There is high scientific and technological interest to develop photocatalytic coatings on stainless steels surface to remove fouling under light radiation. In this study, a novel method is described to prepare photocleanable stainless steel by anodization to form aligned nanopore arrays (NPAs) on the surface in ethylene glycol containing perchloric acid. Perchloric acid concentration, applied voltage and anodization time of anodization process were investigated. The NPAs are mainly composed of iron (III) oxide and chromium (III) oxide. This photocleanable stainless steel has remarkable visible-light photocatalytic activities, which show potential applications particularly for outdoor purpose. Moreover, the stainless steel surface remains highly polished and exhibits good corrosion resistance after anodization.

The present study aims to determine the optimum radio frequency (RF) sputtering power to obtain the desired W–TiO2 nanotubes for the best photoelectrochemical (PEC) performance. Tungsten (W) was deposited on titania (TiO2) nanotube arrays via RF sputtering technique under different sputtering powers from 50 to 250 W. The optimum content of W on TiO2 nanotube arrays play a significant role in maximizing the photocurrent generation efficiency to promote charge separation by accumulation of photogenerated electrons. The sputtering power below 180 W exhibited high-ordered and unbroken TiO2 nanotube arrays. However, the sputtering power over 180 W exhibited broken nanotube arrays and an oxide layer was formed due to the impact of high energy ions accelerated by a high sputtering power. The TiO2 nanotube arrays sputtered with tungsten at 50 W showed a better photocurrent density (1.55 mA/cm2), with a photoconversion efficiency of 2.2% in the PEC performance among the samples due to the effective charge separation and reduced recombination center in the resultant W–TiO2 nanotubes.

In this study highly-ordered titania nanotube arrays of variable wall-thickness and length are used to photocleave water under ultraviolet irradiation. We demonstrate that the wall thickness, and length, of the nanotubes can be controlled via anodization bath composition and temperature. The nanotube length and wall thickness are key parameters influencing the magnitude of the photoanodic response and the overall efficiency of the water-splitting reaction. For 22 nm inner-pore diameter nanotube-arrays 6 μm in length, with 9 nm wall thickness, upon 320–400 nm illumination at an intensity of 100 mW/cm2, hydrogen gas was generated at the power-time normalized rate of 51 mL/hr•W at an overall conversion efficiency of 12.5%. To the best of our knowledge, this hydrogen generation rate is the highest reported for a titania-based photoelectrochemical cell.