Theoretical Insights into the Hydrogen Evolution Reaction on VGe(2)N(4) and NbGe(2)N(4) Monolayers

[Image: see text] Catalytically active sites at the basal plane of two-dimensional monolayers for hydrogen evolution reaction (HER) are important for the mass production of hydrogen. The structural, electronic, and catalytic properties of two-dimensional VGe(2)N(4) and NbGe(2)N(4) monolayers are demonstrated using the first-principles calculations. The dynamical stability is confirmed through phonon calculations, followed by computation of the electronic structure employing the hybrid functional HSE06 and PBE+U. Here, we introduced two strategies, strain and doping, to tune their catalytic properties toward HER. Our results show that the HER activity of VGe(2)N(4) and NbGe(2)N(4) monolayers are sensitive to the applied strain. A 3% tensile strain results in the adsorption Gibbs free energy (ΔG(H*)) of hydrogen for the NbGe(2)N(4) monolayer of 0.015 eV, indicating better activity than Pt (−0.09 eV). At the compressive strain of 3%, the ΔG(H*) value is −0.09 eV for the VGe(2)N(4) monolayer, which is comparable to that of Pt. The exchange current density for the P doping at the N site of the NbGe(2)N(4) monolayer makes it a promising electrocatalyst for HER (ΔG(H*) = 0.11 eV). Our findings imply the great potential of the VGe(2)N(4) and NbGe(2)N(4) monolayers as electrocatalysts for HER activity.