IrO₂ as a promising support to boost oxygen reduction reaction on Pt in acid under high temperature conditions

Metal oxide nanoparticle (NP) supports of both good conductivity and stability have the potential to enhance both the reaction activity and stability of the loaded electrocatalysts. In this paper, a facile two-step approach to disperse Pt nanoparticles on the surface of an IrO₂ NP support (Pt/IrO₂) was developed. Physical characterization by x-ray diffraction spectroscopy and transmission/scanning electron microscopy suggests a good dispersion of the Pt NPs. The temperature effect (from 293 to 353 K) of oxygen reduction reaction on Pt/IrO₂ was studied by using a rotating ring disk electrode The results show that although the kinetic current density on Pt/IrO₂ is close to that on commercial Pt/C at room temperature, the apparent activation energy (E_a,app) in the former case is much lower, suggesting a much higher activity at elevated temperatures. The superiority in E_a,app is attributed to the electron interaction between Pt and the IrO₂ support, as supported by the change of surface chemical state given by x-ray photo-electron spectroscopy.