Comparative Characteristics of Catalytically Active MoS_x Films in the Hydrogen Evolution Reaction on a MoS_x/WSe₂ Heterojunction Photocathode

The method of pulsed laser deposition (PLD) has attracted increasing attention as a promising approach for optimizing catalysts to enhance their efficiency in various applications. One of the current challenges is the simple and controllable synthesis of materials based on transition metal chalcogenides (in particular, MoS_x), which can exhibit an increased electrocatalytic activity in the hydrogen evolution reaction. Changes in the chemical states of sulfur and molybdenum as a result of photoelectrochemical tests are studied in this work. By varying the laser fluence and buffer gas pressure, deposition regimes have been determined that result in catalytic layers with minimal substoichiometric states, which are responsible for shifting the Fermi level to the conduction band edge. Combining experimental results and DFT calculations, catalytically active sites on the film surfaces have been identified.