Solid-state synthesis of amorphous TiB_2 nanoparticles on graphene nanosheets with enhanced catalytic dehydrogenation of MgH_2

摘要

A bi-component catalyst TiB_2/GNSs (GNSs is the abbreviation of graphene nanosheets) is synthesized by a solid-state method. Microstructural characterizations based on SEM (scanning electron microscopy), TEM (transmission electron microscopy) and N_2 phys-isorption show that the size of TiB_2/GNSs catalyst is at nanoscale (20-30 nm) with a surface area of 84.69 m~2 g~1. The TiB_2/GNSs nanoparticles ball milled with MgH_2 and exhibit enhanced catalytic effects on the dehydrogenation properties of MgH_2 compares to TiB_2 and GNSs individually. DSC (differential scanning calorimetry) measurements confirm that the peak desorption temperature of MgH_2-5 wt%TiB_2/GNSs composites can be lowered more than 44 ℃ than the pure as-milled MgH_2. And the dehydrogenation kinetics of TiB_2/GNSs-doped MgH_2 is severalfold acceleration compares to the pure as-milled MgH_2. It is proposed that the TiB_2/GNSs nanoparticles could significantly enhance the intimate interface between TiB_2/GNSs and hydride, therefore, provide more active "catalytic sites" and H "diffusion channels" to reduce the dehydrogenation temperature and improve the dehydrogenation kinetics of MgH_2. The synergistic effect of nano-GNSs and TiB_2 nanoparticles contributes to the highly efficient for dehydrogenation of MgH_2-5wt%TiB_/GNSs composites.