In this study, we utilize near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) to monitor in real time, the redox-driven surface restructuring of model Pt–M alloys (M = Co, Ni, Cu) with systematically tailored compositions. Samples underwent sequential oxidative (5 mbar O₂) and reductive (5 mbar H₂) treatments across a temperature range from room temperature to 300°C, for real-time tracking of surface composition, oxidation states, and electronic structure as a functions of reactive environment, temperature, alloy type and stoichiometry. Results reveal that exposure to reactive gas atmospheres induces substantial surface dynamics. Overall, in oxidative atmospheres, the less noble component preferentially oxidized and segregated to the surface, triggering dealloying, while in subsequent reductive atmospheres, its reduction induces partial realloying with Pt. The extent and reversibility of these processes are discussed depending on alloy type and composition, providing insights into redox-driven surface dynamics and offer a basis for the rational design of durable, high-performance Pt-based multimetallic catalysts.
Khalakhan et al. (Thu,) studied this question.