Direct synthesis of hydrogen peroxide from hydrogen and oxygen over single-crystal cubic palladium on silica catalysts

The activities of Pd metal catalysts for direct hydrogen peroxide synthesis are influenced by the morphological and crystallographic properties of the Pd species. We prepared {1 0 0}-facet-enclosed Pd nanocubes of uniform shape, size, and crystallinity using an aqueous colloidal method. The nanocube size was adjusted, without affecting the shape, by changing the composition of the halide-ion capping agent. The Pd nanocubes were impregnated on silica, and tested as a catalyst in direct hydrogen peroxide synthesis. The {1 0 0} Pd facet catalyzed hydrogen peroxide formation but promoted side reactions, decreasing hydrogen peroxide selectivity; the selectivity was improved by blocking active sites on the {1 0 0} facet with bromide ions.