Photosensitisation of reactive oxygen species with titanium dioxide nanoparticles decorated with silver sulphide quantum dots

Abstract

At present, the development of methods for sensitisation to the visible and IR spectral regions of systems for the photocatalytic production of reactive oxygen species based on titanium dioxide nanoparticles is of great interest. The purpose of this work was to establish the regularities of the photogeneration of reactive oxygen species during the formation of TiO2 nanoparticle – Ag2S quantum dots nanoheterosystems under the action of radiation in visible and near-infra-red spectral regions. The paper analyses the photocatalytic properties of anatase nanoparticles 10–15 nm in size decorated with colloidal Ag2S quantum dots with an average size of 2.5 nm passivated with thioglycolic and 2-mercaptopropionic acids. Selective sensor dyes were used to estimate the effectiveness of sensitisation of various reactive oxygen species with the studied photocatalysts under excitation in the UV and visible region. It was shown that decorating TiO2 nanoparticles with quantum dots leads to an increased efficiency of the production by the system of hydroxyl radical, superoxide anion, and hydrogen peroxide under photoexcitation in the TiO2 absorption region (UV range). Sensitisation of the production of reactive oxygen species by nanosystems was detected during excitation by radiation in the visible spectral region (outside the intrinsic TiO2 absorption band). It was also found that there is an increase in the efficiency of the production of reactive oxygen species (up to 1.5 times) when thioglycolic acid is replaced with 2-mercaptopropionic acid as a passivator of Ag2S quantum dots. The obtained data were used to develop a schematic diagram of photoprocesses in the system.

Keywords

• reactive oxygen species
• photocatalysis
• nanoparticles
• titanium dioxide
• quantum dots
• silver sulphide
• photosensitisation