Sol-Gel Synthesis of TiO2/WO3 and TiO2/WO3-graphene nanoparticles, investigation of their photocatalytic proprieties

In today's society, air and water pollution, as well as clean energy, have become major concerns. Photocatalysis could be one of the ways used to address this new set of problems. Photocatalysis is a type of advanced oxidation method that involves light to activate a semiconductor. The semiconductor materials most likely to generate these reactions are titanium dioxide-based. However, TiO2 has its drawbacks, as light absorption limited to the UVA region of the solar radiation due to its wide band-gap (~3.2 eV), and a high rate of photogenerated electron-hole recombination in the photocatalyst. To address those problems, the sol-gel process was adopted for the synthesis of TiO2 nanoparticles, and TiO2 heterojunction with WO3 was carried out to decrease the rate of electron-hole pair recombination and enhance photocatalytic properties. In addition, graphene nanoplatelets were introduced to the TiO2/WO3 system to aid the transport and separation of photogenerated exciton. In this work, various parameters affecting the photocatalytic activity of the synthesized materials were investigated, including the ratio of WO3 to TiO2, the introduction of graphene, and the nature of the photocatalytic application (degradation of gaseous benzene and generation of H2). The structural and optical characteristics, as well as the properties of the adsorption surfaces, were all investigated. It was found that for materials containing more than 10 mol % of WO3, the addition of graphene in to the TiO2/WO3 system appears to boost photocatalytic activity for H2 generation under UV light compared to the TiO2/WO3 system, suggesting the existence of an optimal proportion allowing a greater photocatalytic activity.