TiO₂−WO₃ Photoelectrochemical Anticorrosion System with an Energy Storage Ability

Abstract

TiO2 coatings are known to protect some metals, including type 304 stainless steel, from corrosion on the basis of its reductive energy generated under UV irradiation. A TiO2 coating is coupled with a WO3 coating as an electron pool, in which the reductive energy can be stored. A WO3 film on a type 304 stainless steel plate can be charged by a UV-irradiated TiO2 coating on the same plate, in a 3 wt % NaCl aqueous solution, pH 5. The charged WO3 coating can protect the stainless steel plate from the corrosion for a while even after the UV light is turned off. Thus, the TiO2 coating protects the plate and charges the WO3 coating during the day, and the charged WO3 coating protects the plate during the night. The charge−discharge cycles are repeatable. A TiO2−WO3 composite coating also has the same effects.

Metal Oxides and Hydroxides as Rechargeable Materials for Photocatalysts with Oxidative Energy Storage Abilities

“…In order to retain its useful effects even after dark, we have developed photocatalysts with energy storage abilities. [3][4][5][6][7][8][9][10][11][12][13][14][15] They can store surplus charges from photocatalysts in rechargeable materials during the day, and the stored charges are used to carry on redox reactions during the night.…”

“…We have combined TiO 2 3-8 or SrTiO 3 9 as well as Au-TiO 2 , 10 which exhibits photocatalytic activity on the basis of plasmoninduced charge separation, [16][17][18][19] with a rechargeable material such as WO 3 , [3][4][5][6]9,10 MoO 3 , 7,10 or H 3 PW 12 O 40 (PWA), 8 which undergoes redox reactions at negative potentials. Those photocatalysts with reductive energy storage abilities retain some photocatalytic effects based on cathodic reactions, such as anti-bacterial 6 and anticorrosion 3 effects, even after dark.…”

Erratum to: Sol–gel synthesis of mesoporous WO3–TiO2 composite thin films for photochromic devices

“…The photocatalytic activity of WO 3 -TiO 2 films was found to be three times higher than that of pure TiO 2 films for the gas-phase oxidation of 2-propanol [18]. A TiO 2 coating was coupled with a WO 3 ''electron pool'' in the design of a photoelectrochemical anticorrosion system with built-in energy storage capability [19]. A WO 3 -TiO 2 buffer layer between the transparent conducting oxide substrate and a P25 TiO 2 layer was found to be beneficial in the operation of a Ru(II)-dye sensitized solar cell [20].…”

Long-Term Photoelectrochemical Cathodic Protection by Co(OH)2-Modified TiO2on 304 Stainless Steel in Marine Environment

“…The TiO 2 coating plays the role of providing electrons like a sacrificial anode in cathodic protection. Subsequently, Fujishima et al 5 studied the mechanism of the photoelectrochemical cathodic protection of TiO 2 -WO 3 in 3 wt% NaCl solution with pH = 5. So far, TiO 2 -protection of metals using sunlight has been a focus of great attention as a possible means for converting solar energy to electrical energy by generating the required negative electrode potential.…”