The role of catalysts in enhancing the hydrogen storage kinetics of the Mg/MgH_(2)system is pivotal.However,the exploration of efficient catalysts and the underlying principles of their design remain both a prominent ...The role of catalysts in enhancing the hydrogen storage kinetics of the Mg/MgH_(2)system is pivotal.However,the exploration of efficient catalysts and the underlying principles of their design remain both a prominent focus and a significant challenge in current research.In this study,we present a bimetallic oxide of Bi_(2)Ti_(2)O_(7)hollow sphere as a highly effective catalyst for MgH_(2).As a result,the Bi_(2)Ti_(2)O_(7)-catalyzed Mg/MgH_(2)system lowers the hydrogen desorption initiation temperature to 194.3℃,reduces the peak desorption temperature to 245.6℃,decreases the dehydrogenation activation energy to 82.14 kJ·mol^(−1),and can absorb 5.4 wt.%of hydrogen within 60 s at 200℃,demonstrating outstanding hydrogen ab/desorption kinetics,compared to pure MgH_(2).Additionally,it can maintain a high hydrogen capacity of 5.2 wt.%,even after 50 dehydrogenation cycles,showing good cycle stability.The characterization results show that the high-valent Bi and Ti in Bi_(2)Ti_(2)O_(7)are reduced to their low-valent or even zero-valent metallic states during the dehydrogenation and hydrogenation process,thus establishing an in-situ multivalent and multi-element catalytic environment.Density functional theory calculations further reveal that the synergistic effects between Bi and Ti in the Bi-Ti mixed oxide facilitate the cleavage of Mg-H bonds and lower the kinetic barrier for the dissociation of hydrogen molecules,thereby substantially enhancing the kinetics of the Mg/MgH_(2)system.This study presents a strategic method for developing efficient catalysts for hydrogen storage materials by harnessing the synergistic effects of metal elements.展开更多
基金supported by the National Key Research and Development Program of China(No.2024YFB4007204,2022YFB4004301)the National Natural Science Founda-tion of China(Grant Nos.52477220,52301287,22005353)+2 种基金the Two-chain Integration Key Project of Shaanxi Province(2021LLRH-09)the Key Research and Development Program of Shaanxi Province(No.2024CY2-GJHX-44,2024CY2-GJHX-53,2024GX-ZDCYL-04-06)the Key Industrial Chain Technology Research Program of Xi’an city(23LL-RHZDZX0017).
文摘The role of catalysts in enhancing the hydrogen storage kinetics of the Mg/MgH_(2)system is pivotal.However,the exploration of efficient catalysts and the underlying principles of their design remain both a prominent focus and a significant challenge in current research.In this study,we present a bimetallic oxide of Bi_(2)Ti_(2)O_(7)hollow sphere as a highly effective catalyst for MgH_(2).As a result,the Bi_(2)Ti_(2)O_(7)-catalyzed Mg/MgH_(2)system lowers the hydrogen desorption initiation temperature to 194.3℃,reduces the peak desorption temperature to 245.6℃,decreases the dehydrogenation activation energy to 82.14 kJ·mol^(−1),and can absorb 5.4 wt.%of hydrogen within 60 s at 200℃,demonstrating outstanding hydrogen ab/desorption kinetics,compared to pure MgH_(2).Additionally,it can maintain a high hydrogen capacity of 5.2 wt.%,even after 50 dehydrogenation cycles,showing good cycle stability.The characterization results show that the high-valent Bi and Ti in Bi_(2)Ti_(2)O_(7)are reduced to their low-valent or even zero-valent metallic states during the dehydrogenation and hydrogenation process,thus establishing an in-situ multivalent and multi-element catalytic environment.Density functional theory calculations further reveal that the synergistic effects between Bi and Ti in the Bi-Ti mixed oxide facilitate the cleavage of Mg-H bonds and lower the kinetic barrier for the dissociation of hydrogen molecules,thereby substantially enhancing the kinetics of the Mg/MgH_(2)system.This study presents a strategic method for developing efficient catalysts for hydrogen storage materials by harnessing the synergistic effects of metal elements.
