HER activity of nanosheets of 2D solid solutions of MoSe₂ with MoS₂ and MoTe₂

MoS_xSe_(2−x) and MoSe_xTe_(2−x) solid solutions with various S:Se and Se:Te ratios have been prepared by high temperature solid-state reactions, and thinned down to few-layers by Li-intercalation followed by exfoliation. Photocatalytic as well as electrocatalytic hydrogen evolution reaction (HER) activity of exfoliated MoS_xSe_(2−x)/MoSe_xTe_(2−x) 2D nanosheets have been studied. It is found that Se-rich compositions exhibit good HER activity. The MoS_0.5Se_1.5 nanosheets show high photocatalytic HER activity yielding 29.6 mmol h⁻¹ g⁻¹ of H₂, while MoS_1.0Se_1.0 displays good electrocatalytic activity with an onset potential of −0.220 V. Amongst MoSe_xTe_(2−x) solid solutions, MoSe_1.8Te_0.2 shows relatively high photocatalytic HER activity (5.0 mmol h⁻¹ g⁻¹), while MoSe_1.0Te_1.0 exhibits a low onset potential (−0.190 V vs. RHE).