Key Role of Local Chemistry in Lattice Nitrogen-Participated N2-to-NH3 Electrocatalytic Cycle over Nitrides

Metal nitrides offer great opportunities for improving activity and selectivity of electrocatalytic nitrogen reduction reaction (ENRR) via the lattice nitrogen-participated mechanism. Understanding the role of local chemistry of lattice nitrogen is important for establishing rational design principles of nitride catalysts. Herein, high-throughput theoretical calculations are employed to investigate lattice nitrogen-participated ENRR over a family of antiperovskite nitrides (M ' M3N, M and M ' are different metal atoms) with highly tunable surrounding environments of N atoms. The M ' M3N structure comprises isolated N atoms in the center, M atoms in the first coordination shells, and M ' atoms in the second coordination shells. An appropriate M-N bond strength is found to be crucial for designing ideal nitride catalysts. Specifically, weak M-N bonding facilitates the participation of lattice nitrogen and better activity, but too weak M-N bonding results in structural instability of antiperovskite. The type of M element governs M-N bond strength through adjusting hybridization interactions between M orbital and N orbital, and the M ' element can further finely regulate M-N bond strength via M-M ' polarization effects. Finally, AgBa3N, AlBa3N, GaBa3N catalysts are screened to possess greater ENRR activity than the benchmarking Ru (0001) catalysts and high selectivity toward hydrogen evolution reaction.