Robust architecture of 2D nano Mg-based borohydride on graphene with superior reversible hydrogen storage performance  

作　　者：Xuancheng Wang Yuxiao Jia Xuezhang Xiao Panpan Zhou Jiapeng Bi Jiacheng Qi Ling Lv Fen Xu Lixian Sun Lixin Chen 

机构地区：[1]State Key Laboratory of Silicon Materials,School of Materials Science and Engineering,Zhejiang University,Hangzhou 310027,China [2]Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials,School of Material Science and Engineering,Guilin University of Electronic Technology,Guilin 541004,China [3]Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province,Hangzhou 310013,China

出　　处：《Journal of Materials Science & Technology》2023年第15期121-130,共10页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.52171223 and U20A20237);the Zhejiang Provincial Natural Science Foundation of China(No.LZ21E010002).

摘　　要：Efficient technical strategies to synthesize hydrides with high capacity and favorable reversibility are significant for the development of novel energy materials.Herein,nano Mg-based borohydride,Mg(BH_(4))_(2),with robust architecture was designed and prepared by confining on graphene through a solution selfconfinement method.The Mg(BH_(4))_(2) confined on graphene displays a wrinkled 2D nano layer morphology within 8.8 nm thickness.Such 2D nano Mg(BH_(4))_(2) can start dehydrogenation at 67.9℃ with a high capacity of 12.0 wt.%,which is 190.5℃ lower than pristine Mg(BH_(4))_(2).The isothermal dehydrogenation tests and kinetics fitting results indicate the 2D nano Mg(BH_(4))_(2) possesses much-enhanced dehydrogenation kinetics of 31.3 kJ/mol activation energy,which is only half of pristine Mg(BH_(4))_(2).The thermodynamics of the 2D nano Mg(BH_(4))_(2) is also verified by PCT tests,of which Gibbs free energy value for the confined 2D nano Mg(BH_(4))_(2) is estimated to be-18.01 kJ/mol H_(2),lower than-16.36 kJ/mol H_(2) of pristine Mg(BH_(4))_(2).Importantly,the reversibility of the confined 2D nano Mg(BH_(4))_(2) is significantly enhanced to over 90%capacity retention with relatively kinetics stability during 10 cycles.The mechanism analyses manifest that Mg(BH_(4))_(2) exhibits stable 2D nano morphology during 10 cyclic tests,resulting in the greatly reduced H diffusion path and the improved de/rehydrogenation kinetics of the 2D nano Mg(BH_(4))_(2).Based on theoretical calculations of Mg(BH_(4))_(2) and the intermediate MgB12H12 confined on graphene,the charge transfer status of both samples is modified to facilitate de/rehydrogenation,thus leading to the significant thermodynamic improvements of the reversible hydrogen storage performances for 2D nano Mg(BH_(4))_(2).Such investigation of the Mg-based borohydride will illuminate prospective technical research of energy storage materials.

关 键 词：Mg(BH_(4))_(2) Nano-confinement Kinetics THERMODYNAMICS Reversible hydrogen storage 

分 类 号：TB332[一般工业技术—材料科学与工程] TM912[电气工程—电力电子与电力传动]