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

Abstract

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.