He Mengci, Kong Fanpeng, Yin Geping, Lv Zhe, Sun Xiudong, Shi Hongyan, Gao Bo
Institute of Modern Optics, Key Lab of Micro-optics and Photonic Technology of Heilongjiang Province, Key Laboratory of Micro-Nano Optoelectronic Information System, Ministry of Industry and Information Technology, Department of Physics, Harbin Institute of Technology Harbin 150001 China
School of Chemistry and Chemical Engineering, Harbin Institute of Technology Harbin 150001 China.
RSC Adv. 2018 Apr 17;8(26):14369-14376. doi: 10.1039/c8ra01147h.
Molybdenum disulfide (MoS) is a promising electrocatalyst for hydrogen evolution reaction (HER), but only edges and S-vacancies are catalytic active sites for the HER. Therefore, it is crucial to increase edge sites and S-vacancies for enhancing the HER activity of MoS. Here, we report an enhanced HER activity of MoS by combing vertical nanosheets and H annealing. Compared to horizontal MoS nanosheets, pristine vertical MoS nanosheets showed better HER activity due to a larger amount of edges. H annealing further enhanced the HER activity of vertical MoS nanosheets remarkably. Scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS) and electrochemical impedance spectroscopy (EIS) were used to elucidate the enhanced HER activity by H annealing. SEM images showed that H annealing roughened the MoS edges, leading to more edge sites. XPS data revealed the smaller S : Mo ratio after H annealing, meaning more S-vacancies. Meanwhile, EIS measurements showed that charge transfer was accelerated by H annealing. These findings elaborated the H annealing induced enhancement of the HER activity, which were further confirmed by the subsequent re-sulfurization experiment.
二硫化钼（MoS）是一种很有前景的用于析氢反应（HER）的电催化剂，但只有边缘和硫空位是HER的催化活性位点。因此，增加边缘位点和硫空位对于提高MoS的HER活性至关重要。在此，我们报道了通过结合垂直纳米片和氢退火来提高MoS的HER活性。与水平的MoS纳米片相比，原始的垂直MoS纳米片由于具有大量边缘而表现出更好的HER活性。氢退火进一步显著提高了垂直MoS纳米片的HER活性。利用扫描电子显微镜（SEM）、X射线光电子能谱（XPS）和电化学阻抗谱（EIS）来阐明氢退火对HER活性的增强作用。SEM图像显示氢退火使MoS边缘变得粗糙，从而产生更多边缘位点。XPS数据显示氢退火后硫与钼的比例变小，这意味着有更多的硫空位。同时，EIS测量表明氢退火加速了电荷转移。这些发现阐述了氢退火诱导的HER活性增强，随后的再硫化实验进一步证实了这一点。
