Literature Seminar Abstract

In past years, the need to develop technologies to make use of solar energy has led to extensive research into the semiconductor materials for such applications. Due to their electronic structure, semiconductor materials can be used to drive photocatalysis through the photogeneration of charge carriers that can partake in oxidation or reduction reactions. Specifically, semiconductor nanoparticles are attractive materials for such applications as they offer a larger surface area compared to bulk materials. A larger surface area leads to a greater number of reactive sites for the photocatalytic reaction to occur. However, the photocatalytic efficiency of these nanoparticles systems is limited by the ability of the charge carriers to separate. To improve the photocatalytic efficiency, methods to enhance the charge carrier separation need to be developed. The Durrant group has demonstrated two such methods. They have shown that for a nanostructured film of TiO2, charge carrier separation can be improved by changed the applied potential on the system. To further investigate the what causes the increase in charge carrier separation, transient absorption was used to understand the decay of the charge carriers. They showed that the carrier lifetime increases with applied potential and is likely the source of the improved charge carrier separation. The second method makes use of sacrificial scavengers to improve charge carrier separation. They showed again that for a nanostructured film of TiO2, the carrier lifetime can be extended through the use of either a hole or electron scavenger. These two strategies can be used to improve the photocatalytic efficiency of TiO2 nanoparticles and could be extended to other semiconductor materials as well.