Asymmetric S Heteroatom Coordinated Dual-Atom Catalysts and Coupled Anodic Sulfion Oxidation to Boost Electrocatalysis Oxygen Reduction

Abstract

Considering the exceptional electronic regulation capability, p-block elements can be used to regulate the charge density of traditional transition metal catalysts. In this work, CoGa-NS-C dual-atom catalysts (DACs) are successfully synthesized through co-precipitation and post-annealing treatment. The atomic dispersion of Co and Ga and the synergistic coordination structure of CoN₃S₁ and GaN₄ are confirmed by AC-TEM, EXAFS, and XPS. Due to the steric hindrance effect of adsorbed ^*OH on the Ga site and the asymmetric S heteroatom coordination on Co species, the adsorption energy of ^*OOH intermediation on neighboring Co is thus enhanced greatly, resulting in the enhancement of the 2e-ORR pathway. Besides, ^*OOH and Co─OH intermediates are detected by in situ FT-IR and EC-SHINERS spectroscopy. A high H₂O₂ selectivity of 90.3% and a fast H₂O₂ production rate of 1.12 mol h⁻¹ g⁻¹ can be reached. In addition, the cathodic oxygen reduction is used to couple with sulfion oxidation reaction (SOR) instead of the energy-intensive OER reaction. In this coupling system, the SOR potential is 1.31 V lower than the OER process at the current intensity of 100 mA. Both the proposed dual-atom DACs regulation strategy by p-block elements and the ORR-SOR coupling system are beneficial for achieving efficient and energy-effective 2e-ORR.