Niobium fluoride-modified hydrogen evolution reaction of magnesium borohydride diammoniate  

作　　者：Yujie Lv Bao Zhang Haixiang Huang Bogu Liu Wei Lv Jianguang Yuan Guanglin Xia Xuebin Yu Dalin Sun Ying Wu 

机构地区：[1]School of Energy Power and Mechanical Engineering,North China Electric Power University,Beijing,102206,China [2]Institute of Energy Power Innovation,North China Electric Power University,Beijing,102206,China [3]Jiangsu JITRI Advanced Energy & Materials Research Institute Co.,Ltd.,Changzhou,213000,China [4]Department of Materials Science,Fudan University,Shanghai,200433,China

出　　处：《Journal of Materials Science & Technology》2023年第25期197-205,共9页材料科学技术（英文版）

基　　金：supported by the National Key Research and Development Plan(Grant No.2021YFB3802400);the National Natural Science Foundation of China(Grant Nos.52071141,52271212,52201250);the Equipment Pre-research Field Foundation(Grant No.6140721040101);the Interdisciplinary Innovation Program of North China Electric Power University(Grant No.XM2112355).

摘　　要：Metal borohydride ammoniates have become one of the most promising hydrogen storage materials due to their ultrahigh capacities.However,their application is still restricted by the high temperature of hydrogen desorption and the release of ammonia.Here,to promote the dehydrogenation evolution and suppress the ammonia release,different amounts of NbF 5 were introduced into Mg(BH4)2·2NH3.Compared to the pure Mg(BH_(4))_(2)·2NH_(3),the Mg(BH_(4))_(2)·2NH_(3)-NbF_(5) composites exhibit lower onset dehydriding temperatures(53–57℃)and higher dehydriding capacities(5.6 wt.%–8.2 wt.%)at below 200℃,with the complete suppression of ammonia.In addition,7.4 wt.%H_(2) could be released from Mg(BH_(4))_(2)·2NH_(3)–5 mol%NbF5 composite at 200℃ within 20 min and the apparent activation energy is calculated to be 60.28 kJ mol^(-1),which is much lower than that of pure Mg(BH_(4))_(2)·2NH_(3)(92.04 kJ mol^(-1)).Mg(BH_(4))_(2)·2NH_(3) should mechanochemically react with NbF5,forming dual-metal(Mg,Nb)borohydride ammoniate and spherical MgF2.The introduction of electronegative Nb cation results in-situ formation of(Mg,Nb)borohydride ammoniate towards a lower dehydrogenation temperature and a higher hydrogen release purity.The increased phase boundaries among the Mg(BH_(4))_(2)·2NH_(3),dual-metal(Mg,Nb)borohydride ammoniate,and MgF2 phases further facilitate the hydrogen diffusion during the dehydrogenation of the composites.

关 键 词：Hydrogen storage Magnesium borohydride Ammoniates NbF5 CATALYSIS 

分 类 号：TB34[一般工业技术—材料科学与工程]