Design of effective graphenes co-doped by transition metal and nonmetal atoms for nitrate electroreduction: A first-principles study

Developing high-efficient electrocatalysts driven by renewable electricity to eliminate hazardous nitrate (NO3-) in daily life is of great scientific value. Thereby, a valid heterogeneous catalyst is proposed based on single titanium atom supported on sulfur co-doped graphene (TiS-G) for nitrate reduction reaction (NO3RR) using density functional theory (DFT). Under an external potential of 0.53 V, the overall reduction progress is thermodynamic spontaneous at ambient temperature and the maximum kinetic determining step is the formation of ammonia with a barrier of 0.63 V, comparable with experimental benchmark Cu(111). Intriguingly, this increased activity originates from reasonable accumulation of d orbital electrons around Fermi level, which contributes to a linear relationship between the atomic charge and classic d band center of the transition metal. Furthermore, metal clustering aggression, oxide poisoning, and dynamic stability are thorough examined in order to ensure the robustness of TiS-G structure under actual environment. This work not only opens up a novel avenue for the potential application of carbon-based electrodes in NO3RR, but also offers an atomic insight into catalytic reaction mechanism.