DEVELOPMENT OF Mnffi02 PHOTOCATALYST FOR HYDROGEN PRODUCTION FROM WATER UNDER VISIBLE LIGHT

TiOz photocatalyst doped with manganese are prepared by wet impregnation
methods. By doping TiOz with manganese, hydrogen can be produced with
photocatalytic decomposition of water under visible light irradiation. Manganese(II)
nitrate has been used to prepare manganese doped catalyst via wet impregnation. In
order to find the best calcination temperature, three calcination temperature are
selected; 300 °C, 400 °C and 500 °C. The samples were characterized by
thermogravimetric analysis (TGA), diffuse reflectance UV-Vis (DR-UV-Vis), Field
emission-Scanning electron microscopy (FE-SEM), Fourier transform infrared
(FTIR) spectroscopy and X-ray diffraction (XRD). Doping Ti02 with manganese
metal reduce the energy levels for the band gap of Ti02, shifting activity from UV
region (wavelength, "A < 400 mn) to visible light region. It was found that 5 wt%
Mnffi02 calcined at 400 °C produced the maximum amount of hydrogen (6.3 mL in
distilled water and 6.6 mL in sea water). The reduction in band gap energy was
estimated from transformed of Kubelka-Munk plot. The estimated band gap energy
for 5Mn _ 4 was 2.95. The influence of the process parameters on catalytic activity is
also explained.