CuO Electrode Research Articles

Studies on Biosensing Properties of Electrodeposited Copper Oxide Films

AbstractThe copper oxide (CuO) based films have been prepared for biosensing application. Electrodeposition mode has been used for preparation of CuO films on cost effective stainless steel substrates. The structural properties of CuO material are studied by X‐ray diffraction (XRD) pattern and it shows (ī11) more intensive plane. Hierarchical multilayer nanosheets clusters have been displayed in scanning electron microscopic images. The energy dispersive X‐ray analysis (EDAX) pattern displays wt% of Cu and oxygen in CuO material and it is found to be 52.80% and 57.61%. The glucose sensing of CuO electrodes is carried out in NaOH and glucose electrolyte at different concentration of glucose and 10–50 mV s−1 scan rates. The effect of glucose sensing on CuO electrode has been studied.

Correction to: Efficient electrochemical oxidation of reactive dye using a novel Ti/nanoZnO–CuO anode: electrode characterization, modeling, and operational parameters optimization

In the current study, electrochemical removal of reactive orange 7 (RO7) dye in aqueous solution was examined over a novel Ti/nanoZnO–CuO electrode prepared through electrophoretic deposition technique. Surface morphology, crystal structure, and elemental investigation of the prepared electrode were done by Field emission scanning electron microscopy, X-ray energy dispersive spectrometry, and X-ray diffraction analysis, which confirmed the presence of CuO nanoparticles along with ZnO nanoparticles in uniform coated layer. Besides, some electrochemical properties of the Ti/nanoZnO–CuO electrode were evaluated applying linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy analysis. Based on these analyses, the Ti/nanoZnO–CuO electrode behaves as a non-active electrode as well as it possessed smaller charge-transfer resistance and higher current density than Ti and Ti/nanoZnO electrodes. Further, chrono-amperometry along with chrono-potentiometry tests were conducted to assess the novel electrode stability and service lifetime. Obtained results indicated the presence of CuO nanoparticles conducive to the enhancement of stability and conductivity properties. To evaluate the prepared electrode performance and optimize the removal process, four independent variables of pH, electrolyte concentration, current, and reaction time as inputs along with RO7 removal efficiency as response function in central composite design were investigated. Under optimal conditions, the RO7 removal efficiency and chemical oxygen demand of 99.16% and 66.66% were obtained after 60 min for Ti/nanoZnO–CuO electrode. According to the obtained results, Ti/nanoZnO–CuO electrode can be used in the electrochemical treatment of organic pollutants as a promising electrode.

Microstructural and electrochemical supercapacitive properties of Cr‐doped CuO thin films: Effect of substrate temperature

Transition metal oxides have attracted a special interest in the applications of energy storage and conversion devices because of their distinctive structural, electronic, and catalytic properties. In the current study, the effect of substrate temperature on binder-free undoped CuO and Cr-doped CuO (~4.5 at. %) thin-film electrodes prepared by radio frequency sputtering technique is reported for supercapacitor applications. X-ray diffraction studies revealed the formation of undoped CuO and Cr-doped CuO films with monoclinic structure, while field emission scanning electron microscopy showed a significant change in the shape and size of the grains as a function of the substrate temperature. X-ray mapping indicated a uniform distribution of the elements present in these films. Substitution of Cr of ~4.5 at. % has not altered the primary monoclinic structure of CuO, but the doped CuO thin-film electrodes showed an improved conductivity. The electrochemical supercapacitive performance of the thin-film electrodes was studied using cyclic voltammetry, galvanostatic cycling with potential limitation, and electrochemical impedance spectroscopy techniques in 1 M KOH. The electrochemical measurements revealed that the thin-film electrode of Cr-doped CuO electrode developed at the substrate temperature of 573 K exhibited the highest areal capacitance of 209 mF cm−2 at a scan speed of 10 mV s−1, which is five times higher than that of the pure CuO (38 mF cm−2) thin-film. Furthermore, the Cr-doped CuO thin-film electrode exhibited excellent cycling stability with the capacity retention of 88% for 3000 continuous CV cycles in 1 M KOH. These results suggested that the binder-free Cr-doped CuO film electrodes prepared at the substrate temperature of 573 K is an excellent candidate material for the supercapacitor applications.

Chemically synthesized CuO nanostructures for non-enzymatic glucose sensor: effect of deposition time

In the present work, the chemical bath deposition technique was used to synthesize CuO electrodes. Their electrochemical properties were examined for non-enzymatic glucose sensors. In order to analyse, the crystallinity of prepared electrodes X-ray diffractometer (XRD) was used whereas Field Emission Scanning Microscope (FE-SEM) was for morphological study. The synthesized bundles of CuO nanosheets exhibited the monoclinic phase. For the study of electrochemical properties of prepared CuO electrodes, cyclic voltammetry and chronoamperometry techniques have been adopted. The developed CuO electrodes are the best candidates for non-enzymatic glucose sensing, showing excellent response. It shows high sensitivity 1594 µAmM−1cm−2 with potential of + 0.6V, active time period of approximately 5 s, and linear range 3 μm to 3 mM. The CuO electrode’s selectivity toward interfering species such as ascorbic acid is also studied. The prepared electrode shows an excellent response to glucose compared to ascorbic acid.

Surfactant concentration influences the morphology and electrochemical properties of CuO Nanoparticles synthesized via microwave method

Here, we detail the influence of the surfactant concentration on the morphological, structural and energy-storage property of CuO electrode material. When proposed as a supercapacitor material in neutral electrolyte (NaCl), it shows excellent electrochemical nature. Besides, it attains high specific capacitance (303F g−1 at 2 mVs−1), good rate performance (102F g−1 at 25 mVs−1) and good cyclic stability. In count, it has low charge transfer resistance (2.04 Ω), which is very essential when performing supercapacitive study at high current rates. These results are enhancing the study of CuO based electrodes for supercapacitor applications.

The Optical and Electrical Performance of CuO Synthesized by Anodic Oxidation Based on Copper Foam.

Metal oxide semiconductor materials have a wide range of applications in the field of solar energy conversion. In this paper, CuO was prepared directly on copper foam substrate by anodic oxidation. The effects of current density and anodizing temperature on sample preparation and performance were studied. Field emission scanning electron microscopy (FESEM) and X-ray diffractometer (XRD) had been used to determine the morphology and phase structure of the sample, and its optical and electrical properties were discussed through UV-vis spectrophotometer and electrochemical tests. In addition, the influences of experimental conditions such as current density and reaction temperature on the morphology and properties of CuO were systematically discussed. The FESEM images showed that as the anodic oxidation temperature increase, the morphology of the prepared sample changed from nanowires to leaf-like CuO nanosheets. According to the results of XRD, the structure of prepared CuO was monoclinic, and the intensity of diffraction peaks gradually increased as anodizing temperature increased. We found that the optimum current density and anodizing temperature were 20 mA cm−2 and 60 °C, respectively. The results of electrochemical indicated that the CuO electrode based on copper foam (CuO/Cu foam) prepared at the optimum exhibited the highest specific capacitance (0.1039 F cm−2) when the scan rate was 2 mV s−1.

Photoelectrocatalytic H2 evolution enhancement over CuO-decorated TiO2 nanocatalysts and promoting E. coli degradation

The objective of this research is to improve cathode electrode fabrication for high-efficiency hydrogen (H2) evolution and to promote Escherichia coli (E. coli) degradation at the anode electrode. The heterojunction of the TiO2/CuO photocathode was synthesized via sputtering of the TiO2 nanocatalyst on the CuO electrode for enhancing the H2 evolution efficiency. The effect of calcination temperatures for Cu2O conversion to high-catalytic CuO and priority deposition of the TiO2 layer were optimized to improve the photoelectrocatalytic (PEC) activity and charge transfer process. The optical properties, morphology, crystalline structure, and chemical composition were characterized to clarify the PEC activity improvement. The developed TiO2/CuO photocathode combined with the BiVO4/WO3 photoanode was designed in the PEC cell for H2 production and simultaneous E. coli degradation. Cu2O was changed to a narrower bandgap energy of CuO at the calcination temperature over 400 °C and presented high crystallinity and proper morphology when the temperature was increased to 550 °C. The CuO-decorated TiO2 nanocatalyst can improve the morphology and charge transfer process at the heterojunction of the TiO2/CuO electrode. The small particle size of TiO2 at the outer side can improve the surface roughness and serve as electron separation to reduce the recombination effect of CuO, resulting in high-efficiency H2 evolution. The developed PEC cell can produce H2 up to 5800 μL for 150 min and E. coli degradation up to 100% for 22 min under the PEC process. We can confirm that the developed TiO2/CuO cathode electrode is highly effective in H2 production and is sufficient in promoting the E. coli degradation process at the BiVO4/WO3 anode electrode. The findings of this research are beneficial in high-efficiency heterojunction semiconductor electrodes development and PEC cell designs for energy and environmental applications.

Recovery of copper oxide nanoparticles from waste SIM cards for supercapacitor electrode material

The advanced developments of supercapacitors are of great significance to meet the growing demands of portable electronic products. The current work describes the supercapacitive behavior of copper oxide nanoparticles recovered from waste SIM cards via one-pot green recovery route. The as-recovered copper oxide nanoparticles (CuO NPs) were characterized by spectral and analytical tools. In view of the potentiality of CuO in wide technological applications, the recovered CuO NPs were examined for their supercapacitive behavior. Typical pseudocapacitive behavior was noticed for the recovered CuO NPs with the specific capacitance of 542 Fg-1 at the current density of 1 Ag-1 by Galvanostatic Charge-Discharge (GCD) studies. The cyclic stability of CuO electrode material was obtained with 95.3% retention in specific capacitance even after 5000 GCD cycles. Moreover, Electrochemical impedance spectral (EIS) analysis revealed lower Equivalent series resistance (ESR) value, excellent rate and good reversibility response of CuO electrode. The prominent electrochemical properties of CuO NPs electrode proved its viable applicability for high performance supercapacitors.

Photoactive and self-cleaning properties of copper oxide thin film non-enzymatic glucose biosensor

In this study, CuO thin film has been prepared using a solution deposition process for the non-enzymatic electrocatalytic oxidation of glucose. The structure of the CuO was analyzed using X-ray diffraction technique while its electrocatalytic performance was investigated using cyclic voltammetry and chronoamperometry. The as-prepared CuO electrode exhibited a good response towards the oxidation of glucose due to its excellent electrocatalytic activity and electron transfer ability. In addition, the electrode demonstrated a good photocatalytic and self-cleaning ability during and after its exposure to light. These satisfactory performances make the electrode material promising for the development of effective non-enzymatic glucose sensors. In addition, the simple and low-cost fabrication procedure can be used to prepare electrodes on a large scale.

Multicore–Shell Ag–CuO networked with CuO nanorods for enhanced non-enzymatic glucose detection

This article describes a non-enzymatic electrocatalyst with high sensitivity and selectivity towards glucose. The electrocatalyst is based on a multicore–shell Ag–CuO nanocomposite networked with CuO nanorods. The composition of Ag–CuO plays a critical role in the formation of the unique network-like structure of Ag–CuO as well as in its electrocatalytic and sensing effects towards glucose. The electrocatalytic activity of CuO towards glucose was drastically improved by the incorporation of silver nanoparticles (Ag NPs) into the CuO nanostructures, which was accompanied by a substantial decrease in the charge transfer resistance (as confirmed by electrochemical impedance spectroscopic analysis). Among the different Ag–CuO composites prepared by varying the Ag-to-Cu atomic ratio, Ag–CuO(1:2.5) exhibited the best electrocatalytic activity towards glucose. The limit of detection and sensitivity of the Ag–CuO(1:2.5)-modified electrode were calculated to be 5 μM and 150.17 μA mM−1 cm−2, respectively, with a wide glucose detection range from 5 μM to 30 mM. Furthermore, the Ag–CuO(1:2.5) electrode exhibited excellent selectivity towards glucose in the presence of typical interfering agents (i.e., ascorbic acid, uric acid, dopamine, sucrose and NaCl) in blood. The Ag–CuO(1:2.5)-modified electrode further showed excellent reproducibility (relative standard deviation (RSD) of 2.9 %) and repeatability.

CuO/ZnO/TiO2 photocathodes for a self-sustaining photocell: Efficient solar energy conversion without external bias and under visible light

We report the results of a p-CuO nanoflake photocathode combined with an n-type TiO2 nanorod-based photoanode in a solar-water-splitting photocell, operating without external bias under visible light illumination. Both p-CuO nanoflakes and n-TiO2 nanorods were successfully fabricated by a low-cost solution-based method on transparent conductive substrates. Photocorrosion of the CuO electrode was suppressed by coating with a 200-nm ZnO/TiO2 protective film, which demonstrated a stability of over 70%. The visible-light response of single crystalline n-TiO2 nanorods was enhanced by sensitization with CdS/CdSe nanoparticles. Finally, the two n- and p-type photoelectrodes were short-circuited in the photocell, and their current-voltage (I–V) characteristics evaluated under visible-light illumination. The results of the I–V measurements reveal that the performance of the photocell strongly depends on the electrochemical properties of each electrode. The photocell comprising highly stable p-CuO and visible-light-active n-TiO2-based photoelectrodes operating without external bias demonstrated a short-circuit current and photoconversion efficiency of ~1 mA and 0.57%, respectively, under visible-light illumination.

Tuning Band Gaps and Photoelectrochemical Properties of Electrodeposited CuO Films by Annealing in Different Atmospheres

The band gaps and photoelectrochemical properties of electrodeposited CuO films were tuned through annealing as-electrodeposited films in different atmospheres at various temperatures. The direct band gaps of the CuO film descended from 1.80 eV for as-electrodeposited film to 1.76 eV for the film annealed in O2 at 300 °C or 1.64 eV for the film annealed in N2 at 300 °C. The stable photocurrent density for CuO electrode annealed in O2 at 300 °C measured at −0.4 V vs Ag/AgCl under a simulated sun light reached to 0.44 mA cm−2 while the value was only 0.29 mA cm−2 for the electrode annealed in N2 in a solution with 10 mM potassium ferricyanide, 10 mM potassium ferrocyanide, and 0.5 M Na2SO4. The mechanism for photoresponse enhancement was studied and could be due to faster charge transfer and higher doping density for the CuO film annealed at 300 °C in O2.

High energy and power density of self-grown CuS@Cu2O core-shell supercapattery positrode

A self-grown copper sulfide@copper oxide (CuS@Cu2O) positrode synthsis by a hydrothermal method followed by 2 h of air annealing method (at 300 °C) from copper-foam (Cu-F) is envisaged as supercapattery electrode material in 0.1 M KOH electrolyte solution where remarkable capacities of 145, 134, 125, and 112 mA h g−1 at current densities of 1, 2, 3, and 4 A g−1, respectively, with about 80% retention ability after 2000 redox cycles, are obtained. The electrochemical performance obtained for self-grown CuS@Cu2O positrode is better than those reported previously for self-gown CuS, Cu(OH)2, and CuO electrode materials. An asymmetric supercapattery device fabricate using CuS@Cu2O as a positrode with Bi2O3 as negatrode, i.e., CuS@Cu2O//Bi2O3, demonstrates an energy density of 52 Wh kg−1 at a power density of 750 W kg−1 at 0.5 A g−1 which, when connected in series with another similar device, lightens a LED with its full-bright intensity, confirming a commercial potential of designed electrochemical supercapattery device.

The effects of CuO additives as the dendrite suppression and anti-corrosion of the Zn anode in Zn-air batteries

The new copper oxide-zinc composites (CuO–Zn) can be used to relieve the dendrite formation, corrosion reaction, and increase the reversibility of Zn anode. CuO–Zn composites were produced by mixing Zn and additive powders to prevent dendrites and the Zn corrosion and can be easily manufactured technically by simply adding it. To confirm the dendrite suppression, an electrodeposition method was conducted. Surface of Zn anode was analyzed by FE-SEM images and CuO showed a more controlled dendrite morphology than other Cu compounds. After the CuO–Zn electrodes were produced using 0.1, 0.5, 1.0, and 3.0wt.% CuO in Zn, an H2 gas evolution test was adapted to examine the anti-corrosion. The 0.5wt.% CuO electrode exhibited the lowest H2 gas evolution. To assess the improved performances, several electrochemical measurements like cathodic overpotential, tafel polarization, cyclic voltammetry, and DC-cycling test (full cell test) were conducted and the 0.5wt.% CuO mixed Zn electrode showed the best reversibility of all samples and longer cycle life until 19 cycles than 13 cycles of pristine Zn.

3D porous structured polyaniline/reduced graphene oxide/copper oxide decorated electrode for high performance nonenzymatic glucose detection

In this study, graphene oxide (GO) was directly co-deposited with polyaniline (PANI) on a Pt electrode and a 3D cluster structure of GO with wrinkled and rough surface was formed during the electro-polymerization and deposition process. Results of Raman spectra, X-ray photoelectron spectroscopy (XPS) showed that strong conjugated interactions had formed between GO clusters and PANI nanofibers. After GO was reduced, XPS measurements and electrochemical impedance spectra (EIS) studies indicated that most of the oxygen functional groups in GO were successfully removed and the conductivity of the composite material was dramatically increased. The morphology and structure of the prepared Pt/PANI/rGO/CuO electrodes were characterized by scanning electron microscopy (SEM) and the electrochemical response of the proposed electrodes in presence of glucose was investigated. Results showed that the 3D structure of rGO clusters greatly increased its effective surface area and improved the electronic transmission efficiency of the composite nanomaterial thus the Pt/PANI/rGO/CuO modified electrodes displayed much higher electrocatalytic activity than the Pt/PANI/CuO modified electrodes towards glucose, exhibiting a high sensitivity of 1252μA mM−1cm−2, a fast response time of <3s, a low detection limit of 1.5μM (S/N=3) and a wide linear range from 0mM to 13mM. The Pt/PANI/rGO/CuO electrode effectively resisted the effect of interferences such as l-ascorbic acid (AA), acetaminophen (AP) and uric acid (UA) and retained ~ 90% of its initial sensitivity after 15days.

Hierarchically porous CuO nano-labyrinths as binder-free anodes for long-life and high-rate lithium ion batteries

The ability to rationally design binder-free electrode materials that possess interconnected nanostructures is highly desirable for lithium-ion batteries (LIBs) with long cycling and excellent rate performances. Such electrode containing pores between nanostructures imparts large-area contact with electrolyte, improved electrical conductivity with current collector, and good structural stability and mechanical integrity. Herein, we report, for the first time, outstanding cycling stability and rate performance of CuO electrode in LIBs. CuO nano-labyrinths (NLs) composed of densely interlaced nanowalls on Cu foil are crafted via a facile solution-based etching process. It is notable that macroscopic and mesoscopic pores are found to ubiquitously present among the adjacent CuO nanowalls and within the nanowall, respectively (i.e., forming hierarchically porous CuO NLs). Intriguingly, CuO NLs anodes yield an ultralong cycling stability, that is, a specific capacity of 320 mA h g−1 after 800 cycles without the capacity fading at high current density of 1 A g−1, and an outstanding high-rate performance (up to 30 C). This is a direct consequence of unique synergistic effects of hierarchical pores and interlaced nanostructures. Moreover, a further enhancement of reversible capacity is achieved by deposition Si thin film on the surface of CuO NLs. Such interlaced nanowall-containing structures with hierarchical pores represent an important type of architectures that underpin the development of electrode materials for long cycle-life energy storage devices.

The supercapacitive performance of woollen-like structure of CuO thin films prepared by the chemical method

The woollen-like structure of Copper Oxide (CuO) thin films has been synthesized via chemical method using aqueous ammonia as a complexing agent which is directly used as an electrode material for supercapacitor application. CuO electrode achieved maximum specific capacitance of 576 F/g, exhibited for 5 mV/s scan rate with the small Equivalent Series Resistance (ESR) value of 0.72 Ω. The highest energy density, power density and Coulomb efficiency of CuO electrode was observed having values of 19.65 Wh/kg, 916.66 W/kg and 82.01% respectively at current density of 1 mA/cm2. CuO thin films are found to have monoclinic structure as confirmed from X-ray Diffraction (XRD). It is observed that as the deposition time enhances the crystallite size also increases, whereas micro-strain, dislocation density and distortion parameters decrease. The FESEM results confirmed woollen-like structure of CuO thin films. Surface wettability shows hydrophilic nature with the liquid interface. The EDS spectra confirmed the Cu and O elements present in the prepared samples. The BET analysis shows that the CuO thin film has high surface area of 39.58 m2/g with mesoporous characteristics. These results show that electrode will be a potential material in the supercapacitor applications besides it is cost-effective.

Cotton as a sustainable source of CuxO/C anode for high-performance Li-ion battery

This paper reports a simple-assembling synthesis of CuxO/C composite as the anode for lithium-ion batteries. The CuxO/C composite can be easily attained through using cotton as the template. Used as the anode material, the CuxO/C electrode has shown a relatively stable electrochemistry performance compared with the pristine CuO electrode. The cycling test results showed that the CuxO/C electrode achieved the steady specific capacity values of 381 mAhg−1 at 335 mAg−1 after 350 cycles while the capacity of the CuO electrode decreased after several cycles before it increased to 375 mAhg−1. This CuxO/C anode electrode stability is considered attributed to its core/shell structure, which can help keep the electrode structure stable during cycling.

Vertical CuO nanowires array electrodes: Visible light sensitive photoelectrochemical biosensor of ethanol detection

Photoelectrochemical (PEC) sensing using visible light has attracted great attention for high sensitivity with low undesired background noise. A CuO electrode with nanowires on Cu foil was synthesized by thermal oxidation and the devices was used to explore the PEC sensing for ethanol detection under visible light. The morphology, composition, optical, and PEC properties of CuO nanowires have been systematically investigated. The results showed that the CuO nanowires were present on the top surface of specimens with single phase and the thick interface layer were made of Cu2O between CuO nanowires and Cu foil substrate. The CuO nanowires on surface contained two types of nanowire (bend CuO Nws and vertical CuO Nws). With the temperature increasing, the Nws of first type decreased, and the Nws of second type started to increase. When the Cu foil were annealed at 700 °C, densely bundled CuO Nws array was vertically fabricated on the foil. The band gaps of CuO nanowires annealing at 400 °C, 500 °C, 600 °C, and 700 °C, were 1.715, 1.714, 1.698, 1.691 eV, indicating that CuO nanowires annealing at 700 °C can obtain the highest photoreponse. The photocurrent of the vertical CuO nanowires array annealing at 700 °C were calculated with 668 μA cm−2 about 2-fold, 6-fold and 10-fold higher than that to CuO nanowires annealing at 600 °C, 500 °C and 400 °C, respectively. Combing with the morphology of CuO nanowires annealing at different temperature, the vertivally-aligned nanowires array at 700°Cwas attractive than others. This vertical CuO nanowires device prepared at 700 °C is visible-light irradiation and shows the fast photoresponse, present a detection limit of 23.2 nM, which is much lower than those with the similar configurations reported previously. It is probable that the vertical CuO nanowires array may be applied as the proposed PEC sensor to determine ethanol in further.

Regulation of Breathing CuO Nanoarray Electrodes for Enhanced Electrochemical Sodium Storage

AbstractCupric oxide (CuO) represents an attractive anode material for sodium‐ion batteries owing to its large capacity (674 mAh g−1) associated with multiple electron transfer. However, the substantial volume swelling and shrinking (≈170%) upon Na uptake and release, which mimics an electrode breathing process, disturbs the structural integrity, leading to poor electrochemical durability and low Coulombic efficiency. Here, a structural strategy to regulate the breathing of CuO nanoarray electrodes during Na cycling using an atomic layer deposition of cohesive TiO2 thin films is presented. CuO nanoarrays are electrochemically grown on 3D Cu foam and directly used as anodes for sodium storage. The regulated CuO electrode arrays enable a large reversible capacity (592 mAh g−1), a high cycle efficiency (≈100%), and an excellent cycling stability (82% over 1000 cycles), which are some of the best sodium storage performance values reported for CuO systems. Electrochemical impedance and microscopic examination reveal that the enhanced performance is a direct outcome of the efficient regulation of the breathing of CuO nanowires by TiO2 layer.