Influence of vacant CeO2 nanostructured ceramics on MgH2 hydrogen desorption properties

The hydrogen desorption (HD) properties of MgH2-CeO2 composites prepared by mechanically milling MgH2 and cubic CeO2 nano were examined. The morphology and microstructure of the composites were studied by XRD, SEM, laser scattering analysis and correlated with desorption properties obtained by means of temperature programmed desorption (TPD). A decrease in the crystallite and particle size of the samples led to a significant lowering of the desorption temperature. The activation energy for desorption was calculated using the Kissinger equation. Values of 60 plus or minus 10 kJ/mol were obtained and indicated that the activation energy for hydrogen desorption was sufficiently decreased by the catalytic effect of the vacant CeO2 structure. Consequently, the surface activation of the sample played a major role in the HD reaction.