Synthesis Of Anatase TiO₂ Nanotube Array Films Coated With Exposed High Reactive Nanofacets And The Their Activities

Highly ordered TiO2 nanotube had wide application in energy, environment and catalysis because of its unique one dimensional structure and large surface area. Anatase TiO2 with exposed high reactive {001} facets was also frequently applied in photocatalysis, solar energy cells and lithium-ion batteries, owing to separation effect for electron and hole by the facets. Unfortunately, the report about the synthesis of Anatase TiO2 nanotube array films with exposed{001} facets was rare. Herein, we have successfully synthesized the Anatase TiO2 nanotube array films with exposed different percentage of {001} facets by a modified low hydrothermal process using amorphous ATNOAs as starting material.1. Anatase TiO2 nanotube array films with exposed {001} facets were synthesized through the optimizing experimental variables, including the temperature duration pH values and volume of HF solution during hydrothermal process. The results demonstrated that anatase TiO2 nanotube array films with exposed 76.5%{001} facets were prepared enven at a rather low temperature,130℃.2. The revelation of a new mechanism for the transformation from amorphous TiO2 nanotube array films to anatase TiO2 nanotube array films consisting of nanonparticles with exposed{001} facets. It was found that the reaction between gas phase HF molecules and solid state Ti(OH)4 played a key role during the transformation process. The driving force for this transformation could be the surface energy change caused by F- chemically absorpted on{001} and {101}.3. Anatase TiO2 nanotube array films with exposed different percentage of {001} facets were fabricated and their photocatalytic degradation of MO under UV-vis were also evaluated. The results indicated that the degradation efficiencies increased with increase of the percentage of {001}. It was also found that the k value of HT-20 was more than 150 times than the pure TiO2 nanotube array films through the analyzing the kinetics of the photo degradation process.4. Different metal oxide coated anatase TiO2 nanotube array films with exposed {001} facets (M-001-TiO2, M=Fe, Cu, Mn and Ce)) were also synthesized and their selective catalytic reduction of NOx were also studied. The results demonstrated that the NOx conversion efficies of them were all better than the films without coating. Especially for Cu-001-TiO2, the efficiency was more than 2 times than the pure anatase TiO2 nanotube array films with exposed {001} facets. The better performance could be the synergy effect between {001} facets and metal oxides.