Ultra-fine TiO₂ nanoparticles supported on three-dimensionally ordered macroporous structure for improving the hydrogen storage performance of MgH₂

Three-dimensionally ordered macroporous (3DOM) materials have attracted sizable attention due to their unique interconnected and periodically arranged macroporous structures. 3DOM TiO₂ prepared by colloidal crystal template method was firstly applied to enhance the hydrogen storage properties of MgH₂. TiO₂ nanoparticles with the size of 5 ∼ 10 nm were supported on 3DOM structure with ordered and homogeneous pores about 150 nm. MgH₂-5 wt% 3DOM TiO₂ can quickly absorb 4.17 wt% H₂ within 1800 s at 100 °C and desorb 5.75 wt% H₂ at 300 °C within 1000 s. Ultra-fine and uniformly dispersed TiO₂ particles can provide numerous reactive sites for the hydrogen de/absorption of MgH₂. In addition, the electron transfer on contact interface between MgH₂ and TiO₂ can be observed by the binding energy shift of TiO₂, and further be verified by work function and charge density calculations. Therefore, the in-situ formed multiple valence Ti can be an intermediate medium for transformation from MgH₂ to Mg, which leads to the destabilization of MgH₂ and ultimately promotes dehydrogenation. This finding will attract more attention to elaborate highly efficient catalysts based on 3DOM structure in hydrogen storage materials.