LaCl3提高菠菜光系统Ⅱ活性的作用机制

The effect of LaCl3 on the K3Fe(CN)6 (FeCy) reduction rate and the oxygen-evolving rate of PSU particles of spinach, and the spectral characterization of the D1/D2/Cytb559 of a PSII reaction center complex consisting of three polypeptides from spinach were studied. The experimental results showed that LaCl3 could significantly accelerate the transformation from light energy to electric energy, the electron transport, water photolysis and oxygen evolution of PSII of spinach, which was related to the spectral characterization of the D1/D2/Cytb559 complex.Soret band and Q band of Chl-a of UV-vis spectrum of D1/D2/Cytb559 complex were blue shifted, and the fluorescence emission peak was blue shifted in LaCl3 treated spinach compared with that in the control. The EXAFS (extended X-ray absorption fine structure spectroscopy) revealed that La^3 was coordinated with 8 nitrogen or oxygen atoms in the first coordination shell with La-N or La-O bond length of 0.254 nm, and with 6 nitrogen or oxygen atoms in the second coordination shell with La-N or La-O bond length of 0.321 nm in the D1/D2/Cytb559 complex. The CD suggested that the secondary structure of D1/D2/Cytb559 complex have been litfie affected by the treatment of LaCl3.     

Effect of Ce<Superscript>3+</Superscript> on spectral characteristic of D1/D2/Cytb559 complex from spinach

It was studied by spectroscopy that PSII reaction center complex consisting of three polypeptides, D₁, D₂ and Cytb559, were purified from PSII particle of CeCl₃ treated spinach. The results of the experiment show that Ce³⁺ could improve the growth of spinach, and accelerate electron transport of PSII particles. Of chl-a of UV-Vis spectrum of D1/D2/Cytb559 complex, Soret band was blue-shifted by 3 nm and Q band by 2 nm, respectively, and the fluorescence emission peak was blue-shifted by 5 nm in CeCl₃-treated spinach compared with the one in control. By the extended X-ray absorption fine structure (EXAFS) spectroscopy methods, it has been found that Ce³⁺ is coordinated with 8 nitrogen atoms in the first coordination shell with Ce-N bond length of 0.253 nm, and Ce³⁺ with 6 oxygen atoms in the second coordination shell with Ce-O bond length of 0.32 nm. However, the secondary structure of D1/D2/Cytb559 complex by circular dichroism (CD) spectroscopy has no significant change after CeCl₃ treated. It might be that Ce³⁺ binds to porphyrin rings of chlorophyll and oxygen of amino acid residue of polypeptide in D1/D2/Cytb559 complex, and then accelerates the primary reaction of PSII, intensifies function of P680⁺ primary electron donor of D1/D2/Cytb559, but there is little change in conformation of PSII reaction center complex.     

Effect of Ce~(3+) on spectral characteristic of D1/D2/Cytb559 complex from spinach

In our early researches, lanthanum and cerium could enter plant and bind to porphyrin of chlorophyll to form Ln3+-chllorophyll. La and Ce greatly increase photosystem II (PSII) activity and PSII electron transport rate, and the fluorescence emission peaks of PSII are blue-shifted [1—4]. Do REEs coordinate with PSII reaction center complex in vivo? Moreover, do REEs coordinate with D1(30 kD)/D2(32 kD)/Cytb559 (~9 kD) reaction center complex of site of producing pri-mary reaction-p…     

Solar photocatalytic activities of porous Nb-doped TiO2 microspheres prepared by ultrasonic spray pyrolysis

Ultrasonic spray pyrolysis method was used to prepare Nb-doped TiO₂ porous microspheres with an average diameter of 500 nm for solar photocatalytic applications. The effect of Nb-doping on morphology, structure, surface area, as well as spectral absorption properties of TiO₂ microspheres was investigated with SEM, TEM, XRD, Raman spectra, BET, and UV-Vis absorption spectra. The Nb-doping decreased the grain size of TiO₂ porous microsphere, and influenced its surface area and pore size distribution dependent on the doping concentration, but changed negligibly the morphology and size of TiO₂ microspheres. Moreover, the Nb-doping was observed to extend the spectral absorption of TiO₂ into visible spectrum, and the absorption onset was red-shifted for about 88 nm at a doping level of 5% compared to pristine TiO₂ microspheres. Under solar or visible irradiation, Nb-doped TiO₂ microspheres showed higher photocatalytic activity for methylene blue degradation compared with TiO₂ microspheres, which could be ascribed to the extended light absorption range and the suppression of electron-hole pair recombination.     

Phase transitions in A-site substituted perovskite compounds: The (Ca1-2xNaxLax)TiO3 (0?x?0.5) solid solution

The (Ca_1-2xNa_xLa_x)TiO₃ (0?x?0.5) A-site substituted perovskite compounds have been synthesized and characterized by XRD and Raman spectroscopy at room temperature. The XRD powder diffraction study suggests that the end-member Na_1/2La_1/2TiO₃ crystallizes in the tetragonal space group I4/mcm. The phase transition from Pbnm to I4/mcm is located between x=0.34 and 0.39 and is driven by the variation of ionic radii at the A-site. The observed Raman modes are in agreement with group theory analysis, and the relationships between the behavior of structural parameters (e.g. Ti-O-Ti bond angle), indicated by long-range order, and the corresponding Raman frequency shifts and intensity evolution, indicated by short-range order, are established and discussed in terms of the radius effect and the mass effect.     

Comparison of CO2 Reduction Performance with NH3 and H2O between Cu/TiO2 and Pd/TiO2

The aim of this study is to clarify the effect of doped metal type on CO₂ reduction characteristics of TiO₂ with NH₃ and H₂O. Cu and Pd have been selected as dopants for TiO₂. In addition, the impact of molar ratio of CO₂ to reductants NH₃ and H₂O has been investigated. A TiO₂ photocatalyst was prepared by a sol-gel and dip-coating process, and then doped with Cu or Pd fine particles by using the pulse arc plasma gun method. The prepared Cu/TiO₂ film and Pd/TiO₂ film were characterized by SEM, EPMA, TEM, STEM, EDX, EDS and EELS. This study also has investigated the performance of CO₂ reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that the CO₂ reduction performance with Cu/TiO₂ under the illumination condition of Xe lamp with UV light is the highest when the molar ratio of CO₂/NH₃/H₂O = 1:1:1 while that without UV light is the highest when the molar ratio of CO₂/NH₃/H₂O = 1:0.5:0.5. It is revealed that the CO₂ reduction performance of Pd/TiO₂ is the highest for the molar ratio of CO₂/NH₃/H₂O = 1:1:1 no matter the used Xe lamp was with or without UV light. The molar quantity of CO per unit weight of photocatalyst for Cu/TiO₂ produced under the illumination condition of Xe lamp with UV light was 10.2 μmol/g, while that for Pd/TiO₂ was 5.5 μmol/g. Meanwhile, the molar quantity of CO per unit weight of photocatalyst for Cu/TiO₂ produced under the illumination condition of Xe lamp without UV light was 2.5 μmol/g, while that for Pd/TiO₂ was 3.5 μmol/g. This study has concluded that Cu/TiO₂ is superior to Pd/TiO₂ from the viewpoint of the molar quantity of CO per unit weight of photocatalyst as well as the quantum efficiency.     

TiO2纳米管阵列覆盖Si薄膜光催化还原CO2性能的研究

本工作采用CVD法在阳极氧化TiO2纳米管阵列膜表面沉积一层非晶Si膜,通过退火后得到晶化了的Si膜/TiO2纳米管阵列的复合结构,并初步就其光催化还原CO2制备碳氢化合物的活性进行研究。拉曼光谱(Raman)、X射线衍射(XRD)、场发射扫描电镜(FE-SEM)、高分辨透射电子显微镜(TEM)等微结构表征结果表明所制备的TiO2纳米管阵列的厚度为270 nm左右,管直径约为70 nm,管壁厚度约为16 nm。覆盖的Si膜已晶化,其厚度约为300 nm。通过高效液相色谱(HPLC)及总有机碳(TOC)来检测光催化还原液相产物中的甲酸及总有机碳含量,发现负载Si膜后的TiO2纳米管阵列光催化性能有所提高,在装有400cut滤光片氙灯照射2 h下TOC含量从21.2 mg.L-1增长到29.5 mg.L-1,表明Si与TiO2的复合可有效的提高光催化还原CO2的活性,这可能与该异质结结构可增加对光的吸收并且可降低光生空穴-电子对复合有关。光催化循环实验表明所制得的催化剂在循环5次后仍可保持91.6%的催化活性。     

Au改性TiO2纳米复合物对人结肠癌细胞的光催化杀伤作用

提出了通过TiO₂表面修饰纳米Au的方法来提高纳米TiO₂光催化杀伤癌细胞的效率. 采用化学还原法合成了Au改性的TiO₂ (Au/TiO₂)纳米复合物, 并研究了不同掺杂量(1 wt%, 2 wt%, 4 wt%)的Au/TiO₂对人结肠癌LoVo细胞的光催化杀伤效应. 结果显示, Au的掺杂大大地提高了TiO₂纳米粒子光催化杀伤结肠癌LoVo细胞的效率, 而且Au掺杂量的高低影响Au/TiO₂光催化杀伤癌细胞的效率, 掺金量为2%的Au/TiO₂对结肠癌LoVo细胞具有最高的光催化杀伤效率. 在光强为1.8 mW/cm²的紫外灯(λ_max＝365 nm)下光照110 min, 50 μg/mL掺金量为2%的Au/TiO₂能够杀死所有的癌细胞, 而同样浓度的TiO₂只能杀死70%的癌细胞.     

2D/2D atomic double-layer WS2/Nb2O5 shell/core nanosheets with ultrafast interfacial charge transfer for boosting photocatalytic H2 evolution

Low-efficiency charge transfer is a critical factor to limit the photocatalytic H₂ evolution activity of semiconductor photocatalysts. The interface design is a promising approach to achieve high charge-transfer efficiency for photocatalysts. Herein, a new 2D/2D atomic double-layer WS₂/Nb₂O₅ shell/core photocatalyst (DLWS/Nb₂O₅) is designed. The atom-resolved HAADF-STEM results unravel the presence of an unusual 2D/2D shell/core interface in DLWS/Nb₂O₅. Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra, the average lifetime of charge carriers for DLWS/Nb₂O₅ (180.97 ps) is considerably shortened as compared to that of Nb₂O₅ (230.50 ps), strongly indicating that the 2D/2D shell/core interface enables DLWS/Nb₂O₅ to achieve ultrafast charge transfer from Nb₂O₅ to atomic double-layer WS₂, thus yielding a high photocatalytic H₂ evolution rate of 237.6 μmol/h, up to 10.8 times higher than that of pure Nb₂O₅ nanosheet. This study will open a new window for the development of high-efficient photocatalytic systems through the interface design.     

Boosting Charge Transport in a 2D/3D Perovskite Heterostructure by Selecting an Ordered 2D Perovskite as the Passivator

We demonstrate that an ordered 2D perovskite can significantly boost the photoelectric performance of 2D/3D perovskite heterostructures. Using selective fluorination of phenyl-ethyl ammonium (PEA) lead iodide to passivate 3D FA_0.8Cs_0.2PbI₃, we find that the 2D/3D perovskite heterostructures passivated by a higher ordered 2D perovskite have lower Urbach energy, yielding a remarkable increase in photoluminescence (PL) intensity, PL lifetime, charge-carrier mobilities (ϕμ), and carrier diffusion length (L_D) for a certain 2D perovskite content. High performance with an ultralong PL lifetime of ≈1.3 μs, high ϕμ of ≈18.56 cm² V⁻¹ s⁻¹, and long L_D of ≈7.85 μm is achieved in the 2D/3D films when passivated by 16.67 % para-fluoro-PEA₂PbI₄. This carrier diffusion length is comparable to that of some perovskite single crystals (>5 μm). These findings provide key missing information on how the organic cations of 2D perovskites influence the performance of 2D/3D perovskite heterostructures.     

Fe_2O_3/TiO_2纳米管阵列的制备及其光催化性能

在钛基体上采用阳极氧化法制备了TiO2纳米管阵列,采用化学浴方法在TiO2纳米管阵列上修饰了Fe2O3纳米颗粒。利用扫描电镜、X射线衍射和紫外可见漫反射光谱等手段对材料进行了表征,同时测试了材料的光电化学性能及其光催化降解亚甲基蓝染料废水的性能。结果表明,Fe2O3纳米颗粒的修饰将TiO2纳米管阵列的光响应拓宽至可见光区域,提高了光电流,Fe2O3/TiO2纳米管阵列的光电流是未修饰的TiO2纳米管阵列的9倍。而在光催化反应中,亚甲基蓝最高降解率可达80%,比未修饰的TiO2纳米管阵列高出30%。     

香豆素343敏化TiO2纳米粒子光致电子转移的荧光和拉曼光谱

通过对香豆素343(C343)染料敏化TiO₂纳米粒子光致电子转移的荧光和拉曼光谱特性的研究表明,C343染料敏化TiO₂纳米粒子稳态吸收光谱和稳态荧光光谱的红移归因于从被吸附的C343染料分子激发态和C343/TiO₂复合物到TiO₂纳米粒子导带的光致电子转移. 由时间分辨荧光光谱确定了C343染料敏化TiO₂纳米粒子的逆向电子转移速率常数为τ₁=31 ps. C343 染料敏化TiO₂纳米粒子体系拉曼光谱的研究表明, 被吸附在界面处的染料分子主链碳键的伸缩振动和碳环的呼吸运动的振动模式对超快界面光致电子转移有着重要的促进作用.     

In Situ Synthesis of Cu3P/P-Doped g-C3N4 Tight 2D/2D Heterojunction Boosting Photocatalytic H2 Evolution†

Heterojunction design in a two-dimensional (2D) fashion has been deemed beneficial for improving the photocatalytic activity of g-C₃N₄ because of the promoted interfacial charge transfer, yet still facing challenges. Herein, we construct a novel 2D/2D Cu₃P nanosheet/P-doped g-C₃N₄ (PCN) nanosheet heterojunction photocatalyst (PCN/Cu₃P) through a simple in-situ phosphorization treatment of 2D/2D CuS/g-C₃N₄ composite for photocatalytic H₂ evolution. We demonstrate that the 2D lamellar structure of both CuS and g-C₃N₄ could be well reserved in the phosphorization process, while CuS and g-C₃N₄ in-situ transformed into Cu₃P and PCN, respectively, leading to the formation of PCN/Cu₃P tight 2D/2D heterojunction. Owing to the large contact area provided by intimate face-to-face 2D/2D structure, the PCN/Cu₃P photocatalyst exhibits significantly enhanced charge separation efficiency, thus achieving a boosted visible-light-driven photocatalytic behavior. The highest rate for H₂ evolution reaches 5.12 μmol·h^–1, nearly 24 times and 368 times higher than that of pristine PCN and g-C₃N₄, respectively. This work represents an excellent example in elaborately constructing g-C₃N₄-based 2D/2D heterostructure and could be extended to other photocatalyst/co-catalyst system.      

Fe2O3/TiO2纳米管阵列的制备及其光催化性能

在钛基体上采用阳极氧化法制备了TiO₂纳米管阵列,采用化学浴方法在TiO₂纳米管阵列上修饰了Fe₂O₃纳米颗粒.利用扫描电镜、X射线衍射和紫外可见漫反射光谱等手段对材料进行了表征,同时测试了材料的光电化学性能及其光催化降解亚甲基蓝染料废水的性能.结果表明,Fe₂O₃纳米颗粒的修饰将TiO₂纳米管阵列的光响应拓宽至可见光区域,提高了光电流,Fe₂O₃/TiO₂纳米管阵列的光电流是未修饰的TiO₂纳米管阵列的9倍.而在光催化反应中,亚甲基蓝最高降解率可达80%,比未修饰的TiO₂纳米管阵列高出30%.     

GO/TiO2-g-C3N4纳米复合材料的制备及可见光催化性能

以水热法制备的20% g-C₃N₄/TiO₂（20%为质量分数）为基,将其与不同质量分数的氧化石墨烯（GO）复合制备出可见光催化性能优良的GO/TiO₂-g-C₃N₄三元复合材料。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）、紫外-可见漫反射光谱（UV-Vis DRS）、光致荧光光谱（PL）、瞬态光电流响应等分析测试手段对样品的结构、形貌和光电性能进行表征。研究了不同质量分数GO的加入对GO/TiO₂-g-C₃N₄在可见光下降解亚甲基蓝（MB）溶液的影响。结果表明： g-C₃N₄/TiO₂与GO复合后,锐钛矿相TiO₂颗粒形成小团簇附着在g-C₃N₄和GO片层表面,且当GO含量为15%时,TiO₂形成的团簇最小,对可见光的吸收最多且光生电子-空穴对的复合率最低。可见光照射下,15% GO/TiO₂-g-C₃N₄复合材料对MB的降解率在3 h内可达98.4%,且其降解速率常数（0.022 4 min^-1）分别是纯TiO₂（0.001 5 min^-1）和g-C₃N₄/TiO₂（0.002 5 min^-1）的15倍和9倍。     

Photocatalytic activity of polyaniline/Fe-doped TiO2 composites by in situ polymerization method

This study was focused on the photocatalytic activity of polyaniline (Pani)/iron doped titanium dioxide (Fe–TiO₂) composites for the degradation of methylene blue as a model dye. TiO₂ nanoparticles were doped with iron ions (Fe) using the wet impregnation method and the doped nanoparticles were further combined with Pani via an in situ polymerization method. For comparison purposes, Pani composites were also synthesized in the presence undoped TiO₂. The photocatalyst and the composites were characterized by standard analytical techniques such as FTIR, XRD, SEM, EDX and UV–Vis spectroscopies. Fe–TiO₂ and its composites exhibited enhanced photocatalytic activity under ultraviolet light irradiation. Improved photocatalytic activity of Fe–TiO₂ was attributed to the dopant Fe ions hindering the recombination of the photoinduced charge carriers. Pani/Fe–TiO₂ composite with 30?wt.% of TiO₂ nanoparticles achieved 28% dye removal and the discoloration rate of methylene blue for the sample was 0.0025?min^?1. FTIR, XRD, SEM, EDX and UV–Vis spectroscopies supported the idea that Fe ions integrated into TiO₂ crystal structure and Pani composites were successfully synthesized in the presence of the photocatalyst nanoparticles. The novelty of this study was to investigate the photocatalytic activity of Pani composites, containing iron doped TiO₂ and to compare their results with that of Pani/TiO₂.     

中空Ta_2O_5/TiO_2复合光催化剂的可控氧化制备及性能

以钛粉、钽粉为原料,炭黑作为反应性模板,通过熔盐法在炭黑表面原位生长了TaTiC_2纳米碳化物涂层,并以所得TaTiC_2/C复合物为碳化物前驱体,再经可控氧化制备出中空Ta_2O_5/TiO_2复合光催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见(UV-Vis)漫反射(DRS)及N2物理吸附等手段对所制备的光催化剂进行形貌、显微结构及孔结构表征。以高压汞灯为紫外光源,以亚甲基蓝为目标降解物,通过光催化降解实验评价中空Ta_2O_5/TiO_2复合光催化剂的光催化活性。结果表明,熔盐法生长碳化物涂层厚度均匀(20~30 nm),碳化物主要以TaTiC_2晶相存在且具有纳米级的颗粒尺寸。中空Ta_2O_5/TiO_2复合光催化剂同时具有200 nm左右的中空大孔结构及壳层10 nm左右的介孔结构。中空大孔和介孔的存在提高了所制备催化剂对亚甲基蓝的吸附能力。此外,TiO_2与Ta2O5通过电子能带结构的耦合,有效提高了光生电子和空穴的分离效率,从而显著提高了光催化活性。nTi∶nTa=2.5∶1.5时,相应的中空Ta_2O_5/TiO_2复合光催化剂表现出最佳的光催化活性,对亚甲基蓝的紫外光催化降解率高达97%。     

Enhancement of photoelectric catalytic activity of TiO2 film via Polyaniline hybridization

A Polyaniline (PANI)/TiO₂ film coated on titanium foil was successfully prepared using the sol-gel method followed by a facile chemisorption. Compared with pristine TiO₂, the photocatalytic (PC) and photoelectrocatalytic (PEC) degradation rates of 2,4-dichlorophenol (2,4-DCP) with the PANI/TiO₂ film were enhanced by 22.2% and 57.5%, respectively. 2,4-DCP can be mineralized more effectively in the presence of PANI/TiO₂ film. The best PEC degradation efficiency of 2,4-DCP with the PANI/TiO₂ film was acquired at an external potential of 1.5 V with a layer of 1 nm thick PANI. The PANI/TiO₂ film was characterized by Raman spectra, Fourier transform infrared spectra (FT-IR), Auger electron spectroscopy (AES), and electrochemical analysis. These results indicated that there was a chemical interaction on the interface of PANI and TiO₂. This interaction may be of significance to promote the migration efficiency of carriers and induce a synergetic effect to enhance the PC and PEC activities.     

Preparation and properties of amorphous titania-coated zinc oxide nanoparticles

Amorphous TiO₂-coated ZnO nanoparticles were prepared by the solvothermal synthesis of ZnO nanoparticles in ethanol and the followed by sol-gel coating of TiO₂ nanolayer. The analyses of X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the resultant ZnO nanoparticles were hexagonal with a wurtzite structure and a mean diameter of about 60 nm. Also, after TiO₂ coating, the TEM images clearly indicated the darker ZnO nanoparticles being surrounded by the lighter amorphous TiO₂ layers. The zeta potential analysis revealed the pH dependence of zeta potentials for ZnO nanoparticles shifted completely to that for TiO₂ nanoparticles after TiO₂ coating, confirming the formation of core-shell structure and suggesting the coating of TiO₂ was achieved via the adhesion of the hydrolyzed species Ti-O⁻ to the positively charged surface of ZnO nanoparticles. Furthermore, the analyses of Fourier transform infrared (FTIR) and Raman spectra were also conducted to confirm that amorphous TiO₂ were indeed coated on the surface of ZnO nanoparticles. In addition, the analyses of ultraviolet-visible (UV-VIS) and photoluminescence (PL) spectra revealed that the absorbance of amorphous TiO₂-coated ZnO nanoparticles at 375 nm gradually decreased with an increase in the Ti/Zn molar ratio and the time for TiO₂ coating, and the emission intensity of ZnO cores could be significantly enhanced by the amorphous TiO₂ shell.     

Nanosized TiO<Subscript>2</Subscript> particles decorated on SiO<Subscript>2</Subscript> spheres (TiO<Subscript>2</Subscript>/SiO<Subscript>2</Subscript>): synthesis and photocatalytic activities

Nanosized TiO₂ and nano-anatase TiO₂ decorated on SiO₂ spherical core shells were synthesized by using a sol–gel method. The synthesized pure TiO₂ nano particle and TiO₂ grafted on SiO₂ sphere with various ratios have been characterized for their structure and morphologies by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrophotometry (FTIR) and transmission electron microscopy (TEM). Their surface areas were measured using the BET method. The photocatalytic activity of all nanocomposites was investigated using methylene blue as a model pollutant. The synthesized TiO₂/SiO₂ particles appeared to be more efficient in the degradation of methylene blue pollutant, as compared to pure TiO₂ particles.