Construction of a Novel Cascade Electrolysis-Heterocatalysis System by Using Zeolite-Encaged Ultrasmall Palladium Catalysts for H₂O₂ Generation

In situ generation of hydrogen peroxide (H2O2) has attracted extensive attention, especially in water treatment. However, traditional anthraquinones can only produce high-concentration H2O2 and its transportation and storage are not convenient and dangerous. Herein, an in situ and on-demand strategy to produce H2O2 by using a cascade water electrolysis together with a heterocatalysis system is provided. Beginning with water, H-2,H- and O-2 can be generated via electrolysis and then react with each other to produce H2O2 immediately on efficient zeolite-encaged ultrasmall Pd catalysts. Significantly, the H2O2 generation rate in the optimized cascade system reaches up to 0.85 mol L-1 h(-1) g(Pd)(-1), overcoming most of the state-of-the-art catalysts in previous literature. The confinement effect of zeolites is not only beneficial to the formation of highly dispersed metal species, promoting the H2O2 generation, but also inhibits the H2O2 decomposition, enhancing the production yield of H2O2. In addition, the effect of electrolytes, sizes of Pd species, as well as zeolite acidity are also systematically studied. This work provides a new avenue for H2O2 generation via a highly efficient cascade electrolysis-heterocatalysis system by using zeolite-supported metal catalysts. The high catalytic efficiency and green process for H2O2 generation make it very promising for further practical applications.