以柠檬酸为络合剂,聚乙二醇(PEG)为表面活性剂,偏钒酸铵、乙酸锰、磷酸二氢铵、氢氧化锂为原料,采用溶胶-凝胶法合成了xLiMnPO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和微观形貌...以柠檬酸为络合剂,聚乙二醇(PEG)为表面活性剂,偏钒酸铵、乙酸锰、磷酸二氢铵、氢氧化锂为原料,采用溶胶-凝胶法合成了xLiMnPO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和微观形貌进行表征,结果表明在700℃下烧结15 h合成的3LiMnPO4·Li3V2(PO4)3为结晶良好的两相结构,颗粒粒径相对较小且分布均匀。电化学性能研究表明,3LiMnPO4·Li3V2(PO4)3在室温0.2 C倍率下首次充放电容量分别为148.2 m Ah/g和141.5 m Ah/g,循环50次后放电容量为136.7 m Ah/g。展开更多
Ag3PO4/Ag/Ag2Mo2O7 composite photocatalyst was successfully prepared via an in situ precipitation method. The as-prepared Ag3PO4/Ag/Ag2Mo2O7 nanocomposite included Ag3PO4 nanoparticles （NPs） as well as Ag NPs assemb...Ag3PO4/Ag/Ag2Mo2O7 composite photocatalyst was successfully prepared via an in situ precipitation method. The as-prepared Ag3PO4/Ag/Ag2Mo2O7 nanocomposite included Ag3PO4 nanoparticles （NPs） as well as Ag NPs assembling on the surface of Ag2Mo2O7 nanowires. Under visible light irradiation （λ〉420 nm）, the Ag3PO4/Ag/Ag2Mo2O7 com- posite degraded rhodamine B （Rh B） efficiently and showed much higher photocatalytic efficiency than pure AgaPO4, Ag2Mo2O7, or Ag3PO4/Ag2Mo2O7. It was elucidated that the excellent photocatalytic performance of Ag3PO4/Ag/Ag2Mo2O7 for the degradation of Rh B under visible light could be ascribed to the high specific surface area, the extended absorption in the visible light region resulting from the Ag3PO4/Ag loading, and the effi- cient separation of photogenerated electrons and holes through the ternary heterostrucure composed of Ag3PO4, Ag and Ag2Mo2O7.展开更多
通过简单的溶胶-凝胶辅助静电纺丝法得到(113)晶面优势导向的Na_3V_2(PO_4)_3/C钠离子电池正极材料,并通过对比最佳纺丝条件下分别用聚乙烯吡咯烷酮(PVP)和聚氧化乙烯(PEO)作为晶面导向剂制备的两种Na_3V_2(PO_4)_3电极材料的电化学性能...通过简单的溶胶-凝胶辅助静电纺丝法得到(113)晶面优势导向的Na_3V_2(PO_4)_3/C钠离子电池正极材料,并通过对比最佳纺丝条件下分别用聚乙烯吡咯烷酮(PVP)和聚氧化乙烯(PEO)作为晶面导向剂制备的两种Na_3V_2(PO_4)_3电极材料的电化学性能,证明静电纺丝有利于实现Na_3V_2(PO_4)_3(113)晶面择优取向。在相同的电流密度(0.1 C)下,NVP-PVP和NVP-PEO的首周放电比容量分别为112.5 m A·h/g和96.3 m A·h/g,电池循环50周后,NVP-PVP仍然有98.1 m A·h/g的可逆容量保持,NVP-PEO仅仅只剩下34 m A·h/g的可逆容量保持,而即使循环100周后,NVP-PVP的可逆容量仍然在88.2 m A·h/g。结果表明,PVP静电纺丝有利于构建特定的纳米纤维结构和均一的导电碳网络骨架,进而提升主体材料Na_3V_2(PO_4)_3的电化学性能。展开更多
Co3O4/SiO2 catalysts for CO oxidation were prepared by conventional incipient wetness impregnation followed by calcination at various temperatures. Their structures were char- acterized with X-ray diffraction （XRD）,...Co3O4/SiO2 catalysts for CO oxidation were prepared by conventional incipient wetness impregnation followed by calcination at various temperatures. Their structures were char- acterized with X-ray diffraction （XRD）, laser Raman spectroscopy, X-ray photoelectron spectroscopy （XPS）, temperature-programmed reduction （TPR） and X-ray absorption fine structure （XAFS） spectroscopy. Both XRD and Raman spectroscopy only detect the existence of Co3O4 crystallites in all catalysts. However, XPS results indicate that excess Co2＋ ions are present on the surface of Co3O4 in Co3O4（200）/Si02 as compared with bulk Co3O4. Meanwhile, TPR results suggest the presence of surface oxygen vacancies on Co3O4 in Co3O4（200）/SiO2, and XAFS results demonstrate that Co3O4 in Co3O4（200）/SIO2 contains excess Co2＋. Increasing calcination temperature results in oxidation of excess Co2＋ and the decrease of the concentration of surface oxygen vacancies, consequently the for- mation of stoichiometric Co3O4 on supported catalysts. Among all Co3O4/SiO2 catalysts, Co3O4（200）/SiO2 exhibits the best catalytic performance towards CO oxidation, demonstrating that excess Co2＋ and surface oxygen vacancies can enhance the catalytic activity of Co3O4 towards CO oxidation. These results nicely demonstrate the effect of calcination temperature on the structure and catalytic performance towards CO oxidation of silicasupported Co3O4 catalysts and highlight the important role of surface oxygen vacancies on Co3O4.展开更多
文摘以柠檬酸为络合剂,聚乙二醇(PEG)为表面活性剂,偏钒酸铵、乙酸锰、磷酸二氢铵、氢氧化锂为原料,采用溶胶-凝胶法合成了xLiMnPO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和微观形貌进行表征,结果表明在700℃下烧结15 h合成的3LiMnPO4·Li3V2(PO4)3为结晶良好的两相结构,颗粒粒径相对较小且分布均匀。电化学性能研究表明,3LiMnPO4·Li3V2(PO4)3在室温0.2 C倍率下首次充放电容量分别为148.2 m Ah/g和141.5 m Ah/g,循环50次后放电容量为136.7 m Ah/g。
基金supported by the National Natural Science Foundation of China(No.21407059,No.21576112,No.21407064,and No.21607051)the Science Development Project of Jiangsu Province(BK20140527)+1 种基金the Science and Technology Research Project of the Department of Education of Jilin Province(No.2015220)the Open Subject of the State Key Laboratory of Rare Earth Resource Utilization(RERU2017011)
文摘Ag3PO4/Ag/Ag2Mo2O7 composite photocatalyst was successfully prepared via an in situ precipitation method. The as-prepared Ag3PO4/Ag/Ag2Mo2O7 nanocomposite included Ag3PO4 nanoparticles （NPs） as well as Ag NPs assembling on the surface of Ag2Mo2O7 nanowires. Under visible light irradiation （λ〉420 nm）, the Ag3PO4/Ag/Ag2Mo2O7 com- posite degraded rhodamine B （Rh B） efficiently and showed much higher photocatalytic efficiency than pure AgaPO4, Ag2Mo2O7, or Ag3PO4/Ag2Mo2O7. It was elucidated that the excellent photocatalytic performance of Ag3PO4/Ag/Ag2Mo2O7 for the degradation of Rh B under visible light could be ascribed to the high specific surface area, the extended absorption in the visible light region resulting from the Ag3PO4/Ag loading, and the effi- cient separation of photogenerated electrons and holes through the ternary heterostrucure composed of Ag3PO4, Ag and Ag2Mo2O7.
文摘通过简单的溶胶-凝胶辅助静电纺丝法得到(113)晶面优势导向的Na_3V_2(PO_4)_3/C钠离子电池正极材料,并通过对比最佳纺丝条件下分别用聚乙烯吡咯烷酮(PVP)和聚氧化乙烯(PEO)作为晶面导向剂制备的两种Na_3V_2(PO_4)_3电极材料的电化学性能,证明静电纺丝有利于实现Na_3V_2(PO_4)_3(113)晶面择优取向。在相同的电流密度(0.1 C)下,NVP-PVP和NVP-PEO的首周放电比容量分别为112.5 m A·h/g和96.3 m A·h/g,电池循环50周后,NVP-PVP仍然有98.1 m A·h/g的可逆容量保持,NVP-PEO仅仅只剩下34 m A·h/g的可逆容量保持,而即使循环100周后,NVP-PVP的可逆容量仍然在88.2 m A·h/g。结果表明,PVP静电纺丝有利于构建特定的纳米纤维结构和均一的导电碳网络骨架,进而提升主体材料Na_3V_2(PO_4)_3的电化学性能。
文摘Co3O4/SiO2 catalysts for CO oxidation were prepared by conventional incipient wetness impregnation followed by calcination at various temperatures. Their structures were char- acterized with X-ray diffraction （XRD）, laser Raman spectroscopy, X-ray photoelectron spectroscopy （XPS）, temperature-programmed reduction （TPR） and X-ray absorption fine structure （XAFS） spectroscopy. Both XRD and Raman spectroscopy only detect the existence of Co3O4 crystallites in all catalysts. However, XPS results indicate that excess Co2＋ ions are present on the surface of Co3O4 in Co3O4（200）/Si02 as compared with bulk Co3O4. Meanwhile, TPR results suggest the presence of surface oxygen vacancies on Co3O4 in Co3O4（200）/SiO2, and XAFS results demonstrate that Co3O4 in Co3O4（200）/SIO2 contains excess Co2＋. Increasing calcination temperature results in oxidation of excess Co2＋ and the decrease of the concentration of surface oxygen vacancies, consequently the for- mation of stoichiometric Co3O4 on supported catalysts. Among all Co3O4/SiO2 catalysts, Co3O4（200）/SiO2 exhibits the best catalytic performance towards CO oxidation, demonstrating that excess Co2＋ and surface oxygen vacancies can enhance the catalytic activity of Co3O4 towards CO oxidation. These results nicely demonstrate the effect of calcination temperature on the structure and catalytic performance towards CO oxidation of silicasupported Co3O4 catalysts and highlight the important role of surface oxygen vacancies on Co3O4.
