Hydrogen storage properties of a destabilized MgH2Sn system with TiF3 addition

• Effect of TiF3 on H2 storage properties of MgH2Sn system was investigated.
• The addition of TiF3 improves the dehydrogenation properties of MgH2Sn system.
• The in-situ formation of MgF2 and Ti may play an important role.

The MgH2Sn system is considered a promising reactive metal composite for hydrogen storage. Several ratios of MgH2Sn (2:1, 3:1 and 4:1) destabilized system were investigated experimentally using a ball milling method. Based on the temperature-programme desorption results, the onset dehydrogenation temperature of the MgH2Sn composite was consisted of two steps in the range of 235–250 °C and 325–340 °C. TiF3 catalyst was introduced to enhance the desorption temperature of the MgH2Sn (4:1) system. The onset dehydrogenation temperature of the 4MgH2Sn-10 wt% TiF3 composite was reduced to approximately 100 °C and 205 °C compared to the MgH2Sn (4:1) and the as-milled MgH2. The Kissinger analysis established that the apparent activation energy for the first stage of the 4MgH2Sn composite was reduced from 149.0 kJ/mol to 114.0 kJ/mol after adding 10 wt% TiF3. However, the addition of TiF3 did not result in improvement of the absorption process. The improvement of the dehydrogenation properties of the MgH2Sn composite with the addition of TiF3 was due to the formation of Ti-containing and F-containing species. These species played a catalytic role in improving the dehydrogenation properties of the MgH2Sn system.