Boosting the Durability of High-Pt-Content Fuel Cell Cathode Catalysts Through TaOx Decorating

Abstract

Enhancing the durability of carbon-supported platinum catalysts (Pt/C) for the oxygen reduction reaction remains a significant challenge in the field of proton exchange membrane fuel cells (PEMFCs), especially for catalysts with high-Pt contents. Herein, a TaO_x decorating strategy that is capable of effectively boosting the durability of Pt/C catalysts even with a high-Pt content of 50 wt.% is introduced. This strategy involves introducing reducible Ta₂O₅ nanoparticles into carbon supports, depositing Pt nanoparticles, and finally conducting high-temperature H₂ annealing to convert reducible Ta₂O₅ nanoparticles into amorphous TaO_x decorating the Pt nanoparticles. The annealing temperature found in the Ta₂O₅ incorporation step is critical for the formation of reducible Ta₂O₅ nanoparticles, which, in turn, determines the continuity of the TaO_x subsequently formed around the Pt nanoparticles. By controlling annealing temperature, the formation of a relatively continuous TaO_x distribution on the Pt nanoparticle surface is achieved, thereby maximizing the interaction between Pt and TaO_x and enhancing the electrochemical stability of Pt nanoparticles. Following the accelerated durability test, the resulting high-Pt-content catalyst demonstrates an array of exceptional durability metrics, including an electrochemical surface area loss of 30%, a mass activity loss of 35%, and a voltage loss of 22 mV at 0.8 A cm^‒2.

Keywords: Pt/C catalysts; SMSI; durability; fuel cell; tantalum oxide.