@article{Zhang2021, 
author = {Lingchao Zhang and Ke Wang and Yongfeng Liu and Xin Zhang and Jianjiang Hu and Mingxia Gao and Hongge Pan},
title = {Highly active multivalent multielement catalysts derived from hierarchical porous TiNb2O7 nanospheres for the reversible hydrogen storage of MgH2},
year = {2021},
journal = {Nano Research},
volume = {14},
number = {1},
pages = {148-156},
keywords = {hydrogen storage, magnesium hydride, transition metal catalysts, nanospheres, hydrogenation},
url = {https://www.sciopen.com/article/10.1007/s12274-020-3058-4},
doi = {10.1007/s12274-020-3058-4},
abstract = {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 °C. At 250 °C, 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 °C, exhibiting a superior low-temperature hydrogenation performance. Moreover, nearly constant capacity was observed from the second cycle onward, demonstrating stable cyclability. 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.}
}