High catalytic activity derived from TiNbAlC MAX towards improving the hydrogen storage properties of MgH2

Abstract

MXenes are great catalysts for MgH2 hydrogen storage material. Nevertheless, the synthesis of MXenes needs a large quantity of corrosive HF solution to remove the Al layers from the MAX materials, which is harmful to the environment. In this work, TiNbAlC MAX was employed without HF-treatment to tailor the hydrogen storage of MgH2. The MgH2 + 10 wt% TiNbAlC composite was prepared by ball milling. The addition of 10 wt% TiNbAlC greatly reduces the onset temperature of MgH2 desorption from 332 °C to 197 °C. The composite can desorb 6.2 wt% of H2 in 10 min at a constant temperature of 300 °C. Moreover, the dehydrided MgH2 + 10 wt% TiNbAlC composite can start to absorb hydrogen at room temperature under a H2 pressure of 6 MPa. The hydrogen desorption activation energy of the composite was calculated by Kissinger’s method to be 101 kJ mol−1. Microstructures studies demonstrated that TiNbAlC will partially react with MgH2/H2 to form TiH1.971, which can act as a “hydrogen pump” to facilitate the hydrogen sorption of MgH2. This work suggests that MAX materials are good catalysts for hydrogen storage of MgH2 and provides new insight into the role of MAX phase in tailoring the hydrogen storage of Mg-based hydrogen storage materials.