Supporting Information

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1 Supporting Information Ultra-thin Alumina Masks Assisted Nanopore Patterning on Monolayer MoS 2 for Highly Catalytic Efficiency in Hydrogen Evolution Reaction Shaoqiang Su, Qingwei Zhou, Zhiqiang Zeng, Die Hu, Xin Wang, Mingliang Jin, Xingsen Gao, Richard Nötze, Guofu Zhou, Zhang Zhang, * Junming Liu National Center for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou , P. R. China. Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou , P. R. China. Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou , P. R. China. Laboratory of Solid State Microstructures, Nanjing University, Nanjing, , China Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen , P. R. China Corresponding Author * zzhang@scnu.edu.cn (Zhang Zhang). S-1

2 Figure S1. Illustration of the CVD growth of monolayer 2H MoS2 flakes. Figure S2. (a) Nanopore arrays patterning on a large-area monolayer MoS2 observed under SEM. (b) Nanopore arrays patterning on a large-area monolayer MoS2 observed under TEM. S-2

3 Figure S3. (a) X-ray photoelectron spectroscopy of samles before and after the nanopatterning, (b) the enlarged view of the area in (a) which will contain the characteristic peaks of Mo 6+ at around 236 ev, and (c) the enlarge view of the area in (a) which contain the characteristic peaks of Al 3+ at aroud 74 ev. S-3

4 Exchange edge density edge density MoS 2 area Electrode current per unit area per unit mass coverage kinds density (um/um 2 ) (m/mg) (nm 2 /nm 2 ) (µa/cm 2 ) MoS 2 flakes * LDP MoS * HDP MoS * Table S1. Edge density and exchange current density of MoS 2 before and after nanopatterning. Referred to high density of active sites per unit mass, highly efficient catalyst can achieve a better hydrogen evolution reaction (HER) performance with less material consumption. Therefore, in order to assess the density of active sites per unit mass in our electrode, the edge length density values was determined by the specific value of edge length/coverage area of all measured MoS 2 flakes. To perform it accurately, the software of Photoshop 5.0 was used. First, a top-view SEM image with uniform MoS 2 flakes was opened in the software, and we could get the number of image pixels (represented by X). Then, we measured the MoS 2 coverage area, which related to another number of pixels (represented by Y). The edges of all MoS 2 flakes were marked with 1-pixel wide lines (the thinner the line is, the more accurate the result will be). The software will show the number of pixels of the edge lines (represented by Z). In the end, the edge length density values were determined by Z/Y. In our experiment, we used the image of Figure 2 (a). And the X , Y 93512, Z 73688, then the Z/Y Similarly, we can get the edge density per area in LDP and HDP electrodes are um/um 2 and um/um 2 respectively. This method was also applied to calculate the MoS 2 area coverage (nm 2 /nm 2 ). The edge density per unit mass (m/mg) was obtained through the pure mathematic mathematical conversions from edge density per unit area S-4

5 (um/um 2 ). We take 0.65 nm and 4.8 g/cm 3 as the thickness and density of monolayer MoS 2. Then, for the MoS 2 flakes loaded working electrode (edge density per unit area is um/um 2 ), the edge density per unit mass will be: *10 6 m/mg. Similarly, we can get the edge density per unit mass in LDP and HDP electrodes are about 7.44*10 6 m/mg and 2.02*10 7 m/mg respectively. Electrode kinds R CT / Ω R over all / Ω CPE-T CPE-P MoS 2 flakes E LDP MoS E HDP MoS E Table S2. Electrochemical parameters of MoS 2 before and after nanopatterning. Figure S4. Cyclic voltammograms in the region of V vs. RHE for the (a) CVD growth of MoS 2 flakes. (b) LDP MoS 2. (c) HDP MoS 2. The double-layer capacitance (C dl ) of various samples can be determined from the cyclic voltammograms, which is expected to be linearly proportional to the effective surface area. The capacitance can be calculated from the scan rate S-5

6 dependence of charging current density at 0.15 V vs. RHE, where the slope of the J (Ja-Jc) vs. scan rate curve is twice the C dl. 1,2 Electrode kinds Specific activity per unit mass (C/mg) MoS 2 flakes LDP MoS HDP MoS Table S3. Specific activity parameters of MoS 2 before and after nanopatterning. REFERENCES (1) Lukowski, M. A.; Daniel, A. S.; Meng, F.; Forticaux, A.; Li, L.; Jin, S. Enhanced Hydrogen Evolution Catalysis from Chemically Exfoliated Metallic MoS 2 Nanosheets. Journal of the American Chemical Society 2013, 135 (28), (2) Merki, D.; Vrubel, H.; Rovelli, L.; Fierro, S.; Hu, X. Fe, Co, and Ni Ions Promote the Catalytic Activity of Amorphous Molybdenum Sulfide Films for Hydrogen Evolution. Chemical Science 2012, 3 (8), S-6