Direct Synthesis\nof H<sub>2</sub>O<sub>2</sub> over\nAuCu@AuPd Core–Shell Catalysts with Highly Dispersed Pd Sites

The PdAu alloy catalyst exhibits\nremarkable performance\nin the\ndirect synthesis of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>)\nfrom hydrogen and oxygen, but it still faces many challenges such\nas poor activity and H<sub>2</sub>O<sub>2</sub> selectivity under\nambient pressure as well as low utilization of precious metals. In\nthis work, AuCu@AuPd core–shell catalysts with a Cu-enriched\ncore and highly dispersed Pd sites on the alloy surface were successfully\nprepared by the simple incipient wetness impregnation method and galvanic\nreplacement reaction. Among them, the AuCu<sub>1.5</sub>@AuPd catalyst\nshows the highest H<sub>2</sub>O<sub>2</sub> selectivity of 89.5%\nunder ambient pressure. Combined with multiple characterizations and\ncatalytic performance studies, it was proved that the highly dispersed\nPd sites coordinated with Au atoms on the surface are beneficial to\nthe synthesis of H<sub>2</sub>O<sub>2</sub>, while the highly dispersed\nPd sites coordinated with Cu atoms show low activity for the synthesis\nof H<sub>2</sub>O<sub>2</sub> due to the easy spillover of H* and\ndifficulty of reaction between O<sub>2</sub>* and H*. Since both Pd\nand Au atoms are located on the surface, the core–shell structure\nof AuCu@AuPd can improve not only the selectivity and productivity\nof H<sub>2</sub>O<sub>2</sub> but also the utilization rate of precious\nmetals Pd and Au.