Acetate Bath Research Articles

ELECTROCATALYTIC OXIDATION OF ALCOHOLS ON Cu2O/Cu THIN FILM ELECTRODEPOSITED ON TITANIUM SUBSTRATE

A novel class of nanomaterials consisting of a composite thin film of cooper metal nanoparticles and cuprous oxide (Cu2O/Cu) for the catalytic electrooxidation of methanol, ethanol and ethylene glycol is considered here. The material was prepared by electrochemical deposition under a potentiostatic condition of [Formula: see text][Formula: see text]mV vs saturated calomel electrode (SCE) from acetate bath at titanium substrate. The effect of electrodeposition time on the structure, composition and morphology of the deposit was investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated the formation of pure cuprous oxide Cu2O thin film at low electrodeposition time (5 min) and Cu2O oxide thin film decorated with Cu nanoparticles (Cu2O/Cu) at high electrodeposition time. The obtained Cu2O and Cu2O/Cu thin films were explored for the electrochemical oxidation of alcohols in 1 M NaOH alkaline medium using cyclic voltammetry (CV) method. The Cu2O/Cu thin film grown at electrodeposition time of 15 min shows the best electrocatalytic performance toward ethanol oxidation. The effect of concentration of alcohols on the oxidation reaction was studied by CV and chronoamperometry. It was found that the reaction is governed by an irreversible diffusion process. The promising electrocatalytic activity of the Cu2O/Cu electrode provides a new platform for the fabrication of high-performance thin films for alcohols oxidation in alkaline medium. Therefore, the Cu2O/Cu electrode is a suitable as a less expensive electrocatalyst for alcohols oxidation.

Electrodeposited Cu2O homojunction solar cells: Fabrication of a cell of high short circuit photocurrent

A Cu2O homojunction solar cell was fabricated using a consecutive electrodeposition method of deposition of an n-Cu2O film followed by a p-Cu2O film, in two different acetate baths. Both n-type and p-type film growth conditions were optimized separately to yield high photocurrents in a photoelctrochemical (PEC) cell. Further, the resulted bi-layer films were investigated in the PEC for the verification of the formation of the p-n homojunction. In addition, p-Cu2O film surfaces of the bi-layers were sulphided using Na2S and (NH4)2S in order to improve the photoresponse of the homojunction before depositing a Au film for the solar cell device. The structural, morphological and optoelectronic properties of the Cu2O films were investigated using X-ray diffraction (XRD), scanning electron micrographs (SEMs), dark and light current–voltage (I-V) and spectral response measurements and observed that the films are of good quality. Incident photon to current efficiency (IPCE) and I-V characteristics of the solar cell device demonstrated that the Cu2O homojunction can produce a high short circuit current density Jsc. However, the overall conversion efficiency of the device is low due to poor fill factor and Voc. The solar cell characteristics of the structure Ti/n-Cu2O/p-Cu2O/Au were Voc=287.0±0.1mV, Jsc=12.4±0. 1mA/cm2, FF=25±2% and η=0.89±0.02%, under AM 1.5 illumination. The record high Jsc value of the device demonstrates the prospect being improved the efficiency of Cu2O homojunction solar cells by optimizing deposition, pretreatment and post treatment processes.

Preparation of porous nanostructured Ag electrodes for sensitive electrochemical detection of hydrogen peroxide

Porous Ag layers have been prepared by hydrogen bubble templated electrodeposition from an ammonium acetate bath, under application of a large current density (–2Acm−2). SEM images of the layers show macroscopic porosity and a spongy dendritic structure, analogous to those observed for other porous metals/alloys deposited with a similar procedure. A deposition charge of 30Ccm−2 produces a porous deposit with a mass of ca 1.7mgcm−2. The roughness factor fr is evaluated by impedance and from the charge density of Pb UPD; both methods provide estimates of fr in the order of several hundreds but values obtained from impedance analysis are more than twice larger. Mass transport to the porous electrodes is studied by linear sweep voltammetry at stationary and rotating disk electrodes. In comparison with flat Ag cathodes, porous Ag electrodes show larger sensitivity, lower limit of detection and extended range of linear response in H2O2 reduction.

Microstructure and corrosion behavior of electrodeposited nanocrystalline nickel prepared from acetate bath

The present investigation deals with the electrodeposition of nanocrystalline nickel onto mild steel metallic foil from electrolytes containing nickel acetate as the major metal salt. Two different chlorides, potassium chloride and nickel chloride, were tried for two different baths. Potassium citrate was used as buffer for alternate to boric acid. The additives tried were sodium lauryl sulfate as wetting agent, saccharin as primary brightener and 2-butyne 1,4-diol as secondary brightener. These additives are found to improve the hardness, grain size, surface morphology of the electrodeposited nickel films and throwing power of the nickel acetate electrolytes. The nickel films prepared from nickel chloride containing electrolytes showed higher corrosion resistance as compared to potassium chloride containing electrolytes, because the nickel films produced from the nickel chloride electrolytes are compact and possess fine grained structure. The XRD pattern obtained for electrodeposited nickel shows polycrystalline face centered cubic structure. The crystal size was calculated using Scherrer formula. A uniform and pore free surface was observed under SEM analysis.

Characterizations of electrodeposited Ni–CeO2 nanocomposite coatings

The expansion of current machinery requires metallic materials with better surface properties. In the present investigation, CeO2 reinforced nickel nanocomposite coatings were deposited on mild steel substrate by direct current electrodeposition process employing nickel acetate bath. The effect of incorporation of CeO2 particles in the Ni nanocomposite coatings on the micro hardness and corrosion behaviour has been evaluated. Smooth and compact nanocomposite deposits containing well-distributed cerium oxide particles were obtained. The crystallite structure was fcc for electrodeposited nickel and Ni–CeO2 nanocomposite coatings. It has been observed that, the presence of CeO2 nanoparticles favours the [111] and [200] texture of nickel matrix. The co-deposition of CeO2 nanoparticles with nickel was found to be favoured at applied current density of 8 A dm−2. The micro hardness values of the nickel nanocomposite coatings (725 HV) was higher than that of pure nickel (265 HV).The decrease in Icorr values and increase in Constant Phase Element values were investigated in 3.5% NaCl solution which showed the higher corrosion resistant nature of Ni–CeO2 coatings.

Methods for improving n-type photoconductivity of electrodeposited Cu2O thin films

Electrodeposition technique is very useful for depositing n-type Cu2O thin films on various substrates. However, most of the reported n-type Cu2O thin film electrodes exhibit not only n-type photoactivity but also p-type photoactivity in photoelectrochemical cells. In this study, current–voltage characteristics and zero bias spectral response measurements were employed to investigate the possibilities to remove/minimize this unwanted p-type behaviour of n-type Cu2O thin films electrodeposited on Ti substrate. For this, prior deposition of Cu thin films on Ti substrate, low temperature annealing of Cu2O films in air and optimization of deposition bath pH were investigated. Growth of a very thin Cu film improved the n-type photosignal significantly and reduced the p-type photoresponse of the films. Films electrodeposited using an acetate bath of pH 6.1 produced only the n-type photoresponse. Low temperature annealing of Cu2O films in air improved the n-type photoresponse and it was found that annealing at 100 °C for 24 h produces the best result. These methods will be very useful to obtain electrodeposited Cu2O thin film with improved n-type photoactivity suitable for applications in thin film solar cells and other devices.

Pulse electrodeposition and corrosion properties of Ni–Si3N4 nanocomposite coatings

The development of modern technology requires metallic materials with better surface properties. In the present investigation; Si3N4-reinforced nickel nanocomposite coatings were deposited on a mild steel substrate using pulse current electrodeposition process employing a nickel acetate bath. Surface morphology, composition, microstructure and crystal orientation of Ni and Ni–Si3N4 nanocomposite coatings were investigated by scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction analysis, respectively. The effect of incorporation of Si3N4 particles in the Ni nanocomposite coating on the micro hardness, corrosion behaviour has been evaluated. Smooth composite deposits containing well-distributed silicon nitride particles were obtained and the crystal grains on the surface of Ni–Si3N4 composite coating are compact. The crystallite structure was face centred cubic (fcc) for electrodeposited nickel and Ni–Si3N4 nanocomposite coatings. The micro hardness of the composite coatings (720 HV) was higher than that of pure nickel (310 HV) due to dispersion-strengthening and matrix grain refining and increased with the increase of incorporated Si3N4 particle content. The corrosion potential (E corr) in the case of Ni–Si3N4 nanocomposite had shown a negative shift, confirming the cathodic protective nature of the coating.

Effect of additives on electrodeposition of nickel from acetate bath: cyclic voltammetric study

The electrochemical reactions occurring during the deposition of nickel from the acetate bath with various additives have been studied using a cyclic voltammetric technique. The influence of the addition of nickel chloride, boric acid and additives such as 2-butyne-1,4-diol, coumarin and saccharin in the acetate bath has been systematically investigated. From the surface coverage data, the Gibbs free energy change () for the absorption of the brightener has been calculated.

Sulfidation of electrodeposited microcrystalline/nanocrystalline cuprous oxide thin films for solar energy applications

Grain size of polycrystalline semiconductor thin films in solar cells is optimized to enhance the efficiency of solar cells. This paper reports results on an investigation carried out on electrodeposited n-type cuprous oxide (Cu2O) thin films on Ti substrates with small crystallites and sulfidation of them to produce a thin-film solar cell. During electrodeposition of Cu2O films, pH of an aqueous acetate bath was optimized to obtain films of grain size of about 100 nm, that were then used as templates to grow thicker n-type nanocrystalline Cu2O films. XRD and SEM analysis revealed that the films were of single phase and the substrates were well covered by the films. A junction of Cu2O/CuxS was formed by partially sulfiding the Cu2O films using an aqueous sodium sulfide solution. It was observed that the photovoltaic properties of nano Cu2O/CuxS heterojunction structures are better than micro Cu2O/CuxS heterojunction solar cells. Resulting Ti/nano Cu2O/CuxS/Au solar cell structure produced an energy conversion efficiency of 0.54%, Voc = 610 mV and Jsc = 3.4 mA cm−2, under AM 1.5 illumination. This is a significant improvement compared to the use of microcrystalline thin film Cu2O in the solar cell structure where the efficiency of the cell was limited to 0.11%. This improvement is attributed mainly to the increased film surface area associated with nanocrystalline Cu2O films.

Physical and electrochemical characterizations of Ni-SiO2 nanocomposite coatings

Advances in materials performance often require the development of composite system. In the present investigation, SiO2-reinforced nickel composite coatings were deposited on a mild steel substrate using direct current electrodeposition process employing a nickel acetate bath. Surface morphology, composition, microstructure and crystal orientation of the Ni and Ni-SiO2 nanocomposite coatings were investigated by scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction analysis, respectively. The effect of incorporation of SiO2 particles in the Ni nanocomposite coating on the microhardness and corrosion behaviour has been evaluated. Smooth composite deposits containing well-distributed silicon oxide particles were obtained. The preferred growth process of the nickel matrix in crystallographic directions , and is strongly influenced by SiO2 nanoparticles. The average crystallite size was calculated by using X-ray diffraction analysis and it was ~23 nm for electrodeposited nickel and ~21 nm for Ni-SiO2 nanocomposite coatings. The crystallite structure was fcc for electrodeposited nickel and Ni-SiO2 nanocomposite coatings. The incorporation of SiO2 particles into the Ni matrices was found to improve corrosion resistance of pure Ni coatings. The corrosion potential (Ecorr) in the case of Ni-SiO2 nanocomposite coatings had shown a negative shift, confirming the cathodic protective nature of the coating. The Ni-SiO2 composite coatings have exhibited significantly improved microhardness (615 HV) compared to pure nickel coatings (265 HV)

Composition, morphology and electrical transport properties of Co–Pb electrodeposits

Bath compositions were elaborated for the codeposition of Co and Pb by taking into account the chemical compatibility of Co2+ and Pb2+ with the appropriate anions. Electrolytes containing either acetate, chloride or nitrate anions were tested, but only the acetate bath proved to be appropriate for the preparation of compact Co–Pb films. Deposits were obtained with constant current, with constant potential or by using various current and potential pulses in order to investigate the possibility of multilayer formation. The variation in deposit composition as a function of the deposition parameters was elucidated by using cyclic voltammetry, current transient measurements and gravimetry. X-ray diffraction (XRD) patterns recorded for two-pulse plated deposits revealed a nanocrystalline structure with grain sizes in the range 5–20nm. The XRD peaks could be well indexed to pure face-centered cubic Co and Pb, indicating that the Pb codeposited with Co is not dissolved in Co but is segregated. Both the d.c. – plated and the two-pulse plated deposits exhibited anisotropic magnetoresistance without an indication for a noticeable giant magnetoresistance contribution. This means that the observed magnetoresistance arises from spin-dependent electron scattering events dominantly within the sufficiently large Co regions and not along electron paths between two Co regions via the Pb regions. Low-temperature resistivity measurements revealed a superconducting transition slightly below that of pure Pb. This may be ascribed to a proximity effect: the ferromagnetic Co grains suppress somewhat the superconductivity of the Pb phase due to the nanoscale phase mixture of the two constituents.

Layer-by-layer analysis of hot-dip zinc coating by anodic dissolution in acetate bath

To analyze the distribution of the alloying elements in hot-dip zinc coatings, a layer-by-layer electrochemical dissolution method was studied by using an acetate bath. The research was performed by means of galvanostatic anodic polarization, chemical analysis and metallographic analysis. A suitable cell was constructed to perform this study. Results show that the electrochemical dissolution of η-phase is uniform, while δ-phase dissolves partially together ζ-phase, due to the formation of cracks in the coating during polarization. Faraday's law was used to demonstrate that galvanostatic dissolution of hot-dip zinc coating at 12.7mAcm−2 proceeds by electrochemical mechanism without chemical dissolution; on the contrary, the occurrence of this second process was found at lower stripping current density. During polarization, the formation of a black film which interferes with the subsequent dissolution process was found. Mechanical removal of black film from electrode surface leads to the decrease of cracks formation and to a more uniform layer-by-layer dissolution. A method to obtain layer-by-layer analysis of the alloying elements of a hot-dip zinc coating, as a function of its thickness, by controlled electrochemical dissolution is suggested.

Enhanced crystal grain size by bromine doping in electrodeposited Cu2O

Extremely large crystal grains are obtained by bromine doping in electrodeposited Cu2O on indium tin oxide (ITO) substrate through an acetate bath. The grains are as large as 10,000μm2 in area, or ~100μm in linear dimension, while the film is only 1–5μm thick. The enhanced grain size is explained by the effect of over-potential for the Cu2+/Cu+ redox couple on nucleation density of Cu2O on ITO substrate. The over-potential is a function of several deposition conditions including solution pH, deposition potential, deposition temperature, bromine precursor concentration, and copper precursor concentration. In addition, undoped Cu2O displays a high resistivity of 100MΩcm. Bromine doping in Cu2O significantly reduces the resistivity to as low as 42Ωcm after vacuum annealing. Br-doped Cu2O shows n-type behavior.

Preparation of Ni-TiC Nanocomposites by Electrolytic Codeposition from a Non Aqueous Bath and Their Characterization

Nickel-titanium carbide (Ni-TiC) nanocomposite coatings were prepared under direct current conditions by codeposition of nano titanium carbide (TiC) particles (<200 nm) and nickel from a nickel acetate bath using N-methylformamide as a non aqueous solvent. Influence of current density, concentration of TiC particles, agitation and temperature of bath was investigated and the optimum values of these parameters for reaching maximum weight% incorporation of TiC particles in the coating were determined. Coatings morphology and chemical composition were characterized by SEM and EDAX analysis. Crystallographic structures and microhardness were investigated. Also it is seen that the existence of second ceramic phase in the co-deposited layer reduces the average crystallite size of Ni-matrix to 11.5 nm and the composite possessed fcc lattice.

The deposition of smooth metallic molybdenum from aqueous electrolytes containing molybdate ions

This paper details the electrodeposition of metallic molybdenum from an aqueous electrolyte containing molybdate ions. The deposition is performed in an acetate bath that contains a high (up to 10 M) concentration of acetate. The molybdenum deposits are thick (up to 20 μm), adherent and were characterized by XRD and XPS analysis. The deposition is inefficient, with most of the current (up to 99%) used in the electrolysis of water to generate hydrogen. The effect of acetate concentration, pH, additives and current on the deposition efficiency and physical properties of the molybdenum deposit were investigated and optimized to obtain smooth, adherent coatings.

Characterisation of nickel deposits from nickel acetate bath

The electrodeposition of nickel on mild steel was carried out using a nickel acetate bath. Cathodic polarisation studies were conducted, and cathodic current efficiency, throwing power and hardness of electrodeposits from the bath were all assessed. The effects of nickel chloride, and nickel acetate content in the bath, the pH and bath temperature on the above properties were analysed. The optimum conditions of bath composition and operation were established and the bath was found to be stable for the electrodeposition of nickel.

Fortification of Ni–Y2O3 nanocomposite coatings prepared by pulse and direct current methods

Ni–Y2O3 nanocomposite coatings were prepared under direct current (DC) and pulse current (PC) using acetate bath. The microstructure and corrosion resistance of the coatings were characterized by means of XRD, SEM, AFM, and EIS. The results showed that the microstructure and performances of the coatings were greatly affected by Y2O3 content on the deposits prepared by DC and PC methods. The microhardness and corrosion resistance were enhanced in the optimum percentage of Y2O3 composite coatings. The PC composite coatings were exhibited compact surface, higher microhardness, and good corrosion resistance compared with that of the DC composite coatings.

Electrodeposition of p-type, n-type and p-n Homojunction Cuprous Oxide Thin Films

Potentiostatic electrodeposition of cuprous oxide (Cu 2 O) thin films in aqueous acetate baths was investigated to study the conduction type, n-type or p-type, and the p-n homojunction formation of the films, using photocurrent spectral response and capacitance-voltage measurements to determine the conduction type. The study reveals that not only the pH value but also the cupric ion concentration of the acetate bath determines the conduction type of the films. Electrodeposition of p-n homojunction of Cu 2 O is possible with a single or a two step electrodeposition. Both parameters of the deposition bath, pH and cupric ion concentration, can be adjusted to control conduction type and p-n homojunction formation of Cu 2 O films. Keywords : cuprous oxide; electrodeposition; n- and p-type; spectral response; p-n homojunction DOI: http://dx.doi.org/10.4038/sljp.v9i0.2509 Sri Lanka Journal of Physics Vol.9 (2008) pp.35-46

Nonenzymatic Electrochemical Glucose Sensor Based on Novel Copper Film

AbstractNovel copper (Cu) film composed of pillar‐like structure was synthesized on indium‐doped tin oxide (ITO) substrate by electrodeposition in acetate bath with proline as additive for the first time and used to construct nonenzymatic glucose sensor. When applied to detect glucose, such prepared electrode showed low operating potential (0.4 V), high sensitivity (699.4499 µA mM−1 cm−2), and fast response time (&lt;3 s) compared with other Cu‐based electrodes. In addition, the prepared electrode also offered good anti‐interference ability to ascorbic acid, uric acid and acetaminophen. Present study provides new insights into the control of Cu film morphology for sensor fabrication.

Ni–Co–TiO 2 nanocomposite coating prepared by pulse and pulse reversal methods using acetate bath

Ni–Co/nano TiO 2 (Ni–Co–TiO 2) composite coatings were prepared under pulse current and pulse reverse current methods using acetate bath. The microstructure and corrosion resistance of the coatings were characterized by means of XRD, SEM and EIS. Both the Ni–Co alloy and composite coatings exhibited single phase of Ni matrix with face centered cubic (fcc) crystal structure. The crystal orientation of the Ni–Co–TiO 2 composite coating was transformed from crystal face (2 0 0) to (1 1 1) compared with Ni–Co alloy coatings. The results showed that the microstructure and performances of the coatings were greatly affected by TiO 2 content on the deposits prepared by PC and PRC methods. The microhardness and corrosion resistance were enhanced in the optimum percentage of TiO 2 composite coatings. The PRC composite coatings were exhibited from compact surface, higher microhardness and good corrosion resistance compared with that of the PC composite coating.