High-loading Pt-alloy catalysts for boosted oxygen reduction reaction performance

To improve performance of membrane electrode assembly (MEA) at large current density region, efficient mass transfer at the cathode is desired, for which a feasible strategy is to lower catalyst layer thickness by constructing high loading Pt-alloy catalysts on carbon. But the high loading may induce unwanted particle aggregation. In this work, H-PtNi/C with 33% (mass) Pt loading on carbon and monodisperse distribution of 3.55 nm PtNi nanoparticles, was prepared by a bimodal-pore route. In electrocatalytic oxygen reduction reaction (ORR), H-PtNi/C displays an activity inferior to the low Pt loading catalyst L-PtNi/C (13.3% (mass)) in the half-cell. While in H-2-O-2 MEA, H-PtNi/C delivers the peak power density of 1.51 W.cm(2) and the mass transfer limiting current density of 4.4 A.cm(2), being 21% and 16% higher than those of L-PtNi/C (1.25 W.cm(2), 3.8 A.cm(2 ) respectively, which can be ascribed to enhanced mass transfer brought by the thinner catalyst layer in the former. In addition, the same method can be used to prepare PtFe alloy catalyst with a high-Pt loading of 36% (mass). This work may lead to a range of catalyst materials for the large current density applications, such as fuel cell vehicles. (C) 2021 Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

Automated summary

To improve the performance of membrane electrode assembly (MEA) at large current density, reducing the catalyst layer thickness is an effective strategy. This study demonstrates that constructing high loading Pt-alloy catalysts on carbon can achieve this goal, although high loading might lead to particle aggregation. The H-PtNi/C catalyst with 33% Pt loading exhibits higher peak power density and mass transfer limiting current density in H-2-O-2 MEA, attributed to the thinner catalyst layer and enhanced mass transfer.