Engineering hollow porous platinum-silver double-shelled nanocages for efficient electro-oxidation of methanol

Abstract

Direct methanol fuel cell technology requires high-performance electrocatalysts for practical utilization at the commercial scale. A novel, high-efficiency electrocatalyst composed of hollow porous platinum-silver double-shelled nanocages (Pt-Ag DSNCs) for the electro-oxidation of methanol (EOM) is demonstrated. The Pt-Ag DSNCs were synthesized with a facile one-pot self-template mechanism with the assistance of N, N-Methylenebisacrylamide (MBAA). The double shells can be precisely controlled by regulating the feeding amount of MBAA and the Pt/Ag ratio. The hollow MBAA-based metal polymer acts as a nano-reactor and nucleation site for the deposition of PtAg alloy on its inner (exposed to AgCl nanoparticles) and outer (exposed to bulk solution) sides. To our knowledge, this is the first report of a direct one-pot synthesis of Pt-Ag double-shelled nanocages. Combining a unique double-shelled structure and an optimized bimetallic chemical composition, the Pt-Ag DSNCs (optimized Pt/Ag ratio is 3/1) show more than a two-fold improvement in specific activity and greater stability towards the EOM compared with a commercial Pt catalyst. Density functional theory (DFT) studies demonstrate the introduction of Ag is important for the improvement of EOM performance. The facile synthetic strategy and competitive EOM performance endow Pt-Ag DSNCs with great application potential in direct methanol fuel cells.