Nanoscale hierarchically porous metal-organic frameworks(NH-MOFs)synergistically combine the advantages of nanoscale MOFs and hierarchically porous MOFs,resulting in remarkable characteristics such as increased specif...Nanoscale hierarchically porous metal-organic frameworks(NH-MOFs)synergistically combine the advantages of nanoscale MOFs and hierarchically porous MOFs,resulting in remarkable characteristics such as increased specific surface area,greater porosity,and enhanced exposure of active sites.Herein,nanoscale hierarchically porous UIO-66(UIO-66_X)was synthesized using a defect-induced strategy that employed ethylene diamine tetraacetic acid(EDTA)as a modulator.The introduced EDTA occupies the coordination sites of organic ligands,promoting the formation and growth of UIO-66 crystal nuclei and inducing defects during synthesis.The as-synthesized UIO-66_X crystals exhibit a uniform distribution with an average size of approximately 100 nm.In addition,the total pore volume attains a remarkable value of 0.95 cm^(3)g^(-1),with mesopores constituting 36.8% of the structure.Furthermore,the porosities of UIO-66_X can be easily tuned by controlling the molar ratio of EDTA/Zr^(4+).In addition,the as-synthesized UIO-66_X exhibits excellent adsorption capacities for n-hexane(344 mg g^(-1))and pxylene(218 mg g^(-1)),which are 44.5% and 27.5% higher than those of conventional UIO-66,respectively.Finally,the adsorption behavior of n-hexane and p-xylene molecules in UIO-66_X was investigated using density functional theory simulations.展开更多
Due to the limited transmission resources for data relay in the tracking and data relay satellite system （TDRSS）, there are many job requirements in busy days which will be discarded in the conventional job scheduli...Due to the limited transmission resources for data relay in the tracking and data relay satellite system （TDRSS）, there are many job requirements in busy days which will be discarded in the conventional job scheduling model. Therefore, the improvement of scheduling efficiency in the TDRSS can not only help to increase the resource utilities, but also to reduce the scheduling failure ratio. A model of nonhomogeneous parallel machines scheduling problems with time window （NPM-TW） is firstly built up for the TDRSS, considering the distinct features of the variable preparation time and the nonhomogeneous transmission rates for different types of antennas on each tracking and data relay satellite （TDRS）. Then, an adaptive subsequence adjustment （ASA） framework with evolutionary asymmetric path-relinking （EvAPR） is proposed to solve this problem, in which an asymmetric progressive crossover operation is involved to overcome the local optima by the conventional job inserting methods. The numerical results show that, compared with the classical greedy randomized adaptive search procedure （GRASP） algorithm, the scheduling failure ratio of jobs can be reduced over 11% on average by the proposed ASA with EvAPR.展开更多
金属锂因具有高理论容量和低化学电位被认为是电化学储能系统的"圣杯",但无规则的锂枝晶生长和与电解液的高反应活性导致其安全性能差和库伦效率低,这严重阻碍了锂金属负极的大规模应用。电解液添加剂具有用量小、效果显著等...金属锂因具有高理论容量和低化学电位被认为是电化学储能系统的"圣杯",但无规则的锂枝晶生长和与电解液的高反应活性导致其安全性能差和库伦效率低,这严重阻碍了锂金属负极的大规模应用。电解液添加剂具有用量小、效果显著等特点,是改善电池性能的有效手段之一。本研究首次报道一种植物多酚—丹宁酸(TA)用作电解液添加剂改善锂金属负极的电化学性能。通过在基础电解液1 mol·L^-1 LiPF_6-EC/DMC/EMC (1:1:1,质量比)中添加质量分数0.15%TA,Li|Li对称电池在电流密度为1 m A·cm^-2和容量为1 m Ah·cm^-2的条件下能稳定循环270 h (以0.1 V为截止电压),而没有TA添加剂的Li|Li电池在相同条件下只能循环170 h。电化学阻抗、扫描电镜、傅里叶红外、循环伏安和X射线能谱分析测试结果表明,丹宁酸能在锂金属表面参与形成了一层稳定且致密的固态电解质界面层。推测其可能的机理为多羟基酚有助于LiPF_6的水解反应并形成LiF,多羟基酚的锂盐能与碳酸二甲酯发生酯交换反应而形成交联聚合物,从而形成了稳定且均匀的有机/无机复合SEI膜、显著提高了锂金属负极的电化学性能。展开更多
基金financial support from the National Natural Science Foundation of China(22008032)the Guangdong Basic and Applied Basic Research Foundation(2023A1515011881,2020A1515110817,2022A1515011192,2023A1515010679,and 2020A1515110325)+1 种基金the Guangdong Provincial Key Laboratory of Intelligent Food Manufacturing(2022B1212010015,GPKLIFM-KF202206)the University Characteristic Innovation Foundation of Guangdong(2021KTSCX114 and 2022KTSCX122)。
文摘Nanoscale hierarchically porous metal-organic frameworks(NH-MOFs)synergistically combine the advantages of nanoscale MOFs and hierarchically porous MOFs,resulting in remarkable characteristics such as increased specific surface area,greater porosity,and enhanced exposure of active sites.Herein,nanoscale hierarchically porous UIO-66(UIO-66_X)was synthesized using a defect-induced strategy that employed ethylene diamine tetraacetic acid(EDTA)as a modulator.The introduced EDTA occupies the coordination sites of organic ligands,promoting the formation and growth of UIO-66 crystal nuclei and inducing defects during synthesis.The as-synthesized UIO-66_X crystals exhibit a uniform distribution with an average size of approximately 100 nm.In addition,the total pore volume attains a remarkable value of 0.95 cm^(3)g^(-1),with mesopores constituting 36.8% of the structure.Furthermore,the porosities of UIO-66_X can be easily tuned by controlling the molar ratio of EDTA/Zr^(4+).In addition,the as-synthesized UIO-66_X exhibits excellent adsorption capacities for n-hexane(344 mg g^(-1))and pxylene(218 mg g^(-1)),which are 44.5% and 27.5% higher than those of conventional UIO-66,respectively.Finally,the adsorption behavior of n-hexane and p-xylene molecules in UIO-66_X was investigated using density functional theory simulations.
基金supported by the National Natural Science Foundation of China(6113200291338101+3 种基金91338108)the National S&T Major Project(2011ZX03004-001-01)the Research Fund of Tsinghua University(2011Z05117)the Co-innovation Laboratory of Aerospace Broadband Network Technology
文摘Due to the limited transmission resources for data relay in the tracking and data relay satellite system （TDRSS）, there are many job requirements in busy days which will be discarded in the conventional job scheduling model. Therefore, the improvement of scheduling efficiency in the TDRSS can not only help to increase the resource utilities, but also to reduce the scheduling failure ratio. A model of nonhomogeneous parallel machines scheduling problems with time window （NPM-TW） is firstly built up for the TDRSS, considering the distinct features of the variable preparation time and the nonhomogeneous transmission rates for different types of antennas on each tracking and data relay satellite （TDRS）. Then, an adaptive subsequence adjustment （ASA） framework with evolutionary asymmetric path-relinking （EvAPR） is proposed to solve this problem, in which an asymmetric progressive crossover operation is involved to overcome the local optima by the conventional job inserting methods. The numerical results show that, compared with the classical greedy randomized adaptive search procedure （GRASP） algorithm, the scheduling failure ratio of jobs can be reduced over 11% on average by the proposed ASA with EvAPR.
文摘金属锂因具有高理论容量和低化学电位被认为是电化学储能系统的"圣杯",但无规则的锂枝晶生长和与电解液的高反应活性导致其安全性能差和库伦效率低,这严重阻碍了锂金属负极的大规模应用。电解液添加剂具有用量小、效果显著等特点,是改善电池性能的有效手段之一。本研究首次报道一种植物多酚—丹宁酸(TA)用作电解液添加剂改善锂金属负极的电化学性能。通过在基础电解液1 mol·L^-1 LiPF_6-EC/DMC/EMC (1:1:1,质量比)中添加质量分数0.15%TA,Li|Li对称电池在电流密度为1 m A·cm^-2和容量为1 m Ah·cm^-2的条件下能稳定循环270 h (以0.1 V为截止电压),而没有TA添加剂的Li|Li电池在相同条件下只能循环170 h。电化学阻抗、扫描电镜、傅里叶红外、循环伏安和X射线能谱分析测试结果表明,丹宁酸能在锂金属表面参与形成了一层稳定且致密的固态电解质界面层。推测其可能的机理为多羟基酚有助于LiPF_6的水解反应并形成LiF,多羟基酚的锂盐能与碳酸二甲酯发生酯交换反应而形成交联聚合物,从而形成了稳定且均匀的有机/无机复合SEI膜、显著提高了锂金属负极的电化学性能。
