Synthesis And Photocatalytic Acitivity Of Titania Arrays With Ordered Nanostructures OnComplicated Titanium Substrates

As one of the advanced oxidation techniques, photocatalysis utilizing nanostructured titania has attracted more and more attention in industry. Continuous efforts have been made to improve the photocatalytic efficiency. Titania arrays with ordered nanostructures have been achieved by direct oxidation of metallic Ti substrates with hydrogen peroxide. In this thesis, motivated by industrial applications, we tried to deposit nanostructured titania arrays on complicated Ti substrates, such as Ti expanded plate and Ti wire mesh. The photocatalytic activity for dye degradations has been studied. The effects of trace hydrogen peroxide additives on the efficiency were also investigated.Major conclusions as follows.1. Hydrogen peroxide solutions with specific ingredients were utilized to oxidize pickled Ti expanded plate or wire mesh, at80℃for72h. After different follow-up treatments, titania with different ordered nanostructures such as nanorods, nanowires and nanoflowers, was achieved. SEM, XRD, and etc, were used to characterize the titania films. The results showed that, the obtained nanostructured titania film has uniform morphology and high crystallinity. Also, we found that the structure of complicated titanium substrates has influence on the growth of titania films, which means that one can’t achieve the same nanostructures on normal titanium plates and the complicated titanium substrates even following the same reaction procedure.2. After many photocatalytic reactions, we found that different ordered nanostructures of titania have different photocatalytic activity, and titania with nanorods structure has higher activity than that of the nanowires. In addition, the follow-up treatments for titania fabrications have a much more significant impact on the films’photocatalytic property. The results showed that after heating at450℃for1h, the absorption ability of the films toward rhodamine B decreased remarkably when compared with the as-synthesized film. Amorphous titania nanowire arrays have been deposited on Ti wire mesh, utilizing the hydrogen peroxide solution containing Hexamethylenetetramine and nitric acid. After immersing in acid solutions (pH=2.0,3.0) or deionized water at80℃for72h, the amorphous arrays transformed to well-aligned nanorod arrays with excellent photocatalytic property. The additive of trace hydrogen peroxide in the dye effluents enhances significantly the efficiency of the present titania films to assist photodegradation of dyes. The present approach to fabricate titania nanorod arrays on Ti wire mesh is appropriate for a scale-up production.