Zhu Wen, Ren Li, Lu Chong, Xu Hao, Sun Fengzhan, Ma Zhewen, Zou Jianxin
National Engineering Research Center of Light Alloys Net Forming & State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
Shanghai Engineering Research Center of Mg Materials and Applications & School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
ACS Nano. 2021 Nov 23;15(11):18494-18504. doi: 10.1021/acsnano.1c08343. Epub 2021 Oct 26.
MXenes are considered as potential support materials for nanoconfinement of MgH/Mg to improve the hydrogen storage properties. However, it has never been realized so far due to the stacking and oxidation problems caused by unexpected surface terminations (-OH, -O, .) on MXenes. In this study, hexadecyl trimethylammonium bromide was used to build a 3D TiCT architecture of folded nanosheets to reduce the stacking risk of flakes, and a bottom-up self-assembly strategy was successfully applied to synthesize ultradispersed MgH nanoparticles anchored on the surface of the annealed 3D TiCT (Ti-MX). The composite with a 60 wt % loading of MgH NPs, 60MgH@Ti-MX, starts to decompose at 140 °C and is capable of releasing 3.0 wt % H at 150 °C within 2.5 h. In addition, a reversible capacity up to 4.0 wt % H was still maintained after 60 cycles at 200 °C without obvious loss in kinetics. high-resolution TEM observations of the decomposition process together with other analyses revealed that the nanosize effect caused by the nanoconfinement and the multiphasic interfaces between MgH(Mg) and Ti-MX, especially the formed catalytic TiH, were main reasons accounting for the superior hydrogen sorption performances.
MXenes被认为是用于纳米限域MgH/Mg以改善储氢性能的潜在载体材料。然而，由于MXenes上意外的表面端基（-OH、-O等）导致的堆积和氧化问题，到目前为止这一目标尚未实现。在本研究中，使用十六烷基三甲基溴化铵构建了折叠纳米片的三维TiCT结构，以降低薄片的堆积风险，并成功应用自下而上的自组装策略合成了锚定在退火后的三维TiCT（Ti-MX）表面的超分散MgH纳米颗粒。负载60 wt% MgH纳米颗粒的复合材料60MgH@Ti-MX在140°C开始分解，在150°C下2.5小时内能够释放3.0 wt%的氢。此外，在200°C下循环60次后，仍保持高达4.0 wt% H的可逆容量，动力学没有明显损失。对分解过程的高分辨率透射电镜观察以及其他分析表明，纳米限域引起的纳米尺寸效应以及MgH（Mg）与Ti-MX之间的多相界面，特别是形成的催化TiH，是其优异的氢吸附性能的主要原因。
