Potential of Tandem Catalysts for Excellent H₂O₂ Electrosynthesis at Industrial-Relevant Current.

Abstract

Direct electrosynthesis of hydrogen peroxide (H₂O₂) serves as an innovative and less-energy-demanding alternative to the conventional anthraquinone process. As the process involves active hydrogen (*H) production and hydrogenation of oxygen-containing intermediates, catalysts containing dual functional sites for *H and *OOH intermediate generation might boost the H₂O₂ electrosynthesis activity. Here, we report a tandem catalyst with a uniform distribution of single-atom Al sites around Al₂O₃ species, constituting the adjacent catalytic centers (Al₂O₃/Al₁-O-C). The Al₂O₃/Al₁-O-C catalysts exhibit high H₂O₂ selectivity in alkaline conditions and achieve a yield rate of 39.4 mol g_cat.^-1 h^-1 with a favorable stability of over 100 h in the flow cell. The direct output concentration of H₂O₂ can reach 1659.2 mmol L^-1 (5.61 wt %) at 400 mA cm^-2. The in situ measurements and simulated calculations reveal that the Al₂O₃ sites catalyze the Volmer step in water decomposition to generate *H, which significantly promotes the *OOH generation from the reduction of *O₂ on single-atom Al sites, thus promoting H₂O₂ electrosynthesis at high current densities. This tandem design enables industrially relevant H₂O₂ electrosynthesis, demonstrating the potential for practical applications in the future.