TiO₂Nanotube Films Prepared by Anodization in Glycerol Solutions for Photocathodic Protection of Stainless Steel

Abstract

TiO 2 nanotube array films were prepared on titanium foils by anodic oxidation in aqueous glycerol solutions with NH 4 F. The morphologies and properties of the films prepared in the solutions with different water contents were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis spectroscopy. The photocathodic protection effect of the films were evaluated by measuring the time evolution of the potential of 403 stainless steel coupled to the film photoanodes. The results showed that the TiO 2 nanotube film prepared in the solution with 40 vol% water exhibited excellent photoelectrochemical properties. When the 403 stainless steel in a 0.5 M NaCl solution was coupled to the film under illumination, its potential decreased by 400 mV, showing that the TiO 2 nanotube film provided effective photocathodic protection effect on the steel. Furthermore, the photoelectrochemical performance of the TiO 2 nanotube film could be further improved by a TiCl 4 solution treatment.The study of corrosion control is an urgent task for modern society because corrosion has caused considerable waste of resources and resulted in a huge economic loss throughout the world. 1 Many methods have been applied to inhibit metal corrosion, such as electrochemical protection, 2-4 the use of corrosion inhibitors, 5,6 and coatings. 7,8 In the 1990's, Yuan et al. 9 reported that TiO 2 coatings could be used as a semiconductor photoanode and provide a photocathodic protection effect on copper substrates, which is a new type of cathodic protection. The basic idea of the present photocathodic protection method is to replace the sacrificial anode with a semiconductor photoanode that can generate photoelectrons under illumination. 9 This method does not require an external power supply or a sacrificial anode, which is beneficial to the sustainable use of environmental resources. Therefore, some efforts have been made to study photocathodic protection in the academic world. 10-12 There are two main ways for the application of photocathodic protection in corrosion control of metals. One is that a TiO 2 coating is prepared directly on metal surfaces, 13-17 and the other is that a TiO 2 film as a photoanode is coupled to the metal to be protected through an external circuit. [18][19][20][21] More studies on the first way have been adopted since the preparation process of the TiO 2 coating is easy to operate. 13-17 However, crevice corrosion may occur on the metal surfaces due to cracking of the TiO 2 coating. Although the second way is relatively less studied, but it is easier to modify TiO 2 films and has no influence on the protected metal surfaces, which can also further improve the photocathodic protection effects. Our group has made some important progress in using this method to improve the photocathodic protection effects of TiO 2 films. 19-21 For example, Li et al. 19 prepared a flower-like N-doped TiO 2 film by a hydrothermal method, and found that the photocathodic protection effect of the composite film was gr...

Fabrication of CdTe/ZnS core/shell quantum dots sensitized TiO2 nanotube films for photocathodic protection of stainless steel

“…HCOOH or Na 2 SO 4 is often used as a hole scavenger to capture the photogenerated holes and consequently enhance the charge separation of the photogenerated carriers in TiO 2 films [4,19,31,33]. In the photoelectrochemical measurement system for photocathodic protection, HCOOH and Na 2 SO 4 existed in the photoelectrochemical cell (photoanode cell), not in the corrosion cell with stainless steel.…”

Study on the photoelectrical performance of anodized titanium sheets

“…Furthermore, Since Japanese scientists Fujishima and Honda first used semiconductor TiO 2 to decompose water into hydrogen and oxygen in 1972 [15], the photocatalytic material technology using semiconductor as photocatalyst has become one of hot research directions in the field of clean energy. As we know, great effort has been devoted by researchers around the world to the photoelectric catalysis of semiconductor TiO 2 under simulated sunlight, which is widely used in photocatalyst, sensors, biomedicine and other fields [16][17][18][19][20][21][22][23][24][25][26]. The main challenge is still the low photoelectrical conversion efficiency and stability of photocatalytic materials [27][28][29].…”

Photocathodic protection of 304 stainless steel by MnS/TiO2 nanotube films under simulated solar light

“…In recent years, more and more researches were carried out on the photocathodic protection activity of some optoelectronic semiconductors, such as TiO 2 [1][2][3][4], ZnO [5,6], SnO 2 [7] and α-Fe 2 O 3 /Fe 3 O 4 [8]. Among them, TiO 2 -base materials were mostly studied for its high photosensitivity, low cost, low toxicity, and good chemical and thermal stability since Yuan and Tsujikawa [9] found that Cu could be protected from corrosion by adding TiO 2 coating under illumination.…”

“…However, because of the wide band gap of TiO 2 (anatase 3.2 eV, rutile 3.0 eV), the low energy utilization and rapid recombination of photogenerated electrons and holes reduced the photocathodic protection effect of these films. To address these drawbacks, highly ordered TiO 2 nanotube films possessing superior charge transport properties were prepared by electrochemical anodization method [1,10,11] and a variety of strategies have been developed to improve the light absorption of TiO 2 , such as decorating with narrow band gap semiconductors (ZnSe, CdSe, CdS) [12][13][14][15], metals (Au, Co, Ag, Fe) [16][17][18][19], non-metals (graphene, N, Si) [20][21][22], dye-sensitization (bacteriochlorophyll-C, phthalocyanine, porphyrin) [23][24][25] and doping with polymer conductors (polyaniline, pyrrole) [26][27][28].…”