Cu2O镂空材料的制备及其光催化性能研究

采用空气氧化法制备了六角状氧化亚铜的镂空结构。在空气中氧气的辅助下,液相还原法制备的形貌、尺寸均一的六角状氧化亚铜（Cu2O）可被原位镂空成鱼骨状结构。采用扫描电镜(SEM)、X线衍射(XRD)、透射电子显微镜（TEM）、比表面积测试（BET)、紫外 可见吸收（UV Vis）光谱等手段对Cu2O材料进行形貌、结构及催化性能表征。结果表明,六角状Cu2O沿{100}和{111}面逐步向内腐蚀镂空,在空气辅助腐蚀2 h后,材料的比表面积相比镂空前增加了90％。光催化实验结果表明,镂空Cu2O材料的光催化性能提高了30％。     

SO2-4/Bi24O3固体超酸的制备及其可见光催化性能

采用水热法结合H2SO4浸泡处理成功合成了SO2-4/Bi2O3可见光催化材料, 并采用XRD、TG DTA和UV Vis等对合成产物的物相结构、热化学性能、光吸收性能以及可见光催化性能进行了研究, 对H2SO4浸泡工艺条件对产物的可见光催化性能的影响进行了探讨。研究表明, 水热合成产物为α Bi2O3、Bi2O4和Bi2O2CO3的混合物, 其中α Bi2O3为主要成分;H2SO4浸泡处理并未改变产物的物相结构, 但经H2SO4浸泡处理后产物的光催化性能得到了显著的提高, 并且H2SO4浸泡工艺条件对产物的光催化活性有着重要的影响。在实验范围内, 在浓度为0.5mol·L-1的H2SO4溶液中浸泡75min, 再经700℃热处理4h可制备出具有较佳光催化活性的产物, 经75min可见光的照射后对甲基橙溶液的光催化脱色率可达93.1%。     

SO_4~(2-)/Bi_2O_3固体超酸的制备及其可见光催化性能

采用水热法结合H2SO4浸泡处理成功合成了SO42-/Bi2O3可见光催化材料,并采用XRD、TG-DTA和UV-Vis等对合成产物的物相结构、热化学性能、光吸收性能以及可见光催化性能进行了研究,对H2SO4浸泡工艺条件对产物的可见光催化性能的影响进行了探讨。研究表明,水热合成产物为α-Bi2O3、Bi2O4和Bi2O2CO3的混合物,其中α-Bi2O3为主要成分;H2SO4浸泡处理并未改变产物的物相结构,但经H2SO4浸泡处理后产物的光催化性能得到了显著的提高,并且H2SO4浸泡工艺条件对产物的光催化活性有着重要的影响。在实验范围内,在浓度为0.5mol·L-1的H2SO4溶液中浸泡75min,再经700℃热处理4h可制备出具有较佳光催化活性的产物,经75min可见光的照射后对甲基橙溶液的光催化脱色率可达93.1%。     

兰州化物所催化纳米材料结构设计及晶面调控获进展

<正>中国科学院兰州化学物理研究所能源与环境纳米催化材料课题组在半导体光催化纳米材料的结构设计及晶面调控方面取得系列进展。半导体光催化材料的设计合成及晶面调控成为目前光催化研究领域的热点,然而目前所报道的此类异质材料由于自身形貌及结构缺陷普遍具有较低的光生电荷分离效率及可见光催化活性。因此如何设计、制备具     

二维MoS_2纳米材料的制备及在光催化中的应用进展

二硫化钼(MoS2)是一种类石墨烯过渡金属二硫化物。单层MoS2凭借其超薄的层状结构和适宜的禁带宽度(1.9eV),在纳米电子学,光电子学和微纳器件等领域备受关注。此外,凭借丰富的边缘结构、巨大的比表面积、良好的化学稳定性和可调控禁带宽度,二维MoS2逐渐成为新型光催化材料的研究热点。综合近年来国内外关于二维MoS2在光催化领域的研究成果,详细归纳并梳理了二维MoS2的结构、性能及制备方法。特别关注了二维MoS2与其他半导体材料结合形成二元或三元光催化复合体系在光催化水解制氢和光催化降解有机污染物两方面的最新研究进展。最后,对二维MoS2在光催化领域的研究前景进行了展望。     

掺Pb的TiO2纳米功能材料的制备及其光催化性能

采用溶胶－凝胶法制备了掺Pb的摩尔比分别为0.5%、1%、3%、5%、7%、10%的改性TiO2纳米粒子，并利用XRD和UV－VIS检测技术对所制得的样品进行了表征，考察了焙烧温度和掺Pb量对材料组成、结构和光学性质的影响；另外，以模拟太阳光下苯酚的光催化降解为模型反应，对Pb改性的TiO2纳米粒子的光催化活性进行了评价，考察了掺Pb量对材料催化性能的影响。结果表明，掺入适量的Pb后，TiO2纳米粒子的光催化活 性得到较大的提高，这可能是由于Pb进入TiO2晶格中生长成了新相PbxTi1-xO2，从而使材料的光响应范围向可见光区移动，提高了对可见光的利用率。本实验表明，掺Pb的摩尔比为3％的改性TiO2纳米粒子的光催化活性最高。     

银纳米颗粒修饰TiO2薄膜的结构,光学及光催化性能

采用电子束沉积技术在石英玻璃、硅片基板上沉积了TiO₂薄膜,利用热蒸发技术在TiO₂薄膜表面沉积了不同厚度的Ag膜,研究了Ag膜厚度对TiO₂薄膜结构、形貌、光学和光催化 性能的影响。利 用紫外-可见分光光度计(UV-VIS)、X射线衍射仪(XRD)、冷场发射电子显微镜(SEM)对沉积 后的薄膜分别 进行光学、结构、形貌分析。利用能谱仪测定了元素成分及含量。用光催化降解亚甲基橙(M O)的速率评 价了合成的Ag-TiO₂的光催化性能。结果表明:Ag纳米粒子在TiO₂表面均匀分布;制备 的Ag修饰多孔TiO₂纳米薄膜具有优异的光催化性能。测试结果表明:在250 ℃下制备的T iO₂薄膜为无定形结构;随着Ag膜厚度 的增加,样品的光催化活性提高。当Ag膜厚度为3.7 nm时,光催化活 性最高;与纯TiO₂相比,Ag-TiO₂具有更高的光催化活性。     

电沉积工艺制备纳米ZnO及其生长机理

本文以Zn（NO3）2·6H2O和KCl的水溶液为电解液,采用三电极恒电位体系在ITO上电沉积制备了形貌可控的纳米ZnO。通过旋转涂布（CH3COO）2Zn·2H2O溶液,煅烧后可在ITO表面生长一层ZnO种子层。该种子层可以增加ZnO的密度,使c轴取向更加明显。通过场发射扫描电子显微镜（ FESEM）、X射线衍射（ XRD）、光致发光光谱（PL）等测试手段,系统地分析了电沉积参数（Zn（NO3）2·6H2O浓度、电沉积电压、电沉积温度）对电沉积制备纳米ZnO形貌、结构、光催化性能、发光性能的影响,并研究了其生长机理。     

CdSe/TiO_2纳米复合材料的研究进展

CdSe和TiO2复合后,其对可见光的利用率大大提高,光电性能和光催化性能都得到明显改善。对CdSe敏化TiO2的原理做了简要阐述,主要综述了CdSe/TiO2纳米复合材料的制备及性能,重点介绍了目前制备薄膜及粉体CdSe/TiO2纳米复合材料的方法和所得复合材料在光催化和太阳能电池领域中的应用研究,并对不同方法制备的材料的结构与特性作了简要对比。但目前这一复合材料仍存在缺陷,所以人们又对其进行了改性研究,也对这一方面作了简要介绍。因此,通过对CdSe或TiO2的形貌进行控制或改性来进一步提高复合材料的性能将是今后研究的重点,不能只偏重对其光电性能的研究,也要加大对其光催化性能的研究。     

温度条件下光催化甲醇燃料电池的光电化学性质

采用双室带有质子交换膜和石英窗的H型电池,以甲醇为燃料,构建了ZnO、BiVO4、TiO2和TiO2/SrTiO3四种光阳极材料的光催化甲醇燃料电池.通过体系在不同温度下的间歇运行,应用线性扫描伏安、交流阻抗、极化曲线等电化学方法探究了温度对光催化甲醇燃料电池性能的影响.在低温条件下,光催化燃料电池依然有较好的光电化学...     

Microstructure of reactively sputtered oxide diffusion barriers

Molybdenum oxide (Mo_1-x O _x ) and ruthenium oxide (RuO₂) films were prepared by rf reactive sputtering of Mo or Ru targets in an O₂/Ar plasma. Both films exhibit metallic conductivities. The influence of the deposition parameters on the phase that forms and on the microstructure of Mo_1-x O _x and RuO₂ films is reported. A phase transformation is observed in Mo_1-x O _x films subjected to heat treatment. The diffusion barrier performance of Mo_1-x O _x and RuO₂ layers interposed between Al and Si is compared.     

Sn掺杂对(In0.95-xSnxFe0.05)2O3薄膜的结构、电学及磁特性的影响

我们利用脉冲激光沉积的方法制备了一系列(In0.95-xSnxFe0.05)2O3 (x=0~0.09)薄膜,并在其中发现了室温铁磁性。X射线衍射结果表明锡与铁离子已掺入氧化铟晶格。随着锡的掺入,样品内的载流子浓度得到了很大的提高,但相应的铁磁性却几乎没有变化。我们认为氧空位相关的束缚磁极化子模型能够跟好的解释我们的铁掺杂氧化铟薄膜中的铁磁耦合的机制,而载流子传导的RKKY相互作用则不适用于这一系统。     

溅射压力对制备a-GaAs1-xNx 薄膜光学常数的影响

采用反应磁控溅射法在室温条件下制备了a-GaAs_1-xN_x 薄膜。实验测定了薄膜厚度、氮含量、载流子浓度和光学透过率及并研究了其随溅射压的变化。系统研究了溅射压对所制备薄膜的光学带隙、折射率和色散参数的影响。所制备的薄膜为直接带隙材料,利用Cauchy和Wemple模型能够很好地拟合所制备薄膜的折射率色散曲线。     

Hybrid functional calculations on the band gap bowing parameters of InxGa1-xN

The electronic band structures and band gap bowing parameters of In_xGa_1-xN are studied by the firstprinciples method based on the density functional theory. Calculations by employing both the Heyd-ScuseriaErnzerh of hybrid functional（HSE06） and the Perdew-Burke-Ernzerhof（PBE） one are performed. We found that the theoretical band gap bowing parameter is dependent significantly on the calculation method, especially on the exchange-correlation functional employed in the DFT calculations. The band gap of In_xGa_1-xN alloy decreases considerably when the In constituent x increases. It is the interactions of s–s and p–p orbitals between anions and cations that play significant roles in formatting the band gaps bowing. In general, the HSE06 hybrid functional could provide a good alternative to the PBE functional in calculating the band gap bowing parameters.     

利用拉曼谱鉴别锗硅合金微结构变化

随着硅浓度的增大,计算的拉曼谱结果表明,Ge-Si模式和Si-Si模式向高波数移动,而Ge-Ge模式向低波数移动,这种拉曼谱的变化强烈的依赖于合金微结构的变化。它的模式频率的线性变化依赖于Ge/Si的力学常熟的变化。这种现象可以用来鉴别合金中Si含量的浓度。可以通过拉曼散射表征这种复杂的微结构变化。     

Large signal and noise properties of heterojunction AlxGa1-xAs/GaAs DDRIMPATTs

Simulation studies are carried out on the large signal and noise properties of heterojunction (HT) Al_xGa_1-xAs/GaAs double drift region (DDR) IMPATT devices at V-band (60 GHz). The dependence of Al mole fraction on the aforementioned properties of the device has been investigated. A full simulation software package has been indigenously developed for this purpose. The large signal simulation is based on a non-sinusoidal voltage excitation model. Three mole fractions of Al and two complementary HT DDR structures for each mole fraction i.e., six DDR structures are considered in this study. The purpose is to discover the most suitable structure and corresponding mole fraction at which high power, high efficiency and low noise are obtained from the device. The noise spectral density and noise measure of all six HT DDR structures are obtained from a noise model and simulation method. Similar studies are carried out on homojunction (HM) DDR GaAs IMPATTs at 60 GHz to compare their RF properties with those of HT DDR devices. The results show that the HT DDR device based on N-Al_xGa_1-xAs/p-GaAs with 30% mole fraction of Al is the best one so far as large signal power output, DC to RF conversion efficiency and noise level are concerned.     

Rare-earth-modified Sr0.5Ba0.5Nb2O6, ferroelectric crystals and their applications as infrared detectors

Rare-earth-modified ferroelectric crystals with the formula (Sr_1−xBa_x)1− 3y/2 R_yNb2₂O₆, where R = La, Nd, Sm, Gd, and Lu, have Been prepared and studied. When R = La, Nd, x ≃ .5 and y = 0.02, the modified material, at room temperature, exhibited twice the pyroelectric coefficient and four times the dielectric constant of the unmodified Sr_1−xBa_xNb₂O₆ (x ≃ .5). Curie temperatures decreased, dielectric constants increased, while loss factor and detector signal-to-noise ratios remained nearly the same with the addition of rare earth doping. The calculated response based on the measured properties agree with the measured response of actual detectors. These properties suggested that the modified SBN are good materials for small element or array pyroelectric infrared detector applications.     

InP-based InxGa1-xAs metamorphic buffers with different mismatch grading rates

Linearly graded In_xGa_1-xAs metamorphic buffers with different mismatch grading rates were grown on InP substrate by gas source molecular beam epitaxy.Room temperature photoluminescence spectra show that the sample with lower mismatch grading rate in the buffer has stronger photoluminescence signal,indicating the improved optical property.Atomic force microscope images show that the lower mismatch grading rate in the buffer leads to a slightly rougher surface.The relaxation procedure with two steps in the buffer layers has been observed by X-ray diffraction reciprocal space mapping.The measurements of X-ray diffraction also reveal that the lower mismatch grading rate in the buffer is beneficial for the lattice relaxation and release of residual strain.To further increase the relaxation degree,a lower mismatch grading rate and composition "overshoot" are suggested.     

Comparative study on the influence of Al component at GaAlAs layer for GaAs/AlGaAs photocathode

We designed two transmission-mode GaAs/AlGaAs photocathodes with different AlxGa_1-xAs layers, one has an Al_xGa_1-xAs layer with the Al component ranging from 0.9 to 0, and the other has a fixed Al component 0.7. Using the first-principle method, we calculated the electronic structure and absorption spectrum of Al_xGa_1-xAs at x=0, 0.25, 0.5, 0.75 and 1, calculation results suggest that with the increase of the Al component, the band gap of Al_xGa_1-xAs increases. Then we activated the two samples, and obtained the spectral response curves and quantum efficiency curves; it is found that sample 1 has a better shortwave response and higher quantum efficiency at short wavelengths. Combined with the band structure diagram of the transmission-mode GaAs/AlGaAs photocathode and the fitted performance parameters, we analyze the phenomenon. It is found that the transmission-mode GaAs/AlGaAs photocathode with variable Al component and various doping structure can form a two-stage built-in electric field, which improves the probability of shortwave response photoelectrons escaping to the vacuum. In conclusion, such a structure reduces the influence of back-interface recombination, improves the shortwave response of the transmission-mode photocathode.     

Melt growth and stoichiometry control of (Cd1−xZnx)1+yTe single crystals

Growth of (Cd_1−xZn_x)_1+yTe(CZT) single crystals is tried by a modified Bridgman method using a reservoir chamber containing Cd and Zn metals with a fixed mole ratio. The aim of this method is to obtain the single crystals with controlled deviation y from stoichiometry and homogeneous target composition x. A suitable growth condition was examined experimentally and the effectiveness of this method for controlling the deviation y from stoichiometry and the composition x is confirmed.