Effects of Ball Milling on Hydrogen Release Performance of Titanium Dihydride

Abstract

TiH₂─a common, simple metal-based material that can store 4% hydrogen of gravimetric hydrogen density─is being explored as a catalyst to improve the properties of hydrogen storage materials. To develop methods for enhancing the capabilities of TiH₂, understanding the relationship between its H₂ release performance and size is vital. Notably, ball milling can regulate the crystallite size, grain size, and surface states of powder samples. In this study, the influence of ball milling on the H₂ release performance of TiH₂ was investigated. TiH₂ samples ball-milled for different durations were compared with commercial TiH₂. The particle and crystallite size decreased with an increase in ball-milling time. A 150 °C reduction in the first H₂ release temperature from TiH₂ in temperature-programmed desorption was induced by ball milling. X-ray photoelectron spectroscopy revealed that the surface of commercial TiH₂ is composed of an oxide layer, which was decimated by high-energy ball milling. Long-term ball milling curbed the extent of H₂ release. These results underscore the benefits of adopting facile ball milling for suitable durations to enhance the H₂ release performance of TiH₂ by decreasing the crystallite and particle size and disrupting the surface oxide layer.