硫酸盐电镀锡添加剂的探讨

目前,硫酸盐镀锡使用的添加剂易使镀液不稳定、变质、多泡,为此,从镀液变黄和变浊时间以及pH值等方面,筛选合适的稳定剂和不同光亮剂组合,研究其对镀液性能的影响.用电化学工作站测试钒酸盐含量对镀锡溶液开路电位以及苄叉丙酮和复合添加剂含量对镀液阴极极化曲线的影响.通过划痕试验、弯曲试验、热震试验和盐雾试验检测了添加剂对镀液和...     

Synthesis and electrochemical properties of LiY0.1V3O8

LiY_0.1V₃O₈ compound was successfully prepared by using a simple, rapid and easily scaled up method, i.e. the rheological phase reaction method. The microstructural characteristics of LiY_0.1V₃O₈ materials were examined by X-ray diffraction and scanning electron microscopy (SEM). Compared with LiV₃O₈ compound, the LiY_0.1V₃O₈ shows expanded crystal lattices, and the expansion is more significant along the c-axis. The electrochemical properties of the as-synthesized LiY_0.1V₃O₈ compounds were investigated. It was found that the LiY_0.1V₃O₈ electrodes exhibited better reversibility and higher capacities than LiV₃O₈ electrodes. The reasons for the improved electrochemical performance of the LiY_0.1V₃O₈ electrodes are also discussed.     

Patterning of YVO4:Eu3+ Luminescent Films by Soft Lithography

Ordered arrays of luminescent YVO₄:Eu³⁺ films with square (side length 19.17 ± 2.05 μm) and dot (diameter 11.20 ± 1.82 μm) patterns were fabricated by two kinds of soft lithography processes, namely, microtransfer molding (μTM) and microcontact printing (μCP), respectively. Both soft‐lithography processes utilize a PDMS elastomeric mold as the stamp combined with a Pechini‐type sol‐gel process to produce luminescent patterns on quartz plates, in which a YVO₄:Eu³⁺ precursor solution was employed as ink. The ordered luminescent YVO₄:Eu³⁺ patterns are revealed by optical micro­scopy and their microstructure, consisting of nanometer‐scale particles, is unveiled by scanning electronic microscopy (SEM) observations. Additionally, photoluminescence (PL) and cathodoluminescence (CL) were carried out to characterize the patterned YVO₄:Eu³⁺ samples. A strong red emission as a result of ⁵D₀–⁷F₂ transition of Eu³⁺ was observed under UV‐light or electron‐beam excitation, which implies that combining soft lithography with a Pechini‐type sol‐gel route has potential for fabricating rare‐earth luminescent pixels for next‐generation field‐emission display devices.     

稀土离子掺杂钒酸盐发光材料的研究现状及进展

以稀土钒酸盐为基质的纳米发光材料在紫外光以及真空紫外光激发下具有很好的发光性质,而且在恶劣工作环境下具有很好的稳定性,因而在发光二极管、显示器、生物探针、纳米光电器件、零阈值激光器等领域存在潜在的应用前景,近年来一直是研究的热点。随着纳米科学与技术的发展,稀土钒酸盐发光材料将步入新的发展阶段。主要介绍了稀土钒酸盐发光材料的研究现状、主要的合成方法、发光机理及其应用,预测了其研究趋势。     

Coelectrolysis of steam and CO2 in a solid oxide electrolysis cell with ceramic composite electrodes

Lanthanum strontium vanadate (LSV) was used as the cathode of a solid oxide electrolysis cell (SOEC) containing a yttria-stabilized zirconia (YSZ) electrolyte for the coelectrolysis of steam and CO₂. Pd and CeO₂ were added to the composite cathode, and the electrolysis mechanism in the coelectrolysis mode changed according to the type of catalyst in the LSV/YSZ composite cathode. The effect of steam on the coelectrolysis performance was investigated by varying the steam vapor pressure. The electrolysis performance under dry CO₂ without steam degraded with time under electrochemical reduction conditions owing to the deactivation of catalysts.     

Hydrothermal synthesis of CuV2O6 supported on mesoporous SiO2 as SO3 decomposition catalysts for solar thermochemical hydrogen production

Hydrothermal synthesis of CuV₂O₆ supported on 3-D ordered mesoporous SiO₂ (CuV/SiO₂) was studied to evaluate the catalytic activity for SO₃ decomposition, which is a key step in solar thermochemical hydrogen production. A composite oxide hydrate, Cu₃O(V₂O₇)·H₂O, and an oxide hydroxide hydrate, Cu₃(OH)₂V₂O₇·(H₂O)₂, were formed at lower hydrothermal temperatures (≤200 °C). The oxide hydrate phase mainly yielded Cu₂V₂O₇ after calcination at 600 °C in air. By contrast, the hydrothermal synthesis at 250 °C (CuV/SiO₂@250) directly crystallized CuV₂O₆ from the oxide hydroxide hydrate, although its very large particle size (∼5 μm) is not suitable for the catalytic application. The SO₃ decomposition activity measured at 600 °C was associated with the yield as well as the dispersion of CuV₂O₆, giving rise to the maximum for the hydrothermal synthesis at 200 °C. CuV/SiO₂@250 achieved the highest catalytic activity at the reaction temperature of 650 °C, because the melting phase of CuV₂O₆ penetrated mesoporous SiO₂ and thus improved the dispersion of the active phase.     

Visible light assisted photocatalytic activity of TiO2–metal vanadate (M=Sr,Ag and Cd) nanocomposites

TiO₂–metal vanadate nanocomposites (TiO₂–MV) were synthesized by the precipitation method and successfully characterized using UV–visible diffuse reflectance spectroscopy (UV–vis-DRS), powder X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) techniques. The photocatalytic activity of TiO₂–MV was investigated for the degradation of fast green (FG) dye under visible light irradiation. The photocatalytic activity of TiO₂–silver vanadate [TiO₂–Ag₃VO₄] was found to be much higher than that of TiO₂–cadmium vanadate [TiO₂–CdV₂O₆], TiO₂–strontium vanadate [TiO₂–Sr₃(VO₄)₂] and TiO₂. The effect of operational parameters such as pH, photocatalyst concentration and initial dye concentration on the photodegradation of FG was examined in detail. The mineralization of FG was confirmed by chemical oxygen demand (COD) and total organic carbon (TOC) measurements. Moreover, TiO₂–Ag₃VO₄ was found to be a reusable photocatalyst.     

织物基CNT/BiVO4光催化材料的制备及其在可见光下对染料的降解

利用钒酸铋(BiVO₄)具有无毒、降解效率高等优点,研究采用酸化碳纳米管(α-CNT)对BiVO₄进行改性,制备α-CNT/BiVO₄复合催化剂,采用泡沫法将α-CNT/BiVO₄复合催化剂处理在棉织物上,对亚甲基蓝(MB)溶液进行降解。结果显示:可见光照射90 min的降解效率高达95.8%,更容易降解有机污染物,同时还能解决催化剂颗粒在废水处理中难以回收利用的问题,对处理印染废水具有广阔的应用前景。     

An ultra-thin NiOOH layer loading on BiVO4 photoanode for highly efficient photoelectrochemical water oxidation

Monoclinic bismuth vanadate has been widely used as a promising n-type semiconductor for photoelectrochemical (PEC) water decomposition due to its high reserves, good stability in neutral solutions, and relatively narrow band gap. Here, we developed a simple method to prepare a thin NiOOH layer on the surface of BiVO₄ nanorod arrays. The heterostructured photoanode shows great enhancement for the photocurrent density of 2.7 mA cm⁻² at 1.23 V vs. RHE, which is ~2.3 times higher than that of pristine BiVO₄ electrode, due to NiOOH as an efficient oxygen-releasing catalyst with abundant oxygen vacancies. The NiOOH/BiVO₄ photoanodes are systematically studied with X-ray diffraction, Raman, X-ray photoelectron spectra, scanning electron microscopy, transmission electron microscopy, and UV–vis diffuse-reflectance spectrum. The heterostructured photoanode shows excellent PEC activity, which can provide a promising and easy strategy to prepare such photoanode with high-efficient oxygen evolution co-catalysts.     

Highly sensitive spectrometric method for determination of hydroquinone in skin lightening creams: application in cosmetics

A highly sensitive, simpler, faster and economical UV/visible spectrophotometric method has been established for the estimation of hydroquinone (HQ) in dilute organic matrices. The method is based on using ammonium meta‐vanadate as an oxidizing catalyst for conversion of HQ to p‐benzoquinone (BQ) in the presence of oxygen. As a result of higher absorption of UV light by BQ than by HQ, its signal has been utilized for determining HQ at the trace level. The effect of various parameters such as amount of oxidizing agent, stability time, temperature, acids and bases, solvents and interference by various compounds has been studied upon the absorption of BQ as HQ. Under optimized conditions, Beer’s Law was obeyed in the range of 0.025–2.00 μg ml^?1 HQ at 245.5 nm using 1 : 1 (V/V) 2‐propanol/water system with a lower detection limit of 7 ng ml^?1 and linear regression coefficient of 0.9998. Relative standard deviation of 1.5% was observed for 0.5 μg ml^?1 HQ solution (n = 11). The newly developed method has been successfully applied to diluted samples of various skin lightening creams for free HQ determination at the trace level. Comparison of the results obtained by the proposed method with those by a previously reported method proved its validity.