Molybdenum-Based Nanomaterials As High Efficient Electrocatalysts for HER

Abstract

a, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P.R. China b, Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA * Email: wangdl81125@hust.edu.cn Electrochemical hydrogen evolution reaction (HER) as an efficient and eco-environmental approach to produce hydrogen has attracted tremendous attention1. Currently, the most efficient catalysts for HER are platinum group metals (e.g. Pt). However, the scarcity and high cost of precious metals limit their large-scale applications2. Therefore, it is of great importance to explore highly active catalysts for HER based on earth-abundant materials for the large scale hydrogen generation in both acid and alkaline media3. Here, carbon supported different molybdenum-based materials (MoP, MoS2, Mo2C) have been systematically synthesized via a simple solvothermal-high temperature treatment method. Different morphologies were obtained such as few layers and nanoparticles structures (Figure 1a and b). Electrochemical tests reveal that the prepared molybdenum- based electrocatalysts exhibit excellent HER performance in both acid and alkaline electrolytes (Figure 1c and d). This could be attributed to the excellent conductivity and the exposed substantial active sites for the nano-structure. In acid medium, carbon supported MoP exhibits the best catalytic activity for HER with an overpotential of 136 mV at a current density of 10 mA cm-2. While Mo2C-C possess the most predominant catalytic performance in alkaline medium compared with MoP and MoS2 with an overpotential of 149 mV. Unexpectedly, in the present work, carbon supported MoS2 possess outstanding catalytic activity in both acid and basic electrolytes which is not common for molybdenum chalcogenides reported. This probably due to the low conductivity and strongly layer numbers dependent on the the active sites. Based on the facile preparation method and excellent electrocatalytic activities, this work will open a novelty avenue to prepare earth abundant based catalysts for energy conversion and storage. Figure 1. TEM images of MoS2-C (a) and Mo2C-C (b). LSVs of molybdenum compounds in 0.5 M H2SO4(c) and 1 M KOH (d). Acknowledgements This work was supported by the National Natural Science Foundation (21306060, 21573083), the Program for New Century Excellent Talents in Universities of China (NCET-13-0237), the Doctoral Fund of Ministry of Education of China (20130142120039).