Gao Haiguang, Zhao Yingyan, Zhang Xu, Zhao Baozhou, Jia Zhen, Liu Yana, Hu Xiaohui, Zhu Yunfeng
School of Petrochemical Engineering, Changzhou University, Changzhou 213164, PR China.
College of Materials Science and Engineering, Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing 211816, PR China.
J Colloid Interface Sci. 2023 Dec 15;652(Pt A):979-988. doi: 10.1016/j.jcis.2023.08.122. Epub 2023 Aug 21.
Although MXene catalysts etched from precursor MAX have greatly improved the hydrogen storage performance of magnesium hydride (MgH), the use of dangerous and polluting etchers (such as hydrofluoric acid) and the direct removal of potentially catalytically active A-layer substances (such as Al) present certain limitations. Here, solid-solution MAX phase TiVAlC catalyst without etching treatment has been directly introduced into MgH system to improve the hydrogen storage performance. The optimal MgH-10 wt% TiVAlC can release about 6.00 wt% hydrogen at 300 °C within 378 s and absorb about 4.82 wt% hydrogen at 175 °C within 900 s. After 50 isothermal hydrogen ab/desorption cycles, the excellent cyclic stability and capacity retention (6.4 wt%, 99.6%) can be found for MgH-10 wt% TiVAlC. The superb catalytic activity of TiVAlC catalyst can be explained by abundant electron transfer at external interfaces with MgH/Mg, which can be further enhanced by impurity phase TiAlC due to strong H affinity brought from abundant electron transfer at internal interfaces (TiAlC/TiVAlC). The influence of impurity phase which is common in MAX phase on the overall activity of catalysts has been firstly studied here, providing a unique method for designing composite catalyst to improve hydrogen storage performance of MgH.
尽管从前驱体MAX蚀刻得到的MXene催化剂极大地改善了氢化镁（MgH）的储氢性能，但使用危险且有污染的蚀刻剂（如氢氟酸）以及直接去除潜在具有催化活性的A层物质（如Al）存在一定局限性。在此，未经蚀刻处理的固溶体MAX相TiVAlC催化剂已被直接引入MgH体系以改善储氢性能。最优的MgH - 10 wt% TiVAlC在300℃下378秒内可释放约6.00 wt%的氢，在175℃下900秒内可吸收约4.82 wt%的氢。经过50次等温吸/放氢循环后，MgH - 10 wt% TiVAlC表现出优异的循环稳定性和容量保持率（6.4 wt%，99.6%）。TiVAlC催化剂的卓越催化活性可通过其与MgH/Mg的外部界面处大量的电子转移来解释，由于内部界面（TiAlC/TiVAlC）处大量电子转移带来的强H亲和力，杂质相TiAlC可进一步增强这种电子转移。本文首次研究了MAX相中常见的杂质相对催化剂整体活性的影响，为设计复合催化剂以改善MgH的储氢性能提供了一种独特方法。
