Nanocarbon Materials Coupled with TiO2 Nanotubes for the Photoelectrochemical Degradation of Organics

Shuli Halevy, Chemical engineering, Ben Gurion University, Beer Sheva, Israel
Eli Korin, Chemical engineering, Ben Gurion University, Beer Sheva, Israel
Armand Bettelheim, Chemical engineering, Ben Gurion University, Beer Sheva, Israel Many sources of organic waste are contaminating our valuable water sources. Waste treatment therefore becomes a major problem in the world and various technologies have been suggested for this purpose. Photoelectrochemical oxidation is one of the promising technologies for the treatment of organic pollutants in water since it enables oxidation of organic compounds to CO₂. The concept of photoanodes preparation today is to use a planar and transparent electrode coated with a nanostructured photocatalyst. However, the coating methods employed usually require high cost equipment and not always allow loading of electrodes with a complex geometry and a high surface area.

In the present work we prepare porous photoanodes based on TiO₂ nanotubes arrays with a good exposure to light and a high surface area for photocatalytic reaction. Anodization of Ti allowed to obtain a photoanode with TiO₂ nanotubes arrays. SEM images revealed vertically and highly ordered TiO₂ nanotubes arrays with a length of  ~ 10 µm and an average tube diameter in the range of 50-150 nm. XRD showed that anatase TiO₂ was formed after annealing the anodized Ti foil. These photoanodes was decorated with graphene oxide (GO) in an attempt to improve the photoelectrochemical responses. The performances of Ti/TiO₂ and Ti/TiO₂/GO photoanodes were examined in a PEC cell for methanol degradation. The methanol photooxidation onset potential in a solution of 1 M methanol shifted cathodically for Ti/TiO₂/GO as compared to Ti/TiO₂. Moreover, an increase of the methanol (1 M) limiting photocurrent density was observed for TiO₂/GO.