One-step Electrochemical Deposition Research Articles

Electrochemical fabrication of 3D quasi-amorphous pompon-like Co-O and Co-Se hybrid films from choline chloride/urea deep eutectic solvent for efficient overall water splitting

The development of earth-abundant, low-cost, highly active, and durable bifunctional catalysts competent for efficient electrochemical water-splitting is intensively demanding and of vital importance to realize high-purity hydrogen production. Herein, we report that 3D quasi-amorphous pompon-like Co-O and Co-Se hybrid films grown on copper foil (Co-O@Co-Se/Cu) can be electrochemically synthesized from a choline chloride and urea mixed deep eutectic solvent, denoted as Reline, via a facile one-step electrochemical deposition approach. Benefiting from the induction effect of Se, the obtained Co-O@Co-Se/Cu hybrid electrode exhibits strongly enhanced catalytic activity. The optimal Co-O@Co-Se/Cu sample shows good activity and excellent durability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline solution with low overpotentials of 85 mV for HER and 340 mV for OER, respectively to reach a catalytic current of 10 mA cm−2. The Co-Se component within the hybrid films is gradually converted into Co-O species during the course of the OER, which are responsible for the good OER performance. In addition, when performed as bifunctional catalysts in a two-electrode configured electrolyzer, the Co-O@Co-Se/Cu couple displays a water-splitting current of 10 mA cm-2 at 1.65 V with reasonable stability for long-term electrolysis over 100 h. This simple one-step electrochemical synthesis route operated in the Reline-based deep eutectic solvent is demonstrated as an efficient strategy to fabricate active non-noble-free electrocatalysts toward overall water splitting applications.

Self-Standing Polypyrrole/Black Phosphorus Laminated Film: Promising Electrode for Flexible Supercapacitor with Enhanced Capacitance and Cycling Stability.

With the rapid development of portable electronics, solid-state flexible supercapacitors (SCs) are considered as one of the promising energy devices in powering electronics because of their intrinsic advantages. Polypyrrole (PPy) is an ideal electrode material in constructing flexible SCs owing to its high electrochemical activity and inherent flexibility, although its relatively low capacitance and poor cycling stability are still worthy of improvement. Herein, through the innovative introduction of black phosphorus (BP) nanosheets, we developed a laminated PPy/BP self-standing film with enhanced capacitance and cycling stability via a facile one-step electrochemical deposition method. The film exhibits a high capacitance of 497.5 F g-1 (551.7 F cm-3) and outstanding cycling stability of 10 000 charging/discharging cycles, thanks to BP nanosheets inducing laminated assembly which hinder dense and disordered stacking of PPy during electrodeposition, consequently providing a precise pathway for ion diffusion and electron transport together with alleviation of the structural deterioration during charge/discharge. The flexible SC fabricated by laminated films delivers a high capacitance of 452.8 F g-1 (7.7 F cm-3) besides its remarkable mechanical flexibility and cycling stability. Our facile strategy paves the way to improve the electrochemical performance of PPy-based SC that could serve as promising flexible energy device for portable electronics.

Electrodeposited molybdenum selenide sheets on nickel foam as a binder-free electrode for supercapacitor application

Two-dimensional nanostructured metal chalcogenides have significant consideration as electrode materials for energy storage application owing to their fascinating properties. In this work, we have grown two-dimensional MoSe2 sheets directly on the surface of nickel foam via facile one-step electrochemical deposition method and examined their use as a binder-free electrode for supercapacitor. The physicochemical characterizations such as X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectrum, and Raman analysis confirmed the formation of MoSe2 sheets on Ni foam. The effect of deposition time (5 and 10 min) on the electrochemical properties of the MoSe2 sheets are examined in detail using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopic analyses, respectively. The cyclic voltammetry profiles confirmed that the charge-storage mechanism in MoSe2 sheets is due to the ion intercalation/de-intercalation kinetics. A high specific capacity of 548 mAh g−1 was obtained for the MoSe2/Ni electrode from CV profile measured using a scan rate of 5 mV s−1. The MoSe2/Ni electrode delivered a specific capacity of 325.92 mAh g−1 from charge-discharge analysis obtained at constant discharge current density of 4 mA cm−2 with good cyclic stability. The capacitive properties and the mechanism of charge-storage in the MoSe2/Ni electrode deposited at different time intervals were examined by the electrochemical impedance spectroscopy using Nyquist and Bode phase angle plot. The experimental results ensure that the MoSe2/Ni electrode might be used as the high-performance electrode for the next-generation energy storage devices.

Construction of 3D polypyrrole/CoS/graphene composite electrode with enhanced pseudocapacitive performance

Herein, 3D graphene/nickel foam (GE/NF) composite matrix was successfully fabricated by using NF as template through a self-catalytic thermal chemical vapor deposition process. By using the prepared GE/NF as substrate, CoS nanosheets were deposited via a facial one-step electrochemical deposition method. Owing to the advantage of GE in boosting the electrical contact between the electroactive host material and current collector, the as-prepared 3D CoS/GE/NF electrode demonstrated a superior capacitance value of 2308 F g−1 at 1 A g−1 and a high rate capability of 70.49% at 20 A g−1. After depositing the polypyrrole (PPY) film on 3D CoS/GE/NF electrode, the electrochemical performance of CoS was further greatly improved and delivered an extremely high capacitance value of 3450 F g−1 at 1 A g−1, with good rate capability (62.61% at 20 A g−1) and improved cycling stability. The enhanced electrochemical performance of PPY/CoS/GE/NF electrode is closely related to the advantage of PPY film in increasing the electrical conductivity and reinforcing the integrity of electrode.

Scalable one-step electrochemical deposition of nanoporous amorphous S-doped NiFe2O4/Ni3Fe composite films as highly efficient electrocatalysts for oxygen evolution with ultrahigh stability

Self-supported 3D nanoporous amorphous S-doped NiFe2O4/Ni3Fe composite films grown on nickel wire were fabricatedviaa facile and scalable one-step electrochemical deposition route in ethaline and developed as highly active and robustly stable electrocatalysts for OER in alkaline media.

Pt-Pd bimetallic nanocoral modified carbon fiber microelectrode as a sensitive hydrogen peroxide sensor for cellular detection

In this work, an ultrasensitive microelectrode for hydrogen peroxide (H2O2) detection was constructed. The carbon fiber microelectrode (CFME) was modified with Pt-Pd nanocoral (Pt-Pd/CFME) by using a one-step electrochemical deposition method. Compared to Pt/CFME and Pd/CFME, the Pt-Pd/CFME has larger active surface area and faster electron transfer efficiency, thus exhibiting higher electrocatalytic activity for H2O2 sensing. Under the optimal condition, the Pt-Pd/CFME presents fast response time (≤5 s), high selectivity (11.6 mA mM−1 cm−2), wide linear range (5–3920 μM) and low detection limit (0.42 μM, S/N = 3) for H2O2 detection. Furthermore, the proposed sensor was successfully employed to monitor H2O2 released from A549 living cells, and the detection of H2O2 in milk was also realized. With the above attractive electrocatalytic properties and convenient fabrication process, the as-prepared microelectrode provides unique advantages in the monitor of H2O2 in biological samples, especially in cellular environment.

Complexing agent-assisted highly dense CuInSe2 thin films prepared by one-step electrochemical deposition

Highly dense CuInSe2 (CISe) thin films were electrochemically deposited on Mo-coated soda-lime glass substrates in aqueous solution. Three compounds, CuCl2, InCl3, and SeO2, were used as precursors with glycine or oxalic acid as complexing agents. The deposition process was carefully selected through preliminary study of the individual electrochemical properties of the three precursors. To achieve ideal stoichiometry and uniform deposition of CISe thin films, the reaction temperature and acidity of precursor solution were investigated. As the reaction temperature increased, Cu deficiency was observed in the CISe thin film. The density and surface morphology of CISe films prepared by one-step electrodeposition were affected strongly by the acidity of deposition solution. The addition of HCl to solution improved the density and surface roughness of as-deposited CISe films. Denser and larger grain size CISe polycrystalline films were prepared in oxalic acid solution. Two-step heat treatments for the prepared CISe samples were applied to fabrication of CISe photovoltaic devices without an additional Se source.

Photoelectrochemical properties of hematite thin films grown via a two-step electrochemical deposition method

In this study, Fe2O3 thin films were deposited via one-step and two-step electrochemical deposition methods. The one-step method used a constant growth potential, and the two-step method used two continuous growth potentials during the deposition. The morphological, electrical, and structural properties of the thin films and the relationships of each property with the photoelectrochemical properties of the thin films from the two methods were analyzed and compared. We determined that the samples grown by the two-step method have better photoelectrochemical properties than those grown by the one-step method. In this study, we attempted to determine the optimum growth potentials for the one-step and two-step methods and the growth durations of the first and second stages in the two-step method in terms of the photoelectrochemical properties. The sample formed at −0.05V for 30s in the first step and −0.25V for 2min 30s in the second step in the two-step method has the highest photocurrent density value of 0.28mA/cm2 (at 0.5V vs. SCE), which is higher than that of the samples grown by the one-step method.

Composition-Graded MoWSx Hybrids with Tailored Catalytic Activity by Bipolar Electrochemistry.

Among transition metal dichalcogenide (TMD)-based composites, TMD/graphene-related material and bichalcogen TMD composites have been widely studied for application toward energy production via the hydrogen evolution reaction (HER). However, scarcely any literature explored the possibility of bimetallic TMD hybrids as HER electrocatalysts. The use of harmful chemicals and harsh preparation conditions in conventional syntheses also detracts from the objective of sustainable energy production. Herein, we present the conservational alternative synthesis of MoWSx via one-step bipolar electrochemical deposition. Through bipolar electrochemistry, the simultaneous fabrication of composition-graded MoWSx hybrids, i.e., sulfur-deficient MoxW(1-x)S2 and MoxW(1-x)S3 (MoWSx/BPEcathodic and MoWSx/BPEanodic, respectively) under cathodic and anodic overpotentials, was achieved. The best-performing MoWSx/BPEcathodic and MoWSx/BPEanodic materials exhibited Tafel slopes of 45.7 and 50.5 mV dec-1, together with corresponding HER overpotentials of 315 and 278 mV at -10 mA cm-2. The remarkable HER activities of the composite materials were attributed to their small particle sizes, as well as the near-unity value of their surface Mo/W ratios, which resulted in increased exposed HER-active sites and differing active sites for the concurrent adsorption of protons and desorption of hydrogen gas. The excellent electrocatalytic performances achieved via the novel methodology adopted here encourage the empowerment of electrochemical deposition as the foremost fabrication approach toward functional electrocatalysts for sustainable energy generation.

Vertically aligned CdTe nanorods array for novel three-dimensional heterojunction solar cells on Ni substrates

In this study, a uniform CdTe nanorods (NRs) arrays are grown on Ni substrates by a simple one-step electrochemical deposition method. The effects of deposition parameters such as the concentration of reactants and reaction time on the growth of CdTe NRs arrays are systematically investigated. Na2TeO3 and CdSO4 have a significantly different influence on the growth of CdTe NRs. With the increase of Na2TeO3 concentration, the diffraction intensity increases slightly at the peak (111) to promote axial growth. The diffraction intensity of (002) can increase with the concentration of CdSO4 increasing, which is conducive to lateral growth. The morphology of CdTe film varies from a thin layer to nanoparticles, and finally to NRs with the extension of time. Based on the characterization results, the possible growth mechanism of CdTe NRs arrays is proposed. The as-prepared CdTe NRs arrays are then embedded into CdS film, forming a novel three-dimensional (3D) heterojunction photovoltaic device. An extensive study of the effect of NRs length on device performance is presented. The results indicate that the device performance is highly dependent on the length of CdTe NRs, and a power conversion efficiency of 2.50% is obtained for optimal length of 1 μm. The better photovoltaic performance can be attributed to its efficient charge separation and direct pathways for carriers transport. What's more, this novel 3D nanostructured concept suggests great potential for other optoelectronic devices.

One-step construction of a molybdenum disulfide/multi-walled carbon nanotubes/polypyrrole nanocomposite biosensor for the ex-vivo detection of dopamine in mouse brain tissue

We developed a new strategy for construction of a biosensor for the neurotransmitter dopamine. The biosensor was constructed by one-step electrochemical deposition of a nanocomposite in aqueous solution at pH 7.0, consisting of molybdenum disulfide, multi-walled carbon nanotubes, and polypyrrole. A series of analytical methods was performed to investigate the surface characteristics and the improved electrocatalytic effect of the nanocomposite, including cyclic voltammetry, electrochemical impedance spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. The constructed biosensor showed high sensitivity (1.130 μAμM−1cm−2) with a dynamic linearity range of 25–1000 nM and a detection limit of 10 nM. Additionally, the designed sensor exhibited strong anti-interference ability and satisfactory reproducibility. The practical application of the sensor was manifested for the ex vivo determination of dopamine neurotransmitters using brain tissue samples of a mouse Parkinson's disease model.

Facile synthesis of Co(OH)2/Al(OH)3 nanosheets with improved electrochemical properties for asymmetric supercapacitor

Sheet-like Co(OH)2/Al(OH)3 or Co(OH)2 nanomaterial has been synthesized on conducting carbon fiber paper (CFP) by a facile one-step electrochemical deposition. The binder-free Co(OH)2/Al(OH)3/CFP displays an improved electrical conductivity, electrochemical activity and material utilization than solitary Co(OH)2, therefore Co(OH)2/Al(OH)3 nanomaterial exhibits improved electrochemical properties (a maximum capacitance of 1006 Fg−1 at 2 Ag−1, with 77% retention even at a high current density of 32 Ag−1, and more than 87% of the capacitance retention after 10000 cycles at 32 Ag−1) in comparison to that of the Co(OH)2/CFP (709 Fg−1, 65%, 79%). In addition, an asymmetric supercapacitor (ASC) fabricated with Co(OH)2/Al(OH)3/CFP positive electrode and AC/CFP negative electrode demonstrates ultrahigh specific capacitance (75.8 Fg−1) and potential window (1.7 V). These encouraging results make these low-cost and eco-friendly materials promising for high-performance energy storage application.

One step electrodeposition of V2O5/polypyrrole/graphene oxide ternary nanocomposite for preparation of a high performance supercapacitor

A new ternary nanocomposite based on graphene oxide (GO), polypyrrole (PPy) and vanadium pentoxide (V2O5) is obtained via one-step electrochemical deposition process. Electrochemical deposition of V2O5, PPy and GO on a stainless steel (SS) substrate is conducted from an aqueous solution containing vanadyl acetate, pyrrole and GO to get V2O5/PPy/GO nanocomposite. Characterization of the electrode material is carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). The electrochemical performance of the as-prepared nanocomposite is evaluated by different electrochemical methods including cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) in 0.5 M Na2SO4 solution. Remarkably, V2O5/PPy/GO nanocomposite shows a specific capacitance of 750 F g−1 at a current density of 5 A g−1, which is far better than PPy (59.5 F g−1), V2O5/PPy (81.5 F g−1) and PPy/GO (344.5 F g−1). Furthermore, V2O5/PPy/GO maintains 83% of its initial value after 3000 cycles, which demonstrates good electrochemical stability of the electrode during repeated cycling. These results demonstrate that the combination of electrical double layer capacitance of GO and pseudocapacitive behavior of the PPy and V2O5 can effectively increase the specific capacitance and cycling stability of the prepared electrode. Also, a symmetric supercapacitor device assembled by V2O5/PPy/GO nanocomposite yielded a maximum energy density of 27.6 W h kg−1 at a power density of 3600 W kg−1, and a maximum power density of 13680 W kg−1 at an energy density of 22.8 W h kg−1.

Facile synthesis of MnOxS2−x nanofiber arrays films on Ti for performance supercapacitor application

MnOxS2−x nanofiber arrays is successfully prepared by one-step electrochemical deposition at 343 K on Ti substrates. The as-prepared MnOxS2−x fibers are amorphous structure, which is confirmed by X-ray diffraction (XRD) results, and the stoichiometry is checked by X-ray photoelectron spectroscopy (XPS). The highest specific capacitance (Cs) of 278.22 F/g is obtained by cyclic voltammogram (CV) in a scan rate of 1 mV/s, and 214.78 F/g by galvanostatic charge discharge (GCD) technique at 1 mA/cm2 current rate, which is higher than that of pure MnO2.

Synthesis and microwave magnetic properties of magnetite nanowire arrays in polycarbonate templates

Abstract Magnetic nanowire arrays have potential applications in magnetic memory, microwave magnetic devices and many other fields. Spinel ferrite nanowire arrays exhibit a higher resistivity compared with metal counterparts; they also possess a strong shape anisotropy, such that they have high feasibility in microwave magnetic devices. Herein crystalline Fe 3 O 4 nanowire arrays were synthesized in polycarbonate porous membranes with pore sizes of 100 nm in diameter by one-step electrochemical deposition without heating. The phase structures, morphologies and magnetic properties were studied by XRD analysis, SEM and TEM observations and microwave magnetic measurements. The results showed that the as-prepared nanowires, characterized by polycrystalline phase structures, were uniform in size, with about 200 nm in diameter and 6–10 µm in length. Microwave magnetic properties of the arrays were characterized from microwave absorption parameters of the flip-chip on a microstrip line using a vector network analyzer (VNA). The ferromagnetic resonance (FMR) frequencies of ferrite arrays reached up to 25 GHz under a magnetic field of 9 kG, and more importantly it could be tuned in a wide frequency range by an external magnetic field. The results indicated that the Fe 3 O 4 nanowire arrays are promising absorbing microwave materials for flexible high-performance microwave devices.

Facile one-step electrochemical deposition of copper nanoparticles and reduced graphene oxide as nonenzymatic hydrogen peroxide sensor

For several decades, hydrogen peroxide has exhibited to be an extremely significant analyte as an intermediate in several biological devices as well as in many industrial systems. A straightforward and novel one-step technique was employed to develop a sensitive non-enzymatic hydrogen peroxide (H2O2) sensor by simultaneous electrodeposition of copper nanoparticles (CuNPs) and reduced graphene oxide (rGO). The electroreduction performance of the CuNPs-rGO for hydrogen peroxide detection was studied by cyclic voltammetry (CV) and chronoamperometry (AMP) methods The CuNPs-rGO showed a synergistic effect of reduced graphene oxide and copper nanoparticles towards the electroreduction of hydrogen peroxide, indicating high reduction current. At detection potential of −0.2V, the CuNPs-rGO sensor demonstrated a wide linear range up to 18mM with a detection limit of 0.601 mM (S/N=3). Furthermore, with addition of hydrogen peroxide, the sensor responded very quickly (<3s). The CuNPs-rGO presents high selectivity, sensitivity, stability and fast amperometric sensing towards hydrogen peroxide which makes it favorable for the development of non-enzymatic hydrogen peroxide sensor.

Microwave magnetic properties of spinel ferrite films deposited by one-step electrochemical method

Spinel ferrites have been widely used in microwave devices due to their excellent electromagnetic properties. In this study, two kinds of spinel ferrite films, Fe3O4 and Co xFe3-xO4, were grown on Pt(111)/Ti/SiO2/Si substrates by one-step electrochemical deposition method. The XRD and SEM characterizations demonstrated that the orientation of the ferrite films changed from (111) to (100) with the increase of depositing time. The cobalt content within Co xFe3-xO4 films was studied in detail by EDS analysis. The ferromagnetic resonance (FMR) responses of the ferrite films were measured by the flip-chip method using a vector network analyzer (VNA). It showed that the FMR frequency of Fe3O4 films reached to 10.5GHz under an out-plane magnetic field of 5 kOe, while it reached to 27GHz under an in-plane magnetic field of 5kOe for Co xFe3-xO4 films. Meanwhile, whether the magnetic field was applied parallelly or perpendicularly, the resonant peaks were increased linearly with increasing the magnetic field, indicating that the films are promising candidates for applications in tunable wave-absorbing materials or other tunable frequency devices.

Highly efficient oxygen evolution from CoS2/CNT nanocomposites via a one-step electrochemical deposition and dissolution method.

The oxygen evolution reaction (OER) has been viewed as a critical step in electrochemical energy conversion and storage devices. However, searching for cheap and efficient OER electrocatalysts still remains an urgent task. Herein, we develop a new strategy involving a one-step electrochemical deposition and dissolution method to fabricate hydrophilic porous CoS2/carbon nanotube (CNT) composites (CNT-CoS2). X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy measurements confirm the formation of hydrophilic groups on the surface of the porous CoS2 during electrochemical oxidation. Our design holds several advantages. The electricity conductivity of CoS2 is increased by introducing CNTs as a conductive substrate. The porous nanostructures of CoS2 increase its surface area, and provide paths to promote charge and reactant transfer. The active edge sites modified with hydrophilic groups can increase the content of electrolyte-electrode contact points, increasing the intrinsic catalytic performance of CoS2. These factors allow CNT-CoS2 to achieve a low onset potential of 1.33 V vs. RHE, a stable current density (j) of 10 mA cm-2 at an overpotential of 290 mV, and excellent stability under alkaline conditions compared to that of IrO2. The comprehensive performance of the CNT-CoS2 electrocatalyst is comparable to or better than that of any reported noble metal-free OER catalyst, even RuO2 and IrO2. This facile synthesis strategy involving synchronous electrochemical deposition and dissolution should be easily adapted for large-scale water electrolysis.

One-step electrochemical deposition of Schiff base cobalt complex as effective water oxidation catalyst

Schiff base metal complexes have been applied in many fields, especially, a potential homogeneous catalyst for water splitting. However, the high overpotential, time consumed synthesis process and complicated working condition largely limit their application. In the present work, a one-step approach to fabricate Schiff base cobalt complex modified electrode is developed. Microrod clusters (MRC) and rough spherical particles (RSP) can be obtained on the ITO electrode through different electrochemical deposition condition. Both of the MRC and RSP present favorable activity for oxygen evolution reaction (OER) compared to the commercial Co3O4, taking an overpotential of 650mV and 450mV to drive appreciable catalytic current respectively. The highly active and stable RSP shows a Tafel plot of 84mVdec−1 and negligible decrease of the current density for 12h bulk electrolysis. The synthesis strategy of effective and stable catalyst in this work provide a simple method to fabricate heterogeneous OER catalyst with Schiff base metal complex.

Cobalt Oxide Nanorods Prepared by a Template-Free Method for Lithium Battery Application

Transition metal oxide-based electrodes for lithium ion batteries have recently attracted much attention because of their high theoretical capacity. Here we report the electrochemical behavior of cobalt oxide nanorods as anodes, prepared by a template-free, one-step electrochemical deposition of cobalt nanorods, followed by an oxidation process. The as-deposited cobalt has a slightly convex columnar structure, and controlled thermal oxidation produces cobalt oxides of different Co/O ratios, while the original shape is largely preserved. As an anode in a rechargeable lithium battery, the Co/O ratio has a strong effect on initial capacity and cycling stability. In particular, the one-dimensional Co@CoxOy core shell structure obtained from a mild heat-treatment results in superior cycling stability. Keywords: Cobalt, Electrodeposition, Template-free, Cobalt oxide, Nanorod