Triggering basal plane active sites of monolayer MoS₂ for the hydrogen evolution reaction by phosphorus doping

Monolayer MoS₂ has attracted much attention due to its catalytic performance in water splitting. However, the low electronic conductivity and limited number of active catalytic sites of monolayer MoS₂ limit the hydrogen production efficiency. In this work, the effect of phosphorus doping on the electronic characteristics and catalytic activity of the hydrogen evolution reaction in monolayer MoS₂ was studied using density functional theory. A semiconductor to conductor transformation occurs in monolayer MoS_2(1-x)P_x for x larger than 0.25. The Gibbs free energy is greatly reduced from 2.18 to 0.03 eV for the adsorption of hydrogen on monolayer MoS_0.5P_0.75. The Gibbs free energy for hydrogen atom adsorption on monolayer MoS_0.5P_0.75 is between 0.03 and 0.16 eV with hydrogen coverage θ_H = 1/12–7/12 ML. The Gibbs free energy is close to zero, indicating that phosphorus doping can trigger the basal plane active sites on monolayer MoS₂; thus, this work provides a new design for the improvement of the catalytic activity of two-dimensional transition metal dichalcogenide-based catalysts by phosphorus doping.