Enhanced hydrogen evolution reaction activity of hydrogen-annealed vertical MoS nanosheets

• Published in: RSC advances Vol. 8; no. 26; pp. 14369 - 14376
• Main Authors: He, Mengci, Kong, Fanpeng, Yin, Geping, Lv, Zhe, Sun, Xiudong, Shi, Hongyan, Gao, Bo
• Format: Journal Article
• Language: English
• Published: 17.04.2018
• ISSN: 2046-2069
• DOI: 10.1039/c8ra01147h

Molybdenum disulfide (MoS 2 ) 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 2 . Here, we report an enhanced HER activity of MoS 2 by combing vertical nanosheets and H 2 annealing. Compared to horizontal MoS 2 nanosheets, pristine vertical MoS 2 nanosheets showed better HER activity due to a larger amount of edges. H 2 annealing further enhanced the HER activity of vertical MoS 2 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 2 annealing. SEM images showed that H 2 annealing roughened the MoS 2 edges, leading to more edge sites. XPS data revealed the smaller S : Mo ratio after H 2 annealing, meaning more S-vacancies. Meanwhile, EIS measurements showed that charge transfer was accelerated by H 2 annealing. These findings elaborated the H 2 annealing induced enhancement of the HER activity, which were further confirmed by the subsequent re-sulfurization experiment. Vertical configuration and H 2 annealing enhanced the hydrogen evolution reaction activity of MoS 2 nanosheets.