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 HAuCl4 and H2PtCl4. In the second step, the Ag component was selectively dealloyed with nitric acid (HNO3), 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 (HAuCl4 and H2PtCl6). 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.

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► Mono-dispersive homogeneous Ag nanoparticles were synthesized in an aqueous medium.
► Hollow and nano-porous Au/Pt alloy nanoparticles were formed via galvanic replacement and subsequent dealloying of Ag.
► Hollow, porous Au/Pt alloy NPs showed enhanced catalytic activity toward formic acid electrooxidation.