Green synthesis of core-shell gold-palladium@palladium nanocrystals dispersed on graphene with enhanced catalytic activity toward oxygen reduction and methanol oxidation in alkaline media

We have developed a simple and green wet-chemical route for large-scale synthesis of core-shell AuPd@Pd nanocrystals, without using any template, seed, organic solvent, or surfactant. HEPES is used here as a reducing agent and a shape-directing agent. The as-prepared nanocrystals were uniformly dispersed on graphene nanosheets (G) by simple ultrasonication. The resulting G-AuPd@Pd displayed the enhanced catalytic activity for oxygen reduction reaction and methanol oxidation reaction in alkaline media, compared with the G-Pd and commercial Pd black catalysts.298