Distribution Pattern of Metal Atoms in Bimetal-Doped Pyridinic-N 4 Pores Determines Their Potential for Electrocatalytic N 2 Reduction.

Doping two single transition-metal (TM) atoms on a substrate host opens numerous possibilities for catalyst design. However, what if the substrate contains more than one vacancy site? Then, the combination of two TMs along with their distribution patterns becomes a design parameter potentially complementary to the substrate itself and the bimetal composition. In this study, we investigate ammonia synthesis under mild electrocatalytic conditions on a transition-metal-doped porous C 24 N 24 catalyst using density functional theory (DFT). The TMs studied include Ti, Mn, and Cu in a 2:4 dopant ratio (Ti 2 Mn 4 @C 24 N 24 and Ti 2 Cu 4 @C 24 N 24 ). Our computations show that a single Ti atom in both catalysts exhibits the highest selectivity for N 2 fixation at ambient conditions. This work is a good theoretical model to establish the structure-activity relationship, and the knowledge earned from the metal-N 4 moieties may help studies of related nanomaterials, especially those with curved structures.