Optimizing Ti3C2Tx to activate passivated Mg for direct and widespread application in hydrogen storage

MgH2 is considered one of the most promising solid-state hydrogen storage materials due to its high theoretical capacity. However, the formation of a passive oxide layer on Mg significantly hinders its direct use for hydrogen storage. In this study, Ti3C2Tx catalysts synthesized via different etching methods were employed to activate passivated Mg. The Mg-Ti3C2Tx composites were further optimized by adjusting the ball-milling time. Results show that ball-milling effectively promotes microstructural evolution and breaks down the Mg surface passivation layer. The optimized system achieves a hydrogen absorption capacity of 5.29 wt%, with a desorption capacity of 5.21 wt%, and a maximum absorption rate of 2.61 wt%/min. Moreover, the apparent activation energy is significantly reduced to 134.33 kJ/mol, 134.09 kJ/mol lower than that of pure MgH2 (268.42 kJ/mol). These improvements are attributed to the catalytic effect of Ti3C2Tx and the increased grain boundaries from refined Mg particles. This work demonstrates a viable strategy for directly utilizing passivated Mg, offering both experimental and theoretical support for the large-scale, low-cost application of Mg-based hydrogen storage materials.