(482d) TiO2-B/Anatase Core-Shell Heterojunction Nanowires for Photocatalysis

Spatial control of electron-hole separation after photogeneration remains a challenge in photochemical processes to create or degrade specific chemical compounds. Ideally, after photogeneration, electrons and holes must be segregated to different parts of the photocatalyst to take part in separate oxidation and reduction reactions. One way to achieve this is by building junctions into the catalyst with built-in electric fields that tend to separate the electron and the hole into two different regions of the catalyst. In this presentation, we describe a two-step synthesis method to prepare core-shell TiO2 nanowires made of TiO2-B core and a nanostructured anatase shell. We control the anatase phase surface coverage on the TiO2-B phase and show that the maximum photocatalytic activity is obtained when the solution containing the reactants can contact both the anatase and TiO2-B phases. The photocatalytic activity drops both with bare TiO2-B nanowires and with completely anatase covered TiO2-B nanowires. In contrast, nanowires partially covered with anatase phase gives the highest photocatalytic activity. The improved photocatalytic activity is attributed to the effective electron-hole separation at the junction between the anatase and TiO2-B phases, which reduces charge recombination and increases the electron and hole lifetimes.