Directional Construction of Vertical Nitrogen-Doped 1T-2H MoSe<sub>2</sub> /Graphene Shell/Core Nanoflake Arrays for Efficient Hydrogen Evolution Reaction.

Deng, Shengjue; Zhong, Yu; Zeng, Yinxiang; Wang, Yadong; Yao, Zhujun; Yang, Fan; Lin, Shiwei; Wang, Xiuli et al. · Adv Mater · 2017

basic_science · Level V

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Abstract

The low utilization of active sites and sluggish reaction kinetics of MoSe<sub>2</sub> severely impede its commercial application as electrocatalyst for hydrogen evolution reaction (HER). To address these two issues, the first example of introducing 1T MoSe<sub>2</sub> and N dopant into vertical 2H MoSe<sub>2</sub> /graphene shell/core nanoflake arrays that remarkably boost their HER activity is herein described. By means of the improved conductivity, rich catalytic active sites and highly accessible surface area as a result of the introduction of 1T MoSe<sub>2</sub> and N doping as well as the unique structural features, the N-doped 1T-2H MoSe<sub>2</sub> /graphene (N-MoSe<sub>2</sub> /VG) shell/core nanoflake arrays show substantially enhanced HER activity. Remarkably, the N-MoSe<sub>2</sub> /VG nanoflakes exhibit a relatively low onset potential of 45 mV and overpotential of 98 mV (vs RHE) at 10 mA cm<sup>-2</sup> with excellent long-term stability (no decay after 20 000 cycles), outperforming most of the recently reported Mo-based electrocatalysts. The success of improving the electrochemical performance via the introduction of 1T phase and N dopant offers new opportunities in the development of high-performance MoSe<sub>2</sub> -based electrodes for other energy-related applications.