Titanate-based one-dimensional nano-heterostructure: Study of hydrothermal reaction parameters for improved photocatalytic application

A novel one-dimensional decorated nano-heterostructure, anatase nanoparticle-decorated titanate nanotubes (TiNT@AnNP), was synthesized from anatase-TiO2 precursor using a fast and economic one-pot microwave-assisted alkaline hydrothermal route. The effect os reaction parameters, such as reaction time and temperature has been investigated in order to identify the best synthesis conditions leading to an improved photocatalyst. It was observed that increasing both the reaction temperature and time lead to complete conversion of the TiO2 precursor to the nano-heterostructures whereas increasing only the reaction time leads to the formation of larger anatase nanoparticles over the surface of the titanate nanotubes. All the samples prepared varying time and temperature showed enhanced discoloration of an anionic dye, remazol blue (RB), under UV–visible light, whereas the samples obtained at 140 °C showed higher photocatalytic efficiency, the best results were obtained for the sample with 2 h of reaction time. In order to investigated the effect of active species on the dye discoloration, a basic scavenger study involving several inhibitors were performed in all samples. It was observed that the singlet oxygen (1O2) was dominant active species for the discoloration of RB. However, the addition of EDTA (scavenger of h+) increased the photocatalytic activity of RB, which may be due to the capture of holes that inhibit the electron-hole recombination, which, in turn facilitates generation of 1O2 the chief reactive oxygen species (ROS).