Graphene-supported Pd catalysts for reversible hydrogen storage in LiBH_4

摘要

The hydrogen release properties of the graphene supported Pd (Pd-G) catalysts doped LiBH_4 were systematically investigated. It was found that the onset hydrogen desorption temperature of the LiBH_4 doped with 5 wt.% Pd-G-60 (with 60 wt.% Pd loading) catalyst was about 105 °C lower than that of the pure LiBH_4 milled under the same conditions, and the other main dehydrogenation peaks of the Pd-G-60 doped LiBH_4 were shifted to 410 and 605 °C with an increased total weight loss of 12.6 wt.%. Moreover, the dehydrogenation enthalpy was reduced from 74 kJ mol~(-1) H_2 for the pure LiBH_4 to ca. 43 kJ mol~(-1) H_2 for the 15 wt.% Pd-G-60 doped LiBH_4. Importantly, the reversible rehydrogenation process was achieved under 3 MPa H_2 at 400 °C for 10 h, and a capacity of ca. 6.6 wt.% was obtained in the 30th cycle, which should be attributed to the evenly dispersed Pd nanoparticles. Meanwhile, LiBH_4 was reformed and one new product, B_(16)H_(20), was detected after the rehydrogenation process.