Electrochemical deposition and mechanism investigation of Prussian blue on graphic carbon paste electrode from an acidic ferricyanide solution

Prussian blue (PB) films were electrochemically deposited on graphite carbon paste electrodes (GCPEs) from an acidic solution of ferricyanide using the potentiodynamic and potentiostatic techniques. Interestingly, we, for the first time, observed that on the surface of GCPE, the electrochemistry of PB films strongly depended on the deposition potential. A maximum formation rate of PB was obtained at a more positive deposition potential (0.4 V vs saturated calomel electrode) on GCPE than that on Au or Pt electrode. The ratio of peak current at ca 0.75 V to the one at 0.19 V varied with the deposition potential. In addition, the electrocatalytic activity of the modified GCPEs towards the reduction of hydrogen peroxide considerably changed with the formation potentials of the PB films. These phenomena can be due to the different formation mechanism of PB at different deposition potentials. Dedicated to Prof. Dr. Teresa Iwasita on the occasion of her 65th birthday in recognition of her numerous contributions to interfacial electrochemistry.     

Potentiodynamic deposition of Prussian blue from a solution containing single component of ferricyanide and its mechanism investigation

Potentiodynamic techniques were used for the direct electrodeposition of Prussian blue nano-clusters from an acidic solution of ferricyanide. Electrochemical, EQCM, IR, AFM, and UV/vis measurements were carried out to characterize deposited nano-sized Prussian blue and to explore the formation mechanism. Results showed that ferricyanide could partially dissociate to free ferric and cyanide ions. The driving force of this dissociation is the formation of PB and the evolution of HCN. The optimal potential window for the potentiodynamic formation of PB from an acidic solution (pH 1.6) is between –0.5 V and 0.4 V. In addition, the influence of surface adsorption of CN^- ions on the formation of PB was discussed.Dedicated to Professor W. Vielstich on the occasion of his 80th birthday.     

Electrochemical deposition of germanium sulfide from room-temperature ionic liquids and subsequent Ag doping in an aqueous solution

A facile room-temperature electrochemical deposition process for germanium sulfide (GeS(x)) has been developed with the use of an ionic liquid as an electrolyte. The electrodeposition mechanism follows the induced codeposition of Ge and S precursors in ionic liquids generating GeS(x) films. The electrodeposited GeS(x) films were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and Raman and X-ray photoelectron spectroscopy (XPS). An aqueous-based Ag doping method was used to dope electrochemically grown GeS(x) films with controlled doping compared to the conventional process, which can be used in next-generation solid-state memory devices.     

Preparation of an active Suzuki-Miyaura catalyst from nanoparticles obtained by deposition of palladium onto a polyvinyl alcohol support

Highly dispersed palladium was obtained by vacuum deposition onto polyvinyl alcohol films, followed by removal of the support via dissolution in hot water, and was characterized by transmission electron microscopy. The dispersed palladium consisted of aggregated nanoparticles with a size of ～10 nm and was used to catalyze the Suzuki-Miyaura reaction of p-iodonitrobenzene with phenylboronic acid in N,N-dimethylacetamide and propan-1-ol at 50–80°C in the presence of potassium phosphate as base. Taking into account that the reaction required atmospheric oxygen (no reaction occurred under argon), it was presumed that the process is homogeneous and that palladium is transferred into solution as a result of leaching by the action of oxygen in the presence of iodide ions. The properties of the examined catalytic system were compared with those reported for other catalytic systems containing palladium nanoparticles.     

Dynamics of copper deposition from a sulfuric acid solution onto electrically isoconducting electrodes made of fibrous carbon materials

Effect of the initial electrical conductivity of an electrically isoconducting flow-through electrode made of a fibrous carbon material on the dynamics of copper electrodeposition from a sulfuric acid solution was studied. The distribution of the copper deposit across the electrode thickness and the variation of the electrolysis parameters (copper deposition rate, current efficiency, uniformity of distribution, and mass of a deposited metal per unit mass of the fibrous carbon material) were considered.     

有机钌螯合物/TiO_2杂化膜修饰电极上Pt纳米团簇的光电流增强效应

利用LB膜技术可控制备了纳米单层和多层的二氧化钛-有机钌螯合物杂化膜,并研究了上述无机-有机杂化膜修饰电极在Pt纳米团簇敏化后的光电流增强效应.实验结果表明:(1)纳米单层TiO2/[Ru(phen)2(dC18bpy)]2+(简称为TiO2-Ru)杂化膜的平均厚度为(3.6±0.5)nm;(2)在光照条件下TiO2-Ru杂化膜能有效催化还原[Pt(NH3)6]4+形成粒径位于20～160nm之间的Pt纳米团簇;(3)Pt纳米团簇的引入消除了金属钌螯合物中配体对电子传递的阻碍作用,改变了电子传递途径,从而有效减少了电子空穴对的复合,提高了Pt纳米团簇敏化的n层杂化膜修饰电极(ITO/(TiO2-Ru)n/Pt)在支持电解质中的光电流.与纳米单层TiO2-Ru杂化膜修饰的ITO电极(ITO/TiO2-Ru)相比,当工作电压为900mV时,ITO/TiO2-Ru/Pt在0.1mol·L-1的NaClO4电解质溶液中和光照(λ360nm)条件下,单位面积的光电流提高了约5倍;(4)ITO/(TiO2-Ru)n/Pt电极光电流的大小与杂化膜的层数密切相关,当TiO2-Ru杂化膜的层数从一层、二层增加到四层时,光电流呈现先升高后下降行为,这表明ITO/(TiO2-Ru)n/Pt电极的电子传递过程直接通过非电活性的二氧化钛纳米单层进行.     

Facile preparation of a visible- and near-infrared-active electrochromic film by direct deposition of a ruthenium dioxolene complex on an ITO/glass surface

An electrochromic film was prepared by simple evaporation of a solution of a ruthenium-dioxolene dye on an ITO/glass surface to give a mechanically attached layer, without the need for special anchoring groups or polymerisation to achieve surface attachment. Using an aqueous solvent/electrolyte system, in which the microcrystalline dye is insoluble, reversible electrochemical behaviour is observed leading to substantial changes in absorbance in the visible and near-infrared regions. Alternation of the applied potential resulted in rapid (≈0.1–1 s timescale) on/off switching of NIR absorbance at 1300 nm which persisted over thousands of cycles with minimal degradation.     

The direct resist-free deposition of a lithographic mask from vapor initiated by an electron beam

A dry resist-free process of electron-beam vapor deposition of an undecane precursor (C₁₁H₂₄) mask on SiO₂-on-silicon and copper-on-silicon substrates was studied. The band section was trapezoidal, and the band width at the base was much larger than the diameter of the electron beam and depended on the substrate (it was three or four times larger on copper than on SiO₂). In mask deposition on copper, the mask thickening rate v was found to depend strongly on the scan time τ_sc when scanning was performed along the band. When τ_sc changed from 20 ms to 13 s, v decreased by a factor of 7.4 (beam current 1.0 nA). This was probably caused by significant diffusion delay of precursor transport to the reaction zone during pixel time when τ_sc was 13 s. The ion-beam etching of the substrates through the deposited masks was performed (the SiO₂ substrate was etched with SF₆ ions, and the copper substrate, with Ar ions).     

Investigation of removal of Ag(I) from aqueous solution by a novel chelating resin containing acyl and thiourea groups

This work aimed at investigating a novel chelating resin (PTDTR) containing acyl and thiourea groups for the removal of Ag(I) from aqueous solution by adsorption tests, FTIR, scanning electron microcopy (SEM), BET and XPS analyses. The maximum adsorption capacity of Ag(I) ions obtained from Langmuir model was 6.078?mmol/g at 30?°C. The uptake of Ag(I) on resin was found to follow liquid film diffusion and pseudo-second-order model. Thermodynamic parameters showed that the adsorption process of Ag(I) ions onto PTDTR resin was spontaneous and endothermic under nature conditions. The regeneration test indicated that PTDTR resin have good stability and the adsorption capacity decreased 2.7% after five cycles of adsorption-desorption. In addition, PTDTR resin showed good selectivity for Ag(I) ions in Ag(I)-Cu(II) binary system. The results of SEM suggested that Ag(I) adsorbed on the surface of PTDTR. The FTIR and XPS analyses further confirmed Ag(I) ions might chemisorb onto PTDTR surfaces through its acyl and thiourea groups.     

Recovery by means of electrodialysis of an aromatic amino acid from a solution with a high concentration of sulphates and phosphates

In the industrial synthesis of -α-p-hydroxyphenylglycine the separation of the amino acid is carried out by precipitation. During this process, a mother liquor is produced with a high salt content (phosphates and sulphates) and an amino acid concentration of approximately 0.12–0.15 M. The disposal of this mother liquor not only causes an environmental problem due its high salinity and COD (chemical oxygen demand) content but also an economic loss due to the high price of the unrecovered amino acid. To avoid this problem an electrodialytic process has been developed that allows the recovery of 85% of the amino acid in the form of a low salinity stream with a salt content 70% lower than that of the initial mother liquor. This low salinity stream can be incorporated into the main process and in this way the amino acid can be recovered.     

Electrocatalytic oxidation of GMP on an ITO electrode modified by the photodeposition of Pd nanoparticles onto a monolayer TiO_2 nanosheets/[Ru(phen)_2(dC18bpy)]~(2+) hybrid film

An indium tin oxide(ITO)electrode coated with monolayer TiO2/[Ru(phen)2(dC18bpy)] 2+ (phen=1,10-phenanthroline, dC18bpy=4,4′-dioctadecyl-2,2′-bipyridyl)hybrid film(denoted as ITO/TiO2-Ru)has been prepared using the modified Langmuir-Blodgett(LB)method,and the electrocatalytic oxidation of mononucleotide of guanosine 5′-monophosphate(GMP)on an ITO/TiO2-Ru electrode after Pd-photodeposition(denoted as ITO/TiO2-Ru/Pd)has been studied.Atomic force microscopy reveals that the single-layered hybrid film of TiO2 n...     

Identification of rat liver glutathione S-transferase Yb subunits by partial N-terminal sequencing after electroblotting of proteins onto a polyvinylidene difluoride membrane from an analytical isoelectric focusing gel

Rat liver glutathione S-transferases were partially purified using S-hexyl glutathione affinity chromatography, followed by native isoelectric focusing employing a pH 7-11 or pH 3-10 gradient. Proteins were excised and eluted from the gel for determination of subunit composition using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In separate experiments, isoelectric focusing gels were equilibrated with a sodium dodecyl sulfate-containing buffer at high pH, and proteins on the gel were electroblotted onto a polyvinylidene difluoride membrane, utilizing graphite plates as electrodes. The membrane-bound proteins were visualized by Coomassie Brilliant Blue staining. The protein bands were then excised from the membrane and inserted into a gas phase sequenator for direct sequencing. N-Terminal sequences thus determined were compared with published cDNA sequences. The isoelectric points (pIs) and positions on the isoelectric focusing gel of Yb1Yb1, Yb1Yb2 and Yb2Yb2 subunits were determined. We have also located on the pH 3-10 focusing gel an N-terminal blocked glutathione S-transferase which has a molecular weight similar to Yb subunits.