Directed Stabilization by Air-Milling and Catalyzed Decomposition by Layered Titanium Carbide Toward Low-Temperature...

AlH₃ is a metastable hydride with a theoretical hydrogen capacity of 10.01 wt % and is very easy to decompose during ball milling especially in the presence of many catalysts, which will lead to the attenuation of the available hydrogen capacity. In this work, AlH₃ was ball milled in air (called "air-milling") with layered Ti₃C₂ to prepare a Ti₃C₂-catalyzed AlH₃ hydrogen storage material. Such air-milled and Ti₃C₂-catalyzed AlH₃ possesses excellent hydrogen storage performances, with a low initial decomposition temperature of just 61 °C and a high hydrogen release capacity of 8.1 wt %. In addition, 6.9 wt % of hydrogen can be released within 20 min at constantly 100 °C, with a low activation energy as low as 40 kJ mol^-1. Air-milling will lead to the formation of an Al₂O₃ oxide layer on the AlH₃ particles, which will prevent continuous decomposition of AlH₃ when milling with active layered Ti₃C₂. The layered Ti₃C₂ will grip on and intrude into the AlH₃ particle oxide layers and then catalyze the decomposition of AlH₃ during heating. The strategy employing air-milling as a synthesis method and utilizing layered Ti₃C₂ as a catalyst in this work can solve the key issue of severe decomposition during ball milling with catalysts economically and conveniently and thus achieve both high-capacity and low-temperature hydrogen storage of AlH₃. This air-milling method is also effective for other active catalysts toward both reducing the decomposition temperature and increasing the available hydrogen capacity of AlH₃.