Catalytic effect of Ti2C MXene on the dehydrogenation of MgH2

In the present work, the Ti2C MXene is prepared by selective etching Al layer from Ti2AlC. The catalytic effect of Ti2C MXene on the dehydrogenation of MgH2 is investigated. Compared with the pure MgH2, the onset desorption temperature, apparent activation energy (E-a) and the overall enthalpy changes (PH) of dehydrogenation of MgH2-5 wt%Ti2C decreased by 37 degrees C, 36.5%, 11%, respectively. The catalytic mechanism of Ti2C on the dehydrogenation of MgH2 is investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). It is suggested that the surface Ti atoms with multivalence serve as the intermediate for electrons shifting between H and Mg2+, which makes the dehydrogenation of MgH2 easier. In addition, the good hydrogen adsorption ability and thermal conductivity of Ti2C MXene could also contribute to the improvement of thermodynamics of MgH2. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.