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 TiO 2 and TiO 2 nanostructures mixed with two tungsten precursors (H 2 WO 4 and Na 2 WO 4 .2H 2 O), aiming to increase the radiation absorption capacity of TiO 2 . 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 TiO 2 /Na 2 WO 4 .2H 2 O (800 °C) nanostructures absorbed light in a wider range of wavelengths, and were consequently more efficient in producing H 2 . The results show that Na 2 WO 4 .2H 2 O plays an important role in the photoactivity of synthesized materials, as it increases the concentration of point defects in TiO 2 networks, enhancing hydrogen production and the absorption range. The TiO 2 , TiO 2 /WO 3 , and TiO 2 /Na 2 WO 4 .2H 2 O 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 m 2 /g, respectively.