Pt NPs Supported on CeO ₂ /C as Electrocatalysts for Oxygen Reduction Reaction: Novel Physicochemical Insights on the Synthesis and on the Improved Activity and Stability

This study emphasizes the effect of CeO₂ on the Pt nanoparticle (NP) dimension, stability, and activity versus the oxygen reduction reaction. It is demonstrated that the one-pot synthesis of Pt NPs along with CeO₂ NPs over carbon support produces small Pt NPs (2 nm) with higher activity, than the sole Pt NPs, thanks to the cooperative interaction exerted by CeO₂. This is nicely demonstrated by using synchrotron wide-angle X-ray total scattering and advanced data analysis, monitoring the in situ nucleation and growth of Pt NPs in the presence of preformed CeO₂ NPs or of a Ce precursor. Raman, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy analyses are carried out to support the formation of oxygen vacancies responsible for the metal-support interaction. Moreover, the most effective catalyst, PtCeO₂/C250 (mass activity: MA_{0.9 V} = 423 Ag^-1; specific activity: SA_{0.9 V} = 446 µAcm^-2), exhibits activity comparable to the commercial benchmark Pt/C, yet significantly greater stability as demonstrated by accelerated stress tests conducted on gas diffusion electrode. Specifically, PtCeO₂/C250 retains 62% ± 7% of its MA_{0.65 V} and 79% ± 9% of its SA_{0.65 V}, compared to 43% ± 5% and 62% ± 7%, respectively, for the benchmark.