General Thermal Texturization Process of MoS_2 for Efficient Electrocatalytic Hydrogen Evolution Reaction

Abstract

Molybdenum disulfide (MoS_2) has been widely examined as a catalyst containing no precious metals for the hydrogen evolution reaction (HER); however, these examinations have utilized synthesized MoS_2 because the pristine MoS_2 mineral is known to be a poor catalyst. The fundamental challenge with pristine MoS_2 is the inert HER activity of the predominant (0001) basal surface plane. In order to achieve high HER performance with pristine MoS_2, it is essential to activate the basal plane. Here, we report a general thermal process in which the basal plane is texturized to increase the density of HER-active edge sites. This texturization is achieved through a simple thermal annealing procedure in a hydrogen environment, removing sulfur from the MoS_2 surface to form edge sites. As a result, the process generates high HER catalytic performance in pristine MoS_2 across various morphologies such as the bulk mineral, films composed of micron-scale flakes, and even films of a commercially available spray of nanoflake MoS_2. The lowest overpotential (η) observed for these samples was η = 170 mV to obtain 10 mA/cm_2 of HER current density.