Epoxy Group Modified Atomic Zn–N2O2 for H2O2 Electrosynthesis and Sulfide Oxidation

In this study, zinc single-atom catalysts (SACs) (Zn SACs) with Zn–N2O2 as the coordination shell and the epoxy group (C–O–C) as the second coordination structure are synthesized. The obtained Zn SACs exhibit a high 2e– ORR selectivity of >85% in a wide potential window of 0–0.65 V vs RHE and achieve a high generation rate of 828.9 mmol gcat–1 h–1 for H2O2. Experimental and theoretical calculations have confirmed that the second coordination structure of adjacent C–O–C can effectively optimize the adsorption energy of Zn–N2O2 for *OOH and tune the 2e– ORR selectivity. In addition, a small onset potential of 0.38 V vs RHE is achieved for sulfides oxidation reaction (SOR) by the obtained Zn SACs. Moreover, a coupled system of anodic SOR and cathodic 2e– ORR is fabricated, which can save 45% energy consumption compared to the OER-2e– ORR system due to a decreased cell voltage of 2.03 V at 20 mA cm–2. This study provides new bifunctional Zn SACs modified by adjacent C–O–C, which are effective as bifunctional catalysts for electrosynthesis of H2O2 and electro-oxidation of sulfides. These two reactions can be performed together in a coupled system with decreased energy cost and thus should have better application potential.