Synthesis of hollow and nanoporous gold/platinum alloy nanoparticles and their electrocatalytic activity for formic acid oxidation.

In this work, hollow Au/Pt alloy nanoparticles (NPs) with porous surfaces were synthesized in a two-step procedure. In the first step, tri-component Ag/Au/Pt alloy NPs were synthesized through the galvanic replacement reaction between Ag NPs and aqueous solutions containing a mixture of HAuCl(4) and H(2)PtCl(4). In the second step, the Ag component was selectively dealloyed with nitric acid (HNO(3)), resulting in hollow di-component Au/Pt alloy NPs with a porous surface morphology. The atomic ratio of Au to Pt in the NPs was easily tunable by controlling the molar ratio of the precursor solution (HAuCl(4) and H(2)PtCl(6)). Hollow, porous Au/Pt alloy NPs showed enhanced catalytic activity toward formic acid electrooxidation compared to the analogous pure Pt NPs. This improved activity can be attributable to the suppression of CO poisoning via the "ensemble" effect.