Plasmonic gold-embedded TiO2 thin films as photocatalytic self-cleaning coatings

[Display omitted] •Colloidal plasmonic Au nanoparticles are made compatible with TiO2 sol-gel process.•One-pot coating suspension contains both TiO2 precursor and plasmonic Au particles.•Homogeneous Au-embedded TiO2 coatings are obtained that are highly transparent.•Up to 40 % photocatalytic efficiency improvement is measured under solar light.•1 wt% Au is an economically favorable metal loading with good enhancement. Transparent photocatalytic TiO2 thin films hold great potential in the development of self-cleaning glass surfaces, but suffer from a poor visible light response that hinders the application under actual sunlight. To alleviate this problem, the photocatalytic film can be modified with plasmonic nanoparticles that interact very effectively with visible light. Since the plasmonic effect is strongly concentrated in the near surroundings of the nanoparticle surface, an approach is presented to embed the plasmonic nanostructures in the TiO2 matrix itself, rather than deposit them loosely on the surface. This way the interaction interface is maximised and the plasmonic effect can be fully exploited. In this study, pre-fabricated gold nanoparticles are made compatible with the organic medium of a TiO2 sol-gel coating suspension, resulting in a one-pot coating suspension. After spin coating, homogeneous, smooth, highly transparent and photoactive gold-embedded anatase thin films are obtained.