溶胶-凝胶法制备TiO2增强LiAlH4放氢性能OA

Lithium alanate(LiAlH4)is considered a promising solid-state hydrogen storage material due to its high theoretical hydrogen capacity(mass fraction about 10.5%).However,its practical application is hampered by high decomposition temperatures and sluggish kinetics.Titanium dioxide(TiO2)has shown potential as an effective catalyst for improving the dehydrogenation properties of hydrides.Nevertheless,the catalytic performance of commercial TiO2 is often limited by its uncontrollable morphology and structure.To overcome this limitation,this study used the Sol-Gel method to synthesize nanostructured TiO2 catalysts with high specific surface area and abundant defects.The as-prepared TiO2 was ball-milled with LiAlH4 at different mass ratios(1%,3%,5%,and 7%)to form composites,whose dehydrogenation properties were systematically investigated.Results demonstrated that the 5%(in mass)TiO2-doped sample exhibited optimal performance,lowering the onset dehydrogenation temperature of LiAlH4 to 112℃,which is 53℃lower than that of pristine LiAlH4(165℃).Under isothermal conditions at 200℃,the composite released a total hydrogen capacity of 7.84%(in mass)within a significantly shorter time,and completed dehydrogenation approximately 30 min faster than the undoped sample.Even at a lower temperature of 150℃,the doped sample released 4.64%(in mass)hydrogen,far exceeding the capacity of pure LiAlH4(<1%(in mass))at the same temperature.Kinetic analysis revealed that TiO2 doping reduced the activation energy for the first dehydrogenation step from 116.2 kJ/mol to 55.6 kJ/mol,a remarkable decrease of 52%.In-situ formation of active AlTi and LiAl intermediate phases during dehydrogenation played a critical role,which served as efficient catalytic centers,providing new pathways for hydrogen recombination and desorption.This work not only verifies that TiO2 synthesized via the Sol-Gel method can effectively break through the performance ceiling of commercial catalysts,but also offers new insights and experimental basis for designing next-generation high-performance catalysts for hydrogen storage materials.