Extension of optical properties of ZnO/SiO2 materials induced by incorporation of Au or NiO nanoparticles

• Optical properties of ZnO/SiO2 modified with Au and NiO nanoparticles.
• Extending light absorption to visible domain by reducing the band gap energy.
• NiO/ZnO/SiO2 and Au/ZnO/SiO2 excellent surface characteristics favour adsorption.
• Effective removal of cationic dyes (97%) under VIS irradiation.

Incorporating noble metal nanoparticles (NPs) and oxides has been proved to be an effective method to tune the optical properties of silica based materials. In this paper the optical and photocatalytic properties have been studied for ZnO/SiO2 modified with Au or NiO nanoparticles. Changes in the optical properties of semiconductor ZnO particles have been observed due to the deposition of coloured Au and NiO nanoparticles by reducing the band gap energy and thus extending light absorption to visible domain. The excellent surface characteristics of NiO/ZnO/SiO2 and Au/ZnO/SiO2 favour the adsorption behaviour of these materials and limit the recombination of electron–holes pairs. Crystal Violet degradation under VIS light proved to have higher efficiency in the presence of Au/ZnO/SiO2 (97%) than for NiO/ZnO/SiO2 (60%).