Highly catalytic hollow palladium nanoparticles derived from silver@silver–palladium core–shell nanostructures for the oxidation of formic acid

Abstract

Hollow Palladium (hPd) nanoparticles (NPs) are prepared via a simple and mild successive method. Firstly, core–shell NPs with silver (Ag) cores and silver–palladium (Ag–Pd) alloy shells are synthesized in aqueous phase by galvanic replacement reaction (GRR) between Ag NPs and Pd2+ ion precursors. Saturated aqueous sodium chloride (NaCl) solution was then employed to remove the Ag component from the core and shell regions of core–shell Ag@Ag–Pd NPs, resulting in the formation of hPd NPs with shrunk sizes in comparison with their core–shell parents. Specifically, the hPd NPs exhibit superior catalytic activity and durability for catalyzing the oxidation of formic acid, compared with the Pd NPs reduced by NaBH4 in aqueous solution and commercial Pd/C catalyst from Johnson Matthey, mainly due to the large electrochemically active surface areas of the hollow particles. In addition, The Ag component in core–shell Ag@Ag–Pd NPs has an unfavorable influence on catalytic activity of NPs for formic acid oxidation. However, the durability could be improved due to the electron donating effect from Ag to Pd atoms in the core–shell NPs.