Electrodeposition Of Thin Films Research Articles

Electrodeposition of Thin Films for Jewels and Fashion Accessories

The interest in scientific research within the metal finishing sector is growing. The demand for durable metals and adaptable manufacturing processes is increasing across a wide range of applications, from aerospace and automotive to machinery and jewelry. An essential step in the production line is the surface engineering of metals, as this determines the final appearance and functionality of a product. Therein electroplating is recognized as a mature technology allowing the low-cost fabrication of defined surfaces with extensive property profiles. Galvanic electrodeposition accounts today for almost 40% of the global market value share with North America and Western Europe leading the scenery. Although technological and processing advancements occurred in the past forty years, industrial firms are still struggling to provide solutions to corrosion protection as well as the reduction of toxic wastes. Specifically, large-scale industrialization of electroplating techniques will continue to be limited by strict environmental regulations. Due to adverse ecological impacts, the adoption of plating processes involving toxic metals such as lead or cadmium is prohibited. Moreover, price volatility of the highly demanding electroplated materials gold, copper, and nickel is expected to impact the market share by more than 60% by 2026.In that respect, alloy plating offers better answers in terms of economic growth and environmental sustainability due to fine-tuning composition, morphology, and crystallinity [1]. Here, current trends in alloy electrodeposition research are reviewed highlighting open challenges and process innovations from an industrial perspective. The main categories of alloy compounds are presented and the most important properties of the manufacturing process are discussed. Particular attention is devoted to advances in industrial quality control and viable solutions for the reduction of precious metal content in electroplated accessories as well as the replacement of cyanide and nickel baths with non-toxic compounds.The authors acknowledge Regione Toscana POR CreO FESR 2014-2020 – azione 1.1.5 sub-azione A1 – Bando 1 “Progetti Strategici di ricerca e sviluppo” which made possible the project: “RAM-PVD” (CUP 3647.04032020.157000057_1225).

Structural, magnetic, dielectric and spectroscopic impedance analysis of magnesium iron oxide thin films synthesized by electrodeposition: Effect of preferred orientation

Magnesium iron oxide is the most valuable and versatile spinel system with reduced eddy current and dielectric losses. Spinel ferrites are electrically non-conductive. The electrodeposition is used to synthesize thin films on Cu substrate. A set of five thin films is prepared by varying the in-situ oxidation time (10 min, 15 min, 20 min, 25 min and 30 min) and a fixed deposition time of 25 min. The x-ray diffractometer XRD (phase confirmation), Scanning Electron Microscope SEM (morphological analysis), Fourier transforms infra-red spectroscope FT-IR (bond-formation), impedance analyzer (dielectric-measurements) and vibratory sample magnetometer VSM (magnetic properties) has been utilized to examine the prepared samples. All the studied samples have been found, single-phase spinel structures. XRD shows the pure phase formation of spinel MgFe2O4 at 20 min, 25 min, and 30 min. The exchange of the preferred orientation (PO) from (731) mixed phase to (533) spinel is observed. This change in preferred orientation has been caused the changes in the properties of prepared thin films. The average lattice constant, cell volume, x-ray density and crystallite size of magnesium-iron oxide were found at 8.3814 Å, 588.58 (Å)3, 3.2098 g/cm3 and 24.0392 nm respectively. In FTIR analysis of magnesium-iron oxide, two characteristic spinel bands are observed below 700 cm−1. The SEM result showed a smooth granular structure at 30 min. The normal behavior of the dielectric constant and single semicircle is observed in cole-cole plot. All the prepared thin films are ferromagnetic in nature. At 30 min, a higher dielectric constant, 20.2 (log f = 5) and 162.3 emu/cm3 saturation magnetization. The remarkable dielectric and magnetic findings are promising for using electrodeposited thin films in electronic and spintronic devices.

Electrodeposition of Copper Thin Films on Screen Printed Carbon Electrodes towards Electrochemical Sensing of Nitrate

Accurate and frequent monitoring of NO3 − levels in water bodies is crucial for human health and environment. In this work, copper (Cu) thin films electrodeposited on screen-printed carbon electrodes (SPCEs) were explored as an electrochemical sensing platform for the detection of NO3 − in water. Scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDX), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS) was employed to characterize the morphology and composition of the thin film modified electrode. The electrochemical response of Cu thin film deposited SPCE under different pH conditions (4 to 10) and various temperature (20 °C–60 °C) was assessed using linear sweep voltammetry (LSV). The developed electrochemical sensor allowed the measurement of NO3 − levels ranging from 50 to 750 μM with a sensitivity of 0.1042 μA mM−1. The sensor exhibited good detection limit in fish culture water (120 nM), reverse osmosis processed water (91 nM) and borewell water (98 nM). The sensor response was found to be stable in the presence of other interfering analytes (NO2 −, K+, Na+, SO4 2−, Mg2+, Cl-, Fe3+, Fe2+, Mn2+, Cu2+, Zn2+). The performance of the sensor was demonstrated in water samples collected from various sources and the sensor showed an acceptable performance rates for practical applications.

CoCrFeMnNi High-Entropy Alloy Thin Films Electrodeposited on Aluminum Support

We investigate the corrosion behavior on the microstructure of CoCrFeMnNi high-entropy thin film potentiodynamic alloys electrodeposited on aluminum support. Using electrolytes based on dimethyformamide (DMF), (HCON(CH₃)₂), dimethylsulfoxide (DMSO, (CH3)2SO), an acetonitrile (AN, CH3CN) organic system (4:1 vol. ratio), LiClO4 in different concentrations and CoCl2, CrCl3 × 6H2O, FeCl2 × 4H2O, MnCl2 × 4H2O and NiCl2 × 6H2O in different conditions, the HEA components were co-deposited on an aluminum foil substrate. Using the CALPHAD method and the MatCalc PC software, the structure of the HEA system under study was investigated by calculating the characteristic kinetic and thermodynamic criteria. The influence of each metal from HEA inside the solid solution zone and over the formation of the solid solution phase were obtained from the ratio between the derived parameters. The electrochemical measurements, which demonstrate that on an aluminum support the HEA thin films have lower corrosion resistance, were performed at ambient temperature in an aerated artificial solution. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to investigate the microstructure of HEA thin films before and after corrosion in artificial seawater. This complex study demonstrates that the electrodeposition of HEA thin films on an aluminum support is more difficult and that the resistance to corrosion is much lower compared to that in the previous work on HEA deposits on a copper support.

Electrodeposited Nickel Sulfide Nanoparticles Incorporated Carbon Nanofibers as Effective Non‐Precious Catalyst for Methanol Electrooxidation in Alkaline Medium

AbstractFor direct methanol fuel cells, developing low‐cost, highly efficient, and long‐term stable electrocatalysts is crucial. In this work, we report easy and single‐step electrodeposition of nickel sulfide thin film incorporating carbon nanofibers on indium tin oxide (denoted as Ni4S3‐CNF/ITO). The electrodeposited materials were characterized by X‐ray Diffraction, Scanning Electron Microscopy, and Energy Dispersive X‐ray spectroscopy. The electrocatalytic activity toward Methanol Oxidation Reaction (MOR) was investigated using Cyclic Voltammetry, Chrono‐Amperometry, and Electrochemical Impedance Spectroscopy. The electrocatalyst exhibited good electrocatalytic activity regarding methanol electrooxidation in an alkaline medium with retention of its activity over a significant period of time. These results indicate that the incorporation of carbon nanofibers into nickel sulfide allows the electrocatalyst to gain higher surface area and high tolerance to the catalyst‐poising species generated during MOR. The electrocatalytic activity of electrodeposited Ni4S3‐CNF/ITO makes it a promising electrocatalyst for low‐cost, high‐efficient fuel cells.

Electrodeposition of Bi2Te3 thin films for thermoelectric applications: effect of electrolyte pH

Electrodeposition of Bi2Te3 thin films for thermoelectric applications: effect of electrolyte pH

Electrodeposition of CdTe thin films using an acetate precursor for solar energy application: The effect of deposition voltage

Cadmium Telluride (CdTe) thin films were synthesized using a low-cost two-electrode electrodeposition configuration in potentiostatic mode and from an aqueous acidic solution. More commonly used cadmium salts for electrodeposition of CdTe include CdSO4, CdCl2 and Cd (NO3)2. In the present work, a less commonly used salt, cadmium acetate, was used as a cadmium precursor for the growth of CdTe thin films. The thin films were deposited on a coated glass fluorine- doped tin oxide (FTO) substrates. The deposition voltage was varied from 1230 to 1270 mV with a 10 mV increment. The structure, optical, conductivity, surface morphological, elemental composition, and surface roughness properties of the as-deposited thin films were investigated by using X-ray diffraction (XRD), UV–VIS spectrophotometry, Photoelectrochemical cell analysis (PEC), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and scanning probe microscopy (SPM), respectively. The XRD results showed that the CdTe thin films displayed a higher intensity at 1250 mV deposition voltage. UV–VIS spectroscopy measurements revealed that the band gap of the CdTe thin films was near that of the bulk CdTe at 1250 mV deposition voltage. The PEC measurement indicated that at a low voltage of 1230 mV, the conductivity of the film was p-type and Te-rich. When the deposition voltage was 1270 mV, the CdTe films became n-type and Cd-rich. EDS results confirmed the presence of both Cd and Te with more stoichiometric values at the growth voltage of 1250 mV. The SEM images showed that the surface morphology changed with deposition voltage. SPM results indicated that the highest average surface roughness value of 94.9 nm was obtained with a deposition voltage of 1250 mV. These results indicate that the film prepared at a deposition voltage of 1250 mV, may have better potential application as an absorber layer in solar cell device.

Electrodeposition of SnO2 nanostructures onto copper substrates and their electrochemical properties

Potentiostatic electrodeposition of SnO2 thin films from an oxygenated tin chloride bath on anodised copper substrates has been achieved at a bath temperature of 85 °C. At the bath temperature of 85 °C, the evolution of nanoplates, nanoparticles and nanocubes are observed. Aqueous battery and bio-sensing characteristics of the SnO2 nanostructures were assessed. The electrodes are cycled between –1 and +1 V in LiOH . H2O, Li2CO3 and Na2SO4 electrolyte solutions by cyclic voltammetry method. The test results exhibit that the nanocrystalline SnO2 anode is a proficient electrode material for the aqueous lithium battery. Electrochemical detection of ascorbic acid (AA) on the nanostructured SnO2 electrode has also been assessed and SnO2 nanocubes displayed eminent electro catalytic activity towards the oxidation of AA.

Co-Electrodeposition of Metallic Precursors for Cd-Doped Cu2ZnSnS4 (CZCTS) Kesterite Absorber for Photoelectrochemical Water Splitting

Electrodeposition is widely studied in the fabrication of semiconductors for solar application, because of the low cost and easy scalability of this technique. For instance, in the last decades large effort has been dedicated to the electrodeposition of Cu2ZnSnS4 (CZTS) through different approaches, including either direct co-electrodeposition of the sulfide, the deposition of metallic alloy precursors or by stacked elemental layer, depositing Cu, Zn and Sn in sequence, then converting it into kesterite with thermal treatment in sulfur atmosphere.1–4 While being a promising alternative to CIGS (CuInGaS2), thanks to the non-toxicity and higher abundance of its constituting elements, CZTS absorbers still encounter some difficulties to their integration of high-performance solar devices. In fact, the electronic and optical properties of the material are affected by the narrow stoichiometric window acceptable for kesterite formation, inducing the segregation of secondary phases, along with the formation of lattice defects that act as recombination sites.5 A reported strategy to suppress the latter limitation is to introduce doping elements such as Ag6 and Cd7,8, partially substituting metallic atoms in the semiconductor, Cu and Zn respectively. The larger atomic radii of these elements can prevent the formation of antisite defects such as CuZn, largely increasing the semiconductor performance7. Here we propose a synthesis route of CZCTS through the co-electrodeposition of a thin film Cu-Sn-Zn-Cd alloy followed by sulfurization treatment. The deposition on SLG/Mo substrate is achieved with a sulfate-based electrolyte with citrate complexing agents and performed in three-electrode potentiostatic conditions. Proper bath formulation is designed to obtain a desirable Zn-rich, Cu-poor composition, varying the degree of Zn substitution with Cd. An alternative 2-step deposition of CuZnSn/Cd stacked precursor is also investigated, as an attempt to compensate the effect of the low H+ adsorption energy of cadmium leading to the formation of blisters in the quaternary alloy. Sulfurized samples characterization shows the formation of good quality of kesterite CZCTS, in spite of the segregation of secondary phases on the surface. Cd doping of CZTS is observed through the characteristic shift of the main kesterite XRD peak (112) and an increase of the average size of grains. The photocurrent of finalized photocathodes with structure SLG/Mo/CZCTS/CdS/Pt is measured under 10 mW/cm2 AM 1.5 radiation reporting an improvement with respect to the undoped analogue, increasing the current density at 0 V vs RHE from -5.73 to -7.18 mA/cm2 in the best case.Bibliography Colombara, D. et al. Electrodeposition of kesterite thin films for photovoltaic applications: Quo vadis? Phys. Status Solidi Appl. Mater. Sci. 212, 88–102 (2015).Ge, J. & Yan, Y. Controllable Multinary Alloy Electrodeposition for Thin-Film Solar Cell Fabrication: A Case Study of Kesterite Cu2ZnSnS4. iScience 1, 55–71 (2018).Clauwaert, K., Binnemans, K., Matthijs, E. & Fransaer, J. Electrochemical studies of the electrodeposition of copper-zinc-tin alloys from pyrophosphate electrolytes followed by selenization for CZTSe photovoltaic cells. Electrochim. Acta 188, 344–355 (2016).Jiang, F. et al. Pt/In2S3/CdS/Cu2ZnSnS4 Thin Film as an Efficient and Stable Photocathode for Water Reduction under Sunlight Radiation. J. Am. Chem. Soc. 137, 13691–13697 (2015).Polizzotti, A., Repins, I. L., Noufi, R., Wei, S. H. & Mitzi, D. B. The state and future prospects of kesterite photovoltaics. Energy Environ. Sci. 6, 3171–3182 (2013).Yuan, Z. K. et al. Engineering Solar Cell Absorbers by Exploring the Band Alignment and Defect Disparity: The Case of Cu- and Ag-Based Kesterite Compounds. Adv. Funct. Mater. 25, 6733–6743 (2015).Tay, Y. F. et al. Solution-Processed Cd-Substituted CZTS Photocathode for Efficient Solar Hydrogen Evolution from Neutral Water. Joule 2, 537–548 (2018).Su, Z. et al. Device Postannealing Enabling over 12% Efficient Solution-Processed Cu2ZnSnS4 Solar Cells with Cd2+ Substitution. Adv. Mater. 32, 1–12 (2020).

(Digital Presentation) Electrodeposition of Thin Films of Femn Alloys for Biodegradable Scaffolds Fabrication

Biodegradable metallic scaffolds are interesting biomaterials for applications in temporary implants for bone regeneration because of their good mechanical properties. In addition, the need for a second surgery to remove the implant is reduced if biodegradable metals are used. Fe has adequate mechanical properties for scaffolds manufacture and suitable biocompatibility. However, Fe shows slow biodegradation rates for the application and, therefore, different approaches have been developed such as the development of alloys or by reducing the thickness of the Fe strut in the scaffold. FeMn alloys are considered ideal materials, as they are not ferromagnetic. In addition, additive manufacturing technologies (3D printing) are considered appropriate to manufacture these scaffolds due to the ability to obtain complicated geometries and customized parts for a specific bone injury site. Electrodeposition is also an interesting technique because it allows the deposition of thinner strut walls of Fe (or alloys) with high purity, in addition to providing a good surface finishing. The aim of the first part of this work is to electrodeposit thin films of FeMn alloys and to evaluate its microstructure and mechanical properties. The thin films were electrodeposited potentiostatically from sulfate electrolytes with different concentrations of FeSO4 and MnSO4. The effect of deaeration, substrate material and electrodeposition potential were evaluated. The microstructure of the electrodeposited films was characterized by SEM/EDX and XRD. The surface finishing was evaluated by AFM and the mechanical properties by microhardness measurements.

Controlled Synthesis of Chromium-Oxide-Based Protective Layers on Pt: Influence of Layer Thickness on Selectivity

Chromium-oxyhydroxide (CrxOyHz)-based thin films have previously been shown in photocatalysis and industrial chlorate production to prevent unwanted reduction reactions to occur, thereby enhancing the selectivity for hydrogen evolution and thus the overall process efficiency. Here, a highly reproducible synthesis protocol was developed to allow for the electrodeposition of CrxOyHz-based thin films with controlled thickness in the range of the sub-monolayer up to (>4) multilayer coverage. Electrodeposited CrxOyHz coatings were electrochemically characterized using voltammetry and stripping experiments, allowing thickness-dependent film selectivity to be deduced in detail. The results are discussed in terms of mass transport properties and structure of the electrodeposited chromium oxyhydroxide films. It is shown that the permeation of diatomic probe molecules, such as O2 and CO, was significantly reduced by films as thin as four monolayers. Importantly, it is shown that the prepared thin film coatings enabled prolonged hydrogen oxidation in the presence of CO (up to 5 vol.%), demonstrating the benefits of thin-film-protected electrocatalysts. In general, this study provides insight into the synthesis and use of thin-film-protected electrodes leading to improvements in (electro)catalyst selectivity and durability.

Simple preparation and investigation of magnetic nanocomposites: Electrodeposition of polymeric aniline-barium ferrite and aniline-strontium ferrite thin films

Abstract In this work, new polymeric aniline-barium ferrite and aniline-strontium ferrite thin layers were synthesized. In the first step, hexaferrites nano-additives were prepared by applying ultra-sound and microwave irradiation. Then, hexaferrites were added to aniline electrolyte solution separately. The electrodeposition of aniline as a polymeric matrix and hexaferrite as nano-additives was performed in an electrochemical cell in the presence of various acids. Scanning electron microscopy images were applied for morphology investigation and measuring average particle size. Energy dispersive X-ray spectroscopy was applied for elemental detection and analysis, as well as presence confirmation of nanoparticles. Atomic force microscopy was applied for surface roughness analysis of thin films. Magnetic property of the nanoparticles and polymeric nanocomposites was checked and measured by vibrating sample magnetometer. The crystallinity, crystallite size, and phase of samples were confirmed by X-ray diffraction pattern analysis.

Effect of the Deposition Time on the Structural, 3D Vertical Growth, and Electrical Conductivity Properties of Electrodeposited Anatase-Rutile Nanostructured Thin Films.

TiO2 time-dependent electrodeposited thin films were synthesized using an electrophoretic apparatus. The XRD analysis revealed that the films could exhibit a crystalline structure composed of ~81% anatase and ~6% rutile after 10 s of deposition, with crystallite size of 15 nm. AFM 3D maps showed that the surfaces obtained between 2 and 10 s of deposition exhibit strong topographical irregularities with long-range and short-range correlations being observed in different surface regions, a trend also observed by the Minkowski functionals. The height-based ISO, as well as specific surface microtexture parameters, showed an overall decrease from 2 to 10 s of deposition, showing a subtle decrease in the vertical growth of the films. The surfaces were also mapped to have low spatial dominant frequencies, which is associated with the similar roughness profile of the films, despite the overall difference in vertical growth observed. The electrical conductivity measurements showed that despite the decrease in topographical roughness, the films acquired a thickness capable of making them increasingly insulating from 2 to 10 s of deposition. Thus, our results prove that the deposition time used during the electrophoretic experiment consistently affects the films’ structure, morphology, and electrical conductivity.

Seccm-IRM: A New Tool for Quantitative in Situ Studies of Crystal Growth

Scanning electrochemical cell microscopy (SECCM) is a versatile scanning probe imaging technique that allows for simultaneous elucidation of structure activity relationships at the nanoscale in defined electrolyte volumes and provides high resolution (nm length scale) information on the topography of surfaces and interfaces1. Since its inception in 2010 SECCM has improved understanding of model systems such as graphene, graphite, carbon nanotubes, nanoparticles and conductive diamond and provided electrochemists with a tool for true single entity measurements. Electrodeposition of microscale thin films has previously been reported2 but not of crystalline species, which is the focus of this work.SECCM can also be used as a tool for the precise delivery of nano to microscale solution droplets to surfaces. By using optically transparent yet conductive substrates (such as indium tin oxide (ITO), gold or graphene ) we can couple SECCM to highly surface-sensitive imaging modes such as interference reflectance microscopy (IRM)3 or traditional brightfield microscopy, allowing the evaporation and consequent precipitation of solutes to be monitored. The SECCM apparatus allows the deposition of large arrays, under well-defined conditions (deposition time, surface potential), with each droplet representing an individual and independent crystallisation experiment and provides statistical data based on single particle level. The emergence of precipitates within these arrays is tracked to investigate the effect of additives and also surface potential on crystallisation.SECCM can use capacitative response to examine minimally ionised systems, non-aqueous solvents etc allowing organic crystals to be studied. This work focuses on the precipitation of two such model organic systems: l-cystine and 5-methyl-2-[(2-nitrophenyl)amino]thiophene-3-carbonitrile (ROY). l-Cystine is of biological relevance due to its role in the formation of kidney stone’s which are resistant to traditional therapies4. The need therefore arises for l-cystine crystallisation inhibitors making it a prime candidate for testing additive screening procedures. ROY is investigated as a model system5 to identify the merits of SECCM-IRM as a polymorph screen method. We show how sensitive precipitation is to substrate, applied potential and solvent system. References Ebejer, N.; Güell, A. G.; Lai, S. C. S.; McKelvey, K.; Snowden, M. E.; Unwin, P. R., Scanning Electrochemical Cell Microscopy: A Versatile Technique for Nanoscale Electrochemistry and Functional Imaging. Annual Review of Analytical Chemistry 2013, 6 (1), 329-351. Aaronson, B. D. B.; Garoz-Ruiz, J.; Byers, J. C.; Colina, A.; Unwin, P. R., Electrodeposition and Screening of Photoelectrochemical Activity in Conjugated Polymers Using Scanning Electrochemical Cell Microscopy. Langmuir 2015, 31 (46), 12814-12822. Valavanis, D.; Ciocci, P.; Gabriel; Morris, P.; Lemineur, J.-F.; McPherson, I. J.; Kanoufi, F.; Unwin, P. R., Hybrid scanning electrochemical cell microscopy-interference reflection microscopy (SECCM-IRM): tracking phase formation on surfaces in small volumes. Faraday Discussions 2022. Rimer, J. D.; An, Z.; Zhu, Z.; Lee, M. H.; Goldfarb, D. S.; Wesson, J. A.; Ward, M. D., Crystal Growth Inhibitors for the Prevention of l -Cystine Kidney Stones Through Molecular Design. Science 2010, 330 (6002), 337-341. Lévesque, A.; Maris, T.; Wuest, J. D., ROY Reclaims Its Crown: New Ways To Increase Polymorphic Diversity. Journal of the American Chemical Society 2020, 142 (27), 11873-11883.

Highly Textured Zinc Thin Films through Novel Pulsed Electrodeposition Techniques and Their Applications

The electrodeposition of zinc thin films has been widely investigated with extensive applications in corrosion, battery electrodes, photo- and electro-catalysis. Traditionally, the direct current (DC) method of electroplating has been explored in terms of varying current density to obtain changes in morphology, grain size, preferred crystalline orientation, which in turn have significant consequences for properties such as catalysis and corrosion resistance. We have recently demonstrated [1] a novel, additive-free pulsed plating method to control the specific crystalline growth orientations and average grain size of zinc electrodeposited on steel substrates.Specifically, we have observed a transition of the preferential (002) facets at low peak current density (or low duty cycle) to (101) preferring facets at higher peak current density (or high duty cycle) as determined by the analysis of texture coefficients. Further analysis using scanning electron microscopy reveals a transition from the conventional hexagonal-shaped particles of zinc to needle-shaped structures, accompanied by a change in average crystallite size from 33 to 19 nanometers, determined from X-ray diffraction studies. The variation in morphology is also correlated to crystallographic textures through the analysis of texture coefficients and an understanding of crystallization mechanisms occurring during deposition.Herein, we report on an application of these highly textured zinc-coated steel substrates towards corrosion resistance, through accelerated electrochemical testing. Using industry-standard ASTM methods such as Linear Polarization Resistance (LPR), Linear sweep voltammetry (LSV) and electro-impedance spectroscopy (EIS) measurements, we report on preliminary findings of corrosion potential, current and corrosion rates expressed in mm per year as a function of crystalline texture of the zinc thin films.

Compensative Electrochromic Device Utilizing Electro-deposited Plasmonic Silver Nanoparticles and Manganese Oxide to Achieve Retention of Chromatic Color

Silver deposition-based electrochromic (EC) device enabled various optical states by using either the electrodeposition of silver thin films or silver nanoparticles on an indium tin oxide electrode. These optical states, including chromatic colors such as cyan, magenta, yellow, and green, are based on absorption by the localized surface plasmon resonance of silver nanoparticles. However, an ideal counter-reaction material that does not affect the color representation by silver nanoparticles and does not dissolve the deposited silver has not been reported. To achieve both color retention and chromatic color representation, MnO2 was utilized as the counter electrode material. The EC properties of the novel device with the MnO2 counter electrode were investigated in terms of charge density and its ability to change color. The novel EC device achieved both representations of chromatic color and retained its color without power supply.

Single-step electrodeposition of CZTS thin film: Influence of complexing agent concentration

Single-step electrodeposition of CZTS thin film: Influence of complexing agent concentration

In- and cross-plane thermoelectric properties of oriented Bi2Te3 thin films electrodeposited on an insulating substrate for thermoelectric applications

Electrodeposition is a useful technique for preparing Bi2Te3 thin film based thermoelectric generators as power sources for wireless sensors because of its many advantages, including low cost, non-vacuum operation, and compatibility with microfabrication processes. However, electrodeposition of thin films on insulating substrates is challenging; moreover, electrodeposited films exhibit inferior thermoelectric properties. Herein, we report electrodeposition of Bi2Te3 thin films on an insulating substrate by incorporating a sputtering step. The thermoelectric properties of the films were improved by performing post-thermal annealing. A 0.5 µm-thick Bi2Te3 layer was sputter-coated on an alumina substrate; subsequently, Bi2Te3 films of different thicknesses (0.5–3.8 µm) were formed by varying the electrodeposition time (10–60 min). The films were oriented along the a,b-axis direction, while the crystallite size remained constant as the electrodeposition time increased. The thermoelectric properties of the films were evaluated at approximately 300 K in both in- and cross-plane directions. Maximum power factors, 11.0 and 13.9 μW/(cm·K2) in the in-plane and cross-plane directions, respectively, were observed at 60 min electrodeposition due to increased electrical conductivity. The dimensionless figure of merit in both plane directions was maximum (0.27) at 10 min electrodeposition because of low thermal conductivity (0.86 W/(m·K)).

Growth mechanism of pulse electrodeposited cadmium sulfide and zinc sulfide thin films with tartaric acid and glycerol as additives

Room temperature electrodeposition of thin films is beneficial, especially for cadmium sulfide (CdS) and zinc sulfide (ZnS), which are utilized in optoelectronic applications. The present study is unique, owing to its utilization of tartaric acid in the electrochemical deposition of these binary sulfides. This organic acid has been shown to play a vital role in mitigating the precipitation of sulfides and facilitating deposition. Also, the impact of this organic acid on the growth mechanism is evaluated by electroanalytical techniques including cyclic voltammetry and chronoamperometry. From the Randles-Sevcik plot, it is verified that the deposition is governed by a diffusion-controlled process. The elemental analyses unveil that the composition at deposition potentials of -1.1 V for cadmium sulfide and -1.4 V for zinc sulfide are near stoichiometric. The electrocrystallization of the films is interpreted employing Scharifker-Hills nucleation model and is observed to follow progressive nucleation for cadmium sulfide and instantaneous nucleation for zinc sulfide. The deposition process is characterized using impedance measurements that have affirmed the formation of cadmium sulfide and zinc sulfide via intermediate metal tartrate complex. The X-ray diffraction and Raman spectroscopy of as-deposited cadmium sulfide and zinc sulfide thin films confirm the hexagonal and cubic phases, respectively. The results show the adequacy of the method for the deposition of crystalline quality thin films at room temperature in the presence of tartaric acid.

Phase Pure Silver Pyrovanadate (Ag4V2O7) Thin Films: Synthesis via a Hybrid Cathodic/Anodic Approach and Characterization

Combining two or more binary compounds to generate a multinary compound is a strategy for enhancing the photoelectrochemical (PEC) performance and properties of the parent binary compounds. In this vein, multinary compound semiconductors have recently come under the spotlight in a variety of device applications. In particular, the low energy band gap of the Ag-V-O ternary family (Ag3VO4, Ag4V2O7, AgVO3, Ag2V4O11, and AgV7O18) has recently sparked interest in using these visible light active semiconductor for photovoltaic solar cells, solar water splitting, CO2 photoreduction, and environmental remediation applications. In particular, Ag4V2O7, a visible light active semiconductor with a low band gap (2.49 eV) has been synthesized in powder form using solid state, hydrothermal, and precipitation methods.1,2 However, for device applications, deposition techniques that facilitate direct synthesis of semiconductor in film form, are attractive.In this vein, electrochemical deposition is a fast, low temperature, and scalable method to prepare large active area films of a given semiconductor. Therefore, this paper presents a hybrid cathodic and anodic route for the electrodeposition of Ag4V2O7 thin films and its subsequent physical and optoelectronic characterizations. Ag4V2O7 thin film on fluorine-doped tin oxide (FTO) substrate was synthesized using a hybrid cathodic and anodic route previously developed in our laboratory.3 In the cathodic step, a metallic silver thin film was electrosynthesized from silver ions in a nonaqueous medium on fluorine-doped tin oxide (FTO) support. In the anodic step, the generated silver ion (Ag+) from anodic stripping of the silver thin film in a pyrovanadate ion (V2O7 4-)containing-solution resulted in an in situ precipitation reaction with V2O7 4- to form Ag4V2O7 thin film on FTO. Electrochemical quartz crystal nanogravimetry (EQCN) confirmed one and four electron stoichiometry for the cathodic and anodic steps respectively.Energy-dispersive X-ray analysis (EDX) of as-prepared sample gave the Ag/V ratio: 1.95 ± 0.02, close to the expected stoichiometric Ag/V ratio for Ag4V2O7. X-ray diffraction analyses of the as-synthesized sample significantly confirmed that room temperature electrodeposited sample was crystalline and phase-pure. To measure the direct and indirect energy band gaps, Tauc plots were constructed from diffuse reflectance spectroscopy (DRS) data. The estimated direct and indirect optical transition energies of Ag4V2O7 thin films were 2.58 ± 0.04 and 2.52 ± 0.02 eV respectively. A valence band energy position as -4.88 ± 0.03 eV (on the vacuum energy scale) was estimated for Ag4V2O7 using atmospheric photoemission spectroscopy (APS) results. By combining the DRS and APS results, the calculated conduction band edge position of Ag4V2O7 was determined to be -2.36 eV on the vacuum energy scale. Kelvin-probe measurement located the Fermi level of silver pyrovanadate thin films at -4.82 ± 0.02 eV on the vacuum energy scale. The corresponding EF for Ag4V2O7 was only 0.06 eV above the valence band position consistent with a moderately-doped p-type semiconductor. These new results will be discussed in the framework of the application of silver pyrovanadate for PEC reduction processes such as hydrogen evolution or CO2 reduction.