Carbon-supported hollow palladium nanoparticles with enhanced electrocatalytic performance

Abstract

Carbon-supported palladium nanoparticles (NPs) with hollow interiors (hPdNPs/C) are fabricated via a facile approach. In this strategy, core–shell NPs with an Ag core and an Ag–Pd alloy shell (Ag@Ag–Pd) are first synthesized in oleylamine by a galvanic replacement reaction between Ag seed particles and Pd²⁺ ion precursors. Then the core–shell Ag@Ag–Pd NPs are loaded on the XC-72 carbon supports and refluxed in acetic acid to remove the original organic surfactant. The carbon-supported core–shell Ag@Ag–Pd NPs are subsequently agitated in saturated Na₂S or NaCl solution for 24 h to eliminate the Ag component from the core and shell regions, leading to the formation of hPdNPs/C. Specifically, the hPdNPs/C generated by NaCl treatment exhibit superior catalytic activity and durability for formic acid oxidation reaction (FAOR) and oxygen reduction reaction (ORR), compared with the commercial Pd/C catalysts from Johnson Matthey, mainly due to the high electrochemically active surface areas (ECSAs) of the hollow structure, whereas the hPdNPs/C obtained by Na₂S treatment display very poor catalytic performance due to the serious poisoning induced by S²⁻ adsorption.