Mn nanoparticles enhanced dehydrogenation and hydrogenation kinetics of MgH2 for hydrogen storage
(1. School of Energy and Power, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
2. Analysis and Testing Center, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
3. State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China)
2. Analysis and Testing Center, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
3. State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China)
Abstract: Mn nanoparticles (nano-Mn) were successfully synthesized and doped into MgH2 to improve its de/hydrogenation properties. Compared with MgH2, the onset desorption temperature of 10 wt.% nano-Mn modified MgH2 was decreased to 175 °C and 6.7, 6.5 and 6.1 wt.% hydrogen could be released within 5, 10 and 25 min at 300, 275 and 250 °C, respectively. Besides, the composite started to take up hydrogen at room temperature and absorbed 2.0 wt.% hydrogen within 30 min at low temperature of 50 °C. The hydrogenation activation energy of MgH2 was reduced from (72.5±2.7) to (18.8±0.2) kJ/mol after doping with 10 wt.% nano-Mn. In addition, the MgH2 + 10 wt.% nano-Mn composite exhibited superior cyclic property, maintaining 92% initial capacity after 20 cycles.
Key words: hydrogen storage material; magnesium hydride; Mn nanoparticles; catalytic mechanism; reversibility