The Interaction of Iodide Film with Platinum Microparticles on Different Electrode Materials for Various Electrocatalytic Reactions

The electrochemical depositions of Pt microparticles and KI film were successfully carried out on glassy carbon electrodes (GCE), gold electrodes (GE), and indium tin oxide electrodes (ITO). The electrochemical studies of Pt micro/KI film on GCE show that the film was stable, active at pH 1.5 electrolyte solutions. The Pt microparticle/KI film modified ITO electrodes were examined by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The SEM and AFM results show that the Pt particle sizes were in the range of 120 nm–1.4 μm, respectively. The proposed film on GCE shows efficient electrocatalysis for oxygen, Cr₂O reduction by using cyclic voltammetry. Further the electrochemical oxidation of sodium meta‐arsenite (As(III)), H₂O₂ were successfully carried out and the detection of H₂O₂ in real samples has been validated.     

Applications of nanostructured Pt-Au hybrid film for the simultaneous determination of catecholamines in the presence of ascorbic acid

Nanostructured platinum-gold (Pt–Au) hybrid film modified glassy carbon electrode (GCE) was fabricated by electro-deposition method in the presence of 2 × 10⁻⁴ mol l⁻¹ l-cysteine. To examine the surface morphological analysis, the (Pt–Au) hybrid film were electrochemically deposited on transparent semiconductor indium tin oxide (ITO) electrodes for scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies. From the SEM analysis, it was observed that the deposited nanoplatinum (250–400 nm) was formed as a cauliflower-shaped structure with the gold nanoparticles (30–90 nm). The concentration variation of additive l-cysteine results in the formation of cauliflower-shaped platinum nanoparticles. Further, the Pt–Au hybrid film modified GCE could be used for the detection of catecholamine neurotransmitters epinephrine (EP), norepinephrine (NEP) individually and in the presence of ascorbic acid (AA) in pH 7 phosphate-buffered solutions (PBS). Furthermore, the proposed Pt–Au hybrid film could be applied for the detection of epinephrine in injection solution and ascorbic acid from commercially available vitamin C tablets.     

Preparation and properties of a high temperature, flexible and colorless ITO coated polyimide substrate

A new high temperature, flexible and colorless indium-tin-oxide (ITO) coated plastic substrate has been prepared from a thermally stable, high glass transition temperature (T_g) and colorless polyimide film. The polyimide was synthesized from 3,3′-diaminodiphenylsulfone (3,3′-DDS) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) monomers. Its heat distortion temperature was 278 °C. The ITO was deposited on the polyimide film using the magnetron-sputtering process. After annealing at 250 °C under nitrogen for 1 h, the resistivity of the ITO film was 4.0 × 10⁻⁴ Ω cm, and its transmittance was 83.5%. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to observe the surface and morphology of the ITO film. UV-visible spectroscopy and the four-probe method were used to study their optical and electrical properties. The high performance ITO-plastic substrate can be used in the next generation flat panel displays.     

Preparation of a Novel NH2 + Ion Implantation Modified Electrode and Its Study of the Electrochemical Behavior of Hemoglobin

Abstract

A novel functional electrode was obtained by implanting NH₂ ⁺ into ITO film (NH₂/ITO) for the first time. The NH₂/ITO surface showed a better affinity to gold nanoparticles than bare ITO. Gold nanoparticles were deposited on the surface of NH₂/ITO electrode (Au/NH₂/ITO). The Au/NH₂/ITO and NH₂/ITO electrodes were used to observe the electrochemical behavior of Hemoglobin (Hb) immobilized on the electrodes surfaces. The peak current value of Hb immobilized on NH₂/ITO increased compared with on bare ITO while peak current value of Hb immobilized on Au/NH₂/ITO increased compared with on Au/ITO. Linkage between the ‐NH₂ implanted into the ITO film and the ‐COOH of Hb was thought to be the reason for the increase of active Hb coverage on NH₂/ITO compared with bare ITO. Increase of active Hb coverage on Au/NH₂/ITO compare with Au/ITO was attributed to the different amount of gold nanoparticles deposited. Results showed the novel NH₂/ITO and Au/NH₂/ITO electrodes exhibited good stability, reproducibility besides selectivity and sensitivity. The electrode process of Hb immobilized on Au/NH₂/ITO was quasi‐reversible with adsorption. The electrode reaction rate constant k_s and other related constants were determined. X‐ray photoelectron spectroscopy (XPS), field‐emission scanning electron microscopy (FE‐SEM), and impedance spectra were used to characterize the different surfaces.     

Substrate temperature effects on the structural,compositional, and electrical properties of VO2 thin films deposited by pulsed laser deposition

The vanadium dioxide (VO₂) thin films were deposited on silicon (100) substrate using the pulsed laser deposition technique. The thin films were deposited at different substrate temperatures (500°C, 600°C, 700°C, and 800°C) while keeping all the other parameters constant. X‐ray diffraction confirmed the crystalline VO₂ (B) and VO₂ (M) phase formation at different substrate temperatures. X‐ray photoelectron spectroscopy analysis showed the presence of V⁴⁺ and V⁵⁺ charge states in all the deposited thin films which confirms that the deposited films mainly consist of VO₂ and V₂O₅. An increase in the VO₂/V₂O₅ ratio has been observed in the films deposited at higher substrate temperatures (700°C and 800°C). Scanning electron microscope micrographs revealed different surface morphologies of the thin films deposited at different substrate temperatures. The electrical properties showed the sharp semiconductor to metal transition behavior with approximately 2 orders of magnitude for the VO₂ thin film deposited at 800°C. The transition temperature for heating and cooling cycles as low as 46.2°C and 42°C, respectively, has been observed which is related to the smaller difference in the interplanar spacing between the as‐deposited thin film and the standard rutile VO₂ as well as to the lattice strain of approximately −1.2%.     

XPS study of the Li intercalation process in sol–gel‐produced V2O5 thin film: influence of substrate and film synthesis modification

We report on the process of lithium intercalation in V₂O₅ thin films deposited onto standard ITO‐coated glass substrates. The films were deposited via a well‐established sol–gel route, and the samples were examined as working electrodes in a range of potentials versus lithium reference electrode. This paper follows up issues arising from parallel spectroscopic characterizations of the films by X‐ray photoelectron spectroscopy (XPS). Specifically, the XPS examination showed that not all of the Li‐ion charge inserted was accounted for by the V(5) to V(4) reduction, but the stoichiometric balance could be maintained only by considering additional oxygens arising from the intercalation procedure, leading to Li₂O formation. In this work, we have examined the possibility that the source of oxygen is the ITO substrate. To this purpose, films of V₂O₅ deposited on silicon substrates have been prepared using the sol–gel process and examined by XPS after electrochemical intercalation/de‐intercalation cycles. We show that in this case a perfect balance between electrochemical charge, inserted Li and reduced vanadium is obtained. A further indication of ITO‐substrate effects was obtained from examination, by the same methods, of some unconventional V₂O₅ films that had been co‐precipitated with a siloxane, designed to provide a template structure. The results obtained from this material imply that a barrier layer is formed at the ITO interface and, therefore, the formation of Li₂O is avoided. The results are discussed in terms of the possible degradation of conventional V₂O₅ on ITO as a result of electrochemically induced interface reactions. Copyright © 2005 John Wiley & Sons, Ltd.     

Modified electrodes with Keggin-type silicotungstates and poly(brilliant cresyl blue)

Electrosynthesis of poly(brilliant cresyl blue) in aqueous solution in the presence of Keggin-type polyoxotungstates, [SiW₁₁Fe(H₂O)O₃₉]^5? or [SiW₁₁Co(H₂O)O₃₉]^6?, was used to prepare modified glassy carbon electrodes. The deposited hybrid organic/inorganic films were studied and characterised by cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry showed that the electrochemical features of the polyoxoanions were maintained after immobilisation, with the first tungsten reduction peak involving the uptake of protons from the solution. The chemically modified electrodes were stable, and their preparation was easy to perform. The results provide valuable information for exploring future applications of these films in electrochemical sensors or electrocatalysis.     

Determination of hemoglobin at a novel NH2/ITO ion implantation modified electrode

A novel electrode was prepared by implanting NH₂ ⁺ into an ITO film (NH₂/ITO). Gold nanoparticles were deposited on the surface of NH₂/ITO electrode. The NH₂/ITO and Au/NH₂/ITO electrodes were used to determine hemoglobin (Hb) immobilized on the electrodes surfaces. The relationship of the reductive peak current value of Hb among different electrodes was: Hb/ITO:Hb/Au/ITO:Hb/NH₂/ITO:Hb/Au/NH₂/ITO=1:1.5:2:4. The linkage between the –NH₂ implanted into ITO film and the –COOH of Hb was recognized to be the reason for the increase of active Hb coverage on NH₂/ITO electrode compared with the ITO electrode. Increase of active Hb coverage on Au/NH₂/ITO compared with Au/ITO was attributed to the different amount of gold nanoparticles deposited. The determination of Hb at an Au/NH₂/ITO electrode was optimized. Calibration curve was obtained over the range of 1.0 × 10⁻⁸ – 1.0 × 10⁻⁶ mol · L⁻¹ with a detection limit of 1.0 × 10⁻⁸ mol · L⁻¹. Results showed that the novel NH₂/ITO and Au/NH₂/ITO electrodes exhibited good stability, reproducibility besides better electrochemical performance. Correspondence: Jing Bo Hu, Department of Chemistry, Beijing Normal University, Beijing 100875, China     

Effect of Annealing on the Electrical Properties of CuxS Thin Films

Copper sulphide CuS was deposited on three substrates; glass, Indium Tin Oxide (ITO) and Ti by using spray pyrolysis deposition (SPD). After depositing CuS thin films on the substrates at 200 °C, they were annealed at 50, 100, 150, and 200 °C for 1 hour. Structural measurements revealed covellite CuS and chalcocite Cu₂S phases for thin films before and after annealing at 200 °C with changes in intensities, and only covellite CuS phase for thin films after annealing at 50, 100, and 150 °C. Morphological characteristics show hexagonal-cubic crystals for the CuS thin film deposited on glass substrate and plates structures for films deposited on ITO and Ti substrates before annealing, these crystals became bigger in size and there were be oxidation and some agglomerations in some regions with formation of plates for CuS on glass substrate after annealing at 200 °C. For Hall Effect measurements, thin films sheet resistivity and mobility increased after annealing while the carrier concentration decreased. Generally, the thin film deposited on ITO substrate had the lowest resistivity and the highest carrier concentration before and after annealing. The thin film deposited on Ti substrate had the highest mobility before and after annealing, which makes it the best thin film for device performance. The objective of this research is to show the improvement of thin films electrical properties especially the mobility after annealing those thin films.     

Efficient degradation of methyl orange via multilayer films of titanium dioxide and silicotungstic acid

We report layer-by-layer (LbL) assembly of TiO2 and H4 SiW12 O40 (SiW 12 ) multilayer film on silicon wafers and glass slides for photocatalytic degradation of methyl orange (MO). The photocatalytic efficiency of the obtained multilayer film increases along with the decrease of pH and salt concentration of the incubation solution. The results show that MO can be almost removed in pH2.0 solution without salt addition in the first 60 min incubation when MO concentration is lower than 15 mg/L. Different salts show an apparent inhibitory effect on photocatalytic degradation of MO with the order of ZnCl2 >KCl> NaCl>LiCl. The TiO2 /SiW12 multilayer film maintains photocatalytic activity even after five degradation cycles. The reaction of MO photodegradation accords with an apparent first-order dynamics.     

Electrochemical Cholesterol Sensor Based on Tin Oxide‐Chitosan Nanobiocomposite Film

A chitosan (CS)‐tin oxide (SnO₂) nanobiocomposite film has been deposited onto an indium‐tin‐oxide glass plate to immobilize cholesterol oxidase (ChOx) for cholesterol detection. The value of the Michaelis–Menten constant (K_m) obtained as 3.8 mM for ChOx/CS‐SnO₂/ITO is lower (8 mM) than that of a ChOx/CS/ITO bioelectrode revealing enhancement in affinity and/or activity of ChOx towards cholesterol and also revealing strong binding of ChOx onto CS‐SnO₂/ITO electrode. This ChOx/CS‐SnO₂/ITO cholesterol sensor retains 95% of enzyme activity after 4–6 weeks at 4 °C with response time of 5 s, sensitivity of 34.7 μA/mg dL^?1 cm² and detection limit of 5 mg/dL.     

Layer-by-layer self-assembly and electrocatalytic properties of poly(ethylenimine)-silicotungstate multilayer composite films

Hybrid multilayer films composed of poly(ethylenimine) and the Keggin-type polyoxometalates [ SiW₁₁O₃₉ ]^{8 -} ( SiW₁₁ ) {\left[ {{\hbox{Si}}{{\hbox{W}}_{{11}}}{{\hbox{O}}_{{39}}}} \right]^{{8} - }}\left( {{\hbox{Si}}{{\hbox{W}}_{{11}}}} \right) and [ SiW₁₁Co^II( H₂O )O₃₉ ]^{6 -} ( SiW₁₁Co ) {\left[ {{\hbox{Si}}{{\hbox{W}}_{{11}}}{\hbox{C}}{{\hbox{o}}^{\rm{II}}}\left( {{{\hbox{H}}_2}{\hbox{O}}} \right){{\hbox{O}}_{{39}}}} \right]^{{6} - }}\left( {{\hbox{Si}}{{\hbox{W}}_{{11}}}{\hbox{Co}}} \right) were prepared on glassy carbon electrodes by layer-by-layer self-assembly, and were characterized by cyclic voltammetry and scanning electron microscopy. UV-vis absorption spectroscopy of films deposited on quartz slides was used to monitor film growth, showing that the absorbance values at characteristic wavelengths of the multilayer films increase almost linearly with the number of bilayers. Cyclic voltammetry indicates that the electrochemical properties of the polyoxometalates are maintained in the multilayer films, and that the first tungsten reduction process for immobilized SiW₁₁ and SiW₁₁Co is a surface-confined process. Electron transfer to [ Fe( CN )₆ ]^{3 - /4 -} {\left[ {{\hbox{Fe}}{{\left( {\hbox{CN}} \right)}_6}} \right]^{{3} - /{4} - }} and [ Ru( NH₃ )₆ ]^{3 + /2 +} {\left[ {{\hbox{Ru}}{{\left( {{\hbox{N}}{{\hbox{H}}_3}} \right)}_6}} \right]^{{3} + /{2} + }} as electrochemical probes was also investigated by cyclic voltammetry. The (PEI/SiW₁₁Co)_n multilayer films showed excellent electrocatalytic reduction properties towards nitrite, bromate and iodate.     

稀碱溶液中水热法制备柔性TiO2纳米须薄膜的生长机制及表征

以柔性不锈钢基底上经磁控溅射沉积的钛膜为钛源, 在1 mol·L^-1的低浓度NaOH溶液中水热法制备了朝基底上方取向生长的大长径比柔性TiO₂纳米须薄膜, 考察了钛膜沉积条件对纳米须薄膜的影响, 系统研究了水热反应条件对薄膜生长过程的影响及TiO₂纳米须薄膜的形成机制. 通过场发射扫描电镜(FESEM)、X射线能谱仪(EDS)、高分辨透射电子显微镜(HRTEM)、X射线衍射仪(XRD)等对样品进行了表征. 结果表明, 与室温沉积的钛膜相比, 600 ℃下沉积的钛膜水热后得到的纳米线薄膜与基底的附着力更好. 所得TiO₂纳米须为单晶锐钛矿, 经由Na₂Ti₂O₄(OH)₂、H₂Ti₂O₅·H₂O转变而来. 纳米须形成于水热阶段, 平行于Na₂Ti₂O₄(OH)₂的(100)晶面择优取向生长, 纳米须经历了纳米片→纳米线束→纳米线的裂解生长过程. 朝基底上方取向生长的纳米须薄膜的形成是低浓度NaOH溶液与较高水热温度(220 ℃)协同作用的结果. 进一步在Na₂SO₄溶液中研究了薄膜电极的光电化学性能, 结果表明, TiO₂纳米须薄膜的光电性能明显优于零维纳米颗粒薄膜和二维纳米片薄膜, 显示了良好的应用前景.     

Electrocatalytic response of GMP on an ITO electrode modified with a hybrid film of Ni(II)–Al(III) layered double hydroxide and amphiphilic Ru(II) cyanide complex

A thin film of Ni(II)–Al(III) layered double hydroxide hybridized with an amphiphilic anionic Ru(II) complex ((N(C₂H₅)₄)₂[Ru(CN)₄(dc18bpy)]:dc18bpy=4,4^′-octadecyl-2,2^′-bipyridine) was prepared by the Langmuir–Blodgett (LB) method. Hybridization was performed by spreading a chloroform solution of (N(C₂H₅)₄)₂[Ru(CN)₄(dc18bpy)] onto an aqueous suspension of Ni(II)–Al(III) layered double hydroxide. The film was deposited onto a solid substrate such as an ITO electrode and mica. Atomic force microscopic (AFM) observation on the deposited film confirmed that about 9.0 nm thick Ni(II)–Al(III) layered double hydroxide particles were uniformly adsorbed by the monolayer of Ru(II) complex. Cyclic voltammograms on an ITO electrode modified with a single layer of the hybrid film gave quasi-reversible reduction–oxidation peaks due to Ni(II)/Ni(III) in a phosphate buffer at pH 7.67. When the mononucleotide of guanosine 5^′-monophosphate (GMP) was added in an electrolyte solution, the increase of oxidation current above 800 mV (vs SCE) was observed at the expense of the reduction peak of Ni(III). The results indicate that Ni(II) in the layered double hydroxide lattice acts as a mediator in oxidation of GMP. The modified electrode shows great enhancement in the oxidation of GMP in comparison with a bare ITO electrode.     

Sol–gel derived nanoporous cerium oxide film for application to cholesterol biosensor

Cholesterol oxidase (ChOx) has been immobilized onto sol–gel derived nano-structured cerium oxide (NS-CeO₂) film deposited on indium-tin-oxide (ITO) coated glass substrate. Phase identification of sol–gel NS-CeO₂ film carried out using X-ray diffraction (XRD) yields reflection peak at 29.4° corresponding to (1 1 1) plane with oriented crystallite (34 nm) along c-axis normal to the substrate. Electrochemical studies reveal that NS-CeO₂ provides electroactive surface for the loading of ChOx and enhances electron transfer rate in the ChOx/NS-CeO₂/ITO bioelectrode. The low value of Michaelis–Menten constant (K_m) obtained as 2.08 mM indicates enhanced ChOx affinity to cholesterol. The observed results show application of sol–gel derived NS-CeO₂ for biosensing without any functionalization.     

Optical constants,dispersion energy parameters and dielectric properties of ultra-smooth nanocrystalline BiVO4 thin films prepared by rf-magnetron sputtering

BiVO₄ thin films have been prepared through radio frequency (rf) magnetron sputtering of a pre-fabricated BiVO₄ target on ITO coated glass (ITO-glass) substrate and bare glass substrates. BiVO₄ target material was prepared through solid-state reaction method by heating Bi₂O₃ and V₂O₅ mixture at 800 °C for 8 h. The films were characterized by X-ray diffraction, UV–Vis spectroscopy, LCR meter, field emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy. BiVO₄ thin films deposited on the ITO-glass substrate are much smoother compared to the thin films prepared on bare glass substrate. The rms surface roughness calculated from the AFM images comes out to be 0.74 nm and 4.2 nm for the films deposited on the ITO-glass substrate and bare glass substrate for the deposition time 150 min respectively. Optical constants and energy dispersion parameters of these extra-smooth BiVO₄ thin films have been investigated in detail. Dielectric properties of the BiVO₄ thin films on ITO-glass substrate were also investigated. The frequency dependence of dielectric constant of the BiVO₄ thin films has been measured in the frequency range from 20 Hz to 2 MHz. It was found that the dielectric constant increased from 145 to 343 at 20 Hz as the film thickness increased from 90 nm to 145 nm (deposition time increased from 60 min to 150 min). It shows higher dielectric constant compared to the literature value of BiVO₄.     

Photoelectrochemical Properties of Sol-Gel Processed Ag-TiO2 Nanocomposite Thin Films

Ag-TiO₂ thin films were prepared with a sol-gel route, using titanium isopropoxide and silver nitrate as precursors, at 0, 0.03 and 0.06 Ag/Ti nominal atomic ratios. After drying at 80°C, the films were fired at 300°C, 500°C, and 600°C for 30 min and 5 h. Glancing angle X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS), with depth profiling of the concentration, were used to study the films. XPS analysis showed the presence of C and N as impurities in the nanocomposite films. Their concentration decreased with increasing the firing temperature. Chemical state analysis showed that Ag was present in metallic state, except for the outer layer where it was present as Ag⁺. For the films prepared with a Agt/Ti concentration of 0.06, depth profiling measurements of the film fired at 300°C showed a strong Ag enrichment at the outer surface, while composition remained almost constant within the rest of the film, at Ag/Ti atomic ratio of 0.02. Two layers were found for the films heated to 500°C, where the Ag/Ti ratios were 0.015 near the surface and 0.03 near the substrate. The photoelectrochemical properties of Ag-TiO₂ were studied for thin films deposited on ITO substrates. Photocurrents of Ag-TiO₂ nanocomposite electrodes fired at 300°C were observed even at visible light, for wavelengths longer than 400 nm.     

Electrocatalysis of the hydrogen evolution reaction by nanocomposites of poly(amidoamine)-encapsulated platinum nanoparticles and phosphotungstic acid

Poly(amidoamine) dendrimer (Generation-4) encapsulated platinum nanoparticles (PtNP-PAMAM) were prepared and used to fabricate nanocomposites with Keggin-type phosphotungstic acid (PW₁₂O₄₀³⁻) using a layer by layer electrostatic assembly technique. Indium tin oxide (ITO) electrodes, which were first modified with a monolayer of 3-aminopropyl triethoxysilane (3-APTES), were used as substrates for assembly of the PW₁₂O₄₀³⁻ monolayer. Nanocomposites were then fabricated by depositing PtNP-PAMAM on the monolayer of PW₁₂O₄₀³⁻. The amount of PtNP-PAMAM deposited was controlled by using different concentrations of PtNP-PAMAM diluted in 0.1 M H₂SO₄ solution. The hydrogen evolution reaction (HER) was used to test electrocatalytic activities of these nanocomposite modified electrodes. Modification of ITO|3-APTES with PW₁₂O₄₀³⁻ |PtNP-PAMAM showed significantly higher electrocatalytic activities toward the HER than electrodes modified with either PW₁₂O₄₀³⁻ or PtNP-PAMAM alone. The electrocatalytic activities were found to depend on the composition of PtNP-PAMAM and PW₁₂O₄₀³⁻ on electrode surfaces, which was attributed to an interaction between these species. Heat treatment of ITO|3-APTES|PW₁₂O₄₀³⁻ |PtNP-PAMAM electrodes at 200 °C produced significantly higher electrocatalytic activities, which supported the suggestion of an interaction. Presented at the 4th Baltic conference on Electrochemistry, Griefswald, March 13.−16., 2005.     

A Novel Chemical Sensor Based on Sb2S3 Film for Highly Sensitive Detection of Hydrazine

The Sb₂S₃ film on indium‐tin oxide (ITO) substrate has been used as an efficient electron transfer mediator for the fabrication of novel chemical sensor towards hydrazine, which is a diamine known as neurotoxin and carcinogen. Sb₂S₃ film is deposited on ITO substrate by drop‐casting process using Sb₂S₃ solution as precursor and possesses reticular structure with the morphology of uniform hollow hemispheres. The fabricated chemical sensor for selective detection of hydrazine displays a high sensitivity of 106.25 μA/(mM cm²) with a low detection limit of 0.5 μM and it also exhibits excellent reproducibility and stability in hydrazine detection.     

Catalytic Effect on Silver Electrodeposition of Gold Deposited on Carbon Electrodes

A new methodology, based on silver electrocatalytic deposition and designed to quantify gold deposited onto carbon paste electrode (CPE) and glassy carbon electrode (GCE), has been developed in this work. Silver (prepared in 1.0 M NH₃) electrodeposition at ?0.13 V occurs only when gold is previously deposited at an adequate potential on the electrode surface for a fixed period of time. When a CPE is used as working electrode, an adequate oxidation of gold is necessary. This oxidation is carried out in both 0.1 M NaOH and 0.1 M H₂SO₄ at oxidation potentials. When a GCE is used as working electrode, the oxidation steps are not necessary. Moreover, a cleaning step in KCN, which removes gold from electrode surface, is included. To obtain reproducibility in the analytical signal, the surface of the electrodes must be suitably pretreated; this electrodic pretreatment depends on the kind of electrode used as working electrode. Low detection limits (5.0×10^?10 M) for short gold deposition times (10 min for CPE and 5 min for GCE) were achieved with this novel methodology. Finally, sodium aurothiomalate can be quantified using silver electrocatalytic deposition and GCE as working electrode. Good linear relationship between silver anodic stripping peak and aurothiomalate concentration was found from 5.0×10^?10 M to 1.0×10^?8 M.