Hydrogen storage performances and reaction mechanism of non-stoichiometric compound Li1.3Na1.7AlH6 doped with Ti3C2

Our previous work found that Li 1.3 Na 1.7 AlH 6 possesses the lowest dehydrogenation onset temperature and the most favorable dehydrogenation thermal stability among Li-Na-Al-H compounds (Fan et al., 2017). In this work, additional Ti 3 C 2 was introduced into Li 1.3 Na 1.7 AlH 6 by ball milling to further enhance its dehydrogenation performances. According to the volumetric release curves, the initial dehydrogenation temperature of the sample Li 1.3 Na 1.7 AlH 6  + 5 wt.%Ti 3 C 2 was lowered by 35 K from that of the pristine Li 1.3 Na 1.7 AlH 6 . The dehydrogenation enthalpy values of Li 1.3 Na 1.7 AlH 6  + 5 wt.%Ti 3 C 2 (46.9 KJ mol H 2 −1 ) was also slightly lower than that of pristine Li 1.3 Na 1.7 AlH 6 (49.7 KJ mol H 2 −1 ). It means that the doped Ti 3 C 2 was actively involved in the reaction with Li 1.3 Na 1.7 AlH 6 during the dehydrogenation process. The investigation by X-ray photoelectron spectroscopy (XPS) demonstrated that the reaction between Ti element and Li 1.3 Na 1.7 AlH 6 was definitely carried out in which the zero valence of Ti was transformed into Ti 3+ .