Study on the improvement of hydrogen storage properties, microstructure, and activation energy of 10 wt% SrTiO3-doped with MgH2+Na3AIH6 composite for solid state hydrogen storage

Abstract

In this study, the hydrogen storage properties of 10 wt% SrTi03 added to MgH2 + Na3AlH6 were investigated for the first time. MgH2 + Na3AlH6 doped with SrTi03 exhibited an improvement on the onset dehydrogenation temperature and isothermal de/rehydrogenation kinetics compared with the un-doped MgH2 + Na3AlH6 composite. The X-ray diffraction result for the MgH2 and Na3AlH6 had confirmed that the samples do not have any impurity as no other peak was detected. Besides, the X­ ray diffraction patterns also showed that SrTi03 did not decompose throughout the heating processes. Meanwhile, result from the pressure-composition-temperature showed that the initial desorption temperature of the doped composite was lowered by 20 ° C and the hydrogen absorption and desorption capacity were improved around 1.15 wt% and 0.4 wt%, respectively. The Kissinger analysis demonstrated that the apparent activation energy of the composite was reduced from 129.7 kJ/mol to 117.1 kJ/mol after doped with SrTi03. Meanwhile, the scanning electron microscope results proved that the composite with the additive of SrTi03 showed the smallest particle sizes compared to the un-doped composite. In conclusion, the hydrogen storage properties of MgH2 + Na3AlH6 were improved with the addition of the SrTi03 additive.