Theoretical design of active GaO monolayer-based catalysts for electrocatalytic HER.

Electrocatalytic hydrogen evolution reaction (HER) offers a sustainable and clean route for hydrogen production. Developing a high-efficiency HER catalyst is extremely essential toward meeting future energy needs. Herein, the Sn-doped GaO monolayer, O-defected GaO monolayer, and Ru-adsorbed GaO monolayer with high electrocatalytic performances toward HER are reported (their H adsorption free energies are 0.169, 0.126 and 0.065 eV, respectively). The Sn-doped GaO monolayer follows the Volmer-Heyrovsky mechanism, and the O-defected GaO monolayer and Ru-adsorbed GaO monolayer are suitable for Volmer-Tafel mechanisms. The strain from -4% to 4% in the - or -direction could linearly modulate the HER activities of the Sn-doped GaO monolayer and O-defected GaO monolayer. The Sn-doped GaO monolayer, O-defected GaO monolayer, and Ru-adsorbed GaO monolayer only manifest high HER catalytic activities in the strong acidic media. These phenomena can provide a rational approach to enhance the HER activity for GaO monolayer-based materials.