Role of Transition Metal Dichalcogenides as a Catalyst Support for Decorating Gold Nanoparticles for Enhanced Hydrogen Evolution Reaction

The two-dimensional (2D) transition metal dichalcogenides (TMDs) have been widely used in various electrochemical applications, such as electrocatalysts, sensors, and energy storage. They have been potentially demonstrated not only as catalysts but also as supporting materials for boosting catalytic performance and durability. However, the different types of TMD nanosheets (transition metals and chalcogenide atoms) for supporting nanoparticles have not yet been investigated for electrocatalytic performance. Herein, we provide mechanistic insights into the hydrogen evolution reaction (HER) of various TMDs (i.e., MoS₂, MoSe₂, and WSe₂) as catalyst supports for the decoration of gold nanoparticles (AuNPs), which represent an active catalyst. Among various TMD supports, it was found that the MoS₂ supports with an optimal amount of AuNPs loading (MoS₂/AuNPs) exhibited excellent catalytic activity (low overpotential and Tafel slope), which is better than that of other TMD supports and the previously reported TMD-based support. This is due to well-dispersed AuNPs with the charge transfer of Au-MoS₂ interaction (increasing <i>n</i>-type), leading to highly active sites for HER performance. Moreover, the perfect laminar stacking of the MoS₂/AuNPs electrode, providing high porosity and good wettability, plays an important role in enhancing the ability of ionic electrolytes to infiltrate through the electrode area (up to ∼50 F g^-1). The MoS₂/AuNPs exhibit long-term stability with no disintegration of the electrode when performing the HER at ultrahigh current density (>200 mA cm^-2) for over 24 h. This work aims to deepen the understanding of TMD materials as catalyst supports, and is advantageous for the development of catalyst-based applications.