Plasmonic ‘rainbow’ photocatalyst with broadband solar light response for environmental applications

•TiO2 is modified with Au-Ag alloy nanoparticles of varying sizes and compositions.•Rainbow photocatalyst exhibits broadband response over the entire UV–vis range.•Such material is used for the first time in a gas-solid environmental application.•Improved efficiency is obtained under both narrow-band VIS and broadband solar light.•Improved efficiency is demonstrated under real solar light in outdoor conditions.

We propose the concept of a ‘rainbow’ photocatalyst that consists of TiO2 modified with gold-silver alloy nanoparticles of various sizes and compositions, resulting in a broad plasmon absorption band that covers the entire UV–vis range of the solar spectrum. It is demonstrated that this plasmonic ‘rainbow’ photocatalyst is 16% more effective than TiO2 P25 under both simulated and real solar light for pollutant degradation at the solid-gas interface. With this we provide a promising strategy to maximize the spectral response for solar to chemical energy conversion.

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