In Situ Surface Decoration of a Titanium Nanosubstrate by a TiO2-WO3 Composite

An efficient TiO2 core/TiO2-WO3 shell structured nano-composite is successfully synthesized by a method of acid precipitation followed by thermal decomposition. The metal weight ratio of TiO2-WO3 is optimized in order to achieve visible-light absorption. We made the mixed-oxide composite on titanium metal turnings in order to enhance the active surface area available for water-splitting reaction. The novelty of the present work mainly lies on the utterly different approach that we adopt for tuning of the composite with titanium turnings as the major material. The structural and morphological changes in the mixed oxide on the turnings are characterized in detail based on X-ray diffraction, Fourier transform infrared, transmission electron microscopy, scanning electron microscopy-energy-dispersive X-ray analysis, and Raman spectroscopy. The enhanced surface properties are evaluated based on Brunauer-Emmett-Teller adsorption. The band-edge position, band gap, and range of light absorption are envisaged by UV-visible spectroscopy. The photocatalytic activity of the composite is evaluated under visible-light irradiation. The volume of hydrogen gas evolved during water-splitting reaction is quantified after confirming the purity of the evolved hydrogen by gas chromatography. The mechanism of the enhanced water-splitting process by the fabricated photocatalytic system is then depicted. An appreciable quantity of pure hydrogen is produced by the catalyst composite, the stability and reproducibility of which is further ascertained by different experiments.