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Engineering single-atom Mn on nitrogen-doped carbon to regulate lithium-peroxide reaction kinetics for rechargeable lithium-oxygen batteries

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Journal of Energy chemistry 2024年第7期94卷 199-207页

作者： Yaling Huang Yong Liu Yang Liu Chenyang Zhang Wenzhang Li Jie Li school of chemistry and Chemical Engineering Central South UniversityChangsha 410083HunanChina school of Minerals Processing and bioengineering Central South UniversityChangsha 4003HunanChina

Precision engineering of catalytic sites to guide more favorable pathways for Li_(2)O_(2) nucleation and decom-position represents an enticing kinetic strategy for mitigating overpotential,enhancing discharge capac-ity,and improving recycling stability of Li-O_(2) *** this work,we employ metal-organic frameworks(MOFs)derivation and ion substitution strategies to construct atomically dispersed Mn-N_(4) moieties on hierarchical porous nitrogen-doped carbon(Mn SAs-NC)with the aim of reducing the over-potential and improving the cycling stability of Li-O_(2) *** porous structure provides more chan-nels for mass transfer and exposes more highly active sites for electrocatalytic reactions,thus promoting the formation and decomposition of Li_(2)O_(2).The Li-O_(2) batteries with Mn SAs-NC cathode achieve lower overpotential,higher specific capacity(14290 mA h g^(-1) at 100 mAg^(-1)),and superior cycle stability(>100 cycles at 200 mA g^(-1))compared with the Mn NPs-NC and *** functional theory(DFT)cal-culations reveal that the construction of Mn-N_(4) moiety tunes the charge distribution of the pyridinic N-rich vacancy and balances the affinity of the intermediates(LiO_(2) and Li_(2)O_(2)).The initial nucleation of Li_(2)O_(2) on Mn SAs-NC favors the O_(2)-→LiO_(2)→Li_(2)O_(2) surface-adsorption pathway,which mitigates the overpoten-tials of the oxygen reduction(ORR)and oxygen evolution reaction(OER).As a result,Mn SAs-NC with Mn-N_(4) moiety effectively facilitates the Li_(2)O_(2) nucleation and enables its reversible *** work establishes a methodology for constructing carbon-based electrocatalysts with high activity and selectivity for Li-O_(2)batteries.

关键词： Single-atom Mn MOFs-oriented architecture Rechargeable Li-O_(2)battery N-doped carbon Density functional theory calculation

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Research progress of permanent ferrite magnet materials

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Journal of Central South University 2024年第6期31卷 1723-1762页

作者： XU Bin CHEN Yu-feng ZHOU Yu-juan LUO Bi-yun ZHONG Shou-guo LIU Xing-ao school of Minerals Processing and bioengineering Central South UniversityChangsha 410083China

Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and *** fast development in electromobile and household appliance industries contributes to a new progress in permanent ferrite *** paper reviews the deveolpement and progress of permanent ferrite magnet industry in recent *** emergence of new raw material,the advancement of perparation methods and manufacturing techniques,and the potential applications of permanent ferrite materials are introduced and ***,nanocrystallization plays a crucial role in achieving high performance at a low cost and reducing reliance on rare earth resources,and therefore it could be a promising development trendency.

关键词： permanent ferrite magnetic materials high-performance nanosizing

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Covalent organic frameworks/carbon nanotubes composite with cobalt(II)pyrimidine sites for bifunctional oxygen electrocatalysis

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Nano Materials Science 2024年第4期6卷 419-427页

作者： Zhuangzhuang Wu Lijuan Feng Zhe Lu Xinxin Yu Yuzhen Zhao Junming Luo Shaolei Wang Xinlong Tian Qi Chen State Key Laboratory of Marine Resource Utilization in South China Sea School of Marine Science and Engineering Hainan University Key Laboratory of Polyoxometalate and Reticular Material chemistry of Ministry of Education School of Chemistry Northeast Normal University school of bioengineering Zhuhai Campus of Zunyi Medical University

With characteristics and advantages of functional composite materials, they are commendably adopted in numerous fields especially in oxygen electrocatalysis, which is due to the significant synergies between various components. Herein, a novel bifunctional oxygen electrocatalyst（Co-CNT@COF-Pyr） has been synthesized through in-situ growth of covalent organic frameworks（COFs） layers on the outer surface of highly conductive carbon nanotubes（CNTs） followed by coordination with Co（II）. For electrocatalytic OER, Co-CNT@COF-Pyr reveals a low overpotential（438 mV） in alkaline electrolyte（1.0 M aqueous solution of KOH） with a current density of 10 mA cm-2, which is comparable to most discovered COF-based catalysts. For electrocatalytic ORR, CoCNT@COF-Pyr exhibits a low H2O2yield range（9.0 %–10.1 %） and a reaction pathway close to 4e-（n =3.82–3.80） in alkaline electrolyte（0.1 M aqueous solution of KOH） within the test potential range of 0.1–0.6 V ***, which is superior to most reported COF-based catalysts. Hence, this research could not only offer an innovative insight into the construction of composites, but also facilitate the practical application of renewable fuel cells, closed water cycle, and rechargeable metal-air batteries.

关键词： Oxygen electrocatalysis Covalent organic frameworks Carbon nanotubes Composite materials

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Ca_(2)MnO_(4)-layered perovskite modified by NaNO_(3)for chemical-looping oxidative dehydrogenation of ethane to ethylene

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Chinese Journal of Chemical Engineering 2024年第4期68卷 53-64页

作者： Weixiao Ding Kun Zhao Shican Jiang Zhen Huang Fang He College of chemistry and bioengineering Guilin University of TechnologyGuilin 541006China Guangzhou Institute of Energy Conversion Chinese Academy of SciencesGuangzhou 510640China school of chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094China

Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the use of Ca_(2)MnO_(4)-layered perovskites modified with NaNO_(3) dopants,serving as redox catalysts(also known as oxygen carriers),for the CL-ODH of ethane within a temperature range of 700-780℃.Our findings revealed that the incorporation of NaNO_(3) as a modifier significantly-nhanced the selectivity for-thylene generation from Ca_(2)MnO_(4).At 750℃and a gas hourly space velocity of 1300 h^(-1),we achieved an-thane conversion up to 68.17%,accompanied by a corresponding-thylene yield of 57.39%.X-ray photoelectron spectroscopy analysis unveiled that the doping NaNO_(3) onto Ca_(2)MnO_(4) not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox ***,formation of NaNO_(3) shell on the surface of Ca_(2)MnO_(4) led to a reduction in the concentration of manganese sites and modulated the oxygen-releasing behavior in a step-wise *** modulation contributed significantly to the enhanced selectivity for ethylene of the NaNO_(3)-doped Ca_(2)MnO_(4) *** findings provide compelling evidence for the potential of Ca_(2)MnO_(4)-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.

关键词： Chemical-looping oxidative dehydrogenation Ethane Ethylene NaNO_(3)-doped Ca_(2)MnO_(4)redox catalyst Layered perovskites

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Super-high bed sintering for iron ores: inhomogeneous phenomena and its mechanism during mineralizing

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Journal of Iron and Steel Research International 2024年第8期31卷 1850-1860页

作者： Hui-bo Liu Liang-ping Xu Xi-duan Yang Zhong-lin Dong Qiang Zhong Guang-hui Li school of Minerals Processing and bioengineering Central South UniversityChangsha 410083HunanChina

The inhomogeneous sinter properties in super-high bed sintering have been reported in our previous *** inves-tigate the reasons for the inhomogeneous phenomena,detailed sampling and analysis of mixed material bed and sintered bed in super-high bed sintering plant were *** results indicated that the higher porosity and thinner dendrite of silico-ferrite of calcium and aluminum in the upper layer as well as dense structure and higher secondary hematite content in the lower layer led to the heterogeneities of mechanical strength and reduction properties exceeding 20%and 10%,*** the bed top downward,the basicity of mixed material decreased from 2.13 to 1.68 because the average particle size increased from 2.65 to 4.56 *** and fuels gathered in finer particles(-3 mm)of mixed material,and the-3 mm particles of mixed material generated more liquid phase than+3 mm *** heat input of super-high sintering bed was inhomogeneous due to the heat accumulation effect and unreasonable fuel *** inhomo-geneous sintering heat condition in sintering bed resulted in the different quantities and properties of liquid *** inhomogeneous quantities and properties of liquid phase that were influenced by inhomogeneous distribution of chemical composition,particle size,and heat input led to inhomogeneous mineralizing *** mineralizing condition is the key for homogeneous super-high bed sintering.

关键词： Iron ore Super-high bed sintering Mineralization Material segregation Heat accumulation

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Super-high bed sintering for iron ores:behaviors,causes and solutions of horizontal segregation on strand

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Journal of Iron and Steel Research International 2024年第7期31卷 1590-1596页

作者： Liang-ping Xu Hui-bo Liu Zhong-lin Dong Qiang Zhong Yu-chao Zhao Guang-hui Li school of Minerals Processing and bioengineering Central South UniversityChangsha 410083HunanChina

Horizontal segregation has been a constraint to the development and application of super-high bed *** eliminate the horizontal segregation of super-high bed sintering,several typical sintering machines were sampled and analyzed,and theoretical calculation was made to compare the bed depth and their differences in different areas within the mixture ***,solutions were proposed and applied to a 265 m^(2) sintering *** results showed that the horizontal seg-regation of the 265 m^(2) sintering machine was dominated by particles larger than 8 mm with horizontal segregation degree of 0.48,while 360 and 550 m^(2) sintering machines were affected by 5-8 mm and 1-3 mm particles with horizontal segregation degree of 0.27 and 0.31,*** analysis indicated the different segregation distribution results from the matching of the bed depth of each area within the mixture ***,the horizontal segregation degree not larger than 0.06 was achieved by optimizing the time parameters and the division of three zones on the 265 m^(2) sintering machine.

关键词： Super-high bed sintering Horizontal segregation Feeder Particle distribution Agglomeration

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Super-high bed sintering for iron ores:problems ascertainment

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Journal of Iron and Steel Research International 2024年第5期31卷 1063-1070页

作者： Liang-ping Xu Hui-bo Liu Yu-chao Zhao Qiang Zhong Zhong-lin Dong Guang-hui Li Tao Jiang school of Minerals Processing and bioengineering Central South UniversityChangsha410083HunanChina

Super-high bed sintering process is an important development direction of iron ore sintering for its lower emission and higher ***,there is a lack of deep understanding of the uneven quality of super-high bed sintering products,and the deterioration of reduction disintegration performance,the thickening of hearth layer and the reduction in energy-saving effect are perplexing enterprises and *** ascertain the problems of super-high bed sintering,ten sintering machines with the areas of 265,280,360,550 and 660 m^(2)and bed depth above 900 mm were sampled and *** results showed that problems were mainly shown in the unevenness of chemical composition,macrostructure,mechanical strength and metallurgical *** chemical composition exhibits severe segregation in both horizontal and vertical directions,with basicity segregation reaching as high as *** uneven macrostructure of sinter is reflected in a 10%difference in porosity and mechanical strength increase in 16%–19%along the vertical *** reducibility and reduction disintegration performance gradually deteriorate along the bed depth,with a difference of 10.5%in reducibility and 7.3%in RDI−0.5 mm(reduction disintegration index of sinter with size smaller than 0.5 mm).

关键词： Super-high bed sintering Uneven sinter performance Segregation Agglomeration Iron ore

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Prediction of suitable water content in granulation of sintering mixture based on Litster's model

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Journal of Iron and Steel Research International 2024年第3期31卷 552-560页

作者： Fang-lei Dai Xiao-hui Fan Xiao-xian Huang Xu-ling Chen Min Gan Zhi-yun Ji Zeng-qing Sun school of Minerals Processing and bioengineering Central South UniversityChangsha 410083HunanChina

Suitable water content plays a decisive role in the granulation of sintering ***,a method was proposed to predict the suitable water content for effective granulation on the basis of Litster's granulation *** granulation effectiveness of a sintering mixture was predicted by the model,with the allowance error of±10%.The effects of the water absorption properties,particle size composition and content of adhesive particles on the suitable water content were *** results showed that the allowable error of prediction was within±0.5%compared to the experimentally determined suitable water *** an increase in adhesive powder content of mixtures with higher water absorption,the suitable water content increased to achieve similar granulation ***,as the amount of concentrates increased,the suitable water content first increased and then remained *** influence of the water absorption characteristics of the adhesive particles on the suitable water content was less than that of their particle size composition in the mixture.

关键词： Adhesive particle Sintering mixture Granulation effectiveness Suitable water content

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MnS–MnO heterogeneous nanocube@N,S-doped carbon as a highly efficient bifunctional water splitting electrocatalyst

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Rare Metals 2024年第5期43卷 1977-1988页

作者： Xue-Qian Wang Xiang-Ying Ma Wang-Zhi Wu Hui-Bing He Nan-Nan Wang Ren-Ji Zheng Shao-Jian Ma Yan-Qiu Zhu Pei-Kang Shen Jin-Liang Zhu school of Resources Environment and MaterialsState Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite StructuresCollege of Chemistry and Chemical EngineeringGuangxi UniversityNanning 530004China school of chemistry and Chemical Engineering Guangxi MinzuUniversity Nanning 530006 China school of Minerals Processing and bioengineering Central South UniversityChangsha 410083China

A stable,efficient,and economical bifunctional electrolytic catalyst would be incredibly beneficial for the development of hydrogen production by electrocatalytic water *** this study,we synthesized a novel MnS–MnO heterogeneous nanocube@N,S-doped carbon(MnS–MnO@NSC).MnS–MnO nanocubes possess rich heterogeneous interfaces and plentiful catalytic active sites to promote electrochemical reactions,while the N,S-doped carbon shell possesses excellent conductivity and catalytic properties and protects the ***–MnO@NSC exhibited excellent electrochemical properties as an effective bifunctional electrocatalyst for the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in KOH *** the HER,the overpotential was as low as 124 mV at a current density of 10 mA·cm^(-2)while in the OER,it was only 340 mV at 100 mA·cm^(-2)under the same *** addition,a MnS–MnO@NSC||MnS–MnO@NSC electrolyzer exhibited almost comparable activity and higher steadiness than those exhibited by the state-of-the-art Pt/C||RuO_(2)/C system for full water splitting in KOH solution.

关键词： Manganese sulfide Manganese oxide Doped carbon Heterogeneous nanocube Water splitting

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Metal complexes of bipyridine-functionalized covalent organic frameworks as efficient electrocatalysts for oxygen evolution reaction

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Rare Metals 2024年第7期43卷 3096-3106页

作者： Zhuang-Zhuang Wu Tian Xia Ying Liang Yong-Peng Li Zhu-Yin Sui Li-Juan Feng Dao-Xiong Wu Xin-Long Tian Qi Chen State Key Laboratory of Marine Resource Utilization in South China Sea School of Marine Science and EngineeringHainan UniversityHaikou 570228China school of chemistry and Chemical Engineering Yantai UniversityZhuhai519041China school of bioengineering Zhuhai Campus of Zunyi Medical UniversityZhuhai519041China

Electrocatalytic water splitting is considered a clean and practic al method for producing *** this study,COF-Bpy,a bipyridine-functionalized covalent organic framework(COF),was prepared via post-synthetic modification,after which electrocatalysts for the oxygen evolution reactions(OER)were formed through coordination to single-or double-transition metals(Fe,Co,Ni,FeCo,FeNi or CoNi).COF-Bpy@FeNi delivered the best OER performance among the studied electrocatalysts,with an overpotential of 399 mV at 10 mA·cm^(-2)in an alkaline electrolyte(1.0 mol·L^(-1)KOH aqueous).Notably,the electrocatalytic performance of COF-Bpy@FeNi showed slight degradation during durability testing,which is ascribable to its irreversible benzoquinoline structure and strong metal *** expected,COF-Bpy@FeNi exhibited a low overpotential of 347 mV at a turnover frequency(TOF)of 0.1 s^(-1),which suggests that COF-Bpy@FeNi possesses excellent intrinsic electroc atalytic OER ***,density functional theory(DFT)calculations reveal that the Ni site plays a major role,while the Fe site adjusts the electronic structure of the Ni ions,which rationalizes the excellent OER properties of COF-Bpy@*** study not only provides a simple and efficient method for complexing COFs with transition metals,but also offers a novel strategy for designing porous organic polymer electrocatalysts.

关键词： Covalent organic framework Oxygen evolution reactions(OER)electrocatalyst Nickel-iron synergy Water splitting

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