Hydrogen production from the photocatalytic hydrolysis of sodium borohydride in the presence of In-, Sn-, and Sb-TiO2s

To enhance the evolution of hydrogen from the photocatalytic hydrolysis of sodium borohydride solution, three photocatalysts; 0.5 mol% In, Sn, and Sb, incorporated into TiO2, were prepared using a hydrothermal method. The particle sizes of well-developed anatase were about 5.0 nm, except those for Sb-TiO2, which were above 5.0 nm, with closed to cubic form shapes, except for pure TiO2 that was spherical. In the X-ray photoelectron spectra (XPS) for Ti2p(3/2), a band at 460.34 eV, attributed to partial MTiO3, was seen in Sn-TiO2. Additionally, two bands of Sn3d(5/2) at 484.5 and 486.8 eV, assigned to the Sn and SnO or SnO2, respectively, appeared over Sn-TiO2, with the ratios of metal-OH/metal-O in the O1s bands, imply a hydrophilic property, also increased in this compared with the other catalysts. The hydrogen evolution from sodium borohydride (NaBH4) hydrolysis was enhanced in the Sn-TiO2 photocatalytic system compared to those for the other catalysts; hydrogen was evolved at 140 ml/g h over Sn-TiO2, which was different from the 100 ml/g h for the hydrolysis of pure NaBH4, and increased to 1350 ml/g after 5 h. In particular, the evolved hydrogen increased with increasing amounts of Sn-TiO2, and the production continued for 150 h. (C) 2008 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.