Improvement of the hydrogen storage kinetics of NaAlH4 with Ti-loaded high-ordered mesoporous carbons (Ti-OMCs) by melt infiltration

Abstract

Combination of nanoconfinement and catalyst addition is a promising strategy to enhance the kinetics and reversibility of hydrogen storage in complex hydrides. Herein, Ti-loaded high-ordered mesoporous carbons (Ti-OMCs) were directly synthesized via a solvent evaporation induced self-assembly method (EISA) with in situ crystallization and carbonation technology using phenolic resols, tetrabutyl titanate (Ti(OBu)₄) and triblock copolymer F127 as organic carbon sources, Ti sources and templates, respectively. The obtained Ti-OMCs exhibit uniform pore sizes (4 nm), high specific surface area (427.9 m² g⁻¹) and large pore volumes (0.34 cm³ g⁻¹), which were used to combine catalyst addition and nanoconfinement to improve the hydrogen storage properties of NaAlH₄ by melt infiltration. The hydrogen desorption curves show that NaAlH₄ with Ti-OMCs exhibits better kinetic properties than both nanocrystalline TiO₂ catalysed NaAlH₄ and melt-infiltrated NaAlH₄ with high ordered mesoporous carbons (OMCs). The hydrogen-release onset temperature of NaAlH₄ with Ti-OMCs is reduced to less than 60 °C, and 80% hydrogen is released in less than 20 min. In addition, NaAlH₄ with Ti-OMCs exhibit good reversibility and cycling stability, and the optimum rehydrogention temperature is 120 °C.