Absorbance determination and photocatalytic production of hydrogen using tungsten and TiO2 oxide nanostructures As catalyst

Abstract In this paper, we described the production of hydrogen using the water splitting method, in which catalytic reactions activate a photocatalyst in the presence of UVA/vis light. This catalyst breaks the water molecule, from which hydrogen is removed. Currently, the substitution of fossil fuels for alternative energy sources is still insufficient. The great advantage of using an alternative energy source such as hydrogen is that in addition to being clean and renewable, it also does not emit carbon-based gases into the atmosphere. To advance the use of hydrogen, we synthesized TiO2 and TiO2 nanostructures mixed with two tungsten precursors (H2WO4 and Na2WO4.2H2O), aiming to increase the radiation absorption capacity of TiO2. Synthesized nanostructures were used as photocatalysts for hydrogen production by water splitting. The synthesized materials were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and absorbance tests performed with a Konica-Minolta spectrophotometer. The TiO2/Na2WO4.2H2O (800 °C) nanostructures absorbed light in a wider range of wavelengths, and were consequently more efficient in producing H2. The results show that Na2WO4.2H2O plays an important role in the photoactivity of synthesized materials, as it increases the concentration of point defects in TiO2 networks, enhancing hydrogen production and the absorption range. The TiO2, TiO2/WO3, and TiO2/Na2WO4.2H2O catalysts showed the best photocatalytic performance for hydrogen production: 33.5%, 61.6%, and 76.6%, respectively. These samples were synthesized at 800 °C and had specific surface areas of 9.8, 28.5, and 30.9 m2/g, respectively.