纳米结构TiO2/聚3-甲基噻吩多孔膜电极光电化学研究

用光电流作用谱、光电流-电势图、紫外-可见吸收光谱等光电化学方法研究了导电玻璃(ITO)/TiO₂/聚3-甲基噻吩(PMT)电极的光电转换性质. 结果表明, PMT膜为p型半导体, 其禁带宽度为1.93 eV. 并通过循环伏安和光电化学方法确定了其导带位置为－3.44 eV, 价带为－5.37 eV, 在纳米TiO₂与PMT之间存在p-n异质结, ITO/TiO₂/PMT电极不仅提高了光电流, 而且使产生光电流的起始波长红移至＞600 nm, 从而提高了宽禁带半导体的光电转换效率.     

3-己基噻吩和2-噻吩甲酸共聚物修饰纳米结构TiO2薄膜电极的光电性能研究

用光电流作用谱、光电流-电势图等光电化学方法研究了铟锡导电玻璃(ITO)/3-己基噻吩和2-噻吩甲酸共聚物(CTCHT)膜电极以及ITO/TiO₂/3-己基噻吩和2-噻吩甲酸共聚物(CTCHT)复合膜电极的光电转换性质. 结果表明, CTCHT膜为p-型半导体, 禁带宽度为2.44 eV, 价带位置为－5.73 eV. 研究表明在ITO/TiO₂/CTCHT复合膜电极中存在p-n异质结, p-n异质结的存在能够使光生电子和空穴有效的分离, 有效地降低了电荷的反向复合几率, 提高了光电转换效率, CTCHT膜修饰ITO/TiO₂电极可使光电流增强, 使宽禁带半导体电极的光电转换效率得到改善.     

3-己基噻吩和2-噻吩甲酸共聚物修饰纳米结构TiO2薄膜电极的光电性能研究

用光电流作用谱、光电流-电势图等光电化学方法研究了铟锡导电玻璃(ITO)/3-己基噻吩和2-噻吩甲酸共聚物(CTCHT)膜电极以及ITO/TiO₂/3-己基噻吩和2-噻吩甲酸共聚物(CTCHT)复合膜电极的光电转换性质. 结果表明, CTCHT膜为p-型半导体, 禁带宽度为2.44 eV, 价带位置为－5.73 eV. 研究表明在ITO/TiO₂/CTCHT复合膜电极中存在p-n异质结, p-n异质结的存在能够使光生电子和空穴有效的分离, 有效地降低了电荷的反向复合几率, 提高了光电转换效率, CTCHT膜修饰ITO/TiO₂电极可使光电流增强, 使宽禁带半导体电极的光电转换效率得到改善.     

纳米结构TiO2/聚3-甲基噻吩多孔膜电极光电化学研究

用光电流作用谱、光电流-电势图、紫外-可见吸收光谱等光电化学方法研究了导电玻璃(ITO)/TiO₂/聚3-甲基噻吩(PMT)电极的光电转换性质. 结果表明, PMT膜为p型半导体, 其禁带宽度为1.93 eV. 并通过循环伏安和光电化学方法确定了其导带位置为－3.44 eV, 价带为－5.37 eV, 在纳米TiO₂与PMT之间存在p-n异质结, ITO/TiO₂/PMT电极不仅提高了光电流, 而且使产生光电流的起始波长红移至＞600 nm, 从而提高了宽禁带半导体的光电转换效率.     

聚3-甲基噻吩修饰硫化物量子点连接纳米结构TiO2膜的光电化学研究

采用原位化学法在纳米结构TiO₂膜上制备了量子点CdS, PbS (Q-CdS, Q-PbS), 并用电化学方法在TiO₂/Q-CdS, TiO₂/Q-PbS表面聚合3-甲基噻吩[poly(3-Methylthiophene, PMeT)]. 用光电化学方法研究了PMeT修饰Q-CdS, Q-PbS连接TiO₂纳米结构膜, 实验结果表明, PMeT和Q-CdS, Q-PbS单独修饰纳米结构TiO₂电极和PMeT修饰Q-CdS, Q-PbS连接纳米结构TiO₂电极的光电流产生的起始波长都向长波方向移动; 一定条件下在可见光区光电转换效率均较纳米结构TiO₂的光电转换效率有明显的提高; 聚3-甲基噻吩(PMeT)与Q-CdS, Q-PbS连接的纳米结构TiO₂之间存在p-n异质结. 在一定条件下p-n异质结的存在有利于光生电子/空穴的分离, 在本文实验条件下PMeT修饰Q-CdS, Q-PbS连接纳米结构TiO₂电极最高的单色光的光电转换效率分别为11%和7%.     

TiO2纳米棒和CdSe纳米棒复合膜与聚3-甲基噻吩杂化太阳能电池研究

采用水热法制备了TiO₂和CdSe两种纳米棒材料, 将两种纳米材料制备成TiO₂/CdSe复合纳米棒膜电极, 并在复合膜上电化学聚合生成聚3-甲基噻吩poly(3-methylthiophene) (PMeT), 研究了其光电化学性能. 实验表明, 当TiO₂与CdSe的物质的量复合比为2∶1, PMeT的聚合时间为40 s, 在电极电势为－0.2 V下ITO/TiO₂/CdSe/PMeT电极光电转换效率(IPCE)达到56%, 对比ITO/TiO₂/CdSe复合膜电极在长波方向的光电转换效率明显提高, 光吸收截止波长发生了明显的红移. 同时以ITO/TiO₂/CdSe/PMeT组装了简易的杂化太阳电池, 初步研究了光电池性能, 光电池总效率为0.08%, V_oc＝0.4 V, j_sc＝0.61 mA/cm², ff＝0.33.     

Bi2S3量子点敏化TiO2纳米阵列结构的制备及光电性能

利用水热法制备一维TiO₂纳米棒阵列,并采用化学浴沉积法(CBD)结合自组装技术在TiO₂纳米棒上敏化Bi₂S₃量子点,形成TiO₂/Bi₂S₃复合纳米棒阵列。系统研究了复合结构的表面形貌、晶体结构、光学及光电性能。结果表明:在修饰有三氨丙基三乙氧基硅烷自组装单分子膜(APTS-SAMs)的TiO₂纳米棒表面形成一层致密的Bi₂S₃量子点敏化层,这一技术的关键是含-NH₂末端的APTS-SAMs可有效促进Bi₂S₃的异相成核作用;Bi₂S₃的沉积时间对复合结构的光吸收及光电响应性能有决定性的影响,薄膜的光电流随着沉积时间呈先增加后减小的趋势,在沉积时间为20min时,光电流密度最大。这是因为随着沉积时间的增加,TiO₂纳米棒表面Bi₂S₃量子点密度增大,光吸收增加;而当沉积时间进一步延长时,Bi₂S₃在TiO₂纳米棒表面的大量负载而形成堆积和团聚,导致表面缺陷增多,光生电子复合几率增大,从而使光电流密度减小。     

Bi2S3量子点敏化TiO2纳米阵列结构的制备及光电性能研究

利用水热法制备一维TiO₂纳米棒阵列,并采用化学浴沉积法(CBD)结合自组装技术在TiO₂纳米棒上敏化Bi₂S₃量子点,形成TiO₂/Bi₂S₃复合纳米棒阵列.系统研究了复合结构的表面形貌、晶体结构、光学及光电性能.结果表明:在修饰有三氨丙基三乙氧基硅烷自组装单分子膜(APTS-SAMs)的TiO₂纳米棒表面形成一层致密的Bi₂S₃量子点敏化层,这一技术的关键是含-NH₂末端的APTS-SAMs可有效促进Bi₂S₃的异相成核作用;Bi₂S₃的沉积时间对复合结构的光吸收及光电响应性能有决定性的影响,薄膜的光电流随着沉积时间呈先增加后减小的趋势,在沉积时间为20 min时,光电流密度最大.这是因为随着沉积时间的增加,TiO₂纳米棒表面Bi₂S₃量子点密度增大,光吸收增加;而当沉积时间进一步延长时,Bi₂S₃在TiO₂纳米棒表面的大量负载而形成堆积和团聚,导致表面缺陷增多,光生电子复合几率增大,从而使光电流密度减小.     

染料敏化太阳能电池中大孔TiO2薄膜电极的制备及应用

采用溶胶-凝胶水热法制备了TiO₂纳晶薄膜电极，晶型为锐钛矿型。为了提高电极的光电性能，利用聚苯乙烯小球做造孔剂，制备了含有大孔隙的TiO₂纳晶薄膜电极，孔径约为200 nm，该电极具有较好的光漫反射性能，更重要的是球形大孔的存在，提高了凝胶电解质在TiO₂薄膜电极中的渗透和I₃^-离子的扩散性能，与不含大孔的TiO₂电极相比，电池的短路光电流提高约2 mA·cm^-2，光电转换效率提高0.6%。     

纳米结构TiO2/3-甲基噻吩和2-噻吩甲酸共聚物复合膜电极光电化学性能

用光电流作用谱、光电流-电势图等光电化学方法研究了ITO/3-甲基噻吩和2-噻吩甲酸共聚物(CTCMT)膜电极和ITO/TiO₂/CTCMT复合膜电极的光电转换性质.结果表明,CTCMT膜为p型半导体,禁带宽度为2.36eV,价带位置为-5.52eV.在ITO/TiO₂/CTCMT复合膜电极中存在p-n异质结,在一定条件下异质结的存在有利于光生电子-空穴对的分离.CTCMT膜修饰ITO/TiO₂电极可使光电流增强,光电流起始波长红移至600nm以上,使宽禁带半导体电极的光电转换效率得到改善.     

Li_(1.3)Ti_(1.7)Al_(0.3)(PO_4)_3,Na_(1.3)Ti_(1.7)Al_(0.3)(PO_4)_3的离子交换研究

研究了在不同温度下的NaNO3和AgNO3水溶液中Li1.3Ti1.7Al0.3(PO4)3和Na1.3Ti1.7Al0.3(PO4)3离子交换行为.实验表明Li1.3Ti1.7Al0.3(PO4)3和Na1.3Ti1.7Al0.3(PO4)3均显示出了高选择性与Na+和Ag+进行离子交换的特征,且对Ag+的选择性高于Na+.升高温度可显著提高Ag/Li和Ag/Na的交换反应速度.     

Crystal growth, structure determination, and optical properties of new potassium-rare-earth silicates K3RESi2O7 (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu)

Single crystals of K₃RESi₂O₇ (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were grown from a potassium fluoride flux. Two different structure types were found for this series. Silicates containing the larger rare earths, RE=Gd, Tb, Dy, Ho, Er, Tm, Yb crystallize in a structure K₃RESi₂O₇ that contains the rare-earth cation in both a slightly distorted octahedral and an ideal trigonal prismatic coordination environment, while in K₃LuSi₂O₇, containing the smallest of the rare earths, lutetium is found solely in an octahedral coordination environment. The structure of K₃LuSi₂O₇ crystallizes in space group P6₃/mmc with a=5.71160(10) Å and c=13.8883(6) Å. The structures containing the remaining rare earths crystallize in the space group P6₃/mcm with the lattice parameters of a=9.9359(2) Å, c=14.4295(4) Å, (K₃GdSi₂O₇); a=9.88730(10) Å, c=14.3856(3) Å, (K₃TbSi₂O₇); a=9.8673(2) Å, c=14.3572(4) Å, (K₃DySi₂O₇); a=9.8408(3) Å, c=14.3206(6) Å, (K₃HoSi₂O₇); a=9.82120(10) Å, c=14.2986(2) Å, (K₃ErSi₂O₇); a=9.80200(10) Å, c=14.2863(4) Å, (K₃TmSi₂O₇); a=9.78190(10) Å, c=14.2401(3) Å, (K₃YbSi₂O₇). The optical properties of the silicates were investigated and K₃TbSi₂O₇ was found to fluoresce in the visible.     

Influence of support acidity on electronic state of platinum in oxide systems promoted by SO4 2− anions

The electronic state of platinum supported on SO₄/ZrO₂, SO₄/TiO₂, SO₄/Al₂O₃, and SO₄/SiO₂ systems and on systems unpromoted by sulfur was investigated by diffuse-reflectance IR spectroscopy using CO as the probe molecule. The introduction of SO₄ ²⁻ anions increases the electron deficit on platinum particles. This suppresses the formation of bridging CO complexes with the metal, leads to the high-frequency shift of absorption maxima of CO adsorbed in the linear form, and stabilizes positively charged metal species (Pt^δ+ and Pt⁺) during the reduction process. The formation of the positively charged species includes the interaction between the acidic protons and the metal particles yielding [Pt−H]^δ+ adducts. The extent of the influence of the support on the electronic state of the metal increases in the series SO₄/SiO₂<SO₄/Al₂O₃<SO₄/TiO₂<SO₄/ZrO₂ in parallel with an increase in the strength of the acid sites in the system. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1094–1099, June, 1998.     

Near infrared study of aqueous rare-earth ethylsulfates

The near infrared spectra of aqueous solutions of the ethylsulfates of La, Nd, Gd, Tb, Er, Yb, Lu, Y, and Na have been determined from about 0.2 mol-dm^–3 to nearly saturation. The extinction coefficients of water have been calculated taking into account the absorption of ethylslfate anions determined in separate experiments. Their values appeared to be nearly the same as that of pure water. The relative contents of free OH groups in 0.5 and 0.7M solutions have been estimated from the absorbances at 1160 nm. They were lower in solutions of the heavy rare-earth ethylsulfates (Tb, Er, Yb, Lu) than in equimolar solutions of the lighter ones (La, Nd), confirming our previous view that secondary hydration of the heavy trivalent rare-earth cations is distinctly stronger than that of the lighter ones. A comparison of the spectra of these aqueous ethylsulfates with those of perchlorates shows that the structure-breaking ability of the C₂H₅SO ₄ ^– ion is much smaller than that of perchlorate anion.     

Structural studies of five layer Aurivillius oxides: A2Bi4Ti5O18 (A=Ca, Sr, Ba and Pb)

The room temperature structures of the five layer Aurivillius phases A₂Bi₄Ti₅O₁₈ (A=Ca, Sr, Ba and Pb) have been refined from powder neutron diffraction data using the Rietveld method. The structures consist of [Bi₂O₂]²⁺ layers interleaved with perovskite-like [A₂Bi₂Ti₅O₁₆]²⁻ blocks. The structures were refined in the orthorhombic space group B2eb (SG. No. 41), Z=4, and the unit cell parameters of the oxides are a=5.4251(2), b=5.4034(1), c=48.486(1); a=5.4650(2), b=5.4625(3), c=48.852(1); a=5.4988(3), b=5.4980(4), c=50.352(1); a=5.4701(2), b=5.4577(2), c=49.643(1) for A=Ca, Sr, Ba and Pb, respectively. The structural features of the compounds were found similar to n=2-4 layers bismuth oxides. The strain caused by mismatch of cell parameter requirements for the [Bi₂O₂]²⁺ layers and perovskite-like [A₂Bi₂Ti₅O₁₆]²⁻ blocks were relieved by tilting of the TiO₆ octahedra. Variable temperature synchrotron X-ray studies for Ca and Pb compounds showed that the orthorhombic structure persisted up to 675 and 475 K, respectively. Raman spectra of the compounds are also presented.     

电感耦合等离子体光谱法(ICP-AES)测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量

针对银精矿样品复杂,难消解的特点,研究了不同酸溶法和碱熔法对样品的消解情况,建立了硝酸,盐酸,氢氟酸,高氯酸消解银精矿的方法。根据元素灵敏度和抗干扰性,选定各元素的测定波长。通过酸溶样和碱熔样测定结果比对,验证了方法准确性。建立了四酸消解-电感耦合等离子体光谱法测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的方法,元素的线性相关系数均在0.9999以上。通过共存元素干扰实验,确定了银精矿中高含量元素(铜、铅、锌、铁、锑、铋等)对测定元素结果没有影响。方法检出限：Cu 0.0063 mg/L, Pb 0.0159 mg/L ,Zn 0.0090 mg/L,As 0.0192 mg/L, Cd 0.0093 mg/L ,Ca 0.0084 mg/L, Mg 0.0075 mg/L, Mn 0.0081 mg/L。测定下限：Cu 0.0105mg/L,Pb 0.0265 mg/L, Zn 0.0150 mg/L, As 0.0320 mg/L, Cd 0.0155 mg/L, Ca 0.0140 mg/L, Mg 0.0125 mg/L,Mn 0.0135 mg/L。3个样品的相对标准偏差在0.87%~3.56%之间,加标回收率在95.00%~103.56%之间。方法流程短,操作简单,快速,灵敏度和再现性高,结果准确可靠,可以满足银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的测定。     

Preparation of ZrO2-TiO2-CeO2 and Its Application in the Selective Catalytic Reduction of NO with NH3

TiO₂,ZrO₂-TiO₂,andZrO₂-TiO₂-CeO₂ were prepared by co-precipitation method and characterized by X-ray diffraction (XRD), specific surface area measurements (BET), temperature programmed desorption (NH₃-TPD), oxygen storage capacity (OSC), and temperature programmed reduction (H₂-TPR). The results showed that ZrO₂-TiO₂-CeO₂ exhibited large number of surface strong acid, possessed some oxygen storage capacity, and strong redox property. The three materials were used as supports and the monolith catalysts were prepared with 1% (w) V₂O₅ and 9% (w)WO₃ for selective catalytic reduction (SCR) of NO with ammonia in the presence of excessive O₂, and the results of catalytic activity showed that the catalyst used ZrO₂-TiO₂-CeO₂ as support yielded nearly 100% NO conversion at 275 °C at a gas hourly space velocity (GHSV) of 10000 h⁻¹, and it had the best catalytic activity and showed great potential for practical application.     

The Phase Relations in the System In2O3–TiO2–MgO at 1100 and 1350°C

The phase relations in the system In₂O₃–TiO₂–MgO at 1100 and 1350°C are determined by a classical quenching method. In this system, there are four pseudobinary compounds, In₂TiO₅, MgTi₂O₅ (pseudobrookite type), MgTiO₃ (ilmenite type), and Mg₂TiO₄ (spinel type) at 1100°C. At 1350°C, in addition to these compounds there exist a spinel-type solid solution Mg_2−xIn_2xTi_1−xO₄ (0≤x≤1) and a compound In₆Ti₆MgO₂₂ with lattice constants a=5.9236(7) Å, b=3.3862(4) Å, c=6.3609(7) Å, β=108.15(1)°, and q=0.369, which is isostructural with the monoclinic In₃Ti₂FeO₁₀ in the system In₂O₃–TiO₂–MgO. The relation between the lattice constants of the spinel phase and the composition nearly satisfies Vegard's law. In₆Ti₆MgO₂₂ extends a solid solution range to In₂₀Ti₁₇Mg₃O₆₇ with lattice constants of a=5.9230(5) Å, b=3.3823(3) Å, c=6.3698(6) Å, β=108.10(5)°, and q=0.360. The distributions of constituent cations in the solid solutions are discussed in terms of their ionic radius and site preference effect.     

Structure Study of Bi2.5Na0.5Ta2O9 and Bi2.5Nam−1.5NbmO3m+3 (m=2-4) by Neutron Powder Diffraction and Electron Microscopy

The crystal structures of Bi_2.5Na_0.5Ta₂O₉ and Bi_2.5Na_m-1.5Nb_mO_3m+3 (m=3,4) have been investigated by the Rietveld analysis of their neutron powder diffraction patterns (λ=1.470 Å). These compounds belong to the Aurivillius phase family and are built up by (Bi₂O₂)²⁺ fluorite layers and (A_m-1B_mO_3m+1)^2- (m=2-4) pseudo-perovskite slabs. Bi_2.5Na_0.5Ta₂O₉ (m=2) and Bi_2.5Na_2.5Nb₄O₁₅ (m=4) crystallize in the orthorhombic space group A2₁am, Z=4, with lattice constants of a=5.4763(4), b=5.4478(4), c=24.9710 (15) and a=5.5095(5), b=5.4783(5), c=40.553(3) Å, respectively. Bi_2.5Na_1.5Nb₃O₁₂ (m=3) has been refined in the orthorhombic space group B2cb, Z=4, with the unit-cell parameters a=5.5024(7), b=5.4622(7), and c=32.735(4) Å. In comparison with its isostructural Nb analogue, the structure of Bi_2.5Na_0.5Ta₂O₉ is less distorted and bond valence sum calculations indicate that the Ta-O bonds are somewhat stronger than the Nb-O bonds. The cell parameters a and b increase with increasing m for the compounds Bi_2.5Na_m-1.5Nb_mO_3m+3 (m=2-4), causing a greater strain in the structure. Electron microscopy studies verify that the intergrowth of mixed perovskite layers, caused by stacking faults, also increases with increasing m.     

Sol-gel synthesis of K3InF6 and structural characterization of K2InC10O10H6F9, K3InC12O14H4F18 and K3InC12O12F18

K₃InF₆ is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K₂InC₁₀O₁₀H₆F₉, K₃InC₁₂O₁₄H₄F₁₈ and K₃InC₁₂O₁₂F₁₈. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. The two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K₃InF₆ by decomposition at high temperature. The crystal structure of K₃InC₁₂O₁₄H₄F₁₈ is characterized by complex anions [In(CF₃COO)₄(OH_x)₂]^(5−2x)− and isolated [CF₃COOH_2−x]^(x−1)− molecules with x=2 or 1, surrounded by K⁺ cations. The crystal structure of K₃InC₁₂O₁₂F₁₈ is only constituted by complex anions [In(CF₃COO)₆]³⁻ and K⁺ cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K₂InC₁₀O₁₀H₆F₉ and K₃InC₁₂O₁₂F₁₈ were also performed at room temperature on pulverized crystals.