R. China State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institution of Ceramics Chinese Academy of Sciences, Shanghai , P. R. China Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej 34, Zabrze , Poland IFW Dresden, Institute for Complex Materials, P.O. Box , D Dresden, Germany ǁ Department of Energy Science, Sungkyunkwan University, Suwon , Republic of Korea # IBS Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Daejon , Republic of Korea *Corresponding authors: zfliu@pku.edu.cn; yanfengzhang@pku.edu.cn S1

2 Figure S1. (a) Representative full range XPS spectrum of the directly grown graphene/quartz glass sample. The absence of transition metal elements such as Fe, Co, Ni, and Cu etc. indicates a catalystfree CVD process taken place. (b) C 1s XPS spectrum showing the featured signals of graphene with an sp 2 carbon peak (284.8 ev), a C-H peak (285.3 ev) and a broad C-O peak, indicative of good quality of as-grown graphene. S2

3 Figure S2. Transmittance spectrum of graphene film directly grown on quartz glass sample, possessing a high optical transmittance of 96.3% at a wavelength of 550 nm. S3

4 Figure S3. (a) HRTEM image of the double layer graphene marked by the cyan-colored 2L in main text in Figure 2f. Scale bar: 0.5 nm. The Moiré pattern wavelength is measured to be about 0.69 nm. The inset is the corresponding fast Fourier transform pattern, displaying two sets of hexagonal spots with a measured rotation angle about (b) Structural representation of two graphene layers with 20.3 rotation, showing excellent agreement with the superstructure displayed in (a). According to LeRoy and colleagues' report (LeRoy BJ et al., Nat. Phys. 2012, 8, ), the wavelength (λ) of a Moiré pattern can be calculated using the following equation: (1 + δ)a λ= 2(1 + δ)(1 cos θ) + δ 2 where δ and θ is the lattice mismatch and relative rotational angle between two layer of graphene, respectively, and a is the graphene lattice constant. For the above equation in our scenario, δ is zero and a is set to be nm, hence θ can be calculated to be 20.3 (λ = 0.69 nm), in good agreement with the measured value in the FFT pattern (20.3 ) shown in Figure S3a. S4

5 Figure S4. Investigation of graphene growth on solid glasses in the catalyst-free APCVD. (a) Raman spectroscopy of the temperature-dependent growth of graphene on sapphire glass. All the Raman spectra are normalized to G peak intensity. (b) Corresponding I D /I G and I 2D /I G ratios as a function of growth temperature extracted from (a). (c) Raman spectroscopic characterization of time-dependent growth of graphene on quartz glass. All the Raman spectra are normalized to G peak intensity. (d) Corresponding I D /I G and I 2D /I G ratios as a function of growth time extracted from (c). S5

6 Figure S5. Schematic of graphene growth on solid glass substrate by catalyst-free APCVD route. Step 1: decomposition and adsorption; Step 1*: desorption; Step 2: nucleation; Step 3: diffusion; Step 4: graphene formation. Analysis: The catalyst-free APCVD growth of graphene on insulators deals with a surface deposition process accompanied by a quite slow lateral growth rate. The direct CVD process on solid glasses is schematically illustrated in Fig. S5. It begins with the decomposition of carbon feedstock, CH 4 in this case. In sharp contrast to the hydrocarbon dissociation in metal-catalyzed CVD, no appreciable catalytic effect occurs during our growth due to the catalytically inert nature of glasses. Instead, thermal decomposition plays a dominant role in CH 4 dissociation, where a relatively high growth temperature is necessary (950 C, 1180 C, 1550 C and 1000 C employed in Ref. 1, Ref. 2, Ref. 3 and this work). This is followed by the adsorption of the thermally-decomposed CH x (x = 0-4) fragments on glass surface (Step 1), accompanied by desorption of carbon species from the substrate (Step 1*). The graphene nucleation (Step 2) could be promoted by the presence of surface oxygen on the glass substrate, which can enhance the capture of these carbon species through C-O and H-O binding 4. In terms of the diffusion pathways of carbons, the surface diffusion (route i in Step 3) would progress less smoothly compared to the case of metal-catalyzed CVD, owing to the higher diffusion barriers on oxides 2. Besides, the carbon atoms landing on the edge of stable nucleus would proceed with the edge diffusion (route ii in Step 3), also accounting for the expansion of graphene islands (Step 4). Finally, these islands coalesce with each other to form a continuous film via an in-plane propagation process (Supporting Information Fig. S6). S6

7 Figure S6. Evolution of direct formation of graphene on SiO 2 substrates by catalyst-free APCVD. (a-c) SEM images of the as-grown samples showing the evolution of graphene formation from (a) graphene islands, (b) merged flakes to (c) continuous films on substrate as a function of reaction time (as marked in each image), where the remaining CVD conditions were set to be identical (1020 C; Ar/H 2 /CH 4 : 100/50/3-5 sccm). Scale bars: 500 nm. (d,e) AFM height micrographs showing that the substrate surface is covered with directly grown (d) monolayer graphene islands and (e) continuous graphene films, respectively. Scale bars: 1 μm. S7

8 Figure S7. Schematic of the preparation of photocatalytic plates based on directly grown graphene glass. The aim of the gentle oxidation process is to ensure that the photocatalyst (the identical dosage with those in control experiments) is chemically attached onto the graphene layer. S8

9 References (1) Song, H. J.; Son, M.; Park, C.; Lim, H.; Levendorf, M. P.; Tsen, A. W.; Park, J.; Choi, H. C. Nanoscale 2012, 4, (2) Chen, J.; Guo, Y.; Jiang, L.; Xu, Z.; Huang, L.; Xue, Y.; Geng, D.; Wu, B.; Hu, W.; Yu, G.; Liu, Y. Adv. Mater. 2014, 26, (3) Hwang, J.; Kim, M.; Campbell, D.; Alsalman, H. A.; Kwak, J. Y.; Shivaraman, S.; Woll, A. R.; Singh, A. K.; Hennig, R. G.; Gorantla, S.; Rummeli, M. H.; Spencer, M. G. ACS Nano 2013, 7, (4) Chen, J.; Wen, Y.; Guo, Y.; Wu, B.; Huang, L.; Xue, Y.; Geng, D.; Wang, D.; Yu, G.; Liu, Y. J. Am. Chem. Soc. 2011, 133, S9