Interfacial Acid Sites-Mediated ZnO-Based Electrocatalysts for Sustainable Dual-Pathway H₂O₂ Production and Rechargeable Zn-H₂O₂ Electrochemical Cell.

Abstract

Facing the challenge of achieving efficient and sustainable hydrogen peroxide (H₂O₂) production, a promising strategy is developing highly selective electrocatalysts with controllable synthesis, structural design and performance optimization. Herein, an interfacial acid sites-mediated ZnSe/ZnO heterojunction is synthesized for highly selective two-electron oxygen reduction reaction (ORR) toward H₂O₂ production. Experimental and theoretical results reveal that surface selenization induced reconstruction, forming a synergistic interface with a built-in electric field and tailored oxygen vacancies (Ovs), which collaboratively optimize the electronic structure and accelerate reaction kinetics of two-electron ORR. Moreover, interfacial unsaturated Zn²⁺ sites and OVs served as Lewis acids sites to enhance O₂ adsorption and activation, while Brønsted acids sites were liable to donate protons to promote *OOH formation. Consequently, a ZnSe/ZnO ‖ ZnO flow cell enabled paired electrolysis for concurrent H₂O₂ production with a high H₂O₂ yield of 754.4 M g_cat ^-1 over 12 h. A rechargeable Zn-H₂O₂ cell using ZnSe/ZnO cathode delivered a power density of 11.99 mW cm^-2 as a self-sustaining process for simultaneous on-site H₂O₂ production and electrical energy generation. This work offers a sustainable route for on-site H₂O₂ synthesis with improved energy efficiency, advancing green chemistry and circular economy.