Transition Metal Co-Induced Phase Transition of Co<sub><i>x</i></sub>Mo<sub>1–<i>x</i></sub>Se<sub>2</sub> to Promote a Hydrogen Evolution Reaction
Jing Cheng, Yimiao Yu, Zhaohui Sui, Shiwen Lei, Qingyu Duan, Yanmin Zhao, Kankan Liu, Lixin Zhang, Fengbo Guo
Abstract
MoSe 2 has been used as a promising alternative strategy to noble metal catalysts in hydrogen evolution reactions (HER). Based on the electronic structure and phase transition of the transition metal Co-induced 2H MoSe 2, Co x Mo 1– x Se 2 ( x = 0–1) was synthesized using a one-step hydrothermal method. With increasing Co doping, the HER performance of Co x Mo 1– x Se 2 shows an increasing and then decreasing trend in alkaline electrolytes, where Co 0.6 Mo 0.4 Se 2 exhibits the strongest HER activity, which is supported by the predicted results of the Gibbs free energy and water dissociation energy. Structural characterization and first-principles calculations consistently show a 2H→1T phase transition of MoSe 2 in Co x Mo 1– x Se 2 at x = 0.4–0.8. The increase in electron density near the Fermi level and the change in the band gap with increasing Co doping confirm that the doping of the Co causes Co x Mo 1– x Se 2 to exhibit pronounced metallicity. The maximum electronic contribution to the partial density of states of Mo atoms at x = 0.67 and a band gap of 0 allow Co 0.6 Mo 0.4 Se 2 to exhibit a very low charge transfer resistance and a good Tafel slope. This study provides inspiration and plays an important role in the design of TMD-based HER catalysts with high catalytic activity.