XPS characterization of a plasmonic sensor for catalysis studies by controlled differential charging

The use of external bias during XPS measurements has been successfully extended to characterization of a plasmonic Au nanostructured catalyst support, with and without deposition of a TiO2 film. Application of pulsed bias voltage indicates that the Au nanoparticles and the silica base are not in complete electrical contact as they do not exhibit the same frequency dependence. This effect is substrate dependent and is not present in a sample of Au nanodiscs on a silicon/SiO2 substrate. Upon deposition of a TiO2 film, the charging capacity of the Au nanodiscs as well as the silica substrate decrease significantly. Finally, we show that controlled differential charging in XPS can help identify defects caused by sample manufacturing.