Impacts of Ce dopants on the hydrogen storage performance of Ti-Cr-V alloys

Vanadium-based alloys are considered to be one of the most promising hydrogen storage materials due to their high hydrogen storage capacity under ambient conditions. However, their complex activation at high temperature and poor stability pose serious challenges for large-scale applications. In this work, a series of TiCr3V16Cex (x = 0, 0.1, 0.2, 0.4, 1) hydrogen storage alloys were developed with different Ce contents using arc melting. The hydrogen storage and desorption performance, activation mechanism, and hydrogen ab-sorption mechanism of the prepared alloys were investigated. Physical characterization confirms that the alloy is body-centered cubic (BCC) with Ce dopants, which exist in the form of oxides. The pressure-composition-temperature (PCT) test showed that the hydrogen storage plateau pressure of the Ce-doped alloy is increased compared to the Ce-free counterparts, while the hydrogen storage capacity decreased slightly with increasing Ce content. In addition, the influence of Ce doping on the alloy kinetics and ther-modynamics is also discussed. The results showed that the TiCr3V16Cex (x = 0.2, 0.4, 1) alloys could absorb and release hydrogen at room temperature without activation. As an optimum, the TiCr3V16Ce0.2 alloy shows a hydrogen absorption rate of up to 3.69 wt%, and an effective hydrogen desorption capacity of 2.29 wt% at 25 degrees C. After hydrogen absorption and desorption cycles, the alloy almost maintains its original capacity. The Ce-doped BCC alloy developed in this work provides a new route to achieve high hydrogen storage performance under mild conditions.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Vanadium-based alloys are promising materials for hydrogen storage due to their high capacity at ambient conditions. However, the challenges of complex activation and poor stability at high temperatures limit their large-scale applications. In this study, TiCr3V16Cex (x = 0, 0.1, 0.2, 0.4, 1) hydrogen storage alloys with different Ce contents were developed and investigated for their hydrogen storage performance, activation mechanism, and absorption mechanism. The results showed that Ce doping increased the plateau pressure while slightly decreasing the hydrogen storage capacity. Ce doping also affected the kinetics and thermodynamics of the alloy. The TiCr3V16Cex (x = 0.2, 0.4, 1) alloys exhibited hydrogen absorption and desorption at room temperature without activation. The optimum alloy, TiCr3V16Ce0.2, showed a high hydrogen absorption rate and effective hydrogen desorption capacity. After cycling, the alloy maintained its original capacity. The Ce-doped BCC alloy developed in this study offers a new route for achieving high hydrogen storage performance under mild conditions.