Phase Evolution of Re1-xMoxSe2 Alloy Nanosheets and Their Enhanced Catalytic Activity toward Hydrogen Evolution Reaction
Phase Evolution of Re1-xMoxSe2 Alloy Nanosheets and Their Enhanced Catalytic Activity toward Hydrogen Evolution Reaction
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DOI：
10.1021/acsnano.0c05159
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发表时间：
2020-09-22
期刊：
影响因子：
17.1
通讯作者：
Kang, Hong Seok
中科院分区：
文献类型：
--
作者：
Kwak, In Hye;Kwon, Ik Seon;Kang, Hong Seok
二维RESe2已成为一种很有前途的析氢反应电催化剂，但其催化活性有待进一步提高。在这里，我们用水热反应合成了整个x范围(0-100%)的Re1-xMoxSe_2合金纳米片。随着x的增加，相的演化顺序为1T‘’(三斜晶系)->；1T‘(单斜晶系)->；2H(六方晶系)。在x=10%的纳米薄片中，取代的Mo原子倾向于聚集在1T“’ReSe2相中，同时存在Se空位。IT‘相的加入使合金纳米片的金属化程度高于端面成分。在0.5M的H_2SO_4中，10%的Mo取代显著提高了对HER的电催化性能，其电流为10 mA cm(-2)，过电位为77 mV(Vs RHE)，Tafel斜率为42 mV dec(-1)。三个相(IT‘’、2H和IT‘)的第一性原理计算预测了在x约为65%时1T’-2H的相变，并沿成分调整产生了一个IT‘相，这与实验结果一致。当x=12.5%时，两个Mo原子倾向于沿Re-4链形成对。沿反应路径的吉布斯自由能表明，当存在相邻的Se空位时，含10%Mo的纳米片的最佳HER性能来自于形成Mo-H的Mo原子。
Two-dimensional ReSe2 has emerged as a promising electrocatalyst for the hydrogen evolution reaction (HER), but its catalytic activity needs to be further improved. Herein, we synthesized Re1-xMoxSe2 alloy nanosheets with the whole range of x (0-100%) using a hydrothermal reaction. The phase evolved in the order of 1T '' (triclinic) -> 1T' (monoclinic) -> 2H (hexagonal) upon increasing x. In the nanosheets with x = 10%, the substitutional Mo atoms tended to aggregate in the 1T '' ReSe2 phase with Se vacancies. The incorporation of the IT' phase makes the alloy nanosheets more metallic than the end compositions. The 10% Mo substitution significantly enhanced the electrocatalytic performance toward HER (in 0.5 M H2SO4), with a current of 10 mA cm(-2) at an overpotential of 77 mV (vs RHE) and a Tafel slope of 42 mV dec(-1). First-principles calculations of the three phases (IT '', 2H, and IT') predicted a phase transition of 1T ''-2H at x approximate to 65% as well as the production of a IT' phase along the composition tuning, which are consistent with the experiments. At x = 12.5%, two Mo atoms prefer to form a pair along the Re-4 chains. Gibbs free energy along the reaction path indicates that the best HER performance of nanosheets with 10% Mo originates from the Mo atoms that form Mo-H when there are adjacent Se vacancies.