TiO2纳米管双室光电化学池光催化制氢的研究

以阳极氧化法在纯钛表面制备了高度有序的TiO₂纳米管阵列,并通过SEM观察其表面形貌。采用双室光电化学池制氢体系,利用太阳光照TiO₂产生的光电压与双室电解液pH差产生的化学偏压的协同效应,不施加外加电压,可直接在阴极室还原制取氢气。通过在碱性电解液中添加乙二醇为电子给体,将光解水制氢与有机物的降解耦合为一体,提高太阳能的利用率,同时考察了阳极室电解液中添加不同含量乙二醇对TiO₂纳米管光阳级的光电化学性能及产氢量的影响。实验结果表明,乙二醇的添加降低了光生电子-空穴对的复合几率,使TiO₂纳米管的光电流、光电压、产氢量得到显著提高。当添加乙二醇的浓度为10vol%时光电流达到13.7mA·cm^-2,无外加电压条件下,双室光电化学池中的产氢速率最高达到3.8μmol·min^-1·cm^-2。     

甘油-DMSO-H2O中阳极氧化TiO2纳米管阵列的生长与性能

采用NH4F-甘油-DMSO(二甲基亚砜)-H2O溶液体系的电化学阳极氧化法, 在金属钛基板上形成厚度为0.4-1.5 μm的有序TiO2纳米管阵列薄膜. 利用场发射电子扫描显微镜(FESEM)技术, 研究了电解液的组成及阳极氧化电压对TiO2纳米管阵列生长形貌的影响. 结果表明, 阳极氧化电压可以影响TiO2纳米管的径向尺寸和长度；通过改变电解液中DMSO/H2O的体积比, 能够调控纳米管的生成速率与形貌. 利用X射线衍射(XRD)对经过不同温度热处理的TiO2纳米管阵列薄膜的物相进行了分析. TiO2纳米管阵列薄膜的光电催化分解水过程的电压-电流特性测量显示, 光电流密度大于0.2 mA·cm-2.     

电化学阻抗谱法研究铈改性TiO2纳米管阵列光电极裂解水产氢动力学

通过阳极氧化法在纯钛板上制备TiO2纳米管阵列电极.在光电化学电解池阳极中加入供电子物质乙二醇,显著减小了TiO2纳米管的电荷传递阻抗,促进了光电催化裂解水产氢反应.采用阴极电沉积和阳极氧化法制备了单质铈和氧化铈共同改性的TiO2纳米管阵列半导体光阳极,其平带电位向电负方向移动.采用电化学阻抗谱法(EIS)对改性后TiO2纳米管阵列在光电催化裂解水产氢中的电子传输性能以及界面性质进行了表征,确定了各阻抗弧对应的电极过程.采用合理的等效电路模型计算了电极的电子传输动力学参数.结果表明,经铈改性后的TiO2纳米管阵列膜电阻明显减小,有利于氢气的产生.探讨了单质铈与氧化铈促进TiO2纳米管阵列电荷传输的作用机理.     

钛基TiO2纳米管阵列电极的光电催化性能

应用电化学阳极氧化法在纯Ti基底上制备高度有序的TiO2纳米管阵列,考察了Ti/TiO2光阳极的光电化学响应.以苯酚溶液为目标污染物,研究Ti/TiO2电极的光电催化性能,并与光催化性能进行比较.结果表明,该电极光电催化性能优于光催化性能.施加0.6 V电压时,光电催化性能最好.电化学阻抗谱分析显示,光电催化和光催化降解过程的速控步骤均为表面反应步骤,外加偏压减小了界面电荷转移阻抗,提高了光生载流子的分离效率.     

MoS_2非贵金属电催化剂担载对p-InP光阴极分解水性能的影响

将MoS2电催化剂担载在InP光阴极表面,提升了InP光阴极光电化学分解水产氢性能,确定了最优的MoS2电催化剂担载电量为15 mC·cm-2;在担载前后,开启电势由-100 mV移动至120 mV;在-0.35 V vs RHE时,电流密度由15 mA·cm-2提升至43 mA·cm-2。另外,通过改变入射光强和加入电子牺牲剂的方法进一步研究了MoS2担载InP光阴极产氢反应的限制步骤为光生电子与空穴在InP表面的复合。     

阳极氧化法制备二氧化钛纳米管阵列的研究

采用电化学阳极氧化法,将纯钛浸入HF酸水溶液,在钛基体表面原位构建高度有序的二氧化钛纳米管阵列,探讨阳极氧化电压、电解液浓度和电解液温度等对二氧化钛纳米管阵列尺寸和形貌的影响。通过SEM、XRD对二氧化钛纳米管阵列的结构特征进行表征,结果表明,不同的阳极氧化电压、电解液浓度和温度都将影响TiO2纳米管阵列的尺寸和形貌,在阳极氧化电压为20V,HF电解液浓度为0.5%t条件下,可制备出结构规整有序的TiO2纳米管阵列。     

TiO_2纳米管阵列光电催化制氢研究进展

以TiO2纳米管阵列为光阳极组成的光电解池光电催化分解水是目前光催化制氢领域内研究最广泛的体系之一。本文综述了近年来TiO2纳米管阵列在光电催化分解水制氢领域的最新研究进展,重点阐述了提高TiO2纳米管阵列光电转换效率和产氢速率的方法,指出了目前存在的问题,并对今后的发展提出了展望。     

光电化学水氧化用多孔单晶金红石TiO_2纳米棒阵列光阳极的设计和构建（英文）

光电化学电池(如染料敏化太阳能电池、量子点敏化太阳能电池以及光电化学水分解电池)是实现太阳能转化及存储的有效手段之一.其中,光电极是光电化学电池的核心组成部分,它集光吸收、光生电荷输运及转移等决定光转化效率的关键过程于一身,因此构筑高活性半导体光电极以实现高效太阳能转化利用引起研究者广泛关注.多孔Ti O2纳米颗粒堆垛薄膜光阳极因具有大的比表面积,可提供更多的染料(量子点)担载和反应活性位点,在光电化学电池中表现出优异活性而被广泛研究.然而,TiO 2纳米颗粒间大量存在的晶界对光生电荷有较强的散射作用,降低了光生电荷的收集效率.英国牛津大学Snaith研究小组利用模板辅助水热过程首次获得了(001)晶面占优的多孔单晶锐钛矿Ti O2微米颗粒,这种多孔单晶Ti O2微米颗粒在具有大比表面积的同时,其单晶结构还能有效去除晶界对电荷的散射作用,因而具有优异的电荷输运特性.利用这种多孔单晶Ti O2微米颗粒组建的光阳极用于染料敏化太阳能电池中,展现出优异的太阳能光电转化性能.受该工作启发,各种形貌的多孔单晶Ti O2微米颗粒作为光催化剂和光电化学分解水用光阳极材料被广泛研究,并表现出优异活性.在单晶微米颗粒堆垛成的薄膜光电极中,虽然单个单晶微米颗粒中晶界对电荷的散射作用被有效抑制,但是单晶颗粒间的晶界仍然存在并影响光生电荷的收集效率.为了彻底抑制晶界对光生电荷的散射作用,每个单晶颗粒都应该贯穿整个薄膜,例如一维Ti O2纳米棒单晶阵列薄膜.虽然一维单晶阵列薄膜能够有效提高光生电荷的收集效率,但相对于多孔薄膜具有较小的比表面积,限制了担载染料(量子点)和反应位点的数量.为了增大TiO 2单晶纳米棒阵列薄膜的比表面积,目前主要的手段包括调控纳米棒长径比、表面修饰Ti O2纳米颗粒以及二次生长构建Ti O2枝晶阵列.本文首次提出通过制备多孔单晶Ti O2纳米棒单晶阵列薄膜来获得高比表面积和高光生电荷收集效率的光阳极,提高光电化学电池的效率.在透明导电薄膜(FTO)表面利用水热生长Ti O2纳米棒阵列薄膜之前,预先在FTO基体上沉积一层Si O2球密堆模板,Ti O2纳米棒单晶阵列在从FTO表面向上生长过程中,会将SiO 2球模板包裹进Ti O2纳米棒中,再通过碱溶液将Si O2球模板溶解,首次在FTO基体上原位生长出多孔单晶Ti O2纳米棒阵列薄膜.将所得多孔单晶金红石Ti O2纳米棒阵列薄膜作为光电化学分解水电池光阳极,其光电化学分解水活性相对于实心单晶金红石Ti O2纳米棒阵列提高了2.6倍.多孔单晶金红石Ti O2纳米棒阵列光阳极性能的提升可归因于:(1)多孔结构赋予多孔单晶金红石Ti O2纳米棒阵列薄膜更大的比表面积,可提供更多的反应活性位点;(2)多孔结构能够有效缩短单晶金红石Ti O2纳米棒中光生电荷体相输运距离,提高光生电荷的收集效率;(3)多孔结构通过对光多次反射吸收可有效增强光吸收,产生更多光生电荷参与水分解反应;(4)在制备过程中引入Si掺杂,导致多孔单晶金红石Ti O2纳米棒带隙扩大了0.1 e V,带隙增大归因于导带位置负移0.1 e V,光生电子具有更强的还原能力,光电流起始电位相应负移约0.1 V.     

氧化钛纳米管阵列制备及形成机理

采用电化学阳极氧化法在HF水溶液体系使纯钛表面形成一层结构规整有序的高密度TiO2纳米管阵列,考察了几种主要的实验参数（阳极氧化电压、温度、时间、电解液浓度）对TiO2纳米管阵列形貌和尺寸的影响.结果表明,阳极氧化电压是影响氧化钛形貌和纳米管尺寸的最主要因素,而温度和电解液浓度只影响TiO2纳米管阵列形成的时间.对TiO2纳米管阵列进行X射线衍射（XRD）和扫描电子显微镜（SEM）的分析,初步表征了TiO2纳米管阵列的电学性质.并讨论了TiO2纳米管的形成机理.     

基于阳极甘油氧化电催化的碱/酸混合电解制氢研究（英文）

耦合可再生电能的电解水制氢是一项极具前景的绿氢技术,该技术仍受限于阳极析氧反应(OER)动力学慢、过电位高等问题的限制。在阳极端采用热力学更容易的电氧化反应代替OER,可大幅降低电耗并且在阳极端获得增值产物,是电解制氢的一种新策略。甘油作为生物柴油生产的主要副产品且产能过剩,其电催化氧化(GOR)理论电位比OER低。基于此,本研究工作报道了一种耦合酸性析氢反应(HER)与碱性GOR的混合酸/碱双电解液的制氢电解器,其以泡沫镍(NF)支撑Co₃O₄纳米片(NS)电极(Co₃O₄·NSs/NF)为阳极,商用碳载铂修饰碳布电极为阴极。在阳极端,Co₃O₄·NSs/NF对GOR电催化表现出较低的过电位和转化为甲酸盐的高选择性。在该混合酸/碱双电解液电解槽中,仅仅需要额外施加0.55 V的外加电压,即可达到10 mA·cm^-2的产氢电解电流密度,并可以在阳极将甘油高选择性地转化为甲酸盐,其中产氢的法拉第效率接近100%。本研究工作为电解制氢提供...     

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.     

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.     

The crystal chemistry of Bi6TP2O15+x, T=Fe, Ni, Zn: Isomorphism and polymorphism, structural relationship to Bi6TiP2O16

The crystal structures of compounds with nominal compositions Bi₆FeP₂O_15+x (I), Bi₆NiP₂O_15+x (II) and Bi₆ZnP₂O_15+x (III) were determined from single-crystal X-ray diffraction data. They are monoclinic, space group I2, Z=2. The lattice parameters for (I) are a=11.2644(7), b=5.4380(3), c=11.1440(5) Å, β=96.154(4)°; for (II) a=11.259(7), b=5.461(4), c=11.109(7) Å, β=96.65(1)°; for (III) a=19.7271(5), b=5.4376(2), c=16.9730(6) Å, β=131.932(1)°. Least squares refinements on F² converged for (I) to R1=0.0554, wR₂=0.1408; for (II) R₁=0.0647, wR₂=0.1697; for (III) R₁=0.0385, wR₂=0.1023. The crystals are complexly twinned by 2-fold rotation about , by inversion and by mirror reflection. The structures consist of edge-sharing articulations of OBi₄ tetrahedra forming layers in the a-c plane that then continue by edge-sharing parallel to the b-axis. The three-dimensional networks are bridged by Fe and Ni octahedra in (I) and (II) and by Zn trigonal bipyramids in (III) as well as by oxygen atoms of the PO₄ moieties. Bi also randomly occupies the octahedral sites. Oxygen vacancies exist in the structures of the three compounds due to required charge balances and they occur in the octahedral coordination polyhedron of the transition metal. In compound (III), no positional disorder in atomic sites is present. The Bi-O coordination polyhedra are trigonal prisms with one, two or three faces capped. Magnetic susceptibility data for compound (I) were obtained between 4.2 and 350 K. Between 4.2 and 250 K it is paramagnetic, μ_eff=6.1 μ_B; a magnetic transition occurs above 250 K.     

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。     

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.     

B2O3-Bi2O3-ZnO-Al2O3玻璃助烧剂对BaTiO3陶瓷烧结条件、晶体结构和介电性能的影响

通过调节B₂O₃-Bi₂O₃-ZnO-Al₂O₃(BBZA)玻璃的添加量研究其对钛酸钡(BaTiO₃)陶瓷烧结条件、晶体结构和介电性能的影响。结果表明：添加适量的BBZA玻璃能够有效地将BaTiO₃陶瓷烧结温度由1 350℃降至950℃,并使其致密化。同时,添加BBZA玻璃后,BaTiO₃的晶体结构随着烧结温度的升高而发生转变(立方相→四方相)。另外,BBZA玻璃的引入使BaTiO₃陶瓷的居里峰得到了有效的抑制和拓宽。陶瓷微观形貌显示,玻璃相均匀分布在BaTiO₃晶粒表面。优化的BaTiO₃陶瓷制备条件如下：BBZA添加量(质量分数)为2.0%,烧结温度为950℃。在该条件下制备的BaTiO₃陶瓷介电常数达到1 364,介电损耗低至1.2%。     

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.     

Microstructures of Some Bi-W-Nb-O Phases

Microstructures of three Bi-W-Nb-O phases have been examined by using high-resolution transmission electron microscopy. Bi₁₇W₂Nb₃O₃₉ and Bi₁₇WNb₃O₃₆ have incommensurate superstructures derived from the defect fluorite-type δ-Bi₂O₃ and can be regarded as intermediate phases between the type II solid solutions in the Bi-Nb-O and Bi-W-O systems. Bi₈W₂Nb₂O₂₃ has a Bi₂WO₆-like subunit cell with a stepped superstructure. Formation mechanisms of various superstructures are discussed.