单个MoS_2纳米片氢析出催化特性研究

Hydrogen Evolution Properties on Individual MoS_2 Nanosheets

MoS_2作为高效的电催化氢析出(HER)催化剂已有大量文献报道.实验和DFT计算结果都表明MoS_2的高氢析出活性来源于边缘,而其基面是催化惰性的.为了进一步验证此结论,本文利用巯基羧酸在恒电位下自组装单层修饰的纳/微米电极固定不同尺寸的单个纳米片状,对MoS_2氢析出催化活性与其尺寸的关系进行研究,发现纳米片状MoS_2具有较高的催化活性,同时较小尺寸的MoS_2氢析出活性更高,说明MoS_2的边缘的增多对其催化活性有巨大提升,即证明了边缘部分具有更高的氢析出催化活性.

Molybdenum disulfide（MoS2） has been acknowledged to play important roles in hydrogen evolution reaction（HER） for hydrogen energy technology. Both computational and experimental results have suggested that the promising catalytic activity of MoS2 for the HER could be attributed to the sulfur edges of two-dimensional nanosheets, while their basal planes were catalytically inert. In order to verify this conclusion, we prepared single MoS2 sheet electrodes which were made of individual MoS2 sheets attached on the self-assembly monolayers（SAM） of SH（CH2）15COOH at Au ultramicroelectrodes（Au/SAM/MoS2）. The single MoS2 sheet electrodes were prepared by dipping the SAM-modified Au ultramicroelectrodes in dilute solutions of MoS2 sheets whose sizes were similar to or slightly smaller than the Au/SAM electrodes. The electrocatalytic properties of the as-prepared single MoS2 sheet electrodes with different sizes for HER were investigated in 0.5 mol·L^-1H2SO4. It is shown that the nanoscale MoS2 sheets exhibited superior HER activity over the microsize MoS2 sheets. This is because of the abundantly exposed active sites on the nanoscale MoS2 and the individual nanosheet could reflect its intrinsic reactivity more exactly. It directly proved that the active sites of MoS2 in HER were at the edges.