Surface and structure characteristics of carbon-supported Pd₃Pt₁ bimetallic nanoparticles for methanol-tolerant oxygen reduction reaction

Surface and structure of carbon-supported Pd₃Pt₁ (Pd₃Pt₁/C) bimetallic nanoparticles of small particle size can be tuned during synthesis through the use or nonuse of trisodium citrate (TC) as the complexing agent. The addition of TC during the synthesis results in Pd enrichment on the surface layers of the Pd₃Pt₁/C catalysts and to an abnormal lattice expansion as compared to that of pure Pd/C and Pt/C. However, without the addition of TC, a normal lattice constant and Pt enrichment on the surface layers of the catalysts are obtained. Among the prepared catalysts, the maximum activity for the oxygen reduction reaction (ORR) occurs for Pd₃Pt₁/C catalyst with Pt surface enrichment. Importantly, the Pd₃Pt₁/C catalysts with Pd surface enrichment exhibited substantially higher methanol tolerance during the ORR than both the Pd₃Pt₁/C catalyst with Pt surface enrichment and the Pt/C catalyst. Thus, Pd₃Pt₁/C catalysts may represent a methanol-tolerant ORR cathode catalyst.