Na_xWO₃ + TiO₂ nanocomposites as plasmonic photocatalysts for the degradation of organic dyes

Abstract The combination of plasmonic metal nanostructures with semiconductor photocatalysts can improve their photocatalytic efficiency by increasing light absorption and aiding in charge separation. Metallic Na x WO3 has been shown to be strongly plasmonic and offers a readily synthesized and low-cost replacement for the noble metals which are conventionally used in plasmonic photocatalysts. In this work, a range of Na x WO3 + TiO2 nanocomposites were fabricated. Composites containing both semiconducting (x < 0.25) and metallic (x > 0.25) Na x WO3 were prepared. The degradation of rhodamine 6G (R6G) under visible and near infrared (NIR) light illumination was observed only when Na x WO3 and TiO2 were both present in the composite. Photocatalytic activity was generally higher in metallic samples than in semiconducting ones, but the sample with the highest activity had a mixture of both. This suggests that a combination of interband transitions and plasmonics-enhanced processes can be used together to catalyse reactions.