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 g_cat^–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.