The hydrogen storage properties and catalytic mechanism of the GuFe_2O_4-doped MgH_2 composite system

摘要

The influence of CuFe2O4 addition on the sorption performances of MgH2 prepared by ball milling was studied for the first time. The MgH2 + 10 wt% CuFe2O4 sample exhibited an enhancement in hydrogen storage performance compared to that of as-milled MgH2, with the onset decomposition temperature decreased from 340 degrees C to 250 degrees C. Dehydrogenation kinetic result revealed that CuFe2O4-added MgH2 released around 5.3 wt% H-2 within 10 min at 320 degrees C, while the as-milled MgH2 released below 1.0 wt% H-2 under the same condition. Furthermore, about 5.0 wt% H-2 was absorbed at 250 degrees C in 30 min for the 10 wt% CuFe2O4-doped MgH2 sample. In contrast, the un-doped MgH2 only absorbed 4.0 wt% H-2 at 250 degrees C in 30 min. From the Kissinger analysis, the apparent activation energy of as-milled MgH2 was 166.0 kJ/mol and this value decreased to 113.0 kJ/mol for 10 wt% CuFe2O4-added MgH2. The enhanced sorption performance of MgH2 in the presence of CuFe2O4 is believed to be due to the role of in situ formed Fe, Mg-Cu alloy, and MgO phases as an active species to catalyse the hydrogen storage properties of MgH2. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.