Predicting two-dimensional pentagonal transition metal monophosphides for efficient electrocatalytic nitrogen reduction

Electrocatalytic reduction of nitrogen (N2) to ammonia (NH3), as an alternative to the traditional energy-consuming Habor–Bosch nitrogen fixation, is a fascinating yet challenging topic. Here, we design a novel group of materials—two-dimensional (2D) pentagonal transition metal phosphides (penta-MP, M=Ti, Zr, Hf) and study their potential applications in the nitrogen reduction reaction (NRR). Penta-MP are predicted to be dynamically, thermally, and mechanically stable through density functional theory calculation and ab initio molecular dynamics simulations. Their quasi-planar structures and metalic properties facilitate the strong N2 adsorption on the surface. Gibbs free energy diagram suggests that NRR on penta-MP prefers the distal reaction mechanism, with the low overpotential of 0.56 eV for penta-TiP, which is beneficial for efficient electrocatalytic NRR. Our findings open up a new avenue for designing novel 2D materials as well as electrocatalysts.