Transparent, Well-Aligned TiO₂ Nanotube Arrays with Controllable Dimensions on Glass Substrates for Photocatalytic Applications

Abstract

Transparent, well-aligned TiO(2) nanotube arrays (NTAs) with controllable dimensions are grown on glass substrates via atomic layer deposition (ALD) of TiO(2) onto free-standing porous anodic alumina (PAA) templates. Photodegradation of aqueous methylene blue (MB) solution and solid stearic acid (SA) film using TiO(2) NTAs of various wall thicknesses are investigated. The Pd functionalized TiO(2) NTAs, with a wall thickness of 15 nm and height of 200 nm, has the highest photodegradation efficiency at 76% after 4 h of UV irradiation. These functionalized NTAs are able to photodegrade MB molecules completely as no obvious demethylated byproducts are observed during the process. It also demonstrates excellent photocatalytic activity for solid contaminants such as SA film. By using the ALD technique, the nanotube wall thickness can be precisely controlled so that it is sufficiently thin to be transparent while sufficiently thick for excellent photocatalytic performances. The transparent TiO(2) NTAs on glass substrates with excellent photocatalytic properties might have potential applications in self-cleaning coating, transparent electronics, and solar cells.

The use of pulsed laser deposited seed layers for the aqueous solution growth of highly oriented ZnO nanowires on sapphire substrates at 95°C: Study of their photocatalytic activity in terms of octadecanoic (stearic) acid degradation

“…Popular techniques include those based on the photo-oxidation of organic films such as stearic acid [40][41][42][43][44][45][46][47][48][49][50] or palmitic acid [51,52], liquid phenolic pollutants [53,54] or organic vapors [55] and contact angle changes [56].…”

“…The photocatalytic activity of our ZnO samples was determined using stearic acid (SA) as a model compound, in which a thin layer of SA is deposited onto the film and its photocatalytic destruction is monitored as a function of time [40][41][42][43][44][45][46][47][48][49][50]. This method has gained preference over the years since SA provides a reasonable model compound for solid films that deposit on exterior and interior surfaces.…”

“…The decomposition of SA can be demonstrated by FT-IR spectroscopy through the monitoring of the asymmetric C H stretching mode of the CH 3 group at 2958 cm −1 and the asymmetric and symmetric C H stretching modes of the CH 2 group at 2923 and 2853 cm −1 , respectively [40][41][42][43][44][45][46][47][48][49][50]. The photocatalytic activity experiments on all ZnO samples for the decomposition of SA were XRD patterns of (a) ZnO nanowires grown by ASG for 5 h (cyan dotted curve) on sapphire substrates pre-coated with a 180 ± 5 nm thick ZnO seed layer deposited at 400 • C (red solid curve), (b) ZnO nanowires grown by ASG for 5 h (gray dotted curve) on sapphire substrates pre-coated with a 180 ± 5 nm thick ZnO seed layer deposited at 700 • C (blue solid curve).…”

Preparation and characterisation of AgIn(WO4)2photocatalyst with high photoreduction activity

“…In the experiment, the initial pH of the reaction solution was 4.0, the amount of the photocatalyst used was 2.0 g/L, and the initial concentration of nitrobenzene was 4.07 Â 10 À4 mol/L. The volume of reaction solution was 300 cm 3 . A 375-W medium pressure mercury lamp (Institute of Electric Light Source, Beijing) with a maximum emission at about 365 nm was used as the UV source.…”

“…Since Fujishima and Honda [1] discovered the evolution of oxygen and hydrogen from water using TiO 2 electrode under the irradiation of light in 1972, the field of photodegradating pollutant and splitting water using TiO 2 as photocatalyst has been widely studied [2][3][4][5][6]. However, the photocatalytic activity of TiO 2 (the band gap of anatase TiO 2 is 3.2 eV and it can be excited by photons with wavelengths below 387 nm) is limited to irradiation wavelengths in the UV region; thereby the effective utilisation of solar energy is limited to about 3-5% of the total solar spectrum.…”