Oscillation of Surface Structure and Reactivity of PtNi Bimetallic Catalysts with Redox Treatments at Variable Temperatures

Over Ni–Pt(111) model catalysts, changes in the surface structure were observed during alternating reduction and oxidation (redox) treatments at variable temperatures (VTs). Pt skin with subsurface Ni and NiO on Pt(111) form upon high-temperature reduction and high-temperature oxidation, respectively. Both Ni and Pt atoms are present on the surface with the low-temperature redox treatments. The similar surface structures can be constructed at supported Pt–Ni nanoparticles through the VT redox treatments. Both the surface structure and the CO oxidation performance of the supported Pt–Ni catalysts showed well-defined oscillations with the treatment temperature and the redox potential. The demonstrated treatment–structure–reactivity relationship at the PtNi catalysts aids in the design of advanced bimetallic catalysts.