Preparation optimization and single cell application of PtNi/C octahedral catalyst with enhanced ORR performance

Highlights: • PtNi/C octahedrals were prepared with benzoic acid as structure directing agent. • Effect of reaction conditions on octahedral morphology was investigated. • PtNi/C octahedral catalyst exhibits higher ORR performance than Pt/C (JM). • MEA fabricated using this octahedral catalyst shows enhanced cell performance. On the basis of research on the effect of reaction conditions on nanocrystal morphology and performance, the preparation process of octahedral catalyst is optimized, and the PtNi/C octahedral nanocrystal catalyst with well-defined structure and enhanced performance is prepared by a one-pot solvothermal method using benzoic acid as structure directing agent. In rotating disk electrode test, its mass activity and specific activity reach 4.7 and 6.6 times of the commercial Pt/C catalyst, and its stability is also higher after accelerated durability testing. In order to fill the research blank on single cell application of octahedral catalyst, membrane electrode assembly is fabricated using this PtNi/C octahedral catalyst in cathode. Compared with the control, although a lower Pt loading is employed, its cell voltage at 1000 mA cm⁻² and maximum power density are increased by 27 mV and 132.8 mW cm⁻², respectively, demonstrating that PtNi/C octahedral catalyst exhibits actual application potential in proton exchange membrane fuel cells. After further regulating composition and structure of alloy nanocrystals, optimizing preparation process of membrane electrode assembly and investigating the durability of single cell and stack under dynamic driving cycle conditions, Pt-based octahedral catalysts are expected to replace the conventional Pt/C catalyst.