Enhanced Hydrogen Desorption Performance of AlH3 via MXene Catalysis

Aluminum hydride (AlH3) features a theoretical hydrogen content of 10.1 wt%, with initial hydrogen desorption temperatures generally ranging from 150 to 200 °C. However, its metastability makes it complicated to achieve low hydrogen desorption temperatures alongside high desorption capacities, which has limited its practical application. This study aims to improve the hydrogen desorption performance of AlH3 by incorporating different MXenes (V2C, Nb2C, Ti3C2, Ti3CN) accompanied by ball milling condition and catalyst content optimizations. It was shown that AlH3 catalyzed with 1 wt% Nb2C, ball milled at 300 rpm for 180 min under an argon atmosphere, exhibits the best performance, achieving an initial hydrogen desorption temperature of 95 °C and a final hydrogen desorption content of 9.3 wt%. It was further demonstrated that Nb2C MXene mainly acts as an efficient catalyst for the hydrogen desorption process of AlH3 and can extend the Al–H bonds of AlH3 in local interphase regions observed by means of theoretical calculation, thus enhancing the hydrogen desorption performance of AlH3. This work proposes a method to achieve high-capacity and low-temperature hydrogen desorption from metastable AlH3 through proper ball milling and the introduction of MXenes.