Highly active multivalent multielement catalysts derived from hierarchical porous TiNb2O7 nanosphere

• 作 者: Lingchao Zhang Ke Wang Yongfeng Liu Xin Zhang Jianjiang Hu Mingxia Gao Hongge Pan
• 机 构: State Key Laboratory of Silicon Materials and School of Materials Science and Engineering Zhejiang U
• 出 处: 纳米研究（英文版）
• 发表日期: 2021年1期
• 关键词: hydrogen storage magnesium hydride transition metal catalysts nanospheres hydrog

Critical limitations in applying MgH2 as a hydrogen-storage medium include the high H2 desorption temperature and slow reaction kinetics.In this study,we synthesized hierarchical porous TiNb2O7 spheres in micrometer scale built with 20-50 nm nanospheres,which showed stable activity to catalyze hydrogen storage in MgH2 as precursors.The addition of 7 wt.％TiNb2O7 in MgH2 reduced the dehydrogenation onset temperature from 300 to 177℃.At 250℃,approximately 5.5 wt.％H2 was rapidly released in 10 min.Hydrogen uptake was detected even at room temperature under 50 bar hydrogen;4.5 wt.％H2 was absorbed in 3 min at 150℃,exhibiting a superior low-temperature hydrogenation performance.Moreover,nearly constant capacity was observed from the second cycle onward,demonstrating stable cydability.During the ball milling and initial de/hydrogenation process,the high-valent Ti and Nb of TiNb2O7 were reduced to the lower-valent species or even zero-valent metal,which in situ created multivalent multielement catalytic surroundings.A strong synergistic effect was obtained for hybrid oxides of Nb and Ti by density functional theory(DFT)calculations,which largely weakens the Mg-H bonding and results in a large reduction in kinetic barriers for hydrogen storage reactions of MgH2.Our findings may guide the further design and development of high-performance complex catalysts for the reversible hydrogen storage of hydrides.