菌紫质光电作用的分子机制

本文介绍了一种新型的生物分子光电功能材料─—细菌视紫红质，对其结构、光电功能和光化学性质作了简单介绍，着重对其光电作用机理从分子生物学角度进行了阐述，对其在光电器件、神经网络和仿视觉功能系统方面的实际应用给出了几个例子。

TiO2／Ni PECO体系降解DMP的动力学和光电协同作用研究

以采用微波辅助法制备的TiO2/Ni光电极为阳极,纤维状石墨毡材料(graphite felt,GF)为阴极,饱和甘汞电极(saturated calomel electrode,SCE)为参比电极建立TiO2/Ni光电催化氧化(PECO)体系。以邻苯二甲酸二甲酯(dimethyphthalate,DMP)为目标物,研究其光电催化降解反应动力学和光电协同作用。结果显示:DMP的降解符合拟一级动力学规律;当DMP初始浓度一定时,影响DMP光电催化降解速率的因素由强到弱依次为:催化剂有效面积,紫外光强度,曝氧速率,外加偏转电压等。实验证明本体系中光电之间具有协同作用。

不同取代基卟啉衍生物敏化纳米TiO_2多孔膜电极的光电性质研究

采用含有不同取代基的卟啉衍生物四羟基苯基卟啉 ( THPP)和四羧基苯基卟啉 ( TCPP)分别对纳米Ti O2 多孔膜电极进行敏化 .对两种敏化电极进行了 UV-Vis光谱、FTIR光谱和 X射线光电子能谱 ( XPS)测试 .结果表明 ,Ti O2 与 TCPP的作用比与 THPP的作用强 .在相同浸泡条件下 ,Ti O2 电极吸附 TCPP的量大于吸附 THPP的量 .将两种敏化电极分别组装成光电化学电池 ,从正背两个方向照射光电池 ,研究它们在不同照射方向下的光电流响应 .从光电化学电池的 I-V曲线计算 TCPP敏化的光电化学池的总光电转换效率( η)为 0 .1 3 % ,而 THPP敏化的光电化学电池的 η为 0 .0 6% .

TiO_2/CdSe纳晶复合薄膜电极的光电性能研究

研究了TiO2/CdSe纳晶复合薄膜电极的瞬态光电流、光电流作用谱、光吸收特性,结果表明TiO2/CdSe纳晶复合薄膜电极阻止了CdSe上光生电子和空穴的复合,从而提高了阳极光电流的响应,获得了较高增幅的稳态光电流。

菁类染料敏化SnO_2、TiO_2、ZnO纳米结构多孔膜电极的光电化学

SnO2、TiO2、ZnO 是具有发展前途的可作为光电极的半导体材料,这些电极的表征及无机物或有机染料的敏化作用已有不少研究[1,2]。为了既降低染料合成成本,又具有较高的光电转换效率及染料稳定性,寻找全新的、替代型光敏染料的工作仍在不断探索之中。目前,有关使用新型有机染料敏化电极的研究较少。

TNTs电极光电协同降解磺胺类抗生素的研究

利用水热法对Ti板进行处理制得钛酸盐纳米管(titanate nanotubes,TNTs)电极,并利用XRD,TEM和SEM对其进行系统表征,对比了TNTs电极在光催化,电催化和光电协同作用下对磺胺嘧啶(sulfadiazine,SD)的降解效果,探索了不同外加电压对降解效果的影响。结果表明,水热法成功制得内径为5 nm的无序排列的TNTs电极。在初始SD浓度80 mg/L,外加稳压5 V的条件下,TNTs电极在光电协同作用下对SD的降解效率较单纯光解或单纯电解均有提升,反应50 min降解率可达97.38%。在SD本身降解率较高的情况下,TOC去除率较低,这一结果表明溶液中存在大量SD降解中间产物。利用Gaussian软件在B3LYP/6-31+g(d,p)水平优化SD分子构象,结合密度泛函理论(density functional theory,DFT)计算福井函数和电子云密度,确定了SD分子中的反应活性位点,利用高效液相色谱串联质谱(liquid chromatograph mass spectrometer,LC-MS)对中间产物测定,检测到质荷比(m/z)为96、187、117等6种中间产物,推测了SD的两种降解途径。经探究,TNTs光电协同降解抗生素的性能优秀,对现今水体抗生素类污染降解有重大意义。

高效光电化学池的构建及机理研究

将基于硼掺杂金刚石薄膜电极的电解池与基于分子筛负载二氧化钛的光催化池组合,构建了用于有机废水快速处理的高效光电化学池。通过考察电极电位、紫外光强度、溶液的pH、硫酸钠电解质浓度等参数对模拟废水酸性橙的降解效率与活性中间产物S2O82-含量的影响,证实所构建的光电化学池遵循SO42--S2O82--SO4-·-·OH转换机理。这种具有光电协同效应的高效光电化学池对酸性橙的降解效果明显优于电化学氧化及光催化简单的加合,可以将酸性橙完全矿化成CO2。

卟啉衍生物敏化纳米TiO_2多孔膜电极的光电性质研究

采用中位-四[邻-(3-磺酸基丙氨基)苯基]卟啉(TArP1)和中位-四[对-(3-磺酸基丙氨基)苯基]卟啉(TArP2)分别对纳米TiO2多孔膜电极进行敏化。对两种敏化电极进行了UV-V is光谱测试,结果表明,TiO2与TArP2的作用比与TArP1的作用强。在相同浸泡条件下,TiO2电极吸附TArP2的量大于吸附TArP1的量。将两种敏化电极分别组装成光电化学电池,从光电化学电池的I-V曲线计算TArP2敏化的光电化学电池的总光电转换效率(η)为0.15%,而TArP1敏化的光电化学电池的η为0.09%。

Preparation of TiO_2-activated carbon complex membranes and their photoelectrocatalytic activity

The experimental process of preparing TiO 2 activated carbon complex membranes with activated carbon powder as main carrier, PTFE as binder and wire netting as matrix is described in detail, and both photo catalysis and photo electro catalysis are measured to study the properties of complex membranes. Experimental results show that the photo catalytic activity of the membranes is high and stable in the process of treating Rhodamine B; the application of an electric field accelerates the speed of photo catalysis, and the efficiency of photo catalysis is increased 2.5 times when the applied voltage is 0.8 V; and the degradation of Rhodamine B follows the dynamics of first order reaction. It is concluded from the discussion of experimental results that the preparation process of TiO 2 activated carbon complex membranes is a simple low cost process suitable for large scale application.

Improved Ligand-Field Theory with Effect of Electron-Phonon Interaction

Traditional ligand-field theory has to be improved by taking into account both 'pure electronic' contribution and electron-phonon interaction one (including lattice-vibrational relaxation energy). By means of improved ligand-field theory, R1, R2, R'3, R'2, and R'1 lines, U band, ground-state zero-field-splitting (GSZFS), and ground-state g factors of ruby and/or GSGG: Cr3+ as well as thermal shifts of GSZFS, R1 line and R2 line of ruby have been calculated.The results are in very good agreement with the experimental data. Moreover, it is found that the value of cubic-field parameter given by traditional ligand-field theory is inappropriately large. For thermal shifts of GSZFS, R1 line and R2 line of ruby, several conclusions have also been obtained.

LSDA+U study on the electronic and anti-ferromagnetic properties of Ni-doped CuO and Cu-doped NiO

Doping is an effective way to improve the activity of photocatalysts.The effect of doping on the magnetic properties of some photocatalysts that are easily recycled was studied using the local spin density approximation(LSDA)+U method on typical divalent metal oxide semiconductors CuO,NiO,Ni‐doped CuO,and Cu‐doped NiO.It is found that the influence of Ni doping on the spatial structure of CuO and that of Cu doping on the spatial structure of NiO are negligible because of the similar radii of Ni2+and Cu2+.The valence band and conduction band for Ni‐doped CuO are clearly spin‐split,corresponding to a net effective magnetic moment ofμeff=1.66μB.This may improve the photocatalytic efficiency and raise the recycle rate of photocatalysts.In the Cu‐doped NiO system,the presence of Cu3d states near to the Fermi level increases the width of the valence band and narrows the band gap with respect to that in pure NiO.Beyond the Cu3d states,within the band gap,appear two energy levels around the Fermi level,which may effectively separate the electron‐hole pair and also lead to enhanced absorption of visible light and infrared light.It can be concluded that the observed changes in the band structure may be helpful for improving the activity of photocatalysts and the doped systems have net magnetic moments,meaning that they are easily recycled and can be reused.

Photoinduced Intramolecular Charge Transfer in Donor-acceptor Dyad and Donor-bridge-acceptor Triad

The ground and excited state properties of the [60]fullerene, diphenylbenzothiadiazole-triphenylamine （PBTDP-TPA） dyad and fullerene-diphenylbenzothiadiazole-triphenylamine （fullerene-PBTDP-TPA） triad were investigated theoretically using density functional theory with B3LYP functional and 3-21G basis set and time-dependent density functional theory with B3LYP functional and STO-3G basis set as well as 2D and 3D real space analysis methods. The 2D site representation reveals the electron-hole coherence on excitation. The 3D transition density shows the orientation and strength of the transition dipole moment, and the 3D charge difference density gives the orientation and result of the intramolecular charge transfer. Also photoinduced intermolecular charge transfer （ICT） in PBTDP-TPA-fullerene triad are identified with 2D and 3D representations, which reveals the mechanisms of ICT in donor-bridge-acceptor triad on excitation. Besides that we also found that the direct superexchange ICT from donor to acceptor （tunneling through the bridge） strongly promotes the ICT in the donor-bridge-acceptor triad.

Effects of Electron-Phonon Interaction on Linear and Nonlinear Optical Absorption in Cylindrical Quantum Wires

The electron-phonon interaction influences on lineax and nonfineax optical absorption in cylindrical quantum wires （CQW） with an infinite confining potential axe investigated. The optical absorption coefficients are obtained by using the compact-density-matrix approach and iterative method, and the numerical results are presented for GaAs CQW. The results show that the electron-phonon interaction makes a distinct influence on optical absorption in CQW. The electron-phonon interaction on the wave functions of electron dominates the values of absorption coefficients and the correction of the electron-phonon effect on the energies of the electron makes the absorption peaks blue shift and become wider. Moreover, the electron-phonon interaction influence on optical absorption with an infinite confining potential is different from that with a finite confining potential.

Photoelectron Spectroscopy, Photoionization Mass Spectroscopy, and Theoretical Study on CCl3SSCN

Trichloromethanesulfenyl thiocyanate, CCl3SSCN, was generated and studied by photoelectron spectroscopy （PES）, photoionization mass spectroscopy （PIMS）, and theoretical calculations. This molecule exhibits a gauche conformation, and the torsional angle around S-S bond is 91.4° due to the sulfur-sulfur lone pair interactions. After ionization, the ground-state cationic-radical form of CCl3SSCN＋ adopts a trans planar main-atom structure with Cs symmetry. The highest occupied molecular orbital （HOMO） of CC13SSCN corresponds to the electrons mainly localized on the sulfur 3p lone pair MO. The first ionization energy is determined to be 10.40 cV.

Highly enhanced visible-light photocatalytic hydrogen evolution on g-C_3N_4 decorated with vopc through π-π interaction

Photocatalytic H2 evolution reactions on pristine graphitic carbon nitrides(g-C3N4),as a promising approach for converting solar energy to fuel,are attractive for tackling global energy concerns but still suffer from low efficiencies.In this article,we report a tractable approach to modifying g-C3N4 with vanadyl phthalocyanine(VOPc/CN)for efficient visible-light-driven hydrogen production.A non-covalent VOPc/CN hybrid photocatalyst formed viaπ-πstacking interactions between the two components,as confirmed by analysis of UV-vis absorption spectra.The VOPc/CN hybrid photocatalyst shows excellent visible-light-driven photocatalytic performance and good stability.Under optimal conditions,the corresponding H2 evolution rate is nearly 6 times higher than that of pure g-C3N4.The role of VOPc in promoting hydrogen evolution activity was to extend the visible light absorption range and prevent the recombination of photoexcited electron-hole pairs effectively.It is expected that this facile modification method could be a new inspiration for the rational design and exploration of g-C3N4-based hybrid systems with strong light absorption and high-efficiency carrier separation.

Ferroelectric polarization-enhanced photocatalytic performance of heterostructured BaTiO_(3)@TiO_(2) via interface engineering

A catalyst of ferroelectric-BaTiO_(3)@photoelectric-TiO_(2) nanohybrids(BaTiO_(3)@TiO_(2))with enhanced photocatalytic activity was synthesized via a hydrolysis precipitation combined with a hydrothermal approach.Compared to pure TiO_(2),pure BaTiO_(3) and BaTiO_(3)/TiO_(2) physical mixture,the heterostructured BaTiO_(3)@TiO_(2) exhibits significantly improved photocatalytic activity and cycling stability in decomposing Rhodamine B(RhB)and the degradation efficiency is 1.7 times higher than pure TiO_(2) and 7.2 times higher than pure BaTiO_(3).These results are mainly attributed to the synergy effect of photoelectric TiO_(2),ferroelectric-BaTiO_(3) and the rationally designed interfacial structure.The mesoporous microstructure of TiO_(2) is of a high specific area and enables excellent photocatalytic activity.The ferroelectric polarization induced built-in electric field in BaTiO_(3) nanoparticles,and the intimate interfacial interactions at the interface of BaTiO_(3) and TiO_(2) are effective in driving the separation and transport of photogenerated charge carriers.This strategy will stimulate the design of heterostructured photocatalysts with outstanding photocatalytic performance via interface engineering.

Corona Discharge Ion Mobility Spectrometry of Ten Alcohols

Ion mobility spectra for ten alcohols have been studied in an ion mobility spectrometry apparatus equipped with a corona discharge ionization source. Using protonated water cluster ions as the reactant ions and clean air as the drift gas, the alcohols exhibit different product ion characteristic peaks in their ion mobility spectra. The detection limit for these alcohols is at low concentration pmol/L level according to the concentration calibration by exponential dilution method. Based on the measured ion mobilities, several chemical physics parameters of the ion-molecular interaction at atmosphere were obtained, including the ionic collision cross sections, diffusion coefficients, collision rate constants, and the ionic radii under the hard-sphere model approximation.

Deposition of GaN thin film on ZnO/Si by DIBD method

The GaN thin film is successfully grown on the sample of ZnO/Si by dual ion beams deposition (DIBD) system.The thin film GaN/ZnO/Si is characterized by the in-situ X-ray photoelectron spectroscopy (XPS).It is shown that after a thin GaN film grown on the Zn/Si,the peaks of the Zn and O are not observed.This indicates that the GaN film can be successfully grown on the ZnO/Si by the dual ion beam deposition (DIBD) system associated with the pulsed laser deposition (PLD) method.

Study of Two-Mode Squeezed Magnetopolarons

In this paper, we conduct an investigation into two-dimensional squeezed magnetopolarons. The Hamiltonian of magnetopolarons is dealt with two-mode squeezed states transformation, which is based on the Lee-Low-Pines and Huybrechts （LLP-H） canonical transformations. This method makes it possible to take account of the linear terms, bilinear ones of phonon operators, and the correlation between two longitudinal optical （LO） phonon modes. The energies of the ground state and excited states are evaluated by variational approach, and accurate results are obtained. Furthermore, the renormalized cyclotron masses for some possible transitions are discussed in detail.