Layered P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 is a promising cathode material. It exhibits a high capacity and suitable operating voltage and undergoes a phase transition from P2 to O2 during charge/discharge.Researchers ha...Layered P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 is a promising cathode material. It exhibits a high capacity and suitable operating voltage and undergoes a phase transition from P2 to O2 during charge/discharge.Researchers have used Ti substitution to improve the cathode, yet the chemical principles that underpin elemental substitution and functional improvement remain unclear. To clarify these principles, we used in situ Raman spectroscopy to monitor chemical changes in P2–Na2/3 Ni1/3 Mn1/3 Ti1/3 O2 and P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 during charge/discharge. Based on the change in the A_(1g) and E_g peaks during charge/discharge, we concluded that Ti substitution compressed the transition metal layer and expanded the planar oxygen layer in the unit cell. Titanium stabilized the P2 phase structure, which improved the cycling stability of P2–NaNMT. Our results provide clear theoretical support for future research on modifying electrodes by elemental substitution.展开更多
Fe_(2)O_(3)/ZnO/Ag ternary composite photocatalytic material was prepared by simple hydrothermal method,and its structure and photocatalytic properties were studied.The experimental results show that Fe_(2)O_(3)/ZnO/A...Fe_(2)O_(3)/ZnO/Ag ternary composite photocatalytic material was prepared by simple hydrothermal method,and its structure and photocatalytic properties were studied.The experimental results show that Fe_(2)O_(3)/ZnO/Ag exhibits better photocatalytic performance.After two hours of UV irradiation,the degradation rates of orange Ⅱ and methyl orange reached 91.9% and 75.9%,respectively.The design and preparation of the photocatalyst provide a theoretical basis for the practical application of photocatalytic technology.展开更多
Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast...Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life.In this work,an ap-proach is pioneered for preparing high-performance Fe_(2)O_(3)anode materials,by innovatively synthesizing a triple-layer yolk-shell Fe_(2)O_(3)uniformly coated with a conductive polypyrrole(Ppy)layer(Fe_(2)O_(3)@Ppy-TLY).The uniform polypyrrole coating introduces more reac-tion sites and adsorption sites,and maintains structure stability through charge-discharge process.In the uses as lithium-ion battery elec-trodes,Fe_(2)O_(3)@Ppy-TLY demonstrates high reversible specific capacity(maintaining a discharge capacity of 1375.11 mAh·g^(−1)after 500 cycles at 1 C),exceptional cycling stability(retaining the steady charge-discharge performance at 544.33 mAh·g^(−1)after 6000 ultrafast charge-discharge cycles at a 10 C current density),and outstanding high current charge-discharge performance(retaining a reversible ca-pacity of 156.75 mAh·g^(−1)after 10000 cycles at 15 C),thereby exhibiting superior lithium storage performance.This work introduces in-novative advancements for Fe_(2)O_(3)anode design,aiming to enhance its performance in energy storage fields.展开更多
NASICON-structured Na_(3)Zr_(2)Si_(2)PO_(12)(NZSP)has been considered as one of the ideal electrolytes for all-solid-state sodium metal batteries(ASSSB).However,the practical application of NZSP-based ASSSB is hindere...NASICON-structured Na_(3)Zr_(2)Si_(2)PO_(12)(NZSP)has been considered as one of the ideal electrolytes for all-solid-state sodium metal batteries(ASSSB).However,the practical application of NZSP-based ASSSB is hindered by the low ionic conductivity and large interfacial resistance caused by the poor contact between NZSP and Na metal.Herein,the introduction of Fe_(2)O_(3) not only improves ionic conductivity and reduces activation energy by the doping of Fe^(3+)in the crystal structure of NZSP,but also reduces the interfacial resistance and enhances interface stability between NZSP and Na metal anode.The synergistic effects significantly enhance the cycling stability,rate capability,and critical current density of the symmetrical solid-state cells.The interfacial reaction mechanism indicates that Fe3+in the interface is reduced Fe2+by Na anode,which effectively even the electric-filed distribution and suppresses the dendrite growth.Consequently,the symmetric solid-state cells exhibit stable cycling performance for 1,500 h at 0.1 mA·cm−1/0.1 mA·h·cm−1 and over 900 h at 0.2 mA·cm−1/0.2 mA·h·cm−1.The Na|NZSP-0.075%Fe_(2)O_(3)|Na_(2)FePO_(4)F solid-state full cells display high capacity retention of 94.2%after 100 cycles at 0.5 C.The stable interface of NZSP/Na and improved ionic conductivity contribute to excellent electrochemical performance,which accelerates the practical application of ASSSB.展开更多
Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added Ni...Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added NiO and its different loadings on Fe_(2)O_(3)/MgO were investigated.Then,a series of oxygen carriers were applied in the CL-ODH of the ethane cycle system.Brunauer-Emmett-Teller(BET),X-ray diffractometry(XRD),X-ray photoelection spectroscopy(XPS),and H2-temperature programmed reduction(TPR)were used to characterize the physicochemical properties of these oxygen carriers.It was confirmed that an interaction between NiO and Fe_(2)O_(3) occurred based on the XPS and H2-TPR results.Based on the CL-ODH activity performance tests conducted in a fixed-bed reactor,it was revealed that ethylene selectivity was significantly improved after NiO addition.Fe_(2)O_(3)-10%NiO/MgO showed the best activity performance with 93%ethane conversion and 50%ethylene selectivity at a reaction temperature of 650℃,atmospheric pressure,and space velocity of 7500 mL/(g·h).展开更多
光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有...光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有良好的化学稳定性、合适的带隙(~2.1 eV)、无毒、储量丰富等优点而成为最有前途的光阳极材料之一.然而,α-Fe_(2)O_(3)丰富的受体表面态和缓慢的水氧化动力学导致光生电荷复合严重,限制了其在光电化学中的实际应用.因此,有必要对α-Fe_(2)O_(3)进行表面工程设计以提高水氧化效率.本文提出了一种新方法,以金属有机框架(Ti-MOFs)为模板,在Ti-Fe_(2)O_(3)表面煅烧合成TiO_(2)层,然后将富活性位点的ZIF-67加载在TiO_(2)/Ti-Fe_(2)O_(3)上作为助催化剂,制备出具有较好光电化学性能的ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极.X射线衍射、高分辨透射电镜、X射线光电子能谱和拉曼光谱等表征结果证实成功合成了ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3).同时,氮气等温吸附脱附曲线和表面接触角测试结果表明,MOFs衍生的TiO_(2)为介孔材料.采用表面光伏技术、光致发光光谱、飞秒-瞬态吸收光谱和电化学阻抗谱分析,研究了光生电荷的分离和复合行为.结果表明,MOFs衍生的TiO_(2)不仅可以作为钝化层有效抑制了表面复合,还作为Ti-Fe_(2)O_(3)的电子阻挡层,显著减少了电子向表面的流失,从而大大提高了Ti-Fe_(2)O_(3)表面和体相的电荷分离效率.进一步的累积电荷量测试、电化学阻抗谱和Bode图分析显示,负载MOFs衍生TiO_(2)后,可以明显促进光生空穴向电解质的注入,其多孔结构也可以增加反应接触面积,这有利于光生电荷在固液界面传输.此外,理论计算结果表明,Ti-Fe_(2)O_(3)水氧化速控步骤的能垒(ΔG=3.38 eV)明显高于TiO_(2)(ΔG=1.67 eV),说明OER更容易在TiO_(2)/Ti-Fe_(2)O_(3)表面发生,这与其光电流密度结果一致.为进一步提高反应活性和加快水氧化动力学,负载助催化剂ZIF-67后,ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极实现了较好的光电化学性能,其在1.23 V vs.RHE时光电流密度高达4.04 mA cm^(‒2),是Ti-Fe_(2)O_(3)的9.3倍,并且复合光阳极的入射光子电流转换效率和空穴注入效率分别达到93%(390 nm)和91%.综上所述,本研究通过MOFs衍生的TiO_(2)和ZIF-67助催化剂改性α-Fe_(2)O_(3)光阳极,显著提升了其光电化学水氧化性能.其中,MOFs衍生TiO_(2)不仅优化了电荷分离,还促进了光生空穴的注入,从而显著提高其光电化学水氧化性能.本研究为构筑高性能的有机-无机杂化光阳极提供了新思路.展开更多
基金supported by the NSFC (21905239, 21925404, and 21775127)the Natural Science Foundation of Shanxi Province of China (201901D211265)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (2019L0609)。
文摘Layered P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 is a promising cathode material. It exhibits a high capacity and suitable operating voltage and undergoes a phase transition from P2 to O2 during charge/discharge.Researchers have used Ti substitution to improve the cathode, yet the chemical principles that underpin elemental substitution and functional improvement remain unclear. To clarify these principles, we used in situ Raman spectroscopy to monitor chemical changes in P2–Na2/3 Ni1/3 Mn1/3 Ti1/3 O2 and P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 during charge/discharge. Based on the change in the A_(1g) and E_g peaks during charge/discharge, we concluded that Ti substitution compressed the transition metal layer and expanded the planar oxygen layer in the unit cell. Titanium stabilized the P2 phase structure, which improved the cycling stability of P2–NaNMT. Our results provide clear theoretical support for future research on modifying electrodes by elemental substitution.
基金Funded in Part by the 14th Five Year Plan Hubei Provincial Advantaged Characteristic Disciplines(Groups) Project of Wuhan University of Science and Technology(No.2023A0203)the Natural Science Foundation of Hubei Province(No.2022CFA003)。
文摘Fe_(2)O_(3)/ZnO/Ag ternary composite photocatalytic material was prepared by simple hydrothermal method,and its structure and photocatalytic properties were studied.The experimental results show that Fe_(2)O_(3)/ZnO/Ag exhibits better photocatalytic performance.After two hours of UV irradiation,the degradation rates of orange Ⅱ and methyl orange reached 91.9% and 75.9%,respectively.The design and preparation of the photocatalyst provide a theoretical basis for the practical application of photocatalytic technology.
基金supported by the Natural Science Foundation of Jiangsu Province of China(No.BK20201008).
文摘Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life.In this work,an ap-proach is pioneered for preparing high-performance Fe_(2)O_(3)anode materials,by innovatively synthesizing a triple-layer yolk-shell Fe_(2)O_(3)uniformly coated with a conductive polypyrrole(Ppy)layer(Fe_(2)O_(3)@Ppy-TLY).The uniform polypyrrole coating introduces more reac-tion sites and adsorption sites,and maintains structure stability through charge-discharge process.In the uses as lithium-ion battery elec-trodes,Fe_(2)O_(3)@Ppy-TLY demonstrates high reversible specific capacity(maintaining a discharge capacity of 1375.11 mAh·g^(−1)after 500 cycles at 1 C),exceptional cycling stability(retaining the steady charge-discharge performance at 544.33 mAh·g^(−1)after 6000 ultrafast charge-discharge cycles at a 10 C current density),and outstanding high current charge-discharge performance(retaining a reversible ca-pacity of 156.75 mAh·g^(−1)after 10000 cycles at 15 C),thereby exhibiting superior lithium storage performance.This work introduces in-novative advancements for Fe_(2)O_(3)anode design,aiming to enhance its performance in energy storage fields.
基金This work was financially supported by the National Natural Science Foundation of China(22179071 and 52072217)the National Key R&D Program of China(2022YFB3807700)+3 种基金the Hubei Natural Science Foundation for Distinguished Young Scholars(2023AFA089)the Hubei Natural Science Foundation Innovation Group Project(2022CFA020)the Major Technological Innovation Project of Hubei Science and Technology Department(2019AAA164)Joint Funds of the Hubei Natural Science Foundation Innovation and Development(2022CFD034).
文摘NASICON-structured Na_(3)Zr_(2)Si_(2)PO_(12)(NZSP)has been considered as one of the ideal electrolytes for all-solid-state sodium metal batteries(ASSSB).However,the practical application of NZSP-based ASSSB is hindered by the low ionic conductivity and large interfacial resistance caused by the poor contact between NZSP and Na metal.Herein,the introduction of Fe_(2)O_(3) not only improves ionic conductivity and reduces activation energy by the doping of Fe^(3+)in the crystal structure of NZSP,but also reduces the interfacial resistance and enhances interface stability between NZSP and Na metal anode.The synergistic effects significantly enhance the cycling stability,rate capability,and critical current density of the symmetrical solid-state cells.The interfacial reaction mechanism indicates that Fe3+in the interface is reduced Fe2+by Na anode,which effectively even the electric-filed distribution and suppresses the dendrite growth.Consequently,the symmetric solid-state cells exhibit stable cycling performance for 1,500 h at 0.1 mA·cm−1/0.1 mA·h·cm−1 and over 900 h at 0.2 mA·cm−1/0.2 mA·h·cm−1.The Na|NZSP-0.075%Fe_(2)O_(3)|Na_(2)FePO_(4)F solid-state full cells display high capacity retention of 94.2%after 100 cycles at 0.5 C.The stable interface of NZSP/Na and improved ionic conductivity contribute to excellent electrochemical performance,which accelerates the practical application of ASSSB.
文摘Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added NiO and its different loadings on Fe_(2)O_(3)/MgO were investigated.Then,a series of oxygen carriers were applied in the CL-ODH of the ethane cycle system.Brunauer-Emmett-Teller(BET),X-ray diffractometry(XRD),X-ray photoelection spectroscopy(XPS),and H2-temperature programmed reduction(TPR)were used to characterize the physicochemical properties of these oxygen carriers.It was confirmed that an interaction between NiO and Fe_(2)O_(3) occurred based on the XPS and H2-TPR results.Based on the CL-ODH activity performance tests conducted in a fixed-bed reactor,it was revealed that ethylene selectivity was significantly improved after NiO addition.Fe_(2)O_(3)-10%NiO/MgO showed the best activity performance with 93%ethane conversion and 50%ethylene selectivity at a reaction temperature of 650℃,atmospheric pressure,and space velocity of 7500 mL/(g·h).
文摘光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有良好的化学稳定性、合适的带隙(~2.1 eV)、无毒、储量丰富等优点而成为最有前途的光阳极材料之一.然而,α-Fe_(2)O_(3)丰富的受体表面态和缓慢的水氧化动力学导致光生电荷复合严重,限制了其在光电化学中的实际应用.因此,有必要对α-Fe_(2)O_(3)进行表面工程设计以提高水氧化效率.本文提出了一种新方法,以金属有机框架(Ti-MOFs)为模板,在Ti-Fe_(2)O_(3)表面煅烧合成TiO_(2)层,然后将富活性位点的ZIF-67加载在TiO_(2)/Ti-Fe_(2)O_(3)上作为助催化剂,制备出具有较好光电化学性能的ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极.X射线衍射、高分辨透射电镜、X射线光电子能谱和拉曼光谱等表征结果证实成功合成了ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3).同时,氮气等温吸附脱附曲线和表面接触角测试结果表明,MOFs衍生的TiO_(2)为介孔材料.采用表面光伏技术、光致发光光谱、飞秒-瞬态吸收光谱和电化学阻抗谱分析,研究了光生电荷的分离和复合行为.结果表明,MOFs衍生的TiO_(2)不仅可以作为钝化层有效抑制了表面复合,还作为Ti-Fe_(2)O_(3)的电子阻挡层,显著减少了电子向表面的流失,从而大大提高了Ti-Fe_(2)O_(3)表面和体相的电荷分离效率.进一步的累积电荷量测试、电化学阻抗谱和Bode图分析显示,负载MOFs衍生TiO_(2)后,可以明显促进光生空穴向电解质的注入,其多孔结构也可以增加反应接触面积,这有利于光生电荷在固液界面传输.此外,理论计算结果表明,Ti-Fe_(2)O_(3)水氧化速控步骤的能垒(ΔG=3.38 eV)明显高于TiO_(2)(ΔG=1.67 eV),说明OER更容易在TiO_(2)/Ti-Fe_(2)O_(3)表面发生,这与其光电流密度结果一致.为进一步提高反应活性和加快水氧化动力学,负载助催化剂ZIF-67后,ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极实现了较好的光电化学性能,其在1.23 V vs.RHE时光电流密度高达4.04 mA cm^(‒2),是Ti-Fe_(2)O_(3)的9.3倍,并且复合光阳极的入射光子电流转换效率和空穴注入效率分别达到93%(390 nm)和91%.综上所述,本研究通过MOFs衍生的TiO_(2)和ZIF-67助催化剂改性α-Fe_(2)O_(3)光阳极,显著提升了其光电化学水氧化性能.其中,MOFs衍生TiO_(2)不仅优化了电荷分离,还促进了光生空穴的注入,从而显著提高其光电化学水氧化性能.本研究为构筑高性能的有机-无机杂化光阳极提供了新思路.
