title: Enhanced hydrogen storage properties of MgH2co-catalyzed with K2NiF6and CNTs.
abstract: The composite of MgH2/K2NiF6/carbon nanotubes (CNTs) is prepared by ball milling, and its hydrogenation properties are studied for the first time. MgH2co-catalyzed with K2NiF6and CNTs exhibited an improvement in the onset dehydrogenation temperature and isothermal de/rehydrogenation kinetics compared with the MgH2-K2NiF6composite. The onset dehydrogenation temperature of MgH2doped with 10 wt% K2NiF6and 5 wt% CNTs is 245 °C, which demonstrated a reduction of 25 °C compared with the MgH2+ 10 wt% K2NiF6composite. In terms of rehydrogenation kinetics, MgH2doped with 10 wt% K2NiF6and 5 wt% CNTs samples absorbed 3.4 wt% of hydrogen in 1 min at 320 °C, whereas the MgH2+ 10 wt% K2NiF6sample absorbed 2.6 wt% of hydrogen under the same conditions. For dehydrogenation kinetics at 320 °C, the MgH2+ 10 wt% K2NiF6+ 5 wt% CNTs sample released 3.3 wt% hydrogen after 5 min of dehydrogenation. By contrast, MgH2doped with 10 wt% K2NiF6released 3.0 wt% hydrogen in the same time period. The apparent activation energy, Ea, for the dehydrogenation of MgH2doped with 10 wt% K2NiF6reduced from 100.0 kJ mol-1to 70.0 kJ mol-1after MgH2was co-doped with 10 wt% K2NiF6and 5 wt% CNTs. Based on the experimental results, the hydrogen storage properties of the MgH2/K2NiF6/CNTs composite is enhanced because of the catalytic effects of the active species of KF, KH and Mg2Ni that are formed in situ during dehydrogenation, as well as the unique structure of CNTs.
authors.affiliation: School of Ocean Engineering, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Malaysia. mohammadismail@umt.edu.my.
authors.forename: N N
authors.initials: NN
authors.lastname: Sulaiman
authors.affiliation: School of Ocean Engineering, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Malaysia. mohammadismail@umt.edu.my.
authors.forename: M
authors.initials: M
authors.lastname: Ismail