Photocatalytic reduction of carbon dioxide using graphene oxide wrapped TiO<inf>2</inf> nanotubes

Photocatalytic conversion of carbon dioxide to valuable chemicals by using semiconductor materials is one of the major challenges in materials science. Higher efficiency and product yield can be achieved by designing of a suitable photocatalyst with retarded recombination of photogenerated electron-hole pair and sufficient potential for the reduction of CO2. In this work, unique composite architecture of graphene-oxide wrapped TiO2 nanotubes for the photocatalytic reduction of CO2 has been developed. The TiO2 nanotubes formed by electrochemical anodization are wrapped with graphene oxide/reduced graphene oxide (GO/rGO)layers which also form interconnecting bridges between the adjacent nanotubes. Such a unique nanostructure helped the separation of photogenerated electron-hole pairs with better charge transfer to perform the reduction of adsorbed CO2 molecules. The rGO/TiO2 multi-leg nanotubes (MLNTs)have shown the highest photocatalytic activity with maximum yield of CO c.a. 1348 μmol g−1 within the first 20 min, which stabilize to about 760 μmol g−1 after 2 h of UV-A irradiation. More importantly, the CO formation rate is about an order of magnitude higher than that from graphene supported TiO2 nanocrystals.