Core-Shell Structuring of Pure Metallic Aerogels towards Highly Efficient Platinum Utilization for the Oxygen Reduction Reaction

Abstract

The development of core-shell structures remains a fundamental challenge for pure metallic aerogels. Here we report the synthesis of Pd_x Au-Pt core-shell aerogels composed of an ultrathin Pt shell and a composition-tunable Pd_x Au alloy core. The universality of this strategy ensures the extension of core compositions to Pd transition-metal alloys. The core-shell aerogels exhibited largely improved Pt utilization efficiencies for the oxygen reduction reaction and their activities show a volcano-type relationship as a function of the lattice parameter of the core substrate. The maximum mass and specific activities are 5.25 A mg_Pt^-1 and 2.53 mA cm^-2 , which are 18.7 and 4.1 times higher than those of Pt/C, respectively, demonstrating the superiority of the core-shell metallic aerogels. The proposed core-based activity descriptor provides a new possible strategy for the design of future core-shell electrocatalysts.

Keywords: aerogels; core-shell structures; electrocatalysis; oxygen reduction reaction; sol-gel processes.