Function Of Deposition Potential Research Articles

Development of phosphor containing functional coatings via cold atmospheric pressure plasma jet - Study of various operating parameters

Abstract In this study, we deposited phosphorous containing functional coatings on the surface of polypropylene (PP) substrate by cold atmospheric plasma assisted polymerization using low temperature plasma jet. Triisopropyl phosphate (TIP) was used as precursor while the coating process was carried out as a function of deposition potential and monomer flow rate. The influence of various plasma polymerization operating parameters on the surface properties of functional coatings are examined by means of atomic force microscopy (AFM), Scanning electron microscopy (SEM) and X-ray photo electron spectroscopy (XPS). The reactive species involved during the in-situ polymerization were studied by optical emission spectroscopy (OES). The variation in hydrophilic properties of the surface coated film was investigated by measuring contact angle. Furthermore, the stability of post-plasma polymerized films was evaluated by measuring contact angle values 15 days after storing in various ambient conditions (air and distilled water). The characterization results clearly exhibited that phosphorus containing functional films could be successfully deposited on the surface of PP films and the retention of the functional groups could be tuned within the framework of the operating parameters.

Effect of Deposition Potential on Synthesis, Structural, Morphological and Photoconductivity Response of Cu2O Thin Films by Electrodeposition Technique

The present work describes the effect of deposition potentials on structural, morphological, optical, electrical and photoconductivity responses of cuprous oxide (Cu2O) thin films deposited on fluorine-doped tin oxide glass substrate by employing electrodeposition technique. X-ray diffraction patterns reveal that the deposited films have a cubic structure grown along the preferential (111) growth orientation and crystallinity of the film deposited at − 0.4 V is improved compared to the films deposited at − 0.2, − 0.3 and − 0.5 V. Scanning electron microscopy displays that surface morphology of Cu2O film has a well-defined three-sided pyramid-shaped grains which are uniformly distributed over the surface of the substrates and are significantly changed as a function of deposition potential. Raman and photoluminescence spectra manifest that the film deposited at − 0.4 V has a good crystal quality with higher acceptor concentration compared to other films. UV–visible analysis illustrates that the absorption of Cu2O thin film deposited at − 0.4 V is notably higher compared to other films and the band gap of Cu2O thin films decreases from 2.1 to 2.04 eV with an increase in deposition potential from − 0.2 to − 0.5 V. The frequency–temperature dependence of impedance analysis shows that the film deposited at − 0.4 V has a high conductivity. I–V measurements elucidate that the film deposited at − 0.4 V exhibits a good photoconductivity response compared to films deposited in other deposition potentials.

Electrochemical co-deposition of tungsten with cobalt and copper: Peculiarities of binary and ternary alloys coatings formation

Abstract Binary Cu-W, Co-W and ternary Co-Cu-W alloy coatings were electrochemically deposited onto stainless steel substrate from a citrate-borate electrolyte under potentiostatic mode at 20 and 60 °C. The cathodic polarization, current efficiency of co-deposition, chemical composition and structure of the prepared alloys as a function of deposition potential and temperature were studied and compared to those of binary Cu-W and Co-W alloys. All deposits were of uniform thickness, without cracks and well adhered to the substrate. The cathodic current efficiency increases with the bath temperature and cathodic deposition potential increase. The polarization studies revealed that Cu-W alloy deposition starts at more negative potentials than those of Co-W and Co-Cu-W that leads to the lowest current efficiency for Cu-W (20%) in comparison with up to ~ 90% obtained for Co-Cu-W and Co-W alloys electrodeposition. Also, this results in the low W content in the Cu-W coatings (

Electrodeposition of Cu–In alloys from a choline chloride based deep eutectic solvent for photovoltaic applications

Electrodeposition and post-annealing is a promising low-cost approach to the growth of Cu(In,Ga)Se2 for photovoltaic applications. However, In and Ga electrodeposition is not facile from aqueous electrolytes. Efficient electrodeposition can be achieved by using deep eutectic solvent (DES) based electrolytes since solvent decomposition reactions (such as hydrogen evolution reaction in water) do not occur.In this work, the electrochemical behavior of InCl3 and CuCl2–InCl3 on the DES 1:2 choline chloride:urea (ChCl:U) on a Mo rotating disk electrode is studied via cyclic voltammetry. The deposited Cu–In thin films are characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) in terms of morphology and composition and X-ray diffraction (XRD) regarding crystal structure. The cyclic voltammetric studies on the ChCl:U–CuCl2–InCl3 system showed multiple cathodic and anodic responses, which were assigned to various crystalline phases. The crystalline phases, composition and morphology of the deposits were potential dependent. Cu–In intermetallics formation is studied as a function of deposition potential and electrolyte composition. Cu–In metal precursors were thermally annealed under selenium pressure to form CuInSe2.

Analysis of the substrate effect on the nucleation and growth mode of electrodeposited cobalt on copper and graphite electrodes

The nucleation, surface growth and roughening of cobalt electrodeposits on a polycrystalline copper and on amorphous graphite substrates have been studied using electrochemical techniques (voltammetry and chrono-amperometry) and surface imaging by Atomic Force Microscopy (AFM). The influence of the substrate nature and surface preparation on the nucleation and growth mode of Co was investigated as a function of deposition potential and Co thickness. The chrono-amperometry analysis of Co deposits on Cu reveals that the nucleation process agrees with the progressive Armstrong model. Graphite substrate leads to a nucleation process described by the instantaneous Scharifker–Hills model. The morphology and topography aspects examined by AFM denote that the roughness exponent α varies with the film deposition time t while a constant value of the growth exponent β is observed with the two substrates. Cu leads to unstable interfaces characterised by an effective roughness α eff(Co) Cu increasing from 0.30 to 0.8 and β(Co) Cu=0.68±0.09 for 10< t<1000 s. Graphite gives rise to 0.77≥ α≥0.66 and β=0.12±0.03 for 10< t<250 s corresponding to a stable interface growth whose dynamics is similar to that of the linear molecular beam epitaxy mode bearing a non-conservative noise.

Analysis of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission

The elemental composition of electrodeposited NiFe thin films was analyzed with particle-induced X-ray emission (PIXE). The thin films were electrodeposited on polycrystalline Au substrates from a 100 mM NiSO4, 10 mM FeSO4, 0.5 M H3BO3, and 1 M Na2SO4solution. PIXE spectra of these films were analyzed to obtain relative amounts of Ni and Fe as a function of deposition potential and deposition time. The results show that PIXE can measure the total deposited metal in a sample over at least four orders of magnitude with similar fractional uncertainties. The technique is also sensitive enough to observe the variations in alloy composition due to sample nonuniformity or variations in deposition parameters.

Octadecanethiol SAMs as Molecular Resists for Electrodeposition of Cobalt

Patterned self-assembled monolayers can be used to direct surface processes to occur at specific locations on a surface. Recently, patterned SAMs have been shown to function as molecular resists in directing electrodeposition. In this paper, we explore the limits of ODT SAMs as molecular resists for the electrodeposition of cobalt as a function of deposition potential, time, and Co(II) concentration. We show that patterned ODT SAMs can serve as effective resists for eletrodeposition of high fidelity features with no breakdown of the ODT-modified regions. Breakdown results in formation of Co islands in the ODT-modified regions and is dependent on deposition potential, time, and Co(II) concentration.

Pt-Ru electrodeposited on gold from chloride electrolytes

Voltammetric behavior of submicron-thick electrodeposited Pt-Ru on gold support is studied in sulfuric acid solution as a function of deposition potential and Pt:Ru ratio in chloride bath. In contrast to Pt-Ru, deposition of pure Ru is observed only at potentials of hydrogen evolution. The reason is found to be of kinetic nature, namely an inhibition of Ru deposition in presence of chloride. Chloride ions remain adsorbed on Ru at more negative potentials than on Pt and Au because of more negative ruthenium potential of zero free charge. Cu-UPD is applied to test the surface content of the oxidized Ru on pure Ru and various Pt-Ru surfaces. An enhancement of Ru oxohydroxides reduction in presence of Pt is observed. The electrocatalytic activity of Pt-Ru in respect to methanol oxidation correlates with the content of rechargeable surface Ru oxide. Ageing and ‘training’ of Pt-Ru electrodeposits under various modes is studied in order to determine the conditions of irreversible Ru oxidation. No manifestations of Ru dissolution from Pt-Ru electrodeposits in 0.5 M H 2SO 4 are found for anodic potential limits up to 1.1 V (RHE), in agreement with thermodynamic predictions. Electrodeposited Pt-Ru can be considered as a convenient model system for the study of Ru dissolution and crossover, as well as for determining the nature of the active surface species in the real composite catalysts for methanol oxidation.

Electrochemical incorporation of copper in polyaniline layers

The electrochemical deposition of copper is studied in polyaniline (PAN) layers with different redox states before the onset of metal deposition. Three characteristic oxidising peaks are found during dissolution of the copper deposit. Their charge contributions depend markedly on both thickness and the redox state of the polymer layers. The combined electrochemical, SEM and XPS studies allow to assign the different dissolution peaks to three types of copper deposits. The most negative peak is ascribed to macrodefects-induced deposition on polymer-free sites on the electrode surface. The middle peak should be connected to copper deposited in/on partially oxidised locations of the PAN coating. The most positive dissolution peak corresponds to copper incorporated in the polymer layer, prone to be dissolved only after driving the polymer layer in its oxidised state. Potentiostatic current transients corresponding to the third type of copper inclusions are studied as a function of deposition potential and PAN layer thickness. The current transients are interpreted by means of a model for instantaneous nucleation and three-dimensional (3D) growth under kinetic control. Data are obtained for the number and size of this type of copper inclusions.

Kinetics of molecular oxygen electroreduction on platinum modified by tin underpotential deposition

The kinetics of molecular oxygen electroreduction were studied on platinum surfaces modified by tin underpotential deposition. The surface process was analysed by cyclic voltammetry in aqueous 10−4 M tin(II)/1 M sulfuric acid in the 0.05 to 0.70 V vs RHE range. Platinum sites involving (1 1 0) planes are mainly related to tin underpotential deposition as observed in the hydrogen sorption region. Kinetic runs for oxygen reduction were performed with the rotating ring-disc electrode technique on tin-modified platinum surfaces. It was concluded that molecular oxygen reduction on tin-modified platinum takes place through bulk hydrogen peroxide and water formation. This interpretation was confirmed by calculating the reaction order with respect to oxygen. Electrochemical rate constants for oxygen reduction pathways were calculated as a function of deposition potential based on Damjanovic's reaction scheme.

Determination of metal ion binding parameters for humic substances

In Part 1 of this series, a straightforward calculation method was applied to the extraction of metal ion binding parameters from reverse pulse polarograms for fulvic substances. In this paper we extend this approach to include ASV pseudo-polarograms. Pseudo-polarography allows measurements to be made at low (environmentally relevant) concentrations and overcomes problems associated with processes occurring during the stripping step. Data presented for simple systems (the labile Pb(II)–pyridine-2,6-dicarboxylic acid, and the inert Pb(II)– and Cu(II)–EDTA systems) establish the validity of the pseudo-polarographic approach. Application of this methodology to Pb(II) and Cu(II) complexation by Suwannee River fulvic acid (SRFA) reveals that the complexation of Pb(II) is less heterogeneous than that of Cu(II). As compared to reverse pulse polarography (RPP), the lability of the complexes was reduced under ASV conditions (greater ligand excess). Pb(II)–SRFA behaviour approached non-lability, and although binding parameters could be determined, the values are probably influenced by loss of lability. For Cu(II)–SRFA, considerable loss of lability occurred and binding parameters could not be calculated. For adequate sensitivity, minimisation of adsorption interferences, and elimination of stripping step effects, we recommend the use of pseudo-polarograms constructed from plots of DC-ASV peak area as a function of deposition potential.

Electrochemical deposition and stripping of copper, nickel and copper nickel alloy thin films at a polycrystalline gold surface: a combined voltammetry-coulometry-electrochemical quartz crystal microgravimetry study

Cyclic voltammetry, anodic stripping voltammetry (ASV) and coulometry were used in conjunction with electrochemical quartz crystal microgravimetry (EQCM) and ex situ X-ray photoelectron spectroscopy (XPS) for a study of the electrodeposition and stripping of Cu, Ni and CuNi alloy thin films at a polycrystalline Au surface. A deaerated Watts bath was employed for the electrodeposition of Ni and CuNi thin films, the bath containing Cu 2+ ions (Ni:Cu = 200:1 mole ratio) in the latter case. These films showed the most satisfactory stripping in either 0.1 M HCl or 0.1 M H 2SO 4. Coulometry was used in conjunction with EQCM data for mapping the (potentiostatic) plating efficiency as a function of deposition potential in the Cu and Ni systems. For the CuNi alloy, similar data were acquired by additionally utilizing XPS compositional information and assuming current additivity in the (non-interactive) co deposition of Cu and Ni. Finally, the feasibility of employing the combined ASV-EQCM technique for analysis of CuNi/Ni bilayers is presented.

Thermal analyses of compound semiconductors using differential scanning calorimetry. Application to compositional analyses of cathodically electrosynthesized cadmium telluride

Differential scanning calorimetry (DSC) was used, we believe for the first time, for compositional analyses of a compound semiconductor. The Cd-Te system electrosynthesized by a cathodic route was used as a model to define the limits and power of this analytical tool. Thus changes in the composition of the electrodeposited material were monitored as a function of deposition potential. Samples deposited at potentials {ge}{minus}600 mV (vs SCE) contained excess Te in addition to CdTe and those synthesized at {minus}696 and {minus}698 mV contained both excess Cd and Te. The composition switched abruptly to a large excess of Cd near 700 mV. The excess Cd and Te were detected and quantitated by their characteristic DSC signals at 318 and 447{degree}C, respectively. Changes in compositional profiles as a function of solution hydrodynamics and TeO{sub 2} concentration as well as chemical reactions between the excess Cd and Te are described.

Electrochemisorption of hexahydroxylplatinate(IV) on thin titania films

The electrochemisorption of hexahydroxyplatinate(IV) on titania films is examined as a function of deposition potential over a range from 0.0 to 1.0 V vs. SCE. The samples were analysed using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Both XPS and AES analyses show that the amount of platinum deposited is maximized at 0.8 V vs. SCE. Also, the oxygen-to-titanium ratio correlates with the amount of platinum deposited. XPS shows that the deposited platinum consists of a mixture several different oxidation states with the two predominant states corresponding to Pt(OH) 2 and Pt bonded as PtOTi. Very little metallic platinum, PtO or PtO 2 is observed.