Hydrogen sorption of magnesium hydride doped with nano-sized TiO2

Various phases of TiO2 such as anatase, rutile and commercial P25 were added to magnesium hydride by high-energy ball milling in order to improve the hydriding properties of the magnesium. After 1 h milling, the sample containing nano-size rutile powder (200-400 nm) showed uniform distribution, while other shapes of TiO2 added samples did in separate phase. The effect of the rutile concentrations (3, 5, 7 and 10 mol%) on the hydrogen sorption property of MgH2 has been investigated and found that the sample containing 5 mol% rutile had the highest hydrogen capacity of 4.40 wt.% at 300 degrees C and 3.54 wt.% at 250 degrees C. This amount of hydrogen absorption is still lower than the pure magnesium requires a long activation time, however, its kinetics of hydrogen sorption was greatly enhanced. Moreover, hydrogen absorption capacity was slightly increased with the increase in number of cycles. The mechanism of catalytic effect of uniformly distributed TiO2 and TiO2 dispersed as discrete particles in magnesium matrix has been discussed based on microstructural observations. (c) 2006 Elsevier B.V. All rights reserved.