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

Direct electrosynthesis of hydrogen peroxide (HO) 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 HO electrosynthesis activity. Here, we report a tandem catalyst with a uniform distribution of single-atom Al sites around AlO species, constituting the adjacent catalytic centers (AlO/Al-O-C). The AlO/Al-O-C catalysts exhibit high HO selectivity in alkaline conditions and achieve a yield rate of 39.4 mol g h with a favorable stability of over 100 h in the flow cell. The direct output concentration of HO can reach 1659.2 mmol L (5.61 wt %) at 400 mA cm. The in situ measurements and simulated calculations reveal that the AlO sites catalyze the Volmer step in water decomposition to generate *H, which significantly promotes the *OOH generation from the reduction of *O on single-atom Al sites, thus promoting HO electrosynthesis at high current densities. This tandem design enables industrially relevant HO electrosynthesis, demonstrating the potential for practical applications in the future.