1. Hydrogen Release and Uptake of MgH 2 Modified by Ti 3 CN MXene.
- Author
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Huang, Xiantun, Lu, Chenglin, Li, Yun, Tang, Haimei, Duan, Xingqing, Wang, Kuikui, and Liu, Haizhen
- Subjects
HYDROGEN ,HYDROGEN storage ,HYDROGEN content of metals ,TRANSITION metals ,ELECTRON diffraction - Abstract
MgH
2 has a high hydrogen content of 7.6 wt% and possesses good reversibility under normal conditions. However, pristine MgH2 requires a high temperature above 300 °C to release hydrogen, with very slow kinetics. In this work, we utilized Ti3 CN MXene to reduce the operating temperature and enhance the kinetics of MgH2 . The initial temperature of MgH2 decomposition can be lowered from 322 °C for pristine MgH2 to 214 °C through the employment of Ti3 CN. The desorbed MgH2 + 7.5 wt% Ti3 CN can start absorption at room temperature, while the desorbed pristine MgH2 can only start absorption at 120 °C. The employment of Ti3 CN can significantly improve the hydrogen release kinetics of MgH2 , with the desorption activation energy decreasing from 121 to 80 kJ mol−1 . Regarding thermodynamics, the desorption enthalpy changes of MgH2 and MgH2 + 7.5 wt% Ti3 CN were 79.3 and 78.8 kJ mol−1 , respectively. This indicates that the employment of Ti3 CN does not alter the thermal stability of MgH2 . Phase evolution studies through the use of X-ray diffraction and electron diffraction both confirm that Ti3 CN remains stable during the hydrogen release and uptake process of the composite. This work will help understand the impact of a transition metal carbonitride on the hydrogen storage of MgH2 . [ABSTRACT FROM AUTHOR]- Published
- 2023
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