过电位
催化作用
化学
掺杂剂
塔菲尔方程
Atom(片上系统)
结合能
物理化学
反应机理
相(物质)
氢
密度泛函理论
过渡金属
金属
活化能
材料科学
氢原子
兴奋剂
化学物理
计算化学
原子物理学
物理
有机化学
嵌入式系统
烷基
电极
电化学
光电子学
计算机科学
标识
DOI:10.1021/acscatal.6b01211
摘要
The 1T phase of transition-metal dichalcogenides (TMDs) has been demonstrated in recent experiments to display excellent catalytic activity for hydrogen evolution reaction (HER), but the catalytic mechanism has not been elucidated so far. Herein, using 1T MoS2 as the prototypical TMD material, we studied the HER activity on its basal plane from periodic density functional theory (DFT) calculations. Compared to the nonreactive basal plane of 2H phase MoS2, the catalytic activity of the basal plane of 1T phase MoS2 mainly arises from its affinity for binding H at the surface S sites. Using the binding free energy (ΔGH) of H as the descriptor, we found that the optimum evolution of H2 will proceed at surface H coverage of 12.5% ∼ 25%. Within this coverage, we examined the reaction energy and barrier for the three elementary steps of the HER process. The Volmer step was found to be facile, whereas the subsequent Heyrovsky reaction is kinetically more favorable than the Tafel reaction. Our results suggest that at low overpotential, HER can take place readily on the basal plane of 1T MoS2 via the Volmer–Heyrovsky mechanism. We further screened the dopants for the HER activity and found that substitutional doping of the Mo atom by metals such as Mn, Cr, Cu, Ni, and Fe can make 1T MoS2 a better HER catalyst.
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