Dehydrogenation characteristics of ZrC-doped LiAlH 4 with different mixing conditions

The catalytic effects of ZrC powder on the dehydrogenation properties of LiAlH4 prepared by designed mixing processes were systematically investigated. The onset dehydrogenation temperatures for the 10 mol% ZrC-doped sample are 85.3 and 148.4 °C for the first two dehydrogenation stages, decreasing by 90.7 and 57.8 °C, respectively, compared with those of the as-received LiAlH4. The isothermal volumetric measurement indicates that adding ZrC powder could significantly enhance the desorption kinetics of LiAlH4. The reaction constant and Avrami index show that the first dehydrogenation stage is controlled by diffusion mechanism with nucleation rate gradually decreasing and the second stage is a freedom nucleation and subsequent growth process. The microstructures and phase transformation characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) reveal that the improved desorption behavior of LiAlH4 is primarily due to the high density of surface defects and embedded catalyst particles on the surface of LiAlH4 particles during the high-energy mixing process.