Improvement of the hydrogen storage kinetics of NaAlH4 with nanocrystalline titanium dioxide loaded carbon spheres (Ti-CSs) by melt infiltration

Nanocrystalline titanium dioxide loaded carbon spheres (Ti-CSs) with 10wt% TiO2 were synthesized through an easy one-step method using phenolic resols, titania nanoparticles and Pluronic F127 as organic carbon sources, inorganic precursors and surfactant, respectively. The results show that the as-prepared Ti-CSs composite is spherical shape with a diameter ranging from 0.3 to 2 μm, and rutile TiO2 nanoparticles are distributed on the surface of the carbon spheres. Then the kinetics of NaAlH4 was improved through depositing it on the surface of as-prepared Ti-CSs by melt infiltration. The results show that NaAlH4 with Ti-CSs exhibits better hydrogen desorption kinetics than TiF3 or nanocrystalline TiO2 catalysted-NaAlH4, and it starts to release hydrogen at about 40 °C and releases about 25% of the hydrogen content during heating to 60 °C. The results from SEM and XPS show that hydrogen storage properties of NaAlH4 were considerably improved due to the formation of special structure during melt infiltration and the nanocrystalline TiO2 and/or amorphous phase Ti–Al clusters near the subsurface sites, which succeed in combining catalyst addition (TiO2 nanoparticles) and nanoconfinement to improve the kinetics of NaAlH4.