Effects of nano-confinement on the hydrogen desorption properties of MgH2

MgH2 particles were synthesized by wet impregnation within the pores of the mesoporous materials SBA15 and CMK3. XRD and TEM results of Mg/SBA15 compounds revealed MgO surface impurities, indicating non-compatibility of SBA15 for the synthesis of MgH2 particles within SBA15 pores. No impurity phase was detected in Mg/CMK3 compounds. Thermal desorption behavior of MgH2/CMK3 compounds were studied by varying the MgH2 loading amount in CMK3. TPD results of MgH2/CMK3 compounds demonstrated that the onset and maximum hydrogen desorption temperatures were significantly influenced by the MgH2 loading amount. MgH2/CMK3 compounds with 20 wt% loading released hydrogen at a temperature of 253 degrees C. Its corresponding decomposition enthalpy was equal to 52.38+/-2.16 kJ/mol H-2. Furthermore, TEM images of this sample demonstrated the existence of well-dispersed MgH2 nanocrystallites (d similar to 4 nm) inside the pores of CMK3 template. (C) 2012 Elsevier Ltd. All rights reserved.