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

Ferrous Centers Confined on Core–Shell Nanostructures for Low-Temperature CO Oxidation

A noble metal (NM) can stabilize monolayer-dispersed surface oxide phases with metastable nature. The formed “oxide-on-metal” inverse catalyst presents better catalytic performance than the NM because of the introduction of coordinatively unsaturated cations at the oxide–metal boundaries. Here we demonstrate that an ultrathin NM layer grown on a non-NM core can impose the same constraint on the supported oxide as the bulk NM. Cu@Pt core–shell nanoparticles (NPs) decorated with FeO patches use much less Pt but exhibit performance similar to that of Pt NPs covered with surface FeO patches in the catalytic oxidation of CO. The “oxide-on-core@shell” inverse catalyst system may open a new avenue for the design of advanced nanocatalysts with decreased usage of noble metals