Supplementary material from "Silver–palladium catalysts for the direct synthesis of hydrogen peroxide"

A series of bimetallic silver–palladium catalysts supported on titania were prepared by wet impregnation and assessed for the direct synthesis of hydrogen peroxide, and its subsequent side reactions. The addition of silver to a palladium catalyst was found to significantly decrease hydrogen peroxide productivity and hydrogenation, but crucially increase the rate of decomposition. The decomposition product; that is predominantly hydroxyl radicals can be used to decrease bacterial colonies. The interaction between silver and palladium was characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results of the TPR and XPS indicated the formation of a silver–palladium alloy. The optimal 1% Ag–4% Pd/TiO₂ bimetallic catalyst was able to produce approximately 200 ppm of H₂O₂ in 30 min. The findings demonstrate that AgPd/TiO₂ catalysts are active for the synthesis of hydrogen peroxide and its subsequent decomposition to reactive oxygen species. The catalysts are promising for use in wastewater treatment as they combine both the disinfectant properties of silver, hydrogen peroxide production and subsequent decomposition.