Pt NPs Supported on CeO2/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 mu Acm(-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.