Synergistic catalytic effect of SrTiO3 and Ni on the hydrogen storage properties of MgH2

Abstract

Study on the synergistic catalytic effect of the SrTiO3 and Ni on the improvement of the hydrogen storage properties of the MgH2 system has been carried out. The composites have been prepared using ball milling method and comparisons on the hydrogen storage properties of the MgH2 – Ni and MgH2 – SrTiO3 composites have been presented. The MgH2 – 10 wt% SrTiO3 – 5 wt% Ni composite is found to has a decomposition temperature of 260 °C with a total decomposition capacity of 6 wt% of hydrogen. The composite is able to absorb 6.1 wt% of hydrogen in 1.3 min (320 °C, 27 atm of hydrogen). At 150 °C, the composite is able to absorb 2.9 wt% of hydrogen in 10 min under the pressure of 27 atm of hydrogen. The composite has successfully released 6.1 wt% of hydrogen in 13.1 min with a total dehydrogenation of 6.6 wt% of hydrogen (320 °C). The apparent activation energy, Ea, for decomposition of SrTiO3-doped MgH2 reduced from 109.0 kJ/mol to 98.6 kJ/mol after the addition of 5 wt% Ni. The formation of Mg2Ni and Mg2NiH4 as the active species help to boost the performance of the hydrogen storage properties of the MgH2 system. Observation of the scanning electron microscopy images suggested the catalytic role of the SrTiO3 additive is based on the modification of composite microstructure.