Theoretical analysis of oxygen reduction reaction activity on single metal (Ni, Pd, Pt, Cu, Ag, Au) atom supported on defective two-dimensional boron nitride materials.

A single atom supported by two-dimensional material is a suitable candidate for an oxygen reduction reaction (ORR) to replace Pt-based catalysts. In this work, new promising single-atom catalysts (SACs) with precise metal-nitrogen coordination (M-N) were investigated, where a single transition metal atom (M = Ni, Pd, Pt, Cu, Ag, Au) was supported by experimentally available defective two-dimensional boron nitride materials (M/BN) with a boron vacancy. ORR performance is predicated by the volcano plot, which indicates that those M/BN catalysts offer optimized binding strength of *OH species exhibiting high ORR activity. Moreover, only a direct 4e- pathway occurs on Ni/BN, Pd/BN and Pt/BN with only d valence electrons of a single metal atom. As an example, Pd/BN catalyzes ORR via a direct 4e- pathway with a small reaction barrier of 0.42 eV, which is smaller than that of Pt-based catalysts (0.79 eV). This high activity is attributed to precise M-N3 coordination in the M/BN catalysts. This work is expected to provide useful insight for development of novel high-efficiency SACs for ORR.