Developing earth-abundant, active, and stable electrocatalysts for the hydrogen evolution reaction (HER) has attracted intense research efforts because of its importance in electrolysis to produce hydrogen.¹ MoS₂ is a promising catalyst for HER. It is structurally a layered material with weak van der Waal forces and is electrically semiconducting with an indirect bandgap of 1.2 eV.¹ Therefore, MoS₂ size can be easily controlled, and hence its electronic properties. Natural MoS₂ is present in the 2H-phase (H for Hexagonal). Edge sites of 2H-MoS₂ are active for HER, and efforts have been made to maximize them by decreasing the size.² Recently, it was found that the electrochemical generation of S-vacancies on the basal plane of 2H-MoS₂ can increase the HER activity.³ Therefore, it is important to obtain stable MoS₂ layers with optimum S-vacancies to improve the HER activity. In this study, we obtained various thicknesses of MoS₂ using liquid cascade centrifugation in 2000, 4000, 7000, and 10000 g. Among them, the MoS₂ obtained at 4000 g resulted in the highest HER activity in 1N H₂SO₄. Controlling the convection of H⁺ could be an efficient approach to accessing the S-atoms located within the layers of MoS₂. Therefore, we employ various magnetic fields (~ 0.01 - 0.5 T) to generate the magnetohydrodynamic mass transport to create the S-vacancies without disturbing the layered structure of MoS₂. Thus created S-vacancies are characterized using Raman analysis, X-ray photoelectron spectroscopy and scanning transmission microscopy, and the enhanced HER activity of desulphurized MoS₂ will be quantified.

References:

(1) D. Gupta, V. Chauhan, R. Kumar, Inorg. Chem. Commun., 121, 108200 (2020).

(2) F. Jaramillo Thomas, P. Jørgensen Kristina, J. Bonde, N. Nielsen Jane, S. Horch, I. Chorkendorff, Science, 317, 5834 (2007)