Densification of Oxide Nanoparticle Thin Films by Irradiation with Visible Light

Abstract

A technique is presented that allows for altering of the physical characteristics of films of TiO2 nanoparticles by exposure to visible light. In this technique, dye‐sensitized oxide nanoparticles are deposited on a substrate by dip‐coating. Photodissociation of the organic ligand layer leads to cross‐linking of the nanoparticles. Consequently, irradiated films have a decreased porosity, an increased index of refraction and an increased hydrophobicity. Films irradiated with green light are compared to films irradiated with UV light. Within experimental error, visible‐ and UV‐illumination induces the same changes in the films. The mechanism of surfactant elimination in dye‐sensitized oxide particles is discussed, patterning is demonstrated, and prospective applications of the technique are considered.

Natural superhydrophilicity and photocatalytic properties of sol–gel derived ZnTiO3-ilmenite/r-TiO2 films

“…The published reports address several critical parameters governing the wetting behaviour of titania coatings: surface roughness, capillary forces within the underlying nano-and mesoporous network as well as the surface hydroxylation controlled by surface ''Lewis'' acidity, interfacial defects and interfacial photo-redox processes under participation of water, molecular oxygen and organic radical intermediates. 2,7,8,20 The goal of our contribution to this rather complex issue was to record the water contact angle (WCA) values for Zn x Ti y O z coatings synthesised and stored differently. The results of these studies are summarized in Fig.…”

An All Low‐Temperature Fabrication of Macroporous, Electrochemically Addressable Anatase Thin Films

“…This strategy is also motivated by the fact that TiO 2 anatase is known to photocatalyze oxidation reactions, i.e. oxidizing toluene and benzyl alcohol upon UV irradiation . Thus, template removal at low temperatures represented another important challenge in this study.…”

“…oxidizing toluene [ 12 ] and benzyl alcohol upon UV irradiation. [ 10 ] Thus, template removal at low temperatures represented another important challenge in this study. Thus, the degradation of PS was systematically studied by Raman spectroscopy.…”

“…Recently, Bertino et al reported the densifi cation of fi lms prepared from dispersions of crystalline TiO 2 nanoparticles by irradiation with UV light. [ 10 ] It was shown that benzyl alcohol molecules, being attached to the nanoparticles' surface as a consequence of the special synthesis (Niederberger route) [ 7 ] , are oxidized by UV light which in turn results in creating linkages between TiO 2 nanoparticles and the densifi cation of the matrix. These fi ndings suggest that the densifi cation and linkage between metal oxide nanoparticles by exposure to UV light can be an alternative to treatment at elevated temperature.…”

Photocatalytic performances of mesoporous TiO2 films doped with gold clusters

“…For example, positive holes have an electrochemical potential which is sufficient to oxidize molecules such as benzyl alcohol. 3,5 The photocatalytic activity is mainly controlled by (1) light absorption (wavelength and efficiency of maximum absorbance), (2) diffusion of the photogenerated charges to the surface of the crystallites, and (3) surface reduction and oxidation rates. To prepare materials with optimum properties, recombination and overall turnover rate are controlled by surface area, concentration of defects and crystallinity of the material.…”