Surface plasma–induced tunable nitrogen doping through precursors provides 1T-2H MoSe2/graphene sheet composites as electrocatalysts for the hydrogen evolution reaction

• Published in: Electrochimica acta 2022-09, Vol.426, p.140767, Article 140767
• Main Authors: Huang, Shih-Yu, Le, Phuoc-Anh, Nguyen, Van-Truong, Lu, Yi-Chun, Sung, Chia-Wei, Cheng, Hao-Wen, Hsiao, Chang-Yu, Dang, Van Dien, Chiu, Po-Wen, Wei, Kung-Hwa
• Format: Article
• Language: English
• Subjects: Electrocatalyst; Hydrogen evolution reaction; N-doped 1T-2H MoSe2/G composites; Surface plasma process; Tunable nitrogen doping
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2022.140767

•Proposed tunable nitrogen doping providing 1T-2H MoSe2/graphene sheet composites with surface-plasma-induced exfoliation and doping.•The amount of doped nitrogen atoms in MoSe2 determines the optimal content of the 1T phase in MoSe2 nanosheets.•Both 1T phase of MoSe2 and incorporated graphene sheets in the composites improve the HER performance. In this paper we present that the surface plasma-induced tunable nitrogen doping that requires short processing time at low temperature through various nitrogen precursors that converted the 2H phase into a coexisting 1T-2H phase in the MoSe2 nanosheets; subsequently combining the N-doped MoSe2 with graphene sheets (G) for synthesis of N-doped 1T-2H MoSe2/G composites (N-MoSe2/G) for the hydrogen evolution reaction (HER). We found that the amount of the 1T phase in the MoSe2 nanosheets can be tuned by selecting suitable N-atom precursors—such as NH4NO3, urea and melamine—with our method; moreover, the amount of the 1T phase of the composites induced increases with nitrogen doping concentration at low concentration range (Ca. 4.7%—7.3%) but decreased when the nitrogen doping is over 7.3%. Subsequently, after covering the N-MoSe2 with graphene sheets, the composites featuring highly active sites that facilitated the hydrogen evolution reaction (HER). As a result, the N-MoSe2/G composites exhibited a low overpotential of 153 mV at a current density of 10 mA/cm2 and a Tafel slope of 67 mV/dec, much better than those of undoped-MoSe2 (252 mV, 123 mV/dec) and the N-MoSe2 nanosheets (197 mV, 83 mV/dec). The N-MoSe2/G composites also functioned as a stable electrocatalyst, undergoing over 10,000 cycles of linear sweep voltammetry without degradation. Our approach to tunable nitrogen doping in MoSe2 nanosheets and forming composites provides a feasible way to produce electrocatalysts in mass-scale and low energy process with two-dimensional transition metal dichalcogenide materials. [Display omitted]