Nanostructured ZrO2-Coated TiO2 Electrodes for Dye-Sensitised Solar Cells

Thin films of ZrO₂ were deposited on nanostructured anatase TiO₂ electrodes via sol-gel route and utilised in the assembly of a dye-sensitised solar cells (DSSCs) forming nanostructured core-shell networks. The ZrO₂-coated TiO₂ electrodes were characterised by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and constructing a DSSC. The characterisation concluded that core-shell morphologies were produced with varying ZrO₂ shell thickness without altering the anatase TiO₂ core. When a DSSC was constructed from the ZrO₂:TiO₂ core-shell electrode, the efficiency increased to 2.27% from 0.42% for the uncoated TiO₂ electrode. As the ZrO₂ shell thickness increased, the cell efficiency was reduced.     

IrO2基体上阳极电沉积MnO2的电化学行为

采用极化曲线和循环伏安等电化学方法, 对不同温度下IrO₂电极在MnSO₄镀液与硫酸溶液中的电化学行为进行对比研究, 并以镀液中极化曲线上不同电流密度值进行阳极电沉积, 测量镀速大小. 研究结果表明:IrO₂电极在镀液中同时发生阳极电沉积反应和析氧副反应, 阳极电沉积反应对析氧反应具有明显的抑制作用; MnO₂的阳极电沉积过程较复杂, 存在Mn³⁺中间产物, 既有Mn³⁺→Mn⁴⁺的电沉积过程, 也有Mn³⁺的水解及水解产物的脱附的过程, 水解反应的存在严重降低了MnO₂的阳极电沉积的电流效率; MnO₂的阳极电沉积存在一定的电位区间, 在此区间, 镀速存在最大值.     

Facile Preparation and Lithium Storage Properties of TiO2@Graphene Composite Electrodes with Low Carbon Content

Over the past decade, TiO₂/graphene composites as electrodes for lithium ion batteries have attracted a great deal of attention for reasons of safety and environmental friendliness. However, most of the TiO₂/graphene electrodes have large graphene content (9–40 %), which is bound to increase the cost of the battery. Logically, reducing the amount of graphene is a necessary part to achieve a green battery. The synthesis of TiO₂ nanosheets under solvothermal conditions without additives is now demonstrated. Through mechanical mixing TiO₂ nanosheets with different amount of reduced graphene (rGO), a series of TiO₂@graphene composites was prepared with low graphene content (rGO content 1, 2, 3, and 5 wt %). When these composites were evaluated as anodes for lithium ion batteries, it was found that TiO₂+3 wt % rGO manifested excellent cycling stability and a high specific capacity (243.7 mAh g^?1 at 1 C; 1 C=167.5 mA g^?1), and demonstrated superior high‐rate discharge/charge capability at 20 C.     

Electrochemical Performance of Free-Standing and Flexible Graphene and TiO2 Composites with Different Conductive Polymers as Electrodes for Supercapacitors

The advantage of using composite electrode materials for energy storage is, to a large extent, the synergistic role of their components. Our work focuses on the investigation of the interactions of each phase, exploring the patterns found with the change of materials to provide theoretical or experimental foundations for future study. Here, conductive polymers (CPs), including polyaniline (PANi), polypyrrole (PPy), and polythiophene (PTh), as well as reduced graphene oxide (rGO), and TiO₂ with the different crystalline phases of anatase and rutile were applied to form a series of free-standing and flexible binary or ternary composite electrodes. The electrochemical behaviors of these composite electrodes are presented. The results indicate that the synergistic improvement in electrochemical performance is due to the incorporation of the different components. CPs significantly increase the current density of these composite films and contribute their pseudocapacitance to improve the specific capacitance, but lead to a decline in cycle stability. After introducing TiO₂, both the specific capacitance and the cycle-stability of rGO-TiO₂-CP were synergistically improved. A CP can magnify the pseudocapacitance behavior of any of the TiO₂ crystalline phases, and interactions vary with the specific CP and the specific TiO₂ crystalline phase employed. The synergistic effects of the as-prepared composites were theoretically predicted and explored.     

Simple Strategy for Selective Determination of Levamisole in Seized Cocaine and Pharmaceutical Samples Using Disposable Screen‐printed Electrodes

Levamisole is the most common adulterant found in cocaine samples and its electrochemical determination in cocaine seized samples is a challenge due to peak overlapping with cocaine. Herein, we propose a deconvolution procedure for levamisole determination in seized cocaine samples using screen‐printed carbon electrodes (SPE). Square‐wave voltammetry in 0.04 mol L^?1 Britton Robinson buffered solution (pH 8.0) was selected in combination with optimized SWV parameters (f=8 s^?1, a=10 mV and ΔE_s=1 mV) to result in the best peak resolution to apply the deconvolution procedure. Deconvoluted responses of levamisole in the presence of cocaine were similar to untreated signals of standard levamisole solutions in absence of cocaine. A linear response was obtained in the range of 20–100 μmol L^?1 (r=0.995). The results obtained for the analysis of a seized cocaine sample was statistically similar to that obtained by gas chromatography. Other adulterants found in cocaine street samples (paracetamol, glucose, phenacetin, caffeine, boric acid and lidocaine) did not affect the treated of voltammetric responses of levamisole. A pharmaceutical sample containing levamisole was also analyzed on SPEs and a recovery of 93±2 % was obtained (no deconvolution required for this sample), showing great applicability of SPEs for forensic and pharmaceutical analyses.     

Low‐Temperature Synthesis of Honeycomb CuP2@C in Molten ZnCl2 Salt for High‐Performance Lithium Ion Batteries

Phosphorus‐rich metal phosphides have very high lithium storage capacities, but they are difficult to prepare. A low‐temperature phosphorization method based on Mg reducing PCl₃ in ZnCl₂ molten salt at 300 °C is developed to synthesize phosphorus‐rich CuP₂@C from a Cu‐MOF derived Cu@C composite. Abnormal oxidation of Cu by Zn²⁺ in the molten salt is observed, which leads to the porous honeycomb nanostructure and homogeneously distributed ultrafine CuP₂ nanocrystals. The honeycomb CuP₂@C exhibits excellent lithium storage performance with high reversible capacity (1146 mAh g^?1 at 0.2 A g^?1) and superior cycling stability (720 mAh g^?1 after 600 cycles at 1.0 A g^?1), showing the promising application of P‐rich metal phosphides in lithium ion batteries.     

4-叔丁基吡啶对纳米晶TiO2电极的能带结构及光电化学性质的影响

应用光谱电化学方法测定了纳米晶TiO2电极在不同浓度的4-叔丁基吡啶(TBP)电解液中的平带电势(Efb). TBP对纳米晶TiO2电极的能带结构具有显著的影响. 在不含和含有0.2或0.4 mol•L-1TBP的0.2 mol•L-1高氯酸四丁基铵(TBAP)/乙腈溶液中,测得TiO2电极的Efb依次为-2.25,-2.46和-2.60 V. 当加入Li+后,TiO2电极的Efb正移,在不含和含有0.2或0.4 mol•L-1TBP的0.2 mol•L-1 LiClO4/乙腈溶液中,测得TiO2电极的Efb依次为-1.12,-1.22和-1.30 V. 用时间分辨电流方法测定了陷阱态分布. 在不含和含有0.2或0.4 mol•L-1TBP的0.2 mol•L-1 TBAP/乙腈溶液中,TiO2电极的陷阱态密度依次为3.52 × 1016, 3.18 × 1016和3.37 × 1016 cm-2,陷阱态分布的最大值位于-1.99, -1.89和-1.85 V处. Li+的加入进一步减少了陷阱态密度. 在不含和含有0.2或0.4 mol•L-1TBP的0.2 mol•L-1 LiClO4/乙腈溶液中,TiO2电极的陷阱态密度依次为8.39 × 1015, 1.11 × 1016和9.22 × 1015 cm-2,陷阱态分布的最大值位于-0.72, -0.84和-0.95V处. 最后,研究了N3染料敏化的纳米晶TiO2电极在含有不同浓度TBP的电解质溶液中的光电化学性质. 结果显示,随着TBP浓度的增加,Voc增大,使TiO2电极的光电转化效率增加.     

Inclined Substrate Deposition of Nanostructured TiO2 Thin Films for DSSC Application

Nanostructured TiO₂ films were deposited onto Indium Tin Oxide (ITO) and glass substrates by dc reactive magnetron sputtering at different substrate inclination angles. The structural and optical properties of the deposited films were studied by X-ray diffraction, scanning electron microscopy and UV–Vis spectrophotometer, respectively. Dye-sensitized solar cells (DSSC) were assembled using these TiO₂ films as photoelectrodes and the effect of the substrate inclination angle in the preparing process of TiO₂ films on the DSSC conversion efficiency was studied.     

Double‐Side Co‐Catalytic Activation of Anodic TiO2 Nanotube Membranes with Sputter‐Coated Pt for Photocatalytic H2 Generation from Water/Methanol Mixtures

Self‐standing TiO₂ nanotube layers in the form of membranes are fabricated by self‐organizing anodization of Ti metal and a potential shock technique. The membranes are then decorated by sputtering different Pt amounts i) only at the top, ii) only at the bottom or iii) at both top and bottom of the tube layers. The Pt‐decorated membranes are transferred either in tube top‐up or in tube top‐down configuration onto FTO slides and are investigated, after crystallization, as photocatalysts for H₂ generation using either front or back‐side light irradiation. Double‐side Pt‐decoration of the tube membranes leads to higher H₂ generation rates (independently of tube and light‐irradiation configuration) compared to membranes decorated at only one side with similar overall Pt amounts. The results suggest that this effect cannot be only ascribed to the overall amount of Pt co‐catalyst as such but also to its distribution at both tube extremities. This leads to optimized light absorption and electron diffusion/transfer dynamics: the central part of the membranes acts as light‐harvesting zone and electrons therein generated can diffuse towards the Pt/TiO₂ active zones (tube extremities) where they can react with the environment and generate H₂.     

还原氧化石墨烯/金纳米修饰电极在新冠病毒检测中的应用

研究使用电化学沉积法在丝网印刷碳电极表面制备了还原氧化石墨烯和金纳米颗粒,构建了一种用于新冠病毒检测的石墨烯电化学传感器。通过扫描电子显微镜(SEM)和相应的电化学方法对纳米复合材料在电极表面的成功修饰进行了表征分析。并采用差分脉冲伏安法对传感器的性能进行检测,实验构建的电化学传感器具有良好的灵敏度,该传感器检线性范围为10_-10^-10_-6^mol/L,具有良好的重复性和特异性。     

Au-CuO／TiO2催化剂用于CO2中微量H2的脱除

用沉积沉淀法制备了Au-CuO/TiO2催化剂和Au/TiO2催化剂,考察了沉淀温度、沉淀pH、焙烧温度和Cu/Au摩尔比等制备工艺条件对Au-CuO/TiO2催化剂性能的影响,确定了适宜的催化剂制备工艺条件.结果表明,Au-CuO/TiO2催化剂对CO2中微量H2的脱除具有较好的活性和稳定性.还考察了还原和H2S中毒处理先后的顺序对催化剂H2脱除活性的影响.结果表明,Au/TiO2催化剂基本上不受处理顺序的影响,而H2S处理顺序对Au-CuO/TiO2催化剂的性能有较为明显的影响,这说明还原后的Au-CuO/TiO2催化剂形成了Au-Cu合金。     

One-pot hydrothermal synthesis of porous anatase TiO2 nanotube formed bundles for lithium ion battery anodes

Anatase phase of TiO₂ nanomaterial has been deemed a potential anode material for lithium ion battery (LIB) applications because of its remarkable electrochemical properties. However, TiO₂ anodes always suffer from intrinsic poor electrical conductivity and slow ion kinetics, which would restrict their practical usage. To address this issue, efficient control and design of the anatase crystal structure of TiO₂ material with desirable morphology is one of the critical approaches. In this work, a good lithium storage capability of 181 mA hr g⁻¹ at rate of 0.2C, high rate performance of 70 mA hr g⁻¹ at 20C, and excellent cyclability of 117 mA hr g⁻¹ with a capacity retention of 93% at 1C after 100 cycles and 84 mA hr g⁻¹ at 10C after 1,000 cycles are observed in an optimized porous anatase TiO₂ one-dimensional nanotube bundle nanomaterial fabricated through a simple hydrothermal process with post calcination treatment. These excellent electrochemical properties of the product can be ascribed to its anatase crystal phase, 1D nanostructure, and porous framework with a large surface area, which provide it with an efficient electrode/electrolyte contact area and a faster ion/electron diffusion pathway.     

BiVO4‐TiO2 Composite Photocatalysts for Dye Degradation Formed Using the SILAR Method

Composite photocatalyst films have been fabricated by depositing BiVO₄ upon TiO₂ via a sequential ionic layer adsorption reaction (SILAR) method. The photocatalytic materials were investigated by XRD, TEM, UV/Vis diffuse reflectance, inductively coupled plasma optical emission spectrometry (ICP‐OES), XPS, photoluminescence and Mott–Schottky analyses. SILAR processing was found to deposit monoclinic‐scheelite BiVO₄ nanoparticles onto the surface, giving successive improvements in the films′ visible light harvesting. Electrochemical and valence band XPS studies revealed that the prepared heterojunctions have a type II band structure, with the BiVO₄ conduction band and valence band lying cathodically shifted from those of TiO₂. The photocatalytic activity of the films was measured by the decolourisation of the dye rhodamine 6G using λ>400 nm visible light. It was found that five SILAR cycles was optimal, with a pseudo‐first‐order rate constant of 0.004 min^?1. As a reference material, the same SILAR modification has been made to an inactive wide‐band‐gap ZrO₂ film, where the mismatch of conduction and valence band energies disallows charge separation. The photocatalytic activity of the BiVO₄–ZrO₂ system was found to be significantly reduced, highlighting the importance of charge separation across the interface. The mechanism of action of the photocatalysts has also been investigated, in particular the effect of self‐sensitisation by the model organic dye and the ability of the dye to inject electrons into the photocatalyst′s conduction band.     

TiO2 Nanoparticles Immobilized on Carbon Nanotubes: An Efficient Heterogeneous Catalyst in Cyclocondensation Reaction of Isatins with Malononitrile and 4-Hydroxycoumarin or 3,4-Methylenedioxyphenol under Mild Reaction Conditions

TiO₂ nanoparticles supported on carbon nanotubes (TiO₂-CNTs) as an efficient heterogeneous catalyst was used for the synthesis of spiro[3,4′]1,3-dihydro-2H-indol-2-one-2′-amino-5′-oxo-4'H,5'H-pyrano[3′,2′-c]chromen-3′-yl cyanides and spiro[3,8′]1,3-dihydro-2H-indol-2-one-6′-amino-8'H-[1′,3′]dioxolo[4′,5′-g]chromen-7′-yl cyanides via the cyclocondensation reaction of isatins with malononitrile and 4-hydroxycoumarin or 3,4-methylenedioxyphenol in aqueous media at room temperature. This reaction offers several sustainable and economic benefits such as high yields of products, convenient operation, and use of non-toxic catalyst in water media.     

纳米结构TiO2/聚3-己基噻吩多孔膜电极光电性能研究

用光电流作用谱、光电流-电势图等光电化学方法研究了ITO/聚3-己基噻吩(ITO/ P3HT)膜和纳米结构TiO2/聚3-己基噻吩(TiO2/P3HT)复合膜的光电转换性质. 结果表明, P3HT膜的禁带宽度为1.89 eV, 价带位置为－5.4 eV. 在ITO/TiO2/ P3HT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. P3HT修饰ITO/TiO2电极可使光电流发生明显的红移, 从而提高了宽禁带半导体的光电转换效率.     

碳纳米管的表面修饰及TiO2-CNTs复合催化剂的光催化性能

运用酸氧化和聚乙烯醇表面修饰碳纳米管, 修饰的碳纳米管的水分散性能显著改善. 进一步地运用低温水热法合成表面修饰的碳纳米管复合TiO₂, 观察到了复合催化剂紫外及可见光激发下的光催化性能的明显提升. 红外光谱、X光电子能谱、差热-热重分析、X光衍射、Brunauer-Emmett-Teller低温氮吸附、透射电镜及紫外-可见漫反射光谱等表征表明, 复合催化剂光催化性能改善与碳纳米管良好水溶液分散性能导致的TiO₂在修饰的碳纳米管表面的均匀、致密分散和密切键合, 从而充分利用碳纳米管的功能密切关联.     

TiO2/ZnO薄膜电极中光生电子的传输及其在太阳电池中的应用

制备了TiO2纳米颗粒和ZnO纳米棒混合的多孔薄膜电极, 利用瞬态光电压技术研究了染料敏化TiO2/ZnO薄膜中光生载流子的传输特性. 实验结果表明, ZnO纳米棒增加了薄膜中自由电子扩散速率, 减小了复合几率, 改善了能量转换效率.     

Influence of the Sacrificial Polystyrene Removal Pathway on the TiO2 Nanocapsule Structure

This study demonstrates the significant influence of the polystyrene removal pathway on the TiO₂ nanocapsules obtained from PS @TiO₂ core‐shell particles. In a first step, the polystyrene spheres were coated with titanium oxide via hydrolysis and condensation of the titanium precursor to form PS @TiO₂ core‐shell particles. Then, the creation of the empty cavity to form TiO₂ nanocapsules was achieved by removing the polystyrene template by i ) thermal decomposition of the polystyrene or ii ) dissolution of the polystyrene using Soxhlet extractor followed by a thermal procedure. These pathways to remove the polystyrene were investigated by thermogravimetric studies, IR spectroscopy, transmission and scanning electron microscopy and powder X‐ray diffraction. The final TiO₂ nanocapsule structure strongly depends on the sacrificial polystyrene removal pathway. The preservation of the TiO₂ nanocapsules was obtained essentially when the polystyrene was dissolved before the crystallization of the TiO₂.     

Free‐Standing Membranes to Study the Optical Properties of Anodic TiO2 Nanotube Layers

In the present work we investigate various optical properties (such as light absorption and reflectance) of anodic TiO₂ nanotube layers directly transferred as self‐standing membranes onto quartz substrates. This allows investigation in a transmission geometry which provides significantly more reliable data than measurements on the metallic Ti substrate. Light transmission and reflectance measurements were carried out for layers of thickness varying from 1.8 to 50 μm, and the layers were investigated in their amorphous and crystalline forms. A series of wavelength‐dependent light attenuation coefficients are extrapolated and found to match the photocurrent versus irradiation wavelength behavior. A feature specific to anodic nanotubes is that their intrinsic carbon contamination content causes a proportional sub‐bandgap response. Overall, the extracted data provide a valuable basis and understanding for the design of photo‐electrochemical devices based on TiO₂ nanotubes.     

Morphology‐Tuned Synthesis of NiCo2O4‐Coated 3D Graphene Architectures Used as Binder‐Free Electrodes for Lithium‐Ion Batteries

Nanostructured NiCo₂O₄ is directly grown on the surface of three‐dimensional graphene‐coated nickel foam (3D‐GNF) by a facile electrodeposition technique and subsequent annealing. The resulting NiCo₂O₄ possesses a distinct flower or sheet morphology, tuned by potential or current variation electrodeposition, which are used as binder‐free lithium‐ion battery anodes for the first time. Both samples exhibit high lithium storage capacity, profiting from the unique binder‐free electrode structures. The flower‐type NiCo₂O₄ demonstrates high reversible discharge capacity (1459 mAh g^?1 at 200 mA g^?1) and excellent cyclability with around 71 % retention of the reversible capacity after 60 cycles, which are superior to the sheet‐type NiCo₂O₄. Such superb performance can be attributed to high volume utilization efficiency with unique morphological character, a well‐preserved connection between the active materials and the current collector, a short lithium‐ion diffusion path, and fast electrolyte transfer in the binder‐free NiCo₂O₄‐coated 3D graphene structure. The simple preparation process and easily controllable morphology make the binder‐free NiCo₂O₄/3D‐GNF hybrid a potential material for commercial applications.