Influence of nickel in the hydrogen production activity of TiO2

Abstract

Sol-gel synthesised TiO2 developed by our group was modified through the addition of nickel nitrate and ammonium carbonate in the synthesis process. Photocatalysts were synthesised with different Ni/Ti molar ratios (0.015, 0.030, 0.045) and constant Ni/N ratio equal to 1.5 and subjected to post-calcination at temperatures of between 400°C and 700°C. Characterisation was carried out with: X-ray diffraction (XRD), UV-vis diffusive reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy-energy dispersive X-ray analysis (TEM-EDX), thermal analysis (TGA, DTA), aggregate size distribution, Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption-desorption isotherm (BET).Photoactivity in terms of photocatalytic hydrogen production was tested using a suspension of photocatalyst at 25vol.% methanol. With a continuous flow of N2 in headspace the hydrogen produced was conducted to a gas chromatograph for quantification. No evidence of the presence of N was found in the photocatalyst. However, the presence of Ni enhanced TiO2 photoactivity, with a calcination temperature of 550°C resulting in the highest photoactivity value of 260.76μmolh-1. © 2014 Elsevier B.V.