Preparation Of Novel TiO₂ Catalysts And Insight Into The Performance

Semiconductor materials with nanostructure possess superior physichemical and optical properties, leading to their potential applications in many areas. Semiconductor photocatalysts, which have long been studied to alleviate the deterioration of natural environments created by pollutants, have attracted increasing attention. Titanium dioxide(TiO2), a very important oxide semiconductor, is regarded as a suitable material for extensively investigating in the photocatalytic field owing to its chemical stability, high chemical inertness, nontoxicity, and low cost.In this paper, TiO2/MWCNTs and TiO2/Graphene nanocomposite photocatalysts with uniform and intimate loading were prepared via hydrothermal and solvothermal methods. The photocatalytic performance of these photocatalysts exhibited a great enhancement compared with pure TiO2 due to the introduction of MWCNTs and graphene. The primary research results are as follows:(1) Nanocomposites consisting of well-defined anatase TiO2 nanoparticles with an average diameter of 8 nm and multi-walled carbon nanotubes were fabricated by a facile two-step hydrothermal method at the temperature of 180 °C using water as the main solvent, which was friendly to the environment. The TiO2 nanoparticles were uniformly grafted on the surface of MWCNTs via intimate chemical bonds, which were beneficial for the enhancement of photocatalytic activity. The photocatalytic activities activity of as-prepared TiO2/MWCNTs nanocomposites for degradation of rhodamine B under solar simulator illumination was investigated systemically. It was found that the photocatalytic activity of as-prepared TiO2/MWCNTs nanocomposites was 8.7 times higher than that of pure TiO2 prepared via the same hydrothermal procedure.(2) TiO2/MWCNTs nanocomposites were prepared through hydrothermal process at the temperature of 150 °C and 160 °C, respectively, compared with the sample fabricated at the temperature of 180 °C to investigate how the temperature affect the morphology, crystal size and crystal structure. The crystal structure of TiO2 prepared at higher temperature developed better according to the XRD characterization results; the resulted product of hydrothermal reaction carried out at 150 °C was amorphous TiO2. The as-prepared TiO2/MWCNTs nanocomposites were annealed at 400 °C and 500 °C to investigate whether the heat treatment would affect photocatalytic performance or not. The XRD patterns showed that after heat treatment, the anatase TiO2 crystal structure developed better, leading to the further enhancement of photocatalytic performance.(3) TiO2/Graphene nanocomposites were prepared through a facile two-step solvothermal method at the temperature of 150 °C, 160 °C, 180 °C and 200°C, respectively. Several technologies were carried out to characterize the morphology, crystal structure, optical properties and photocatalytic performance of as-prepared samples. The results revealed that solvothermal process performed at 150 °C only got amorphous TiO2. The product prepared at 200 °C possessed the best crystal structure, optical property and photocatalytic performance.