Magnesium-based hydrogen storage materials,such as MgH_(2),have attracted considerable attention because of its superior hydrogen storage capacities,inexpensive,and excellent reversibility.However,their high thermodyn...Magnesium-based hydrogen storage materials,such as MgH_(2),have attracted considerable attention because of its superior hydrogen storage capacities,inexpensive,and excellent reversibility.However,their high thermodynamic stabilities and slow kinetics lead to relatively high desorption temperatures,which severely limit the wide application of MgH_(2).In this study,the inclusion of vanadium induced the formation Ni-Co metal-organic frameworks(MOF)from a NiCo layered double hydroxide(LDH),thereby increasing the number of defects and vacancies,and improving the hydrogen storage properties of MgH_(2).The synthesized NiCo-MOF/V-O-doped MgH_(2) system demonstrates excellent hydrogen storage capacity.More specifically,5 wt.%of H_(2) was released over 20 min at a relatively low dehydrogenation temperature of 250℃,and almost complete dehydrogenation was achieved at 300℃ for 5 min.In addition,at 125℃,the hydrogen storage material absorbed 5.5 wt.%H_(2) in 10 min.Furthermore,the activation energy of dehydrogenation was determined to be 69.588±6.302 k J·mol^(-1)which is significantly lower than that of the ball-milled MgH_(2)(i.e.,118.649±2.825 kJ·mol^(-1)).It was therefore inferred that during dehydrogenation process,a Mg_(2)Ni/Mg_(2) NiH_4 hydrogen pump is formed by Ni,while the V-H and Co-H bonds formed by Co and V during the reaction act synergistically to catalyze the absorption and desorption of hydrogen,thereby increasing the hydrogen storage capacity of MgH_(2).These experiments provide new perspectives on the commercial application of MgH_(2).展开更多
以可膨胀物理微球Expancel 920 DU 40为发泡剂,通过物理共混和化学交联的方式制备了发泡杜仲胶(EUG)/高密度聚乙烯(HDPE)形状记忆材料,从而实现了轻量化。采用扫描电镜、差示扫描量热法和万能材料试验机等对不同共混比的发泡EUG/HDPE复...以可膨胀物理微球Expancel 920 DU 40为发泡剂,通过物理共混和化学交联的方式制备了发泡杜仲胶(EUG)/高密度聚乙烯(HDPE)形状记忆材料,从而实现了轻量化。采用扫描电镜、差示扫描量热法和万能材料试验机等对不同共混比的发泡EUG/HDPE复合材料的微观形貌、结晶熔融行为、物理机械性能和形状记忆行为等进行了研究。结果表明,随着HDPE用量的增加,发泡EUG/HDPE形状记忆材料的交联程度和拉伸强度降低,定伸应力增大,物理机械性能与材料内部的交联结构、晶区、泡孔等微观结构密切相关;HDPE的加入使复合材料的发泡程度增大,EUG相的熔融温度和相对结晶度随HDPE用量的增加而降低,HDPE的相对结晶度增大而熔融温度基本无变化;随HDPE用量的增加,复合材料的热刺激响应温度升高,形变回复速率减小,热致形变回复率无明显变化。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U24A2044,52071092).
文摘Magnesium-based hydrogen storage materials,such as MgH_(2),have attracted considerable attention because of its superior hydrogen storage capacities,inexpensive,and excellent reversibility.However,their high thermodynamic stabilities and slow kinetics lead to relatively high desorption temperatures,which severely limit the wide application of MgH_(2).In this study,the inclusion of vanadium induced the formation Ni-Co metal-organic frameworks(MOF)from a NiCo layered double hydroxide(LDH),thereby increasing the number of defects and vacancies,and improving the hydrogen storage properties of MgH_(2).The synthesized NiCo-MOF/V-O-doped MgH_(2) system demonstrates excellent hydrogen storage capacity.More specifically,5 wt.%of H_(2) was released over 20 min at a relatively low dehydrogenation temperature of 250℃,and almost complete dehydrogenation was achieved at 300℃ for 5 min.In addition,at 125℃,the hydrogen storage material absorbed 5.5 wt.%H_(2) in 10 min.Furthermore,the activation energy of dehydrogenation was determined to be 69.588±6.302 k J·mol^(-1)which is significantly lower than that of the ball-milled MgH_(2)(i.e.,118.649±2.825 kJ·mol^(-1)).It was therefore inferred that during dehydrogenation process,a Mg_(2)Ni/Mg_(2) NiH_4 hydrogen pump is formed by Ni,while the V-H and Co-H bonds formed by Co and V during the reaction act synergistically to catalyze the absorption and desorption of hydrogen,thereby increasing the hydrogen storage capacity of MgH_(2).These experiments provide new perspectives on the commercial application of MgH_(2).
基金国家自然科学基金委员会青年科学基金资助项目(51303092)山东省高等学校科技计划项目(J 14 LA 12)
文摘以可膨胀物理微球Expancel 920 DU 40为发泡剂,通过物理共混和化学交联的方式制备了发泡杜仲胶(EUG)/高密度聚乙烯(HDPE)形状记忆材料,从而实现了轻量化。采用扫描电镜、差示扫描量热法和万能材料试验机等对不同共混比的发泡EUG/HDPE复合材料的微观形貌、结晶熔融行为、物理机械性能和形状记忆行为等进行了研究。结果表明,随着HDPE用量的增加,发泡EUG/HDPE形状记忆材料的交联程度和拉伸强度降低,定伸应力增大,物理机械性能与材料内部的交联结构、晶区、泡孔等微观结构密切相关;HDPE的加入使复合材料的发泡程度增大,EUG相的熔融温度和相对结晶度随HDPE用量的增加而降低,HDPE的相对结晶度增大而熔融温度基本无变化;随HDPE用量的增加,复合材料的热刺激响应温度升高,形变回复速率减小,热致形变回复率无明显变化。
