▎ 摘　　要

MgH2 has broad prospects in energy storage applications; however, its poor thermodynamic properties and slow hydrogen absorption and desorption rates are unsuitable for commercial needs. In the present work, TiO@N-C (denoted as TTONC), a highly active catalytic precursor, was employed to improve the hydrogen storage properties of MgH2. The TTONC-catalyzed MgH2 could uptake hydrogen at room temperature, and the onset dehydrogenation temperature of TTONC-catalyzed MgH2 was 94 degrees C lower than that of pristine MgH2 (-300 degrees C). Dehydrogenated TTONC-catalyzed MgH2 had a capacity retention rate of 95.2% after 50 hydrogen absorption-desorption cycles. The dehydrogenation and hydrogenation apparent activation energies of MgH2-TTONC were 90.5 kJ.mol-1 and 52.7 kJ.mol-1, respectively. The catalytic mechanism analysis revealed that the in situ formed Ti generated TiH2 in the hydrogenation process, and Ti/TiH2 acted as a hydrogen pump to diffuse hydrogen atoms in the hydrogen absorption/desorption process. The for-mation of stable CN layers with carbon structural defects on the surface of MgH2 inhibited the fragmen-tation and agglomeration of MgH2 particles, and they served as nucleation sites to enhance hydrogen diffusion. Hence, the dehydrogenation/hydrogenation properties and cyclic stability of MgH2 were greatly enhanced by the addition of TTONC.(c) 2023 Elsevier B.V. All rights reserved.