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

Single-atom catalysts (SACs) feature the excellent potential for H2O2 production via 2e- oxygen reduction re-actions (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 pi-d conjugated coordination polymers with atomically dispersed Ni-N4 and Ni-N2O2 sites are rationally constructed for ORR. The Ni-N2O2 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 Ni-N4 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.

Automated summary

The coordination atoms of single-atom catalysts (SACs) play a critical role in regulating the catalytic performance. By constructing two kinds of Ni-based coordination polymers with atomically dispersed Ni-N4 and Ni-N2O2 sites, it was found that the Ni-N2O2 catalyst exhibited a high H2O2 production rate of 374 mmol gcat -1 h-1 with an excellent selectivity of 91%, while the selectivity on the Ni-N4 catalyst was only 60%, demonstrating a coordination atoms-dependent performance. Experimental and theoretical investigations revealed that introducing O atoms in the first coordination sphere could optimize the energy barriers for the formation of key intermediates, contributing to the efficient regulation of selectivity and activity in the 2e- oxygen reduction reaction.