CVD金刚石的晶体形态及界面位向关系

综述了CVD金刚石的晶体形态及界面位向关系。用SEM观察CVD金刚石晶粒形态主要有立方体、长方体、八面体、立方八面体、孪晶八面体、十面体和二十面体颗粒以及球形金刚石,讨论了晶粒的形成条件。用TEM观察则主要有单晶体、孪晶八面体和五重孪晶体形态。界面位向关系主要有:Si(001)//Diamond(001),Si<110>//Diamond<110>;Si(111)//Diamond(111),Si<110>//Diamond<110>和Si(110)//Diamond(110),Si[110]//Diamond[111]。

界面位场异常的快速正反演计算及其应用

文章推导了快速计算界面位场异常正、反演公式，其原理及性质与R.L.Parker1972－1974提出的基本一致。但符合通常习惯，便于应用。推导途径与Parker有所区别，公式有所不同。迭代反演采取另一种形式，改进了收敛效果。此方法经理论模型验证，效果良好，并有应用实例。

界面位场的遗传反演方法研究

本文分析了Parker—Oldenburg位场反演方法中存在的问题，提出了用位场频率域快速正演方法与遗传算法相结合的位场遗传反演方法。针对遗传算法中收敛速度慢的问题，提出了两方面的改进措施，使这种位场遗传反演方法更为完善。经理论模型验证与实际资料的处理，表明该方法是有效的。

Cu/Al_2O_3扩散焊接头界面晶体位向关系对断裂能量的影响

以单晶α－Ａｌ２Ｏ３陶瓷（蓝宝石）和单晶 Ｃｕ为母材，采用真空扩散焊接获得具有两种不同的界面晶体位向关系的Ｃｕ／Ａｌ２Ｏ３扩散焊接头以及带 Ｎｂ膜中间层的 Ｃｕ／Ｎｂ／Ａｌ２Ｏ３扩散焊接头，研究了界面晶体位向关系对接头断裂能量的影响。结果表明，陶瓷－金属界面的晶体位向关系影响界面粘合功（Ｗａｄ）和断裂过程中金属侧所消耗的塑性变形功（Ｗｐ），从而显著影响接头的断裂能量。界面位向关系为（１００）［０１１］Ｃｕ／／（０００１）［１１２０］Ａｌ２Ｏ３的 Ｃｕ／Ａｌ２Ｏ３接头断裂能量值最低，而具有相同位向关系的带 Ｎｂ膜中间层的 Ｃｕ／Ｎｂ／Ａｌ２Ｏ３接头的断裂能量值则最高。

含咪唑烷基硫醇自组装膜界面铜离子配位研究

合成了6-(咪唑-2-基)-1-己硫醇(IHT),在金电极表面形成纯的自组装膜及其与1-己硫醇(HT)的混合自组装膜,并将这些自组装膜在溶液中与铜离子进行界面配位.应用电化学循环伏安法和交流阻抗谱法探讨了各种自组装膜修饰电极界面配位铜离子的电化学行为.实验结果表明,IHT与HT以1∶4比例进行界面组装得到的混合自组装单分子层最致密,自组装膜的铜离子界面配位浓度最高达到2.3×10-11mol/cm2.界面形成的IHT-Cu2+配合物在不同的pH值溶液中测量结果表明该配合物在pH 6.4时是可以稳定存在的.

氨基酸Schiff碱LB膜的界面配位及分子取向

本文合成了在同一个分子中具有Schiff碱和羧基两个可与金属离子配位的两亲分子,利用等温曲线、紫外光谱和红外光谱研究了其在不同亚相表面LB膜的金属配位和分子结构.对于合成的HSA两亲分子,只有Cu2+离子才能同时与羧基和Schiff碱片段发生配位作用,其它金属离子只与羧基发生配位作用.Cu2+与Schiff碱配位后,Schiff碱片段相对于表面法线倾斜取向,其它金属离子配位后Schiff碱片段的长轴倾向于垂直基底表面取向.

Al_2O_3/Au(111)反相催化剂在CO氧化反应中界面作用的理论研究（英文）

氧化物负载的金催化剂具有温和条件下优异的CO催化氧化活性。实验与理论计算表明,金与氧化物两相界面在催化反应过程中具有重要地位。反相催化剂提供了全新的角度以探究界面的重要地位。本文以Au(111)表面负载Al_2O_3团簇为反相催化剂模型,基于密度泛函理论,对催化剂模型的构型、界面性质以及O_2、CO的吸附与氧化进行了理论计算与研究。理论计算表明:电荷的迁移增强了Al_2O_3小团簇在Au(111)表面的附着,在催化剂金表面与氧化铝的两相界面位置,Au原子与Al原子的协同作用使得氧分子易于在界面位置吸附,并因此高度活化。对催化CO氧化反应路径,分别计算了缔合机理和解离机理不同路径,从活化能分析表明缔合机理比解离机理更可能发生。本文的工作揭示了反相催化剂催化CO氧化的活性本质,表明两相界面在金催化CO氧化中具有重要作用。

纳米硒的界面化学作用

纳米硒的化学和生物学特性源于其界面特性,纳米硒与表面修饰剂之间的界面结构、界面电子结构和电子传递能力以及表面修饰的纳米硒与外部离子、分子和其他个体之间的界面化学反应与纳米硒在材料和生物学中的神奇作用密切相关.开展纳米硒界面化学研究有可能在分子水平上揭示纳米硒的生物活性和生物矿化作用的机制.

Interfacial coordination bonds accelerate charge separation for unprecedented hydrogen evolution over S-scheme heterojunction

Inspired by natural photosynthesis,fabricating high-performance S-scheme heterojunction is regarded as a successful tactic to address energy and environmental issues.Herein,NH_(2)-MIL-125(Ti)/Zn_(0.5)Cd_(0.5)S/NiS(NMT/ZCS/NiS)S-scheme heterojunction with interfacial coordination bonds is successfully synthesized through in-situ solvothermal strategy.Notably,the optimal NMT/ZCS/NiS S-scheme heterojunction exhibits comparable photocatalytic H_(2)evolution(PHE)rate of about 14876.7μmol h^(−1)g^(−1)with apparent quantum yield of 24.2%at 420 nm,which is significantly higher than that of recently reported MOFs-based photocatalysts.The interfacial coordination bonds(Zn–N,Cd–N,and Ni–N bonds)accelerate the separation and transfer of photogenerated charges,and the NiS as cocatalyst can provide more catalytically active sites,which synergistically improve the photocatalytic performance.Moreover,theoretical calculation results display that the construction of NMT/ZCS/NiS S-scheme heterojunction also optimize the binding energy of active site-adsorbed hydrogen atoms to enable fast adsorption and desorption.Photoassisted Kelvin probe force microscopy,in-situ irradiation X-ray photoelectron spectroscopy,femtosecond transient absorption spectroscopy,and theoretical calculations provide sufficient evidence of the S-scheme charge migration mechanism.This work offers unique viewpoints for simultaneously accelerating the charge dynamics and optimizing the binding strength between the active sites and hydrogen adsorbates over S-scheme heterojunction.

多金属氧酸盐化学研究进展与展望

本文在简介多金属氧酸盐(Polyoxometalate,缩为POM)的主要性质与应用领域基础上,主要评述近一两年来的POM化学研究领域中取得的合成化学和催化化学新进展,具体内容包括:用水热方法合成的Keggin型犤SiNb12O40犦16-和犤Ti2O2犦4+构成的一维链结构及犤H2Si4Nb16O56犦14-簇,Silverton型多阴离子犤GdMo12O42犦9-及其三维网结构;POM和有机共轭体系构成的杂化分子亚铃;室温固相条件下得到的项链型多钼铁氧酸盐簇;具有蛋白质尺寸的Mo368簇;通过有机基团(-SH基)联接成的无机/有机杂化纳米粒子γ-SiW10-Au;反胶束体系中制备的星型结构K3PMo12O40纳米棒;具有选择性吸附和分离混合低碳脂肪醇和低碳氰分子的K3犤Cr3O(OOCH)6(H2O)3犦犤α-SiW12O40犦·16H2O三维孔道结构;总结了POM催化的八个典型工业化项目,固体POM的三种催化作用类型及在催化过程中的几种反应场;三明治结构的犤MnⅢ2ZnW(Zn2W9O34)犦活化N2O分子及其对烯烃环氧化催化作用;H5PV2Mo10O40在PEG体系中的选择性氧化催化作用;超临界CO2体系中POM催化高收率合成环氧碳酸酯;高活性PW11O397-/TiO2纳米复合膜及其三维有序大孔材料光催化降解含氮有机染料等;有机硅对SiO2离子的表面修饰及其与取代型POM的界面配位键合状态;浅析我国POM化学研究现状并提出几点展望?

Critical load position for cavities beneath CRCP slab under vehicle loading

In order to study the critical load position that causes cavities beneath the continuously reinforced concrete pavement（ CRCP） slab under vehicle loading, the elliptical load is translated into the square load based on the equivalence principle.The CRCP slab is analyzed to determine the cavity position beneath the slab under vehicle loading. The influences of cavity size on the CRCP slab＇s stress and vertical displacement are investigated. The study results showthat the formation of the cavity is unavoidable under traffic loading, and the cavity is located at the edge of the longitudinal crack and the slab corner.The cavity size exerts an obvious influence on the largest horizontal tensile stress and vertical displacement. The slab corner is the critical load position of the CRCP slab. The results can be used to assist the design of CRCP in avoiding cavities beneath slabs subject to vehicle loading.

Interface,lattice strain and dislocation density of SiC_p/Al composite consolidated by equal channel angular pressing and torsion

Powder mixture of pure A1 and oxidized SiC was consolidated into 10% （mass fraction） SiCp/AI composites at 523 K by equal channel angular pressing and torsion （ECAP-T）. The interfacial bonding of the composites was characterized by transmission electron microscopy （TEM） and high resolution transmission electron microscopy （HRTEM）. The selected area electron diffraction （SAED） for the interface was investigated. The elements at the interface were scanned by energy dispersive spectroscopy （EDS） and the EDS mapping was also obtained. X-ray diffraction （XRD） analysis was carried out for the composites fabricated by 1 pass, 2 passes and 4 passes ECAP-T. According to the XRD analysis, the influences of ECAP-T pass on the Bragg angle and interplanar spacing for AI crystalline planes were studied. The results show that after ECAP-T, the interface between A1 and SiC within the composites is a belt of amorphous SiO2 containing a trace of A1, Si and C which diffused from the matrix and the reinforcement. With the growing ECAP-T pass, the Bragg angle decreases and interplanar spacing increases for A1 crystalline planes, due to the accumulated lattice strain. The increasing lattice strain of A1 grains also boosts the density of the dislocation within A1 grains.

化学功能化增强贵金属纳米晶电催化性能

基于电催化过程的可再生和清洁能源的生产、转换和储存技术(如水电解和燃料电池)是缓解全球能源短缺和环境污染问题的有效手段.目前,水电解和燃料电池技术的实际应用缺乏高效、稳定的电催化剂来驱动动力学迟缓的阴极和阳极反应.贵金属纳米晶由于其独特的电子结构和高化学惰性而具有高电催化活性和稳定性.为了提升贵金属纳米晶的本征电催化性能,大量研究聚焦在利用面积效应、晶面效应和不同组分之间的协同效应来调控贵金属的粒径、形貌和化学成分.事实上,贵金属纳米晶的电催化性能也与其表/界面性质密切相关.电催化剂表面的化学功能化可以改变电极/电解质界面结构,从而提高电催化活性和选择性,这对开发新型高效的电催化剂具有重要的理论意义.本文系统介绍了本课题组开发的聚胺(PAM)功能化贵金属纳米电催化剂的合成方法及其在燃料电池和电解池等能源转换装置中的应用,具体包括:通过引入PAM控制反应动力学来调控纳米晶体的结构和形态,构建界面功能化贵金属纳米电催化剂;利用金属表面修饰的PAM分子改变表面催化位点的电子结构、配位环境等物理化学性质来控制反应物和中间体等的吸附行为,从而达到调节催化活性的目的;采用PAM分子来隔离特定活性位点,形成空间位阻,改变金属表面位点的可及性,影响催化反应中反应物的吸附,从而实现对目标反应的选择性.从优化催化性能和通过电催化过程实现高效能量转换的角度,本文列举了PAM功能化催化剂在氧还原反应、析氢反应、甲酸氧化反应和硝酸盐还原反应等重要反应中的最新研究进展;总结了化学功能化贵金属电催化剂的研究进展、当前不足,提出了挑战和未来前景.综上,本文旨在激发对表面/界面功能化及其催化行为的深入研究,从而推进未来与电催化技术相关的可再生能源的生产和环境保护.

Ohmic Contact Properties of Multi-Metal Films on n-Type 4H-SiC

An investigation of Au/Ti/Ni and Au/Ti/Pt ohmic contacts to n-type 4H-SiC and the behavior of metal films on SiC with thermal anneals is reported. Specific contact resistance as low as 2. 765 x 10^-6Ω·cm^2 was achieved after rapid thermal annealing in N2 for 2min at 950℃. SIMS analysis shows that the formation of Ni silicide after annealing supported a number of carbon atoms＇ outdiffusion from the SiC to form interstitial compound TiC. This process can create abundant C vacancies near the interface. It is the carbon defect layer that enhances the defect-assisted tunneling. The interface band structure within the defect level could make it clear why the metal-SiC contacts become ohmic during annealing.

Effect of atomic structure on migration characteristic and solute segregation of ordered domain interfaces formed in Ni_(75)Al_xV_(25-x)

Based on the microscopic phase-field model, ordered domain interfaces formed between D022 （Ni3V） phases along [001] direction in Ni75AlxV25-x alloys were simulated, and the effects of atomic structure on the migration characteristic and solute segregation of interfaces were studied. It is found that the migration ability is related to the atomic structure of interfaces, and three kinds of interfaces can migrate except the interface （001）//（002） which has the characteristic of L12 （Ni3Al） structure. V atoms jump to the nearest neighbor site and substitute for Ni, and vice versa. Because of the site selectivity behaviors of jumping atoms, the number of jumping atoms during the migration is the least and the jumping distance of atoms is the shortest among all possible modes, and the atomic structures of interfaces are unchanged before and after the migration. The preferences and degree of segregation or depletion of alloy elements are also related to the atomic structure of interface.

Improvement of pump-probe optical measurement technique using double moving stages

In order to improve the measurement precision and increase the reliability of the femtosecond laser transient thermoreflectance system, the relative optical path difference between pump and probe beams is prolonged, which can improve the fitting accuracy of the experimental data to the theoretical model. A modified experimental setup is devised with the pump path intercalated a moving stage identical to the one in the probe path, which extends the optical path difference of the probe beam relative to the pump beam from 4 to 8 ns. The measured results indicate that the uncertainty from the misalignment and divergence of both beams can be ignored when the last 4 ns experimental data are connected with those of the first 4 ns smoothly. The as-obtained thermal conductance of AI/Si and Cr/Si interfaces agrees well with the reported experimental values, which verifies the reliability of this modified version of this measurement.

TLP bonding of dissimilar FSX-414/IN738 system with MBF80 interlayer: Prediction of solid/liquid interface location

Isothermal solidification process of a dissimilar transient liquid phase （TLP） bonding of FSX-414/MBF80/IN738 system was simulated by finite difference method. The TLP joint model was divided into two parts and a moving liquid /solid interface model was used for the parts. Diffusion equations were solved for each half of the joints simultaneously up to the end of isothermal solidification. The completion time of isothermal solidification, concentration profiles and position of the solid/liquid interface for each half were calculated. The intersection of the solid/liquid interfaces of two halves was considered the end of isothermal solidification. To obtain some required diffusion data, TLP bonding of FSX-414/MBF80/IN738 was performed at different temperature and time under vacuum atmosphere. The calculated results show good agreement with the experimental results.

Enhancing catalytic toluene oxidation over MnO2@Co3O4 by constructing a coupled interface

Herein,a bottom-down design is presented to successfully fabricate ZIF-derived Co3O4,grown in situ on a one-dimensional(1D)α-MnO2 material,denoted as α-MnO2@Co3O4.The synergistic effect derived from the coupled interface constructed betweenα-MnO2 and Co3O4 is responsible for the enhanced catalytic activity.The resultantα-MnO2@Co3O4 catalyst exhibits excellent catalytic activity at a T90%(temperature required to achieve a toluene conversion of 90%)of approximately 229℃,which is 47 and 28℃ lower than those of the pureα-MnO2 nanowire and Co3O4-b obtained via pyrolysis of ZIF-67,respectively.This activity is attributed to the increase in the number of surface-adsorbed oxygen species,which accelerate the oxygen mobility and enhance the redox pairs of Mn^4+/Mn^3+ and Co^2+/Co^3+.Moreover,the result of in situ diffuse reflectance infrared Fourier transform spectroscopy suggests that the gaseous oxygen could be more easily activated to adsorbed oxygen species on the surface of α-MnO2@Co3O4 than on that of α-MnO2.The catalytic reaction route of toluene oxidation over theα-MnO2@Co3O4 catalyst is as follows:toluene→benzoate species→alkanes containing oxygen functional group→CO2 and H2O.In addition,the α-MnO2@Co3O4 catalyst shows excellent stability and good water resistance for toluene oxidation.Furthermore,the preparation method can be extended to other 1D MnO2 materials.A new strategy for the development of high-performance catalysts of practical significance is provided.

Ni nanoparticles as electron-transfer mediators and NiS_x as interfacial active sites for coordinative enhancement of H_2-evolution performance of TiO_2

The development of efficient photocatalytic H2-evolution materials requires both rapid electron transfer and an effective interfacial catalysis reaction for H2 production. In addition to the well-known noble metals, low-cost and earth-abundant non-noble metals can also act as electron- transfer mediators to modify photocatalysts. However, as almost all non-noble metals lack the interfacial catalytic active sites required for the H2-evolution reaction, the enhancement of the photocatalytic performance is limited. Therefore, the development of new interfacial active sites on metal-modified photocatalysts is of considerable importance. In this study, to enhance the photocatalytic evolution of H2 by Ni-modified TiO2, the formation of NiSx as interfacial active sites was promoted on the surface of Ni nanoparticles. Specifically, the co-modified TiO2/Ni-NiSx photocatalysts were prepared via a two-step process involving the photoinduced deposition of Ni on the TiO2 surface and the subsequent formation of NiSx on the Ni surface by a hydrothermal reaction method. It was found that the TiO2/Ni-NiSx photocatalysts exhibited enhanced photocatalytic H2-evolution activity. In particular, TiO2/Ni-NiSx(30%) showed the highest photocatalytic rate (223.74 μmol h.1), which was greater than those of TiO2, TiO2/Ni, and TiO2/NiSx by factors of 22.2, 8.0, and 2.2, respectively. The improved H2-evolution performance of TiO2/Ni-NiSx could be attributed to the excellent synergistic effect of Ni and NiSx, where Ni nanoparticles function as effective mediators to transfer electrons from the TiO2 surface and NiSx serves as interfacial active sites to capture H+ ions from solution and promote the interfacial H2-evolution reaction. The synergistic effect of the non-noble metal cocatalyst and the interfacial active sites may provide new insights for the design of highly efficient photocatalytic materials.

Selective adsorption of thiocyanate anions on Ag-modified g-C_3N_4 for enhanced photocatalytic hydrogen evolution

Silver‐modified semiconductor photocatalysts typically exhibit enhanced photocatalytic activitytoward the degradation of organic substances.In comparison,their hydrogen‐evolution rates arerelatively low owing to poor interfacial catalytic reactions to producing hydrogen.In the presentstudy,thiocyanate anions(SCN–)as interfacial catalytic active sites were selectively adsorbed ontothe Ag surface of g‐C3N4/Ag photocatalyst to promote interfacial H2‐evolution reactions.The thiocyanate‐modified g‐C3N4/Ag(g‐C3N4/Ag‐SCN)photocatalysts were synthesized via photodepositionof metallic Ag on g‐C3N4and subsequent selective adsorption of SCN– ions on the Ag surface by animpregnation method.The resulting g‐C3N4/Ag‐SCN photocatalysts exhibited considerably higherphotocatalytic H2‐evolution activity than the g‐C3N4,g‐C3N4/Ag,and g‐C3N4/SCN photocatalysts.Furthermore,the g‐C3N4/Ag‐SCN photocatalyst displayed the highest H2‐evolution rate(3.9μmolh?1)when the concentration of the SCN– ions was adjusted to0.3mmol L?1.The H2‐evolution rateobtained was higher than those of g‐C3N4(0.15μmol h?1)and g‐C3N4/Ag(0.71μmol h?1).Consideringthe enhanced performance of g‐C3N4/Ag upon minimal addition of SCN– ions,a synergistic effectof metallic Ag and SCN– ions is proposed―the Ag nanoparticles act as an effective electron‐transfermediator for the steady capture and rapid transportation of photogenerated electrons,while theadsorbed SCN– ions serve as an interfacial active site to effectively absorb protons from solution andpromote rapid interfacial H2‐evolution reactions.Considering the present facile synthesis and itshigh efficacy,the present work may provide new insights into preparing high‐performance photocatalytic materials