Review on the Versatility of Tungsten Oxide Coatings

Abstract

Tungsten oxide is a versatile material with many advantages such as large availability and low fabrications costs. Additionally, it is suitable to be produced in the form of thin films or coatings, which makes it very attractive for many applications. In this Feature Article, the material properties such as crystallography, chemical stability, and semiconducting properties are presented, followed by examples of coating technologies. Furthermore, the relation between its structure and some of the very important applications fields such as electro‐ and photochromism, as well as pH sensing are analyzed in detail. Its auspicious semiconducting properties make it attractive to be used as photo(electro)catalyst, therefore applications of thin films based on WO3 are emphasized such as photoanodes for water splitting, in healthcare as antimicrobial material and for degradation of pollutants or for CO2 reduction. The article is concluded by a short overview of the current status of research employing tungsten oxide.

Effect of the Ammonium Tungsten Precursor Solution with the Modification of Glycerol on Wide Band Gap WO3 Thin Film and Its Electrochromic Properties

“…It is worth mentioning that it is the transition metal oxides that are the fascinating semiconducting materials which possess a variety of properties, applications and functions [2]. Tungsten trioxide (WO 3 ), the most widely studied and used electrochromic material, has been studied for many years since having been found by Deb in the 1960s, thanks to its attractive characteristics of high coloring efficiency, good optical modulation ability and decent chemical stability in the field of electrochromism [3][4][5][6]. It is remarkable that WO 3 with various crystalline structures by different synthesis methods is extensively appropriate for diverse device applications [7][8][9], such as the electrochromic smart window [10,11], rear-view automatic-dimming rearview mirror [12], gas sensor device [13][14][15], and military camouflage [16], etc.…”

WO3 and Ionic Liquids: A Synergic Pair for Pollutant Gas Sensing and Desulfurization

“…In WO 3 powders, doped with H, Na, Li or other impurity atoms or in WO 3 thin film form, the cubic c-WO 3 phase also occurs [18,19]. This cubic phase is considered as the ideal high temperature phase and is consequently used as the reference for the structure of WO 3 [20]. The cubic perovskite-like structure is shown in Figure 1 and consists of corner sharing of regular octahedra with oxygen atoms at the corners and tungsten atoms at the center of each octahedron.…”

Enhanced Coloration/Bleaching Photochromic Performance of WO3 Based on PVP/PU Composite Matrix

“…Tungsten trioxide (WO 3 ) is a well‐known chromogenic material, which can be used as smart window for its color changing from colorless to blue under different stimuli, such as electric field (electrochromic), hydrogen gas (gasochromic) and photo irradiation (photochromic) . Compared with electrochromic and gasochromic WO 3 smart windows, photochromic WO 3 based smart window shows special advantages, such as simple construction, great solar modulation especially among infrared region, and automatic modulation depends on photoexcitation without any external energy supply accessories …”

“…[3][4][5] Compared with electrochromic and gasochromic WO 3 smart windows, photochromic WO 3 based smart window shows special advantages, such as simple construction, great solar modulation especially among infrared region, and automatic modulation depends on photoexcitation without any external energy supply accessories. [6,7] To date, photochromic WO 3 based smart window still have not realized industrialization application. As to be practical applications, properties includes fast response, high solar modulation efficiency and high cycle stability are required.…”

“…[26,27] However, the intrinsic drawbacks of WO 3 based photochromic smart windows still need further investigation, especially the bleaching process, which has not been studied further yet. [7] In previous study, WO 3 based photochromic foil in bleached state needs more than 24 hours to recover back to original state, or high temperature which can accelerate the migration rate of H + , or ozone atmosphere which can enhance the oxidation reaction. [28] These harsh conditions make it difficult to implement the application.…”