Density functional theory studies of transition metal doped Ti3N2 MXene monolayer

Spin-polarized density functional theory calculations with van der Waals correction were applied to investigate the presence of transition metal dopant atoms (Fe, Co, Ni, Pd and Pt) and their respective nitrogen vacancy complexes in the Ti3N2 MXene monolayer as candidate material for hydrogen evolution reaction (HER). We found that the transition metal dopant atoms as well as transition metal vacancy will feasibly form. However, the cation transition metal dopant atoms with nitrogen vacancy complexes and nitrogen vacancy are endothermic except for the PtTi + VN complex, thus would require additional energy to be realized. To evaluate for the HER activity, the Gibbs free energy and adsorption energetics were calculated. We found that the H atom stably bind to the considered surface configurations. However, the Gibbs free energy is far from optimal for the dopant complexes and the pristine Ti3N2 MXene monolayer. All the considered configurations have magnetic metallic ground state with possible application as 2D magnetic system.