High Catalytic Performance of Silver-Doped Gold Nanocages for Methanol Electrooxidation

Hollow or porous noble metal nanocrystals with large specific electrochemical surface area and stability hold stimulating technological applications in fuel cell catalysis. Here, a simple galvanic replacement reaction synthesis of Ag-doped Au nanocages with a tunable Ag/Au atomic ratio is developed. Without surface ligands being used in the synthesis, the obtained AuAg nanocages with hollow cavity and opened nanoporous shell possess clean surface and enhanced electrocatalytic activity. In the electrocatalysis of the methanol oxidation reaction (MOR), the obtained AuAg nanocages possess high electrocatalysis properties and show morphology and composition-dependent electrocatalytic property. The optimized AuAg cubic nanocages that have 5% Ag exhibit excellent electrocatalytic activity for MOR, and this is attributed to the unique geometric structure and the well-controlled Ag content. The hollow and nanoporous structure can effectively promote the mass transfer and atomic utilization during the catalytic process for MOR. Density functional theory calculations indicate that introducing of a small amount of Ag facilitates methanol adsorption to the surface of catalysts and promotes the break of the O  H bond during the MOR process, thus accordingly enhances the catalytic activity.