Oxidation-Induced Atom Diffusion and Surface Restructuring in Faceted Ternary Pt–Cu–Ni Nanoparticles

Ternary alloy catalysts outperform their binary counterparts in many reactions although the direct observation of structural evolution under reaction conditions to understand the structure–performance relationship significantly lacks. In situ transmission electron microscopy at atmospheric pressure provides a great opportunity to uncover dynamic structure and composition changes of ternary alloy nanoparticles. In this work, the atomic-scale elemental diffusion and surface reconstruction of ternary octahedral Pt2CuNi alloy nanoparticles in an oxidative environment at elevated temperatures are reported. Combining them with multiple characterizations and numerical simulation, it is revealed that the oxidative condition induced the lattice atom diffusion, which leads to the NiOx major/CuOx minor surface oxide layers accompanied by surface restructuring and lattice rearrangement. Further analysis helped to establish the numerical model and visualize the atom distribution variation in the restructuring process. Also, the model catalytic test of the oxygen reduction reaction demonstrates that the catalytic performance of ternary Pt2CuNi alloy nanoparticles can be tuned through oxidative treatment.