Hydrogen Release and Uptake of MgH[sub.2] Modified by Ti[sub.3]CN MXene

• Published in: Inorganics Vol. 11; no. 6
• Main Authors: Huang, Xiantun, Lu, Chenglin, Li, Yun, Tang, Haimei, Duan, Xingqing, Wang, Kuikui, Liu, Haizhen
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.06.2023
• Subjects: Carbon compounds; Diffraction; Magnesium compounds; Mechanical properties; Nitrides; Structure; Thermal properties; Transition metal compounds; X-rays; China
• ISSN: 2304-6740; 2304-6740
• DOI: 10.3390/inorganics11060243

MgH[sub.2] has a high hydrogen content of 7.6 wt% and possesses good reversibility under normal conditions. However, pristine MgH[sub.2] requires a high temperature above 300 °C to release hydrogen, with very slow kinetics. In this work, we utilized Ti[sub.3] CN MXene to reduce the operating temperature and enhance the kinetics of MgH[sub.2] . The initial temperature of MgH[sub.2] decomposition can be lowered from 322 °C for pristine MgH[sub.2] to 214 °C through the employment of Ti[sub.3] CN. The desorbed MgH[sub.2] + 7.5 wt% Ti[sub.3] CN can start absorption at room temperature, while the desorbed pristine MgH[sub.2] can only start absorption at 120 °C. The employment of Ti[sub.3] CN can significantly improve the hydrogen release kinetics of MgH[sub.2] , with the desorption activation energy decreasing from 121 to 80 kJ mol[sup.−1] . Regarding thermodynamics, the desorption enthalpy changes of MgH[sub.2] and MgH[sub.2] + 7.5 wt% Ti[sub.3] CN were 79.3 and 78.8 kJ mol[sup.−1] , respectively. This indicates that the employment of Ti[sub.3] CN does not alter the thermal stability of MgH[sub.2] . Phase evolution studies through the use of X-ray diffraction and electron diffraction both confirm that Ti[sub.3] 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 MgH[sub.2] .