Exploring the microscopic mechanism of pseudocapacitance with electronic structures in monolayer 1T-MoS2 electrodes for supercapacitors†
Quasi-two-dimensional 1T-MoS2 is a promising pseudocapacitance (Credox) electrode material due to its large specific surface area, superior electrical conductivity and mechanical stability. However, the microscopic mechanism of Credox and its further manipulation via modulating the structures and electronic structures are still unclear. Thus, the Credox of monolayer 1T-MoS2 has been explored based on first-principles calculations. For monolayer 1T-MoS2 adsorbed by H+ ions on one side or both sides, a band gap opens, decreases and even disappears with the coverage increase in H+ ions up to 100%. In this process, the charge transfer from the monolayer 1T-MoS2 to the adsorbed H+ ions almost linearly increases with the coverage increase in the H+ ions. In contrast, the potential change rate of the monolayer 1T-MoS2 reduces, resulting in the enhancement of Credox. Herein, the maximum values of Credox reached ∼76.7 μF cm−2 (252.8 F g−1) and ∼213.7 μF cm−2 (704.5 F g−1) for the 100% coverage of H+ ions on one side and both sides, respectively. Furthermore, the manipulation of Credox in the monolayer 1T-MoS2 could be realized through intrinsic defects engineering. Particularly, the Credox was greatly improved in the system with S vacancies. These results would provide significantly fundamental insights for understanding the correlation between the Credox and the electronic structures of 1T-MoS2 and other similar quasi-two dimensional materials.
- This article is part of the themed collections: 2019 Materials Chemistry Frontiers HOT articles and Celebrating the 100th anniversary of Nankai University