TiO2 is a well-known photocatalyst. However, TiO2 was rarely adopted as an anode material in dark electrolysis process due to its poor conductivity. Recently, a group of sub-stoichiometric magnéli phase TiO2-x electrode materials with excellent conductivity were reported. But these materials can only be prepared at ca. 1000 °C in pure H2 atmosphere. Herein we report a series of conductive blue and black TiO2 nanotube arrays (NTA) prepared by facile methods with much less stringent requirements on temperature (450 °C) and atmosphere (air or 5% H2). It is found that the blue and black NTAs’ are degenerately n-type semiconductor, of which conductivity is contributed by the oxygen vacancies as electron donor states. With the aid of XPS and XAFS, we found that the anodic stability and conductivity of blue and black NTA is determined by not only the abundance but also the location of oxygen vacancies. A typical blue NTA has a lifetime of 2-3 h at anodic current of 10 mA/cm2 . By tuning and stabilizing the surface oxygen vacancies, we successfully prepared a novel black nanotube, which can be operated at 10 mA/cm2 for more than 200 h with no sign of deactivation. Blue and black NTA electrodes were further applied in the electrolysis cell to treat human wastewater. Their performance is superior to the IrO2 electrode and similar to the boron-doped diamond electrode.

Journey to enhance the stability of blue and black TiO2 nanotube array elelctrodes for water treatment

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.