Li4Ti5012 (LTO) with rich R-TiO2 (17.06, 23.69, and 34.42 wt%), namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate (TBT) as the precursor. Rietveld refinement o...Li4Ti5012 (LTO) with rich R-TiO2 (17.06, 23.69, and 34.42 wt%), namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate (TBT) as the precursor. Rietveld refinement of X-ray diffraction (XRD) results show that the proportion of Li occupying 16d sites is extraordinary low and the lattice constants of LTO and R-TiO2 change with the ritanium dioxide content. EIS measurements showed that with in creasing R-TiO2 content, both its charge transfer impedance (Rct) and lithium ion diffusion coefficient (DLi) decreased. The changes of Rct and DLi caused by the increase of titanium dioxide content have synergic-antagonistic effects on the rate and cycle properties of Li4Ti5012. The rate performance is positively related to DLi, while the cycle property is negatively correlated with Rct, indicati ng that the rate performs nee is mainly related to DLi, while Rct more significantly affects the cycle performance. LTO-RT-17.06% exhibited excellent rate properties, especially under a high current density (5.0 C, 132.5 mAh/g) and LTO-RT-34.42% showed superior long-term cycle performance (0.012% capacity loss per cycle) compared to that of LTO-RT-17.06% and LTO-RT-23.69%.展开更多
以纳米TiO2(P25)粉末作为催化剂光降解茜素黄R.GC-MS和LC-MS检测结果表明,有3种可能的降解途径:①茜素黄R(C13H8N3O5Na)水解生成的C13H8N3O5-(H)与光催化产生的.OH自由基发生取代反应生成C13H8N3O6-(I)和C13H8N3O7-(J),进一步脱羧分别生...以纳米TiO2(P25)粉末作为催化剂光降解茜素黄R.GC-MS和LC-MS检测结果表明,有3种可能的降解途径:①茜素黄R(C13H8N3O5Na)水解生成的C13H8N3O5-(H)与光催化产生的.OH自由基发生取代反应生成C13H8N3O6-(I)和C13H8N3O7-(J),进一步脱羧分别生成C12H9N3O4(L)和C12H9N3O5(M);②H分子发生脱羧反应生成C12H9N3O3(K),进一步反应生成C12H11N3(C)和C12H12N2(D);③H分子中氮氮键发生断裂而生成C6H6N2O2(A)、C6H4N2O4(B)、C6H8N2(E)、C6H6O(F)和C7H7NO3(G).所有生成的中间产物被继续降解,最终矿化为CO2和H2O等无机小分子物质.利用Molecular Orbital PACkage中的PM3半经验方法对茜素黄R分子构型优化计算,结果表明,茜素黄R的羧基净电荷密度为-0.680,在实验条件下(pH为2.86)羧基易吸附在TiO2表面,而成为.OH进攻的最有利位置,实验检测到羟基化的产物(J和I).茜素黄R的羧基和苯环相连的C—C键长最长,反应过程中易发生脱羧反应,实验检测到脱羧后的产物(K);—N N—键长较长,易断裂生成芳胺类化合物(A,E,G等).茜素黄R带羧基和羟基的苯环电荷密度为-0.160,带硝基苯环电荷为-0.165,易吸附在催化剂表面而被自由基进攻,生成羟基化产物.计算结果和实验检测结果一致.动力学研究表明,茜素黄R光催化降解的动力学符合Langmuir-Hinshelwood模型计算的结果.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51641206)Shandong Natural Science Foundation Project(No.ZR2015EM013)+1 种基金Special Funds for Independent Innovation and Transformation of Achievements in Shandong Province(No.2014CGZH0911)National Key R&D Program of China(No.2016YFB0100508)
文摘Li4Ti5012 (LTO) with rich R-TiO2 (17.06, 23.69, and 34.42 wt%), namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate (TBT) as the precursor. Rietveld refinement of X-ray diffraction (XRD) results show that the proportion of Li occupying 16d sites is extraordinary low and the lattice constants of LTO and R-TiO2 change with the ritanium dioxide content. EIS measurements showed that with in creasing R-TiO2 content, both its charge transfer impedance (Rct) and lithium ion diffusion coefficient (DLi) decreased. The changes of Rct and DLi caused by the increase of titanium dioxide content have synergic-antagonistic effects on the rate and cycle properties of Li4Ti5012. The rate performance is positively related to DLi, while the cycle property is negatively correlated with Rct, indicati ng that the rate performs nee is mainly related to DLi, while Rct more significantly affects the cycle performance. LTO-RT-17.06% exhibited excellent rate properties, especially under a high current density (5.0 C, 132.5 mAh/g) and LTO-RT-34.42% showed superior long-term cycle performance (0.012% capacity loss per cycle) compared to that of LTO-RT-17.06% and LTO-RT-23.69%.
文摘以纳米TiO2(P25)粉末作为催化剂光降解茜素黄R.GC-MS和LC-MS检测结果表明,有3种可能的降解途径:①茜素黄R(C13H8N3O5Na)水解生成的C13H8N3O5-(H)与光催化产生的.OH自由基发生取代反应生成C13H8N3O6-(I)和C13H8N3O7-(J),进一步脱羧分别生成C12H9N3O4(L)和C12H9N3O5(M);②H分子发生脱羧反应生成C12H9N3O3(K),进一步反应生成C12H11N3(C)和C12H12N2(D);③H分子中氮氮键发生断裂而生成C6H6N2O2(A)、C6H4N2O4(B)、C6H8N2(E)、C6H6O(F)和C7H7NO3(G).所有生成的中间产物被继续降解,最终矿化为CO2和H2O等无机小分子物质.利用Molecular Orbital PACkage中的PM3半经验方法对茜素黄R分子构型优化计算,结果表明,茜素黄R的羧基净电荷密度为-0.680,在实验条件下(pH为2.86)羧基易吸附在TiO2表面,而成为.OH进攻的最有利位置,实验检测到羟基化的产物(J和I).茜素黄R的羧基和苯环相连的C—C键长最长,反应过程中易发生脱羧反应,实验检测到脱羧后的产物(K);—N N—键长较长,易断裂生成芳胺类化合物(A,E,G等).茜素黄R带羧基和羟基的苯环电荷密度为-0.160,带硝基苯环电荷为-0.165,易吸附在催化剂表面而被自由基进攻,生成羟基化产物.计算结果和实验检测结果一致.动力学研究表明,茜素黄R光催化降解的动力学符合Langmuir-Hinshelwood模型计算的结果.
