Achieving superior hydrogen storage properties of MgH2 by the effect of TiFe and carbon nanotubes

Xiong Lu a, Liuting Zhang a,*, Haijie Yu a, Zhiyu Lu a, Jiahuan He c, Jiaguang Zheng a,Fuying Wu b, Lixin Chen c,*

a School of Energy and Power, Jiangsu University of Science and Technology, Zhenjiang 212003, China

b Analysis and testing center, Jiangsu University of Science and Technology, Zhenjiang 212003, China

c State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China

Multiple catalysts have exhibited high activity on improving the hydrogen storage performance of magnesium hydride. Herein, TiFe as a superior catalyst was successfully prepared, and then doped into MgH2 via ball milling to improve the de/rehydrogenation properties of MgH2 at low temperatures. Compared with as-prepared MgH2,the onset desorption temperature could be reduced to 175 ?C after adding 15 wt%-TiFe to MgH2. Furthermore,the 10 wt%-TiFe doped MgH2 released approximately 6.5 wt% H2 within 10 min at 300 ?C, and 5.3 wt% H2 could be rapidly absorbed at low temperature of 125 ?C under hydrogen pressure of 3 MPa. Moreover, the additional doping of carbon nanotubes (CNTs) evenly distributed on the surface of MgH2 particles, enabling the MgH2 + 10 wt%-TiFe + 5 wt%-CNTs composite with outstanding cycling performance. The activation energy of hydroge- nation for MgH2 was reduced from 72.5 ± 2.7 kJ/mol to 60.7 ± 8.0 kJ/mol after doping with TiFe and CNTs. However, the addition of TiFe and CNTs had limited influence on the thermodynamic properties of MgH2. The analysis of XRD, TEM, SEM and EDS indicated that uniformly distributed TiFe and CNTs served as active catalytic unit and aggregation preventer on enhancing the hydrogen storage properties of MgH2, respectively.