Tailoring WO₃ Thin Film Properties via Synthesis Parameter Control for Desired Applications

Tungsten oxide (WO3) thin films find application in a variety of fields, including chromism, gas sensing, and photoelectrochemistry. In the context of each application, the necessity arises for the identification of specific material properties. In this study, we propose a sol-gel methodology that facilitates the modulation of material properties through the precise manipulation of synthe-sis parameters. The calcination temperature, template concentration, and number of dip coating steps were found to have a significant impact on the crystallinity, (002) facet exposure, surface area, band gap, and absorption efficiency of mesoporous WO3 thin films. In the context of pho-toelectrochemical water oxidation, it has been determined that the crystallinity, band gap, and light absorption of the material are positively correlated with enhanced bulk processes. Photo-current values of up to 3.75 mA cm-1 at 1.23 V vs RHE under AM 1.5 G illumination were achieved, while external quantum yields of 58 % were also obtained. The systematic correlation between synthesis parameters and material properties, as outlined in the present study, offers a straightforward and efficient method for adjusting WO3 thin film properties to meet specific ap-plication requirements.