Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)are two typical titanate-based sodium-storage materials,featuring the high theoretical capacity and favorable structure stability,respectively.Regulating the ratio of them in the...Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)are two typical titanate-based sodium-storage materials,featuring the high theoretical capacity and favorable structure stability,respectively.Regulating the ratio of them in the composite material is the key to strengthen its electrochemical characteristics.Herein,based on the high specific surface area and abundant surface functional groups of carbon dots(CDs),sodium titanate precursors containing CDs were in situ prepared by one-step hydrothermal method.After the thermal conversion of the precursors,a composite material(NNTO/C)of Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)was obtained,containing conductive carbon derived from CDs.The introduc⁃tion of conductive carbon not only adjusts the composition ratio of the mixed phases,but also provides a small charge transfer impedance(Rct,7.48Ω)and a big specific surface area(100.8 m^(2)/g).As a result,NNTO/C composites exhibit better sodium storage behavior while playing the synergistic interaction of mixed phases.When employed as the anode,after 200 cycles at 0.05 A/g,NNTO/C still maintains a specific capacity of 143.8 mA‧h/g.After 400 cycles at 1.00 A/g,the specific capacity remains as high as 108 mA‧h/g.This study suggests an innovative thinking for designing two-phase structures of electrode materials and the greater use of CDs in electrochemical energy storage.展开更多
为明确生物炭在农业领域的研究进展,本文基于文献计量学方法,利用VOSviewer以及CiteSpace等知识图谱工具,以Web of Science(WOS)和CNKI为数据源,从发文时间分布、国家(区域)分布、期刊分布、主要机构和研究主题等多维角度,综合分析了199...为明确生物炭在农业领域的研究进展,本文基于文献计量学方法,利用VOSviewer以及CiteSpace等知识图谱工具,以Web of Science(WOS)和CNKI为数据源,从发文时间分布、国家(区域)分布、期刊分布、主要机构和研究主题等多维角度,综合分析了1990—2021年全球及中国生物炭技术领域的整体发展路径、脉络、研究热点及发展态势,以期为未来科学研究提供参考。结果表明,在我国生物炭在农业研究领域,年度发文量呈明显上升趋势,表现出缓慢增长—平稳增长—快速增长3个阶段。生物炭技术在农业领域正在进入高速发展期,研究热点为生物炭的制备、生物炭的吸附作用、生物炭的土壤效应等。研究结果从相关文献的角度,定量、客观、科学地描述了生物炭土壤效应研究现状与趋势,并为生物炭在土壤科学问题研究提供理论参考。展开更多
文摘Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)are two typical titanate-based sodium-storage materials,featuring the high theoretical capacity and favorable structure stability,respectively.Regulating the ratio of them in the composite material is the key to strengthen its electrochemical characteristics.Herein,based on the high specific surface area and abundant surface functional groups of carbon dots(CDs),sodium titanate precursors containing CDs were in situ prepared by one-step hydrothermal method.After the thermal conversion of the precursors,a composite material(NNTO/C)of Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)was obtained,containing conductive carbon derived from CDs.The introduc⁃tion of conductive carbon not only adjusts the composition ratio of the mixed phases,but also provides a small charge transfer impedance(Rct,7.48Ω)and a big specific surface area(100.8 m^(2)/g).As a result,NNTO/C composites exhibit better sodium storage behavior while playing the synergistic interaction of mixed phases.When employed as the anode,after 200 cycles at 0.05 A/g,NNTO/C still maintains a specific capacity of 143.8 mA‧h/g.After 400 cycles at 1.00 A/g,the specific capacity remains as high as 108 mA‧h/g.This study suggests an innovative thinking for designing two-phase structures of electrode materials and the greater use of CDs in electrochemical energy storage.
文摘为明确生物炭在农业领域的研究进展,本文基于文献计量学方法,利用VOSviewer以及CiteSpace等知识图谱工具,以Web of Science(WOS)和CNKI为数据源,从发文时间分布、国家(区域)分布、期刊分布、主要机构和研究主题等多维角度,综合分析了1990—2021年全球及中国生物炭技术领域的整体发展路径、脉络、研究热点及发展态势,以期为未来科学研究提供参考。结果表明,在我国生物炭在农业研究领域,年度发文量呈明显上升趋势,表现出缓慢增长—平稳增长—快速增长3个阶段。生物炭技术在农业领域正在进入高速发展期,研究热点为生物炭的制备、生物炭的吸附作用、生物炭的土壤效应等。研究结果从相关文献的角度,定量、客观、科学地描述了生物炭土壤效应研究现状与趋势,并为生物炭在土壤科学问题研究提供理论参考。
