Pt-decorated tantalum oxide on mesoporous carbon supports for enhanced mass activity and start-stop and load cycling durability in PEFCs

Unique Pt/TaO_x/MC cathode electrocatalysts for polymer electrolyte fuel cells (PEFCs) are developed using partially-reduced TaO_x decorated on mesoporous carbon (MC). An initial mass activity (MA) of more than 500 A g⁻¹ was observed for a TaO_x/MC support heat treated at 700°C in H₂ or 1300°C in Ar, more than double that of a conventional Pt/C electrocatalyst. The durability against start-stop and load potential cycling was successfully improved compared with the reference catalysts, as verified by half-cell voltammetry and full membrane-electrode-assembly (MEA) tests. Durability against start-stop cycling was attributed to the use of a thermochemically-stable TaO_x support which prevents direct contact between Pt and MC, thus minimizing carbon corrosion. Durability against load cycling was mainly attributed to the mesoporous structure, preventing the agglomeration of Pt catalyst particles. As such, the Pt/TaO_x/MC cathode electrocatalysts presented in this work have the potential to achieve both high durability and high power output, which is especially attractive for heavy-duty vehicular fuel cell applications.