The Synthesis Of TiO₂ Nanotube Arrays And Nano-ZnO By Horizontal Rotating Electrode And The Photoreduction Of CO₂

Photocatalytic reduction of CO₂ has attracted much attention because it could provoide a new way to utilize solar energy and decrease excessive carbon emissions. Nanostructure material is the most promising CO₂ photocatalytic material due to the special size and properties. Among the materials, the through-hole TiO2 nanotube arrays and nanostructure ZnO prepared by anodization show the most outstanding performance.In this paper, the reason for the fragile property of TiO2 nanotube film is investigated basing upon the anodization method. Anodization by horizontal rotating electrode is invented and developed to strengthen the mechanical properties. At the same time, the preparation of ZnO nanostructures of has been discussed by the same way. Finally, the performances of TiO2 nanotube film and ZnO in photocatalytic reduction of CO₂ are tested. The main conclusions are as follows:?1? TiO2 nanotube arrays film prepared by anodization exist nonuniformity in the degree of oxidation. Nonuniformity of oxidation degree in the preparation of through-hole TiO2 nanotube arrays film is one reason for its frangible. This unevenness is most likely caused by an uneven electric field caused by the electrode polarization.?2? Using a rotating horizontal electrode device, uniform diameter ?average diameter at both ends are in the 100nm? through-hole TiO2 nanotube arrays film was obtained. Moreover, compared with the films prepared on vertical electrode, its toughness has been improved to some extent. Applied in photocatalytic reduction of CO₂, it was found that the tube length is inversely proportional to the activity of CO₂ converting to CH4. Pt modified catalysts presented a significant improvement on their activity of CO₂ converting to CH4, especially for the longer through-hole TiO2 nanotube arrays.?3? Strong acidic and alkali conditions are not conducive to the formation of nanostructure ZnO. Concentration of NH4F is critical on control of nanostructure ZnO morphology. It is easy to form nanosheets at low concentrations and to form nanoparticles at high concentrations. The ZnO nanoparticles prepared at room temperature have clear structure and relatively uniform size. Nevertheless voltage requirements are relatively harsh with the preparation. ZnO nanoparticles could be obtained when 0.2 mol L-1 of oxalic acid was used as pH adjusting agent, water alcohol ratio of 1:1 solution as electrolytic agent and 1% by mass of NH4F as electrolyte, as well as a 40V external voltage and for 10min to get an electrolysis at 25?. CH4 yields can reach 2.48?mol/g when used on photocatalytic reduction of CO₂.