Highly selective oxygen reduction to H2O2 on π-d conjugated coordination polymers: The effect of coordination atoms

Abstract

Single-atom catalysts (SACs) feature the excellent potential for H2O2 production via 2e− oxygen reduction reactions (ORR). The coordination atoms of SACs play a critical role in regulating the catalytic performance, while the underlying relationship between the coordination atoms and performance remains obscure. Here, two kinds of Ni-based π-d conjugated coordination polymers with atomically dispersed NiN4 and NiN2O2 sites are rationally constructed for ORR. The NiN2O2 catalyst exerts a high H2O2 production rate of 374 mmol gcat−1 h−1 with an excellent selectivity of 91 %, while the selectivity on the NiN4 one is only 60 %, demonstrating a coordination atoms-dependent performance. Experimental and theoretical investigations reveal that the energy barriers for the formation of the key *OOH intermediate and the subsequent hydrogenation could be optimized by introducing O atoms in the first coordination sphere, which contributes to the efficient regulation of the selectivity and activity of 2e− ORR process.