甘油是生物质精炼的主要副产物(约占10%),年过剩量与低利用率导致其市场价格(0.24-0.6 US kg^(-1))较低.甘油是具有三个活性羟基的多元醇,被认为是生产高价值产品的理想原料.甲酸作为甘油转化最重要的产品之一,广泛应用于农药、皮革、...甘油是生物质精炼的主要副产物(约占10%),年过剩量与低利用率导致其市场价格(0.24-0.6 US kg^(-1))较低.甘油是具有三个活性羟基的多元醇,被认为是生产高价值产品的理想原料.甲酸作为甘油转化最重要的产品之一,广泛应用于农药、皮革、染料和医药行业,将甘油电氧化(EGOR)为甲酸(FA)不仅能有效避免资源过剩造成浪费,而且能满足未来对甲酸燃料电池的需求.然而甘油电催化氧化途径较为复杂,涉及反应中间产物的脱氢、吸附/解吸和C-C键裂解.本文将密度泛函理论(DFT)与实验相结合,研究了在精细构建的NiCo_(2)O_(4)纳米片上通过EGOR生产FA的反应机制.DFT计算结果表明,活性羟基(OH^(*))物种可以改变EGOR生产FA过程的决速步骤(RDS),通过调节吸附中间体的吸附能可获得理想的FA产率.其中,高度羟基化的NiCo_(2)O_(4)纳米片(311)-OH^(*)晶面上具有最低的吉布斯自由能,能显著提升反应过程动力学.在理论分析的基础上,通过简易的电沉积方法精准制备了超薄NiCo_(2)O_(4)纳米片(~1.7 nm),并采用X射线吸收精细结构谱和高分辨透射电镜对催化剂进行了结构分析.结果表明,NiCo_(2)O_(4)纳米片中四面体(A_(Td))和八面体(B_(Oh))配位具有内角共享的A_(Td)-O-B_(Oh)和边共享的B_(Oh)-O-B_(Oh)构型,金属间的协同作用有效改善了材料的电子效应,有利于提供更多的吸附位点并促进EGOR过程中的电荷转移.NiCo_(2)O_(4)纳米片在EGOR中的电荷转移电阻仅为0.94Ω,电化学活性表面积高达10.25 cm^(2).相比较电催化析氧反应,NiCo_(2)O_(4)纳米片表现出了较好的EGOR性能,在10 mA cm^(-2)的电流密度下阳极功耗降低了320 mV,在100 mA cm^(-2)的电流密度时的阳极电势仅为1.46 VRHE.此外,在120 h的稳定性测试中,甘油的转化率和FA的选择性可分别保持在89%和70%.多电位步骤实验、原位电化学阻抗谱和电子顺磁共振谱结果表明,NiCo_(2)O_(4)纳米片上原�展开更多
Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at ...Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at G96PW91/6-31＋G（3d,2p） level. The small heteroatoms, C, N, O, preferentially occupy vertex 2 with the absolutely lowest relative energy to form the high stabilization closo-heteroboranes. They cap four-membered rings to satisfy the geometrical demand of short B--Z bonds. The electron attractions from the vicinal boron atoms make the frameworks shrink. Differently, Si and Ge preferentially substitute for boron at vertex 1 with six tight B--Z bonds and form stabilized molecules. P, As, S, and Se tend to occupy vertex 4 and the optimized structures belong to the nido configura- tions. In contrast to high electronegative heteroatoms, S and Se transfer less negative charges to framework and the electropositive heteroatoms, Si and Ge transfer more negative charges to framework to form the delocalization structures. The HOMO-LUMO gaps show that most of predicted clusters possess chemical stabilities. The substitutions of heteroatoms for boron atoms in eleven-vertex closo-heteroboranes are consistent with the topological charge stabilization rule proposed by Gimarc.展开更多
The family of ABX half-Heusler materials, also called filled-tetrahedral structures, is a special class of ternary compounds hosting a variety of material functionalities including thermoelectricity, topological insul...The family of ABX half-Heusler materials, also called filled-tetrahedral structures, is a special class of ternary compounds hosting a variety of material functionalities including thermoelectricity, topological insulation, magnetism, transparent conductivity and superconductivity. This class of compounds can be derived from two substitution approaches, i.e.,from Heusler materials by removing a portion of atoms forming ordered vacancies thus becoming half-Heusler, or from tetrahedral zinc blende compounds by adding atoms on the interstitial sites thus become filled-tetrahedral structures. In this paper, we briefly review the substitution approaches for material design along with their application in the design of half-Heusler compounds; then we will review the high-throughput search of new half-Heusler filled-tetrahedral structures and the study of their physical properties and functionalities.展开更多
Designing and synthesizing high-performable electron donor materials are very important for fabricating organic solar cell devices with high power conversion efficiency （PCE）. In this work, quantum chemical and mole...Designing and synthesizing high-performable electron donor materials are very important for fabricating organic solar cell devices with high power conversion efficiency （PCE）. In this work, quantum chemical and molecular dynamics calculations coupled with the Marcus-Hush charge transfer model were used to investigate the photovoltaic properties of 4Cl-BPPQ/PC61BM. Results reveal that 4Cl-BPPQ/PCrlBM system theoretically possesses a large open-circuit voltage （1.29 V）, high fill factor （0.90）, and over 9% PCE. Moreover, calculations also reveal that the 4Cl-BPPQ/PC61BM system has a middle-sized exciton binding energy （0.492 eV）, but relatively small charge-dissociation and charge-recombination reorganization energies （0.345 eV and 0.355 eV）. Based on the 4CI-BPPQ/PC61BM complex, the charge-dissociation rate constant, kdis, is estimated to be as large as 6.575× 10^12 s^-1, while the charge-recombination one, krec, is very small （〈 1.0 s^-1） under the same condition due to the very small driving force （AGree=-1.900 eV）. In addition, by means of an amorphous cell containing one hundred 4C1-BPPQ molecules, the hole carrier mobility of 4CI-BPPQ solid is estimated as high as 3.191 × 10^-3 cm^2·V^-1·s^-1. In brief, our calculation shows that 4Cl-BPPQ/PC61BM system is a very promising organic solar cell system, and is worth of making further device research by experiments.展开更多
Polychlorinated dibenzothiophenes（PCDTs） are a group of important persistent organic pollutants.In the present study,geometrical optimization and electrostatic potential calculations have been performed for all 135 ...Polychlorinated dibenzothiophenes（PCDTs） are a group of important persistent organic pollutants.In the present study,geometrical optimization and electrostatic potential calculations have been performed for all 135 PCDTs congeners at the B3LYP/6-31G＊ level of theory.By means of the VSMP（variable selection and modeling based on prediction） program,one optimal descriptor（molecular polarizability,α） was selected to develop a QSRR model for the prediction of gas chromatographic retention indices（GC-RI） of PCDTs.The estimated correlation coefficients（r2） and LOO-validated correlation coefficients（q2）,all more than 0.99,were built by multiple linear regression,which shows a good estimation ability and stability of the models.A prediction power for the external samples was validated by the model built from the training set with 17 polychlorinated dibenzothiophenes.展开更多
文摘甘油是生物质精炼的主要副产物(约占10%),年过剩量与低利用率导致其市场价格(0.24-0.6 US kg^(-1))较低.甘油是具有三个活性羟基的多元醇,被认为是生产高价值产品的理想原料.甲酸作为甘油转化最重要的产品之一,广泛应用于农药、皮革、染料和医药行业,将甘油电氧化(EGOR)为甲酸(FA)不仅能有效避免资源过剩造成浪费,而且能满足未来对甲酸燃料电池的需求.然而甘油电催化氧化途径较为复杂,涉及反应中间产物的脱氢、吸附/解吸和C-C键裂解.本文将密度泛函理论(DFT)与实验相结合,研究了在精细构建的NiCo_(2)O_(4)纳米片上通过EGOR生产FA的反应机制.DFT计算结果表明,活性羟基(OH^(*))物种可以改变EGOR生产FA过程的决速步骤(RDS),通过调节吸附中间体的吸附能可获得理想的FA产率.其中,高度羟基化的NiCo_(2)O_(4)纳米片(311)-OH^(*)晶面上具有最低的吉布斯自由能,能显著提升反应过程动力学.在理论分析的基础上,通过简易的电沉积方法精准制备了超薄NiCo_(2)O_(4)纳米片(~1.7 nm),并采用X射线吸收精细结构谱和高分辨透射电镜对催化剂进行了结构分析.结果表明,NiCo_(2)O_(4)纳米片中四面体(A_(Td))和八面体(B_(Oh))配位具有内角共享的A_(Td)-O-B_(Oh)和边共享的B_(Oh)-O-B_(Oh)构型,金属间的协同作用有效改善了材料的电子效应,有利于提供更多的吸附位点并促进EGOR过程中的电荷转移.NiCo_(2)O_(4)纳米片在EGOR中的电荷转移电阻仅为0.94Ω,电化学活性表面积高达10.25 cm^(2).相比较电催化析氧反应,NiCo_(2)O_(4)纳米片表现出了较好的EGOR性能,在10 mA cm^(-2)的电流密度下阳极功耗降低了320 mV,在100 mA cm^(-2)的电流密度时的阳极电势仅为1.46 VRHE.此外,在120 h的稳定性测试中,甘油的转化率和FA的选择性可分别保持在89%和70%.多电位步骤实验、原位电化学阻抗谱和电子顺磁共振谱结果表明,NiCo_(2)O_(4)纳米片上原�
文摘Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at G96PW91/6-31＋G（3d,2p） level. The small heteroatoms, C, N, O, preferentially occupy vertex 2 with the absolutely lowest relative energy to form the high stabilization closo-heteroboranes. They cap four-membered rings to satisfy the geometrical demand of short B--Z bonds. The electron attractions from the vicinal boron atoms make the frameworks shrink. Differently, Si and Ge preferentially substitute for boron at vertex 1 with six tight B--Z bonds and form stabilized molecules. P, As, S, and Se tend to occupy vertex 4 and the optimized structures belong to the nido configura- tions. In contrast to high electronegative heteroatoms, S and Se transfer less negative charges to framework and the electropositive heteroatoms, Si and Ge transfer more negative charges to framework to form the delocalization structures. The HOMO-LUMO gaps show that most of predicted clusters possess chemical stabilities. The substitutions of heteroatoms for boron atoms in eleven-vertex closo-heteroboranes are consistent with the topological charge stabilization rule proposed by Gimarc.
基金Project supported by the National Natural Science Foundation of China(Grant No.11774239)the National Key Research and Development Program of China(Grant No.2016YFB0700700)+3 种基金the Fund from Shenzhen Science and Technology Innovation Commission(Grant Nos.JCYJ20170412110137562,JCYJ20170818093035338,and ZDSYS201707271554071)the Natural Science Foundation of Shenzhen University(Grant No.827-000242)the High-End Researcher Startup Funds of Shenzhen University(Grant No.848-0000040251)the Supporting Funds from Guangdong Province for 1000 Talents Plan(Grant No.85639-000005)
文摘The family of ABX half-Heusler materials, also called filled-tetrahedral structures, is a special class of ternary compounds hosting a variety of material functionalities including thermoelectricity, topological insulation, magnetism, transparent conductivity and superconductivity. This class of compounds can be derived from two substitution approaches, i.e.,from Heusler materials by removing a portion of atoms forming ordered vacancies thus becoming half-Heusler, or from tetrahedral zinc blende compounds by adding atoms on the interstitial sites thus become filled-tetrahedral structures. In this paper, we briefly review the substitution approaches for material design along with their application in the design of half-Heusler compounds; then we will review the high-throughput search of new half-Heusler filled-tetrahedral structures and the study of their physical properties and functionalities.
基金This work was supported by the National Natural Science Foundation of China （Nos. 21373132, 21502109）, and the Doctor Research Start Foundation of Shaanxi University of Technology （Nos. SLGKYQD2-13, SLGKYQD2-10, SLGQD14-10）, and the Education Department of Shaanxi Provincial Gov- ernment Research Projects （No. 16JK1142）.
文摘Designing and synthesizing high-performable electron donor materials are very important for fabricating organic solar cell devices with high power conversion efficiency （PCE）. In this work, quantum chemical and molecular dynamics calculations coupled with the Marcus-Hush charge transfer model were used to investigate the photovoltaic properties of 4Cl-BPPQ/PC61BM. Results reveal that 4Cl-BPPQ/PCrlBM system theoretically possesses a large open-circuit voltage （1.29 V）, high fill factor （0.90）, and over 9% PCE. Moreover, calculations also reveal that the 4Cl-BPPQ/PC61BM system has a middle-sized exciton binding energy （0.492 eV）, but relatively small charge-dissociation and charge-recombination reorganization energies （0.345 eV and 0.355 eV）. Based on the 4CI-BPPQ/PC61BM complex, the charge-dissociation rate constant, kdis, is estimated to be as large as 6.575× 10^12 s^-1, while the charge-recombination one, krec, is very small （〈 1.0 s^-1） under the same condition due to the very small driving force （AGree=-1.900 eV）. In addition, by means of an amorphous cell containing one hundred 4C1-BPPQ molecules, the hole carrier mobility of 4CI-BPPQ solid is estimated as high as 3.191 × 10^-3 cm^2·V^-1·s^-1. In brief, our calculation shows that 4Cl-BPPQ/PC61BM system is a very promising organic solar cell system, and is worth of making further device research by experiments.
基金Sponsored by the NSF of Guangxi Province (No. 2011XNSFA018059)Guangxi Key Laboratory Research Fund of Environmental Engineering and Protection Assessment (No. 0801Z026)+1 种基金Major Science of Water Pollution Control and Management (No. 2008ZX07317-02)the Guangxi Zhuang Autonomous Region Department of Education Research (No. 201010LX174) Funding
文摘Polychlorinated dibenzothiophenes（PCDTs） are a group of important persistent organic pollutants.In the present study,geometrical optimization and electrostatic potential calculations have been performed for all 135 PCDTs congeners at the B3LYP/6-31G＊ level of theory.By means of the VSMP（variable selection and modeling based on prediction） program,one optimal descriptor（molecular polarizability,α） was selected to develop a QSRR model for the prediction of gas chromatographic retention indices（GC-RI） of PCDTs.The estimated correlation coefficients（r2） and LOO-validated correlation coefficients（q2）,all more than 0.99,were built by multiple linear regression,which shows a good estimation ability and stability of the models.A prediction power for the external samples was validated by the model built from the training set with 17 polychlorinated dibenzothiophenes.
