Effect of aging on the electrocatalytic activity of gold nanoparticles

The electrocatalytic activities of freshly prepared nanomaterials do not represent normal activities, if they change with aging. We report the dependence of the electrocatalytic activity of gold nanoparticles (AuNPs) upon aging. The activities of AuNPs prepared by four different methods (electrodeposition; reduction of Au ions with NaBH4, citrate, and ascorbate, respectively) slowly decrease with aging in the electrooxidation of H2O2 or formic acid, both in air and in solution. The possible origin of this effect is discussed.