Electronic Metal-Support Interactions at the Catalytic Interfaces of CuO Nanowires Decorated with Pt Nanoparticles for Methanol Oxidation and CO Sensing

Electronic metal-support interactions (EMSIs) in metallic nanoparticle (NP)-supported catalysts are responsible for these nanomaterials' high-performance electronic and catalytic properties. However, the investigation of EMSIs at nanoscale under different environments has not been well studied. In this work, gas-phase synthesized Pt NP and thermally grown CuO nanowire (NW) EMSI evolution is characterized via X-ray photoelectron spectroscopy and Peak-Force Kelvin probe force microscopy, in order to describe the chemical state and surface potential of the nanocatalysts. Changes in the system's EMSIs after NP deposition and thermal annealing have important effects for different nanomaterials' applications. A significant amount of charge transfer was observed on the CuO NWs after deposition of Pt NPs, which greatly enhanced the catalytic performance of this material for methanol oxidation. Heating the Pt NP-CuO NW system elevated the Pt oxidation states and slowed the charge transfer such that the system exhibited different CO gas sensing mechanisms at two different temperatures, one related to the EMSI at 200 degrees C and the other related to oxygen spillover at 250 degrees C. This description of the CuO-NW-supported Pt NP electronic interactions under different reaction environments highlights the importance of EMSI tailoring for supported Pt nanocatalysts.