PtxCuy@TiO2 nanoparticles by low-pressure plasma synthesis

•Successful dry synthesis of Pt, Cu, and PtxCuy nanoparticles anchored onto TiO2 nanopowder.•Pt-Cu alloying formation, demonstrated by XRD analysis.•Pt concentration gradient within nanoparticles is suggested due to different degradation kinetics of Pt and Cu precursors. A new and original method is presented to synthesize Pt, Cu, and PtxCuy nanoparticles (NPs) anchored onto an inorganic nanopowder substrate (TiO2), based on the plasma degradation, within an Ar/NH3 radiofrequency plasma discharge, of solid organometallics (Cu and Pt acetylacetonate), mixed with TiO2. Both chemical and crystallographic characterizations confirm the formation of metastable alloyed Pt-Cu nanoparticles. The difference of Pt and Cu concentrations in NPs measured with a volume technique (X-ray diffraction) and a surface technique (X-ray photoelectron spectroscopy) suggests a Pt concentration gradient within NPs attributed to a difference in organometallics degradation kinetics.