Preparation and photocatalytic activity of TiO2nanotube arrays prepared on transparent spinel substrate

TiO2 nanotubes (TNTs) were prepared on transparent spinel (MgAl2O4) ceramic material by anodic oxidation of magnetron sputtered Ti layer. The properties of TNTs were compared with nanotubes produced on other three different substrates, Si wafer, polymeric Kapton film, and Ti foil. The photocatalytic activity of TNTs was tested by the removal of two model pollutants rhodamine B (RhB) and bisphenol A (BPA). Depending on the used substrate, the efficiency of TNTs in the degradation of both pollutants increases in the order of Kapton < spinel < Si < Ti. Nanotubes grown on Ti foil exhibited the best photocatalytic activity reaching 88% for the removal of RhB and 36% for the removal of BPA. The degradation rates of RhB could be well described by the pseudo-first order reaction, while the degradation of BPA could be better fitted with fractional first-order kinetic model. The calculations of residual stresses and deformations in the prepared materials with TNT surface layer showed that the composite with spinel substrate is the most stable structure with minimal warping of the laminate.