Understanding mechanism conversion in hydrogen evolution reaction on PtSe2: Role of layer number explored by density functional theory

Abstract

The emerging two-dimensional (2D) transition metal dichalcogenide PtSe2 is a promising catalyst for hydrogen evolution reactions (HER). In this study, we performed density functional theory (DFT) calculations to investigate the mechanism conversion of the HER over PtSe2 with respect to the changes in the number of layers of the catalyst. We found that the adsorption energy of hydrogen (ΔGH) changed with an increase in the number of 2D material layers, and the most significant change occurred when the number of layers was increased from one to two. Furthermore, we conducted dynamic calculations to reveal the mechanisms of the HER on the basal and Vse surfaces. Owing to the changes in ΔGH, the HER mechanism undergoes a conversion between Volmer–Heyrovsky and Volmer–Volmer'–Tafel mechanisms. Through frontier orbitals analysis, layer-stacking altered the bonding capability between hydrogen and PtSe2 surfaces by altering the electronic structure of the PtSe2 surface. This study demonstrates the synergistic effect of interlayer interactions on the HER over PtSe2 catalysts and can be helpful in stimulating innovative ideas for 2D material design.