Direct Synthesis of H2O2 over AuCu@AuPd Core-Shell Catalysts with Highly Dispersed Pd Sites

The PdAu alloy catalyst exhibits remarkable performance in the direct synthesis of hydrogen peroxide (H2O2) from hydrogen and oxygen, but it still faces many challenges such as poor activity and H2O2 selectivity under ambient pressure as well as low utilization of precious metals. In this work, AuCu@AuPd core-shell catalysts with a Cu-enriched core and highly dispersed Pd sites on the alloy surface were successfully prepared by the simple incipient wetness impregnation method and galvanic replacement reaction. Among them, the AuCu1.5@AuPd catalyst shows the highest H2O2 selectivity of 89.5% under ambient pressure. Combined with multiple characterizations and catalytic performance studies, it was proved that the highly dispersed Pd sites coordinated with Au atoms on the surface are beneficial to the synthesis of H2O2, while the highly dispersed Pd sites coordinated with Cu atoms show low activity for the synthesis of H2O2 due to the easy spillover of H* and difficulty of reaction between O2* and H*. Since both Pd and Au atoms are located on the surface, the core-shell structure of AuCu@AuPd can improve not only the selectivity and productivity of H2O2 but also the utilization rate of precious metals Pd and Au.