Chemical-Dealloying-Derived PtPdPb-Based Multimetallic Nanoparticles: Dimethyl Ether Electrocatalysis and Fuel Cell Application

In this work, we report a novel multimetallic nanoparticle catalyst composed of Pt, Pd, and Pb and its electrochemical activity toward dimethyl ether (DME) oxidation in liquid electrolyte and polymer electrolyte fuel cells. Chemical dealloying of the catalyst with the lowest platinum-group metal (PGM) content, Pt₂PdPb₂/C, was conducted using HNO₃ to tune the catalyst activity. Comprehensive characterization of the chemical-dealloying-derived catalyst nanoparticles unambiguously showed that the acid treatment removed 50% Pb from the nanoparticles with an insignificant effect on the PGM metals and led to the formation of smaller-sized nanoparticles. Electrochemical studies showed that Pb dissolution led to structural changes in the original catalysts. Chemical-dealloying-derived catalyst nanoparticles made of multiple phases (Pt, Pt₃Pb, PtPb) provided one of the highest PGM-normalized power densities of 118 mW mg_PGM^-1 in a single direct DME fuel cell operated at low anode catalyst loading (1 mg_PGM cm^-2) at 70 °C. A possible DME oxidation pathway for these multimetallic catalysts was proposed based on an online mass spectrometry study and the analysis of the reaction products.