One-step self-assembly of TiO2/MXene heterostructures for improving the hydrogen storage performance of magnesium hydride

Abstract

Self-assembly of TiO2 nanoparticles (M-TiO2, 15–20 nm in size) on few layer Ti3C2Tx (FL-Ti3C2Tx) are conducted via simple one-step ultrasound method at room temperature, in which van der Waals interactions act as the driving force. After introduced into MgH2 system, M-TiO2/FL-Ti3C2Tx heterostructure with mass ratio of 60: 40 (6 M-TiO2/FL-Ti3C2Tx) shows the best catalytic activity. The one-step self-assembly preparation can alleviate the restacking of FL-Ti3C2Tx and the agglomeration of M-TiO2 nanoparticles to a certain extent, which can generate lots of interfaces between M-TiO2 and FL-Ti3C2Tx. The rich interfaces can not only act as hydrogen diffusion channels, but also the electron transfer on the interfaces can enhance the catalytic activity of the whole heterostructure. Besides, abundant electrons from multiple valence Ti (Ti4+, Ti3+, Ti2+, Ti0) can effectively promote the reversible reaction between MgH2 and Mg, H2. The facile preparation method facilitates the understanding of MXene heterostructure catalysts, without the influence of particle growth and impurities. These findings provide new insights to design heterostructure with high catalytic activity and guide the understanding of its catalytic mechanism.