All The Catalytic Active Sites of MoS2 for Hydrogen Evolution
All The Catalytic Active Sites of MoS2 for Hydrogen Evolution
复制标题
DOI：
10.1021/jacs.6b05940
复制
发表时间：
2016-12-28
影响因子：
15
通讯作者：
Cao, Linyou
中科院分区：
文献类型：
--
作者：
Li, Guoqing;Zhang, Du;Cao, Linyou
MoS2是一种很有前途的低成本析氢反应催化剂，但对其活性位点的了解仍然有限。在这里，我们对MoS2所有可能的反应位点的催化活性进行了明确的研究，包括边缘位点、硫空位和晶界。研究表明，除了已知的催化活性边缘位点外，硫空位为HER提供了另一个主要的活性位点，而晶界的催化活性要弱得多。边缘位置、硫空位和晶界的固有周转率（Tafel斜率）分别为7.5 s(-1) （65 ~ 75 mV/dec）、3.2 s(-1) （65 ~ 85 mV/dec）和0.1 s(-1) （120 ~ 160 mV/dec）。我们还证明了硫空位的催化活性在很大程度上取决于空位的密度和空位附近的局部晶体结构。与边位的催化活性与长度线性相关不同，当空位密度在7-10%范围内时，硫空位表现出最佳的催化活性，且高晶质二硫化钼中的硫空位数量高于低晶质二硫化钼，这可能与不同的局部晶体结构靠近空位有关。
MoS2 presents a promising low-cost catalyst for the hydrogen evolution reaction (HER), but the understanding about its active sites has remained limited. Here we present an unambiguous study of the catalytic activities of all possible reaction sites of MoS2, including edge sites, sulfur vacancies, and grain boundaries. We demonstrate that, in addition to the well-known catalytically active edge sites, sulfur vacancies provide another major active site for the HER, while the catalytic activity of grain boundaries is much weaker. The intrinsic turnover frequencies (Tafel slopes) of the edge sites, sulfur vacancies, and grain boundaries are estimated to be 7.5 s(-1) (65-75 mV/dec), 3.2 s(-1) (65-85 mV/dec), and 0.1 s(-1) (120-160 mV/dec), respectively. We also demonstrate that the catalytic activity of sulfur vacancies strongly depends on the density of the vacancies and the local crystalline structure in proximity to the vacancies. Unlike edge sites, whose catalytic activity linearly depends on the length, sulfur vacancies show optimal catalytic activities when the vacancy density is in the range of 7-10%, and the number of sulfur vacancies in high crystalline quality MoS2 is higher than that in low crystalline quality MoS2, which may be related with the proximity of different local crystalline structures to the vacancies.