Silole‐Infiltrated Photonic Crystal Films as Effective Fluorescence Sensor for Fe3+ and Hg2+

We develop a highly effective silole‐infiltrated photonic crystal (PC) film fluorescence sensor with high sensitivity, good selectivity and excellent reproducibility for Fe³⁺ and Hg²⁺ ions. Hexaphenylsilole (HPS) infiltrated PCs show amplified fluorescence due to the slow photon effect of PC because the emission wavelength of HPS is at the blue band edge of the selected PC’s stopband. The fluorescence can be quenched significantly by Fe³⁺/Hg²⁺ ions owing to electron transfer between HPS and metal ions. The amplified fluorescence enhances the sensitivity of detection, with a detection limit of 5 nM for Fe³⁺/Hg²⁺ ions. The sensor is negligibly responsive to other metal ions and can easily be reproduced by rinsing with pure water due to the special surface wettability of PC. As a result, a highly effective Fe³⁺/Hg²⁺ ions sensor based on HPS‐infiltrated PC film has been achieved, which will be important for effective and practical detection of heavy metal ions.     

Epitaxial CeO2 thin films for a mechanism study of resistive random access memory (ReRAM)

A thin epitaxial CeO₂ film was grown on a Cu(111) single crystal in order to investigate the mechanism of resistive memory/switching devices with an ultimately thin high-k dielectric film. A small amount of Pt was deposited on the CeO₂ film and the Pt/CeO₂/Cu structure was characterized by conductive atomic force microscopy and X-ray photoelectron spectroscopy. It was found that the grown epitaxial CeO₂ film was fully oxidized, i.e., the valence of Ce atoms in the film was completely Ce⁴⁺. However, after the deposition of a small amount of Pt, it was revealed that Ce atoms were partially reduced to Ce³⁺ in full thickness of the film. The Pt/CeO₂/Cu structure did not show switching behavior in resistance. The observed reduction of CeO₂ film is considered to be responsible to the non-switching behavior. The thermodynamics of the reduction of the CeO₂ film and the kinetics of oxygen diffusion in the reduced CeO₂ film are discussed.     

Adsorption of UO2+2 by polyethylene adsorbents with amidoxime,carboxyl, and amidoxime/carboxyl group

The polyethylene (PE) adsorbents were prepared by a radiation-induced grafting of acrylonitrile (AN), acrylic acid (AA), and the mixture of AN/AA onto PE film, and by subsequent amidoximation of cyano groups of poly-AN graft chains. With an increase of AA composition in AN/AA monomer mixture, the water uptake of the grafted polyethylene film increased. In AN/AA mixture, the maximum adsorption of UO²⁺₂ was observed in the adsorbent with a ratio of AN/AA (50/50, mol%) in copolymer. The amidoxime, carboxyl, and amidoxime/carboxyl groups onto PE acted as a chelating site for the selected UO²⁺₂. The complex structure of polyethylene with three functional groups and UO²⁺₂ was confirmed by Fourier Transform Infrared (FTIR) spectroscopy.     

Quartz crystal microbalance monitoring of density changes in mesoporous TiO2 phytate films during redox and ion exchange processes

Nanofilm deposits of TiO₂ nanoparticle phytates are formed on gold electrode surfaces by ‘directed assembly’ methods. Alternate exposure of a 3-mercapto-propionic acid modified gold surface to (i) a TiO₂ sol and (ii) an aqueous phytic acid solution (pH 3) results in layer-by-layer formation of a mesoporous film. Ru(NH₃)₆³⁺ is shown to strongly adsorb/accumulate into the mesoporous structure whilst remaining electrochemically active. Scanning the electrode potential into a sufficiently negative potential range allows the Ru(NH₃)₆³⁺ complex to be reduced to Ru(NH₃)₆²⁺ which undergoes immediate desorption. When applied to a gold coated quartz crystal microbalance (QCM) sensor, electrochemically driven adsorption and desorption processes in the mesoporous structure become directly detectable as a frequency response, which corresponds directly to a mass or density change in the membrane. The frequency response (at least for thin films) is proportional to the thickness of the mass-responsive film, which suggests good mechanical coupling between electrode and film. Based on this observation, a method for the amplified QCM detection of small mass/density changes is proposed by conducting measurements in rigid mesoporous structures.     

Conductivity enhancement of PEDOT:PSS film via sulfonic acid modification: application as transparent electrode for ITO-free polymer solar cells

3-Hydroxy-1-propanesulfonic acid(HPSA)was applied as a modification layer on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)film via spin-coating,resulting in a massive boost of the conductivity of PEDOT:PSS film,and thus the as-formed PEDOT:PSS/HPSA bilayer film was successfully used as a transparent electrode for ITO-free polymer solar cells(PSCs).Under the optimized concentration of HPSA(0.2 mol L~(-1)),the PEDOT:PSS/HPSA bilayer film has a conductivity of 1020 S cm~(-1),which is improved by about 1400 times of the pristine PEDOT:PSS film(0.7 S cm~(-1)).The sheet resistance of the PEDOT:PSS/HPSA bilayer film was 98Ωsq~(-1),and its transparency in the visible range was over 80%.Both parameters are comparable to those of ITO,enabling its suitability as the transparent electrode.According to atomic force microscopy(AFM),UV-Vis and Raman spectroscopic measurements,the conductivity enhancement was resulted from the removal of PSS moiety by methanol solvent and HPSA-induced segregation of insulating PSS chains along with the conformation transition of the conductive PEDOT chains within PEDOT:PSS.Upon applying PEDOT:PSS/HPSA bilayer film as the transparent electrode substituting ITO,the ITO-free polymer solar cells(PSCs)based on poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]:[6,6]-phenyl C71-butyric acid methyl ester(PC_(71)BM)(PCDTBT:PC_(71)BM)active layer exhibited a power conversion efficiency(PCE)of 5.52%,which is comparable to that of the traditional ITO-based devices.     

Electrochemical polymerization of polyaniline doped with Zn2+ as the electrode material for electrochemical supercapacitors

Polyaniline doped with Zn²⁺ (PANI/Zn²⁺) films was synthesized by cyclic voltammetric method on stainless steel mesh substrates in 0.2 mol L^?1 aniline and 0.5 mol L^?1 sulfuric acid electrolyte with various concentrations of zinc sulfate (ZnSO₄·7H₂O). The structure and morphology of PANI and PANI/Zn²⁺ films were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques, respectively. The electrochemical properties of PANI and PANI/Zn²⁺ films were investigated by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy in 0.5 mol L^?1 H₂SO₄ electrolyte in a three-electrode system. The results show that the surface morphology of PANI/Zn²⁺ is more rough than that of pure PANI. The specific capacitance of the PANI/Zn²⁺ film displays a larger specific capacitance of 738 F g^?1, lower resistance, and better stability as compared with the pure PANI film. Thus, good capacitive performance demonstrates its potential superiority for supercapacitors.     

Spectrocyclic Voltammetry of Ruthenium Purple Electrodeposited on a WO3/Tris(2,2′-bipyridine)-ruthenium(II)/Polymer Hybrid Film

Summary: Electrochemical reactions of Ruthenium purple, Feequation/tex2gif-stack-1.gif[Ru^II(CN)₆]₃ (RP; Fe^III-Ru^II) were studied using a spectrocyclic voltammetry (SCV) technique. The SCV measurement for an RP film coated on an ITO electrode showed a reversible redox between RP and Ruthenium white (RW; Fe^II-Ru^II) at 0.14 V vs saturated calomel reference electrode (SCE). An RP film was electrodeposited on a hybrid film of tungsten trioxide (WO₃)/tris(2,2′-bipyridine)ruthenium(II) ([Ru(bpy)₃]²⁺; bpy = 2,2′-bipyridine)/poly(sodium 4-styrenesulfonate) (PSS) (denoted as WRP film) from a colloidal solution containing 0.5 mM FeCl₃, 0.5 mM K₄[Ru(CN)₆] and 40 mM KCl using a potentiodynamic multi-sweep technique. In a cyclic voltammogram (CV) of a WRP/RP film, a redox response was observed at 0.61 V in addition to essential redox responses of WRP hybrid film (a [Ru(bpy)₃]²⁺/[Ru(bpy)₃]³⁺ redox at 1.03 V and a H_xWO₃/WO₃ redox below 0.09 V), but a redox response of RW/RP was not observed at 0.14 V. The SCV measurement for the WRP/RP film suggested that the redox response at 0.61 V is attributed to a redox of [Ru(bpy)₃]²⁺/[Ru(bpy)₃]³⁺ interacted electrostatically with RP. It also showed that RW is oxidized to RP via [Ru(bpy)₃]²⁺/[Ru(bpy)₃]³⁺ redox and RP is reversibly reduced to RW via H_xWO₃/WO₃ redox. This unique geared electrochemical reaction for the WRP/RP film leads to a hysteresis property of an RW/RP redox.     

Modified interdigitated arrays by novel poly(1,8-diaminonaphthalene)/carbon nanotubes composite for selective detection of mercury(II)

This study describes a novel type of interdigitated arrays (IDA), microfabricated by electropolymerizing structured Poly(1,8-diaminonaphthalene)/functionalized multi-walled carbon nanotubes (PDAN/CNT) thin film onto a silicon chip for square wave voltammetry (SWV) multi-element heavy metal ion detection. The structure of PDAN/CNT was characterized by Raman, FE-SEM and AFM techniques. Analysed experiments reveal that the uptake of Hg²⁺ by PDAN/CNT is quite specific and it can be used advantageously for electrochemical sensing of Hg²⁺ thanks to original feature of (Hg²⁺/Hg₂²⁺) redox potential with the respect to that of PDAN/CNT. As-developed IDA type electrode can extend its utility in other sensing applications.     

One‐Step Hydrothermal Synthesis of a Porous Cu2O Film and Its Photoelectrochemical Properties

A cuprous oxide (Cu₂O) film with a novel porous structure is successfully synthesized on Cu foil by using a simple hydrothermal method. A redox reaction occurs between Cu and Cu²⁺ in aqueous solution to form the Cu₂O film. The porous structures are formed as a result of the Ostwald ripening mechanism. In addition, photoluminescence measurements indicate that the porous Cu₂O film may reduce the recombination of photogenerated electrons and holes. The UV/Vis absorption property of the porous Cu₂O film is better than that of the granular Cu₂O film, and its high photocurrent is expected to make the porous Cu₂O film more suitable for solar energy applications.     

A viologen-based UV indicator and dosimeter

A UV indicator/dosimeter based on benzyl viologen (BV²⁺) encapsulated in polyvinyl alcohol (PVA) is described. Upon exposure to UV light, the BV²⁺/PVA film turns a striking purple colour due to the formation of the cation radical, BV^•+. The usual oxygen sensitivity of BV^•+ is significantly reduced due to the very low oxygen permeability of the encapsulating polymer, PVA. Exposure of a typical BV²⁺/PVA film, for a set amount of time, to UVB light with different UV indices produces different levels of BV^•+, as measured by the absorbance of the film at 550 nm. A plot of the change in absorbance at this wavelength, ΔAbs(550), as a function of UV index, UVI, produces a linear calibration curve which allows the film to be used as a UVB indicator, and a similar procedure could be employed to allow it to be used as a solar UVI indicator. A typical BV²⁺/PVA film generates a significant, semi-permanent (stable for >24 h) saturated purple colour (absorbance ~0.8–0.9) upon exposure to sunlight equivalent to a minimal erythemal dose associated with Caucasian skin, i.e. skin type II. The current drawbacks of the film and the possible future use of the BV²⁺/PVA film as a personal solar UV dosimeter for all skin types are briefly discussed.      

Bis-ratiometric absorbance detection of Al(III) in the rhodamine B-functionalized bis-polydiacetylene film

A rhodamine B-functionalized bis-polydiacetylene (RB/bis-PDA) film sensor was prepared. Rhodamine B derivatives as the ion-recognition elements were embedded in the bis-polydiacetylene matrix through the hydrolysis/condensation process of organic silicon. The as-prepared blue-phase RB/bis-PDA film could transfer to yellow phase at high temperatures. Upon dipping the blue and yellow RB/bis-PDA films into various metal ion solutions, respectively, only Al³⁺ could induce remarkable changes in absorption and color signals. The UV–Vis absorption spectrum of the Al³⁺-containing film showed two separate absorption peaks at 556 nm and at another wavelength (617 or 470 nm), corresponding to ring opening of the spirolactam structure in rhodamine moiety and PDA (blue- or yellow-phase PDA), respectively. Utilizing the different intensity ratios of the two absorption signals (A₅₅₆/A₆₁₇ or A₅₅₆/A₄₇₀), the RB/bis-PDA system could be used as a bis-ratiometric absorbance sensor for Al³⁺. The reusable and free-standing films have great potential in environmental and biological sensing fields as they are more convenient to achieve real-time sensing than the conventional probes dissolved in aqueous or organic solvents.     

Water‐proton relaxivity of hyperbranched polymers carrying TEMPO radicals

High water‐soluble hyperbranched poly(styrene) (HPS) polymers carrying stable 2, 2, 6, 6‐tetramethylpiperidine‐1‐oxyl (TEMPO) radicals, HPS‐N‐TEMPO, HPS‐Im‐TEMPO, and HPS‐Im‐(TEMPO)₂, were prepared in ca. 60% introducing yield. HPS‐N‐TEMPO and HPS‐Im‐TEMPO were determined to be nearly spherical shapes of the diameter of 2.4 ± 0.6 and 2.2 ± 0.6 nm, respectively, by transmission electron microscope (TEM) images. The values of water‐proton relaxivity, r₁, at 25 MHz, 0.59 T, and 25 °C were 6.0, 5.2, and 14 mM^?1 sec^?1 for HPS‐N‐TEMPO, HPS‐Im‐TEMPO, and HPS‐Im‐(TEMPO)₂, respectively. The spin‐lattice relaxation time (T₁)‐weighted images in phantom were also observed. Copyright © 2009 John Wiley & Sons, Ltd.     

表面In掺杂TiO2的N719/TiO2-Inx%/FTO薄膜电极的光电转换效率

采用溶胶-凝胶法制备出In 表面修饰的TiO₂ (TiO₂-Inx%)纳米粒子, x%代表在In 掺杂的TiO₂样品中In³⁺与In³⁺和Ti⁴⁺离子摩尔百分含量. 利用二(四丁基铵)顺式-双(异硫氰基)双(2,2''-联吡啶-4,4''-二羧酸)钌(II)(N719)作为敏化剂, 制备出N719/TiO₂/FTO (氟掺杂锡氧化物)和N719/TiO₂-Inx%/FTO染料敏化薄膜电极. 光电转换效率实验表明, 在薄膜电极+0.5 mol·L^-1 LiI+0.05 mol·L^-1 I₂的三甲氧基丙腈(MPN)溶液+Pt 光电池体系中,N719/TiO₂-Inx%/FTO薄膜电极的光电转换效率均高于N719/TiO₂/FTO, 其中N719/TiO₂-In0.1%/FTO的光电转换效率比N719/TiO₂/FTO提高了20%. 利用X 射线衍射(XRD)、X 射线光电子能谱(XPS)、漫反射吸收光谱(DRS)、荧光(PL)光谱和表面光电流作用谱确定了TiO₂-Inx%样品中In3+离子的存在方式和能带结构; 利用表面光电流作用谱研究了N719/TiO₂-Inx%/FTO薄膜电极的光致界面电荷转移过程. 结果表明, In3+离子在TiO₂表面形成O-In-Cl_n (n=1, 2)物种, 该物种的表面态能级位于导带下0.3 eV处; 在光电流产生过程中, O-In-Cl_n (n=1, 2)表面态能级有效地抑制了光生载流子在TiO₂-Inx%层的复合, 促进了阳极光电流的增加, 从而导致N719/TiO₂-Inx%/FTO薄膜电极的光电转化效率高于N719/TiO₂/FTO, 并进一步讨论了光致界面电荷转移的机理.     

Preparation and Characterization of Mixed‐Valent Osmium Hexacyanoferrate/Silicomolybdate Hybrid Films and Their Electrocatalytic Properties

A polynuclear mixed‐valent osmium hexacyanoferrate/silicomolybdate film electrode has been prepared using repetitive cyclic voltammetry. The cyclic voltammograms have been recorded for the deposition of a mixed‐valent osmium hexacyanoferrate/silicomolybdate hybrid film directly from the mixture of Os³⁺, Fe(CN₆)^3?, and SiMo₁₂O₄₀^4? ions from the acidic aqueous solutions. The polynuclear mixed‐valent osmium hexacyanoferrate/silicomolybdate film exhibited four redox couples. The electrocatalytic properties of the osmium hexacyanoferrate/silicomolybdate film electrode have been studied. The modified electrode has shown good electrocatalytic properties towards the oxidation of dopamine, ascorbic acid, epinephrine, norepinephrine, and reduction of IO₃^?, Fe³⁺.     

Photoelectrochemical and characterization of intercalation compound of KTiNbO5 with methylviologen

Methylviologen (1,1′-dimethyl-4,4′dipyridinium ion, MV²⁺) has been intercalated into the interlayer space of layered potassium titanoniobate (KTiNbO₅) by a method involving the displacement of guest molecules using a n-hexylammonium titanoniobate (HeNH₃⁺-TiNbO₅) intercalation compound. The methylviologen titanoniobate (MV²⁺-TiNbO₅) intercalation compound was characterized using SEM, TEM, XRD, IR and elemental analysis. The photochemical and electrochemical behaviors of the MV²⁺-TiNbO₅ hybrid thin film were investigated. The photo excitation of oxygen-present MV²⁺-TiNbO₅ thin film with UV light indicated the electron transfer from the titanoniobate layer to MV²⁺ to form MV⁺ radical cation. The cyclic voltammogram of the MV²⁺-TiNbO₅ hybrid thin film exhibited two consecutive electron-transfer steps.     

Dual‐template crown ether‐functionalized hierarchical porous silica: Preparation and application for adsorption of energy metal lithium

Lithium is the lightest energy metal element on earth and it has applications in lithium batteries and nuclear fusion. With the development of high‐tech and widespread applications of lithium, the demand for lithium continues to increase. In this work, a hierarchical porous lithium adsorbent (2M12C4‐HPS) was synthesized from a precursor of hierarchical porous silica (HPS), the HPS being obtained via a dual‐template technique. The microstructure and morphology of 2M12C4‐HPS were characterized using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction and nitrogen adsorption–desorption measurements. The obtained hierarchical porous 2M12C4‐HPS containing two kinds of pores with different sizes (peaking at about 2.01 and 7.82 nm) has a high specific surface area (1143.56 m² g^?1). Fourier transform infrared spectroscopy and thermogravimetric analysis were used to confirm the surface organic functional groups of 2M12C4‐HPS, indicating that the functional group 2‐methylol‐12‐crown‐4 (2M12C4) was grafted on HPS successfully. The lithium adsorption properties, kinetics and isotherms of 2M12C4‐HPS were investigated. The adsorption kinetics can be described by the pseudo‐second‐order kinetic model and the adsorption isotherms well fit the Langmuir isotherm equation. In addition, 2M12C4‐HPS exhibited excellent specificity towards Li⁺. And the maximum adsorption rate of 2M12C4‐HPS is up to about 94.34%. The obtained results indicate that 2M12C4‐HPS has a broad commercial application prospect for adsorption of lithium.     

Electroreductive polymerization of trans-[RuCl 2(vpy) 4] on Nd-Fe-B magnets: electrochemical impedance spectroscopy interpretation, Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy analysis

The electropolymerization of trans-[RuCl₂(vpy)₄] (vpy=4-vinylpyridine) monomer on Nd-Fe-B magnets was studied by electrochemical impedance spectroscopy (EIS). Impedance diagrams obtained during the polymerization process were used to monitor film formation. The EIS results gave insight into the electrochemical phenomena occurring at the magnet surface as the polymerization process progressed. The film structure and morphology were also studied by X-ray photoelectron spectroscopy, scanning electron microscopy and Raman spectroscopy. The Raman spectroscopy results showed that the polymerization takes place at the vinyl groups of the monomer and also that the redox polymer structure is very similar to that of the monomer. The ratio of the intensity of the XPS peaks for fluorine (from the electrolyte PF₆ ^–) and ruthenium present in the film showed that the polymer on Nd-Fe-B contained an equal proportion of Ru²⁺ and Ru³⁺, indicating that part of the film is positively charged, i.e. {[RuCl₂(vpy)₄]⁺} _n .     

A ratiometric fluorescence sensor for Be based on Beryllon II/layered double hydroxide ultrathin films

A ratiometric fluorescence sensor for Be²⁺ has been fabricated via alternate assembly of 2-(3,6-disulfo-8-hydroxynaphthylazo)-1,8-dihydroxynaphthalene-3,6-disulfonate (Beryllon II) and MgAl-LDH nanosheets on quartz substrates using the layer-by-layer (LBL) deposition technique. UV–vis absorption and the fluorescence emission spectroscopy indicate a stepwise and regular growth of the Beryllon II/LDH UTFs upon increasing deposition cycle. The film of Beryllon II/LDH possesses a periodic layered structure perpendicular to the substrate revealed by X-ray diffraction and scanning electron microscopy. Atomic force microscopy images show that the film surface is continuous and uniform. The Beryllon II/LDH UTFs display ratiometric fluorescence response for Be²⁺ with a linear response range in 1.0 × 10⁻⁷–1.9 × 10⁻⁶ mol L⁻¹ and a detection limit of 4.2 × 10⁻⁹ mol L⁻¹. Furthermore, the ratiometric sensor exhibits good repeatability, high stability (thermal, storage and mechanical) as well as excellent selectivity toward Be²⁺. XPS and Raman measurements demonstrate that the specific response of the sensor is attributed to the coordination between Be²⁺ and Beryllon II in the UTF. The Beryllon II/LDH UTFs in this work can be potentially used as a chemosensor for the detection of Be²⁺ in the environmental and biomedical field.     

Characterization of thin metastable vanadium oxide films by Raman spectroscopy

Thin films are potentiodynamically generated on vanadium in Ba²⁺/acetate electrolyte systems at high voltages. The influence of the anodic potential up to 400 V on the composition and structure of the about 500 nm thin anodic conversion films are investigated. Raman spectroscopy indicates that different film types depend on the electrochemical process parameters. The relationship between the Raman laser excitation power and the amorphous or microcrystalline film structure is also discussed. Beside metastable disordered structures the films contain crystalline phases of V₂O₅, V₄O₉ and barium vanadate, respectively.     

Solid-state electrochemiluminescence sensor through the electrodeposition of Ru(bpy)3/AuNPs/chitosan composite film onto electrode

Tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) has been successfully immobilized onto electrode through the electrodeposition of Ru(bpy)₃²⁺/AuNPs/chitosan composite film. In the experiments, chitosan solution was first mixed with Au nanoparticles (AuNPs) and Ru(bpy)₃²⁺. Then, during chronopotentiometry experiments in this mixed solution, a porous 3D network structured film containing Ru(bpy)₃²⁺, AuNPs and chitosan has been electrodeposited onto cathode due to the deposition of chitosan when pH value is over its pK_a (6.3). The applied current density is crucial to the film thickness and the amount of the entrapped Ru(bpy)₃²⁺. Additionally, these doping Ru(bpy)₃²⁺ in the composite film maintained their intrinsic electrochemical and electrochemiluminescence activities. Consequently, this Ru(bpy)₃²⁺/AuNPs/chitosan modified electrode has been used in ECL to detect tripropylamine, and the detection limit was 5 × 10⁻¹⁰ M.