MgH_(2) is a promising high-capacity solid-state hydrogen storage material,while its application is greatly hindered by the high desorption temperature and sluggish kinetics.Herein,intertwined 2D oxygen vacancy-rich V...MgH_(2) is a promising high-capacity solid-state hydrogen storage material,while its application is greatly hindered by the high desorption temperature and sluggish kinetics.Herein,intertwined 2D oxygen vacancy-rich V_(2)O_(5) nanosheets(H-V_(2)O_(5))are specifically designed and used as catalysts to improve the hydrogen storage properties of MgH_(2).The as-prepared MgH_(2)-H-V_(2)O_(5) composites exhibit low desorption temperatures(Tonset=185℃)with a hydrogen capacity of 6.54 wt%,fast kinetics(Ea=84.55±1.37 kJ mol^(-1) H_(2) for desorption),and long cycling stability.Impressively,hydrogen absorption can be achieved at a temperature as low as 30℃ with a capacity of 2.38 wt%within 60 min.Moreover,the composites maintain a capacity retention rate of~99%after 100 cycles at 275℃.Experimental studies and theoretical calculations demonstrate that the in-situ formed VH_(2)/V catalysts,unique 2D structure of H-V_(2)O_(5) nanosheets,and abundant oxygen vacancies positively contribute to the improved hydrogen sorption properties.Notably,the existence of oxygen vacancies plays a double role,which could not only directly accelerate the hydrogen ab/de-sorption rate of MgH_(2),but also indirectly affect the activity of the catalytic phase VH_(2)/V,thereby further boosting the hydrogen storage performance of MgH_(2).This work highlights an oxygen vacancy excited“hydrogen pump”effect of VH_(2)/V on the hydrogen sorption of Mg/MgH_(2).The strategy developed here may pave a new way toward the development of oxygen vacancy-rich transition metal oxides catalyzed hydride systems.展开更多
Planar Na ion micro-supercapacitors(NIMSCs) that offer both high energy density and power density are deemed to a promising class of miniaturized power sources for wearable and portable microelectron-ics. Nevertheless...Planar Na ion micro-supercapacitors(NIMSCs) that offer both high energy density and power density are deemed to a promising class of miniaturized power sources for wearable and portable microelectron-ics. Nevertheless, the development of NIMSCs are hugely impeded by the low capacity and sluggish Na ion kinetics in the negative electrode.Herein, we demonstrate a novel carbon-coated Nb_(2)O_5 microflower with a hierarchical structure composed of vertically intercrossed and porous nanosheets, boosting Na ion storage performance. The unique structural merits, including uniform carbon coating, ultrathin nanosheets and abun-dant pores, endow the Nb_(2)O_5 microflower with highly reversible Na ion storage capacity of 245 mAh g^(-1) at 0.25 C and excellent rate capability.Benefiting from high capacity and fast charging of Nb_(2)O_5 microflower, the planar NIMSCs consisted of Nb_(2)O_5 negative electrode and activated car-bon positive electrode deliver high areal energy density of 60.7 μWh cm^(-2),considerable voltage window of 3.5 V and extraordinary cyclability. Therefore, this work exploits a structural design strategy towards electrode materials for application in NIMSCs, holding great promise for flexible microelectronics.展开更多
Orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))is attractive for fast-charging Li-ion batteries,but it is still hard to realize rapid charge transfer kinetics for Li-ion storage.Herein,F-doped T-Nb_(2)O_(5) microflowers(F-Nb_(...Orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))is attractive for fast-charging Li-ion batteries,but it is still hard to realize rapid charge transfer kinetics for Li-ion storage.Herein,F-doped T-Nb_(2)O_(5) microflowers(F-Nb_(2)O_(5))are rationally synthesized through topotactic conversion.Specifically,F-Nb_(2)O_(5) are assembled by single-crystal nanoflakes with nearly 97%exposed(100)facet,which maximizes the exposure of the feasible Li^(+)transport pathways along loosely packed 4g atomic layers to the electrolytes,thus effectively enhancing the Li^(+)-intercalation performance.Besides,the band gap of F-Nb_(2)O_(5) is reduced to 2.87 eV due to the doping of F atoms,leading to enhanced electrical conductivity.The synergetic effects between tailored exposed crystal facets,F-doping,and ultrathin building blocks,speed up the Li^(+)/electron transfer kinetics and improve the pseudocapacitive properties of F-Nb_(2)O_(5).Therefore,F-Nb_(2)O_(5) exhibit superior rate capability(210.8 and 164.9 mAh g^(-1) at 1 and 10 C,respectively)and good long-term 10 C cycling performance(132.7 mAh g^(-1) after 1500 cycles).展开更多
采用超声辅助室温原位沉淀法合成BC/Bi_(4)O_(5)Br_(2)光催化剂,在可见光下对比了TiO_(2)体系、BC/Bi_(4)O_(5)Br_(2)体系以及BC/Bi_(4)O_(5)Br_(2)耦合过一硫酸盐(PMS)体系处理渗滤液尾水的效果。考察了BC/Bi_(4)O_(5)Br_(2)耦合PMS体...采用超声辅助室温原位沉淀法合成BC/Bi_(4)O_(5)Br_(2)光催化剂,在可见光下对比了TiO_(2)体系、BC/Bi_(4)O_(5)Br_(2)体系以及BC/Bi_(4)O_(5)Br_(2)耦合过一硫酸盐(PMS)体系处理渗滤液尾水的效果。考察了BC/Bi_(4)O_(5)Br_(2)耦合PMS体系中PMS投加量和反应时间的影响,通过紫外可见光谱、三维荧光图谱分析渗滤液尾水有机物成分。结果表明:BC/Bi_(4)O_(5)Br_(2)耦合PMS体系对腐殖质的去除效果较另外两体系的效果优异,BC/Bi_(4)O_(5)Br_(2)对COD、腐殖质(A_(254))、色度(CN)的去除率分别为13.07%、12.74%、52.19%,BOD_(5)/COD从0.08提升至0.18。BC/Bi_(4)O_(5)Br_(2)耦合PMS体系中,0.1 g BC/Bi_(4)O_(5)Br_(2)耦合0.20 g PMS体系对渗滤液尾水有机物有良好的降解效果,尤其在反应开始的前0.5 h作用效果明显,1.5 h后降解效率不再明显增加。BC/Bi_(4)O_(5)Br_(2)耦合PMS体系对TOC的最大去除率为30.5%,较BC/Bi_(4)O_(5)Br_(2)体系提高16.5%;对腐殖质的最大去除率为53.97%,较BC/Bi_(4)O_(5)Br_(2)体系提升41.5%。紫外可见光谱、三维荧光图谱表明渗滤液尾水以类腐殖质为主。研究结果可为非均相耦合过一硫酸盐光催化处理渗滤液尾水提供一定参考。展开更多
基金the support from the National Key Research&Development Program(2022YFB3803700)of ChinaNational Natural Science Foundation(No.52171186)the financial support from the Center of Hydrogen Science,Shanghai Jiao Tong University。
文摘MgH_(2) is a promising high-capacity solid-state hydrogen storage material,while its application is greatly hindered by the high desorption temperature and sluggish kinetics.Herein,intertwined 2D oxygen vacancy-rich V_(2)O_(5) nanosheets(H-V_(2)O_(5))are specifically designed and used as catalysts to improve the hydrogen storage properties of MgH_(2).The as-prepared MgH_(2)-H-V_(2)O_(5) composites exhibit low desorption temperatures(Tonset=185℃)with a hydrogen capacity of 6.54 wt%,fast kinetics(Ea=84.55±1.37 kJ mol^(-1) H_(2) for desorption),and long cycling stability.Impressively,hydrogen absorption can be achieved at a temperature as low as 30℃ with a capacity of 2.38 wt%within 60 min.Moreover,the composites maintain a capacity retention rate of~99%after 100 cycles at 275℃.Experimental studies and theoretical calculations demonstrate that the in-situ formed VH_(2)/V catalysts,unique 2D structure of H-V_(2)O_(5) nanosheets,and abundant oxygen vacancies positively contribute to the improved hydrogen sorption properties.Notably,the existence of oxygen vacancies plays a double role,which could not only directly accelerate the hydrogen ab/de-sorption rate of MgH_(2),but also indirectly affect the activity of the catalytic phase VH_(2)/V,thereby further boosting the hydrogen storage performance of MgH_(2).This work highlights an oxygen vacancy excited“hydrogen pump”effect of VH_(2)/V on the hydrogen sorption of Mg/MgH_(2).The strategy developed here may pave a new way toward the development of oxygen vacancy-rich transition metal oxides catalyzed hydride systems.
基金financially supported by the National Natural Science Foundation of China (Grants. 22075279, 22279137, 22125903, 22109040)National Key R&D Program of China (Grant 2022YFA1504100)+2 种基金Dalian Innovation Support Plan for High Level Talents (2019RT09)Dalian National Labo- ratory For Clean Energy (DNL), CAS, DNL Cooperation Fund, CAS (DNL202016, DNL202019), DICP (DICP I2020032)the Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy (YLU-DNL Fund 2021002, YLU- DNL Fund 2021009)。
文摘Planar Na ion micro-supercapacitors(NIMSCs) that offer both high energy density and power density are deemed to a promising class of miniaturized power sources for wearable and portable microelectron-ics. Nevertheless, the development of NIMSCs are hugely impeded by the low capacity and sluggish Na ion kinetics in the negative electrode.Herein, we demonstrate a novel carbon-coated Nb_(2)O_5 microflower with a hierarchical structure composed of vertically intercrossed and porous nanosheets, boosting Na ion storage performance. The unique structural merits, including uniform carbon coating, ultrathin nanosheets and abun-dant pores, endow the Nb_(2)O_5 microflower with highly reversible Na ion storage capacity of 245 mAh g^(-1) at 0.25 C and excellent rate capability.Benefiting from high capacity and fast charging of Nb_(2)O_5 microflower, the planar NIMSCs consisted of Nb_(2)O_5 negative electrode and activated car-bon positive electrode deliver high areal energy density of 60.7 μWh cm^(-2),considerable voltage window of 3.5 V and extraordinary cyclability. Therefore, this work exploits a structural design strategy towards electrode materials for application in NIMSCs, holding great promise for flexible microelectronics.
基金supported by the National Natural Science Foundation of China(No.51802163)the Natural Science Foundation of Henan Province of China(No.222300420252)the Natural Science Foundation of Henan Department of Education(No.20A480004).
文摘Orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))is attractive for fast-charging Li-ion batteries,but it is still hard to realize rapid charge transfer kinetics for Li-ion storage.Herein,F-doped T-Nb_(2)O_(5) microflowers(F-Nb_(2)O_(5))are rationally synthesized through topotactic conversion.Specifically,F-Nb_(2)O_(5) are assembled by single-crystal nanoflakes with nearly 97%exposed(100)facet,which maximizes the exposure of the feasible Li^(+)transport pathways along loosely packed 4g atomic layers to the electrolytes,thus effectively enhancing the Li^(+)-intercalation performance.Besides,the band gap of F-Nb_(2)O_(5) is reduced to 2.87 eV due to the doping of F atoms,leading to enhanced electrical conductivity.The synergetic effects between tailored exposed crystal facets,F-doping,and ultrathin building blocks,speed up the Li^(+)/electron transfer kinetics and improve the pseudocapacitive properties of F-Nb_(2)O_(5).Therefore,F-Nb_(2)O_(5) exhibit superior rate capability(210.8 and 164.9 mAh g^(-1) at 1 and 10 C,respectively)and good long-term 10 C cycling performance(132.7 mAh g^(-1) after 1500 cycles).
文摘采用超声辅助室温原位沉淀法合成BC/Bi_(4)O_(5)Br_(2)光催化剂,在可见光下对比了TiO_(2)体系、BC/Bi_(4)O_(5)Br_(2)体系以及BC/Bi_(4)O_(5)Br_(2)耦合过一硫酸盐(PMS)体系处理渗滤液尾水的效果。考察了BC/Bi_(4)O_(5)Br_(2)耦合PMS体系中PMS投加量和反应时间的影响,通过紫外可见光谱、三维荧光图谱分析渗滤液尾水有机物成分。结果表明:BC/Bi_(4)O_(5)Br_(2)耦合PMS体系对腐殖质的去除效果较另外两体系的效果优异,BC/Bi_(4)O_(5)Br_(2)对COD、腐殖质(A_(254))、色度(CN)的去除率分别为13.07%、12.74%、52.19%,BOD_(5)/COD从0.08提升至0.18。BC/Bi_(4)O_(5)Br_(2)耦合PMS体系中,0.1 g BC/Bi_(4)O_(5)Br_(2)耦合0.20 g PMS体系对渗滤液尾水有机物有良好的降解效果,尤其在反应开始的前0.5 h作用效果明显,1.5 h后降解效率不再明显增加。BC/Bi_(4)O_(5)Br_(2)耦合PMS体系对TOC的最大去除率为30.5%,较BC/Bi_(4)O_(5)Br_(2)体系提高16.5%;对腐殖质的最大去除率为53.97%,较BC/Bi_(4)O_(5)Br_(2)体系提升41.5%。紫外可见光谱、三维荧光图谱表明渗滤液尾水以类腐殖质为主。研究结果可为非均相耦合过一硫酸盐光催化处理渗滤液尾水提供一定参考。
