Hydrogen storage properties of a Mg-Ce oxide nano-composite prepared through arc plasma method

摘要

Mg based Mg-Ce oxide nano-composite powders were prepared through arc plasma evaporation of Mg-5 wt.%CeO_2 mixture followed by passivation in air. ICP, XRD, TEM and PCT techniques were used to characterize the composition, phase components, microstructure and hydrogen sorption properties of the composite. It is shown that CeO_2 transformed into Ce_2O_3 after arc evaporation and nanoscale Ce_2O_3 particles are attached on the surface of Mg particles, forming a core-shell structured metal-oxide nano-composite. The hydrogenation and dehydrogenation enthalpies of the composite are calculated to be -71 kJ/ mol H_2 and 75.41 kJ/mol H_2, respectively, while the activation energy for hydrogen absorption is 47.75 kJ/ mol H_2. In addition, the composite can absorb 4.07 wt.% of hydrogen at 323 K in 10 h. These results revealed that the minor addition of Ce oxide in Mg through arc plasma method is able to improve significantly the hydrogen absorption kinetics of Mg.