Copper Bismuth Oxide Research Articles

Novel sphere-like copper bismuth oxide fabricated via ethylene glycol-introduced solvothermal method with improved adsorptive and photocatalytic performance in sulfamethazine removal.

In this research, ethylene glycol-introduced solvothermal method was employed to fabricate a novel sphere-like CuBi2O4 material to improve the adsorptive and photocatalytic performance of conventional CuBi2O4. A series of characterization has been applied to investigate properties of the obtained CuBi2O4 (CBO-EG3). Compared with conventional rod-like CuBi2O4 (CBO), the synthesized sphere-like CBO-EG3 exhibited rough surface, larger specific surface area, and more effective separation of photo-generated carriers, which overcome main shortcomings of CuBi2O4. The removal efficiency of typical antibiotic sulfamethazine (SMZ) reached almost 100% under the optimal experimental conditions. About 70% of SMZ could be adsorbed in 180-min dark reaction, with residual being photodegraded in 30min. CBO-EG3 showed much higher photocatalytic efficiency than pure CBO, attributing to its highly effective photo-induced electron and hole separation. Meanwhile, substantial adsorption of pollutant on CBO-EG3 contributed vastly to removal of SMZ, photo-generated electrons and holes inclined to react with adsorbed SMZ directly, and photocatalytic process was mainly led by non-radical reaction. Elimination of SMZ in actual water samples and recycling experiment were also performed to evaluate CBO-EG3's practical application potential. This study delivered a method to promote CuBi2O4's adsorptive and photocatalytic ability, which could expand the application of CuBi2O4 in wastewater treatment.

Nanostructured Copper Bismuth Oxide for Sensitive and Selective Electrochemical Detection of 4-Nitrophenol

Nanostructured Copper Bismuth Oxide for Sensitive and Selective Electrochemical Detection of 4-Nitrophenol

Uplifting the charge carrier separation and migration in Co-doped CuBi2O4/TiO2 p-n heterojunction photocathode for enhanced photoelectrocatalytic water splitting

Here, cobalt-doped copper bismuth oxide (Co-CuBi2O4) was synthesized via a facile hydrothermal method for photoelectrocatalytic (PEC) hydrogen production. The results disclosed that the 5% Co-doped CuBi2O4 has better PEC activity which is ∼3 fold higher than pristine CuBi2O4. The doping of cobalt in CuBi2O4 improves the interfacial charge transfer at an electrode/electrolyte interface and reduces the recombination rate of photogenerated electron-hole pairs. This higher performed 5% Co-doped CuBi2O4 photocathode further modified with TiO2-P25 to form a Co-CuBi2O4/TiO2 p‐n heterojunction. This Co-CuBi2O4/TiO2 photocathode displayed a photocurrent density of 330 μA cm−2 at +0.5 V vs. RHE which was ∼2 fold higher than Co-CuBi2O4. Because this p-n junction affords inner electric field in the space charge region that helps for further minimization of electron-hole recombination, which facilitate efficient charge separation and transport thereby enhance the PEC water reduction.

Electrodeposited copper bismuth oxide as a low-cost, non-enzymatic electrochemical sensor for sensitive detection of uric acid and hydrogen peroxide

We report for the first-time copper bismuth oxide (CuBi2O4) as an electrochemical sensor for the oxidation of uric acid and reduction of hydrogen peroxide. CuBi2O4 films are prepared on FTO via electrodeposition and used as a working electrode. Structural and morphological studies of CuBi2O4 were done by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron microscopy, tunneling electron microscopy (TEM). Electrochemical studies were performed using cyclic voltammetry (CV), chronoamperometry with CuBi2O4 electrode for the detection of uric acid (UA) and hydrogen peroxide (HP). High sensitivities of 206.7 and 280.6 μA mΜ-1 cm−2 were achieved for the detection of UA and HP. Therefore, CuBi2O4 can be a potential candidate to explore for sensing applications.

Simulating the performance of a highly efficient CuBi2O4-based thin-film solar cell

In this study, copper bismuth oxide (CuBi2O4) absorber-based thin film heterojunction solar cell structure consisting of Al/FTO/CdS/CuBi2O4/Ni has been proposed. The proposed solar cell device structure has been modeled and analyzed by using the solar cell capacitance simulator in one dimension (SCAPS-1D) software program. The performance of the proposed photovoltaic device is evaluated numerically by varying thickness, doping concentrations, defect density, operating temperature, back metal contact work function, series and shunt resistances. The current density–voltage behaviors at dark and under illumination are investigated. To realize the high efficiency CuBi2O4-based solar cell, the thickness, acceptor and donor densities, defect densities of different layers have been optimized. The present work reveals that the power conversion efficiency can be enhanced by increasing the absorber layer thickness. The efficiency of 26.0% with open-circuit voltage of 0.97 V, short-circuit current density of 31.61 mA/cm2, and fill-factor of 84.58% is achieved for the proposed solar cell at the optimum 2.0-μm-thick CuBi2O4 absorber layer. It is suggested that the p-type CuBi2O4 material proposed in the present study can be employed as a promising absorber layer for applications in the low cost and high efficiency thin-film solar cells.

CuBi2O4 Synthesis, Characterization, and Application in Sensitive Amperometric/Voltammetric Detection of Amoxicillin in Aqueous Solutions.

CuBi2O4 synthesized by thermolysis of a new Bi(III)-Cu(II) oxalate coordination compound, namely Bi2Cu(C2O4)4·0.25H2O, was tested through its integration within carbon nanofiber paste electrode, namely CuBi/carbon nanofiber (CNF), for the electrochemical detection of amoxicillin (AMX) in the aqueous solution. Thermal analysis and IR spectroscopy were used to characterize a CuBi2O4 precursor to optimize the synthesis conditions. The copper bismuth oxide obtained after a heating treatment of the precursor at 700 °C/1 h was investigated by an X-ray diffraction and scanning electron microscopy. The electrochemical behavior of CuBi/CNF in comparison with CNF paste electrode showed the electrocatalytic activity of CuBi2O4 toward amoxicillin detection. Two potential detections, with one at the potential value of +0.540 V/saturated calomel electrode (SCE) and the other at the potential value of −1.000 V/SCE, were identified by cyclic voltammetry, which were exploited to develop the enhanced voltammetric and/or amperometric detection protocols. Better electroanalytical performance for AMX detection was achieved for CuBi/CNF using differential-pulsed and square-wave voltammetries than others reported in the literature. Very nice results obtained through anodic and cathodic currents recorded at +0.750 V/SCE and −1.000 V/SCE in the same time period using a pseudo multiple-pulsed amperometry technique showed the great potential of the CuBi/CNF paste electrode for practical applications in amoxicillin detection in aqueous solutions.

Bismuth based photoelectrodes for solar water splitting

Photoelectrochemical water splitting is a sustainable path to generate valuable hydrogen using sunlight and water as the only inputs. Despite significant efforts to date, it is still a challenge to achieve photoelectrode with superior performance and long-term stability.Many bismuth-based semiconductor materials have demonstrated excellent visible light harvesting capability and suitable band edge for water splitting. Herein, we summarized the latest studies conducted on bismuth-based photoelectrodes for photoelectrochemical water splitting. Specifically, photoelectrochemical properties of copper bismuth oxide (CuBi2O4), bismuth ferrites (BiFeO3, Bi2Fe4O9), bismuth vanadate (BiVO4), bismuth tungstate (Bi2WO6), bismuth molybdate(Bi2MoO6) and bismuth oxyhalids (BiOX, X = I, Cl, Br) are presented. Strategies to achieve high stability and photolectrochemical performance were discussed in the aspects of nanostructure formation, heterostructure assembly, practical defect engineering, preferential facet growth and oxygen evolution catalyst incorporation.

Relationship between the morphology for the photo-electrode of copper bismuth oxide and the photo-electrochemical activity related to water reduction

The relationship between the morphology of the photo-electrode of copper bismuth oxide (CuBi2O4) and the activity to generate cathodic photo-current in a deoxygenated aqueous electrolyte was investigated. The electrodes were fabricated by the electrodeposition of the precursor on a conductive substrate following heat treatment. As a simple comparison, a randomly porous electrode was compared with a dense electrode. A dense electrode and a porous electrode were fabricated by selecting the potential to deposit the precursor; formation of the electrode was confirmed by measuring X-ray diffraction patterns and scanning electron microscope images. The values of the absorbed photon to current efficiency were calculated by measuring steady photocurrents in a deoxygenated electrolyte at a constant potential under irradiation of monochromatic visible lights. The dense electrode shows larger values than the porous electrode. To consider the difference in the values between the electrodes, the values were also calculated for the current generated in the electrolyte of dissolved oxygen to scavenge electrons. Eventually, it is considered that for CuBi2O4 electrodes, dense morphologies are more suitable than porous morphologies to produce hydrogen by photo-electrochemical water reduction in terms of charge separation inside the electrode. Dense and porous photo-electrodes of copper bismuth oxide were fabricated by selecting the potential to deposit the precursor and following heat treatment. The former is more efficient to generate the current for water photo-reduction in a deoxygenated aqueous electrolyte due to more facile transfer of electrons inside the electrode.

Charge Transfer Kinetics in the Dark at Oxide Semiconductor/ electrolyte Interfaces

Among all the requisite properties of an inorganic semiconductor, the dynamics of interfacial charge transfer is an important common denominator for numerous technologically important applications such as PEC water splitting, photocatalytic pollutant degradation, or photovoltaic solar energy conversion.Most attention in this regard has been paid to the dynamics of minority carrier transfer; only sporadic studies have focused on majority carrier transfer across the solid/electrolyte interface. However, recent studies have underlined the growing realization that the charge transfer kinetics of both minority and majority carriers are often coupled. Performance optimization of the interfaces must address both these charge transfer pathways such that deleterious carrier recombination can be minimized. Therefore, this study addresses the fundamental and experimental understanding of interfacial charge transfer dynamics at semiconductor/electrolyte interfaces in the dark . A variety of interfaces were studied to gain a unified and self-consistent picture.Firstly, binary n-type TiO2 and WO3 semiconductors were chosen because of their excellent chemical/photoelectrochemical (PEC) stability, high PEC activity, and overall robustness over a wide pH range. Secondly, binary and ternary p-type semiconductors such as copper bismuth oxide (CuBi2O4),silver vanadate (AgVO3),and copper (II) oxide (CuO) were selected to compare their charge transfer kinetics in the dark. Such comparative studies are conspicuously absent in the literature, and in particular, dark current-forward bias potential measurements are lacking for these compounds. Tafel analyses were used to evaluate the standard rate constant, k 0 and the exchange current density, jo in all these cases. Based on these kinetics data, a general conclusion could be made that p-type oxide semiconductors exhibited faster kinetics than their n-type counterparts. For comparison, Pt and fluorine doped tin oxide (FTO) electrodes were included as benchmarks in these experiments. The data also indicated that heterogeneous charge transfer at metal/electrolyte interfaces had faster kinetics compared to the semiconductor/electrolyte interfaces. This contrasting and self-consistent behavior stems from surface state density variations in the two sets of cases. The practical implications of these data are finally discussed.

Magnetron sputtered copper bismuth oxide photocathodes for solar water reduction

There is an urgent need for new materials that can catalyze or drive the photoelectrochemical (PEC) conversion of solar energy into chemical energy, i.e. solar fuels. Copper bismuth oxide (CBO) is a promising photocathode material for the photochemical reduction of water. Here, we systematically control the stoichiometry of CBO thin films prepared by reactive, direct-current magnetron co-sputtering from metallic Bi and Cu targets. The intrinsic photophysical and PEC material properties are investigated and evaluated in order to determine the optimum composition for hydrogen formation. Changing the stoichiometry of the films reveals a dramatic change in the optical band gap and crystal structure of CBO. The largest photocurrent density was achieved for a copper-to-bismuth ion ratio of 0.53, close to the CuBi2O4 stoichiometry, which yielded Jph = − 0.48 mA cm−2 at 0 VRHE (RHE = reversible hydrogen electrode). This is the highest value to date for the photochemical reduction of water with CuBi2O4 without an externally applied bias. The absorbed photon-to-current efficiency and the photostability of the films in neutral and alkaline electrolytes were also investigated.

Electrocatalytic performance of cobalt doped copper bismuth oxide for glucose sensing and photoelectrochemical applications

Copper bismuth oxide (CBO), modified with cobalt as dopant has been prepared by coprecipitation and the electrode was prepared by doctor blade method. The cobalt doped copper bismuth oxide (Co-CBO) has been extensively used for selective glucose sensing and photoelectrochemical activity. Physical characterizations like X-ray diffraction, field-emission scanning electron microscopy are studied to confirm the formation of desired electrode. Linear sweep voltammetry, chronoamperometric and impedance studies explain about the electrocatalytic nature of cobalt doped CBO. Oxidation peak for glucose was observed for CBO at 0.54 V while for Co-CBO it occurred at 0.46 V. The reduction in potential is explained through synergistic catalytic enhancement due to cobalt doping. Further, Co-CBO was used for photoelectrochemical application, the electrode has shown current density of −0.80 mA cm−2 while that for CBO is −0.20 mA cm−2. Therefore, CBO has formed a desirable phase with cobalt which resulted in the enhancement of electrocatalytic performance.

Influence of post-deposition annealing on the photoelectrochemical performance of CuBi2O4 thin films

Complex metal oxide semiconductors are promising candidates to be used as photoelectrodes in solar water splitting devices. One particular example is copper bismuth oxide (CuBi2O4), which is a p-type semiconductor with an ideal bandgap of 1.6–1.8 eV and suitable band positions. However, the performance has been reported to be limited by photocorrosion and the mismatch between its optical absorption and charge carrier transport properties. It has been shown that the former can be overcome by the deposition of protection layers, while the latter can be addressed by the modification of the bulk properties of the material. Here, we deposited thin films of CuBi2O4 using pulsed laser deposition (PLD). This results in high quality films, as evident from the internal quantum efficiency, which is comparable to the best-performing CuBi2O4 photoelectrodes. We investigate the bulk modification of the films by exploring post-deposition annealing treatment at various temperatures and oxygen partial pressures. These post-deposition annealing parameters influence the morphology of the films through the formation of aggregated particles/islands with higher crystallinity. The anneal treatment reduces bulk recombination in the film and increases the AM1.5 photocurrent by a factor of more than three. The influence of the high temperature post-deposition annealing treatment on other properties of CuBi2O4 (absorption, formation, and suppression of defects) is also discussed. This study underlines the importance of high temperature post-deposition annealing treatment in optimizing the performance of complex metal oxide photoelectrodes.

Preparation and study of CuBi2O4 thin films by RF magnetron sputtering

Copper bismuth oxide (CuBi2O4 or Bi2CuO4) thin films have been elaborated for the first time by radio-frequency magnetron sputtering using a homemade CuBi2O4 ceramic target. X-ray diffraction characterizations revealed an amourphous phase for as-deposited films. After air annealing at 450 °C for 12 h, a pure polycristalline CuBi2O4 phase can been obtained. Raman spectroscopy confirmed the film phase purity. The influence of the thickness on the structural properties of the films has been studied and we observed that all films treated above 450 °C are crystallized. The thinner films show preferred orientation while there are less crystal defects for the thickest films (∼700 nm). Atomic force microscopy shows a homogeneous polycristalline microstructure at the surface of the film. Optical measurements performed by UV–vis-IR spectrophotometry indicate that these films have one of their optical band gaps in the visible region (Eg∼1.5 eV) which makes them suitable as thin films solar absorption materials.

Near-Infrared-Active Copper Bismuth Oxide Electrodes for Targeted Dissociation of Alzheimer's β-Amyloid Aggregates.

The abnormal accumulation of β-amyloid (Aβ) aggregates in the brain is a major pathological hallmark of Alzheimer's disease. We report a near-infrared (NIR)-active CuBi2O4-based photocathodic platform that can target intact Aβ aggregates and dissociate them into nontoxic species. Because of its relatively narrow band gap, CuBi2O4 exhibits strong absorption of NIR light, which allows for deeper tissue penetration and causes less photodamage to tissues compared to visible light. Furthermore, its high stability in aqueous media, biocompatibility, and robustness against photocorrosion make CuBi2O4 an ideal material for medical applications. For the targeted clearance of Aβ aggregates, we have conjugated the KLVFF peptide which specifically recognizes and captures Aβ aggregates on the surface of silver-doped CuBi2O4 (Ag:CuBi2O4). Upon illumination of NIR light under a cathodic bias, the KLVFF-immobilized Ag:CuBi2O4 (KLVFF-Ag:CuBi2O4) effectively dissociated β-sheet-rich, long, and entangled Aβ fibrillary aggregates into small fragmented, soluble species through photo-oxygenation. We also verified that the KLVFF-Ag:CuBi2O4 photocathode is biocompatible and effective in reducing Aβ aggregate-induced neurotoxicity. Our work demonstrates the potential of the KLVFF-Ag:CuBi2O4 platform for the targeted disassembly of cytotoxic, robust Aβ aggregates with the aid of NIR energy and cathodic bias.

Electrodeposited spruce leaf-like structured copper bismuth oxide electrode for supercapacitor application

Novel spruce leaf-like copper bismuth oxide (CuBi2O4) microstructured films have been deposited on stainless steel (SS) substrate by using a simple and cost-effective electrodeposition chemical route. The morphology of CuBi2O4 was studied using field emission scanning electron microscopy (FESEM) whereas X-ray diffraction (XRD) spectra recorded for phase confirmation. The spruce leaf-like architecture composed of nanoparticles was evidenced for the obtained CuBi2O4 material. The supercapacitor performance for prepared CuBi2O4 electrode calcined at 200, 300, 400, 500 °C temperatures were investigated. The cyclic-voltammetry and charge-discharge studies were carried out at different scan rates and current densities respectively. The highest specific capacitance 484 F/g was noted for CuBi2O4 electrode calcined at 500 °C at 10 mV/ s scan rate via cyclic-voltammetry analysis in 1 M NaOH electrolyte. The specific capacitance of 540.9 F/g was estimated from charge-discharge analysis at 10 mA/cm2 current density. The energy density of 146.8 Wh/Kg and power density 1555.5 W/Kg for optimized CuBi2O4 electrode at 10 mA/cm2 current density. The electrochemical impedance spectroscopy studies were also performed. The nanostructured CuBi2O4 material has exhibited supercapacitive properties for energy storage applications.

CuO/CuBi2O4 heterojunction photocathode: High stability and current densities for solar water splitting

Global energy crisis escalates the emphasis on ways to find green and sustainable solutions. Photoelectrochemical (PEC) conversion is one of the key technologies to fulfill the energy demand by converting solar energy into chemical fuels. Binary copper oxides suffer from severe photocorrosion and ternary copper oxides such as copper bismuth oxide (CuBi2O4) exhibit poor charge separation and transfer. In this work, a composite consisting of CuO annealed at 450 °C and CBO electrodeposited for 5 min on top of it (CuO-450/CBO-5) showed the best performance with a positive shift of 0.2 V in onset potential, a high current density of −0.9 mA cm−2 at 0.1 V vs RHE and high stability over pure CuO. The systematic deposition of CBO on CuO leads to intimate contact between the two semiconductors wherein, CuO acts as a hole carrier and CBO accommodates the hydrogen evolution reaction (HER).

Dual Roles of MoO3 Thin Film in Improving the Performance of Copper Bismuth Oxide Photocathode for Solar Water Splitting

Abstract Promoting the hole extraction from the photocathode semiconductor is crucial to not only enhance the charge separation and suppress the charge recombination but also to protect the oxidation of the photocathode semiconductor by the photogenerated holes. Here, we use a very thin MoO3 film as a hole buffer layer between conductive substrate fluorine-doped tin oxide and the p-type semiconductor CuBi2O4. Through comprehensive photoelectrochemical characterizations, we find that the insertion of a hole buffer layer MoO3 not only accelerates the hole traction from the CuBi2O4 photocathode but also blocks the backward transfer of photogenerated electrons. This optimized charge transfer behavior contributes to the improved photoelectrochemical performance. Based on our results, some interesting designs on CuBi2O4 photocathode are given at the end that will be potentially working as effective photocathodes.

An iron oxide -copper bismuth oxide photoelectrochemical cell for spontaneous water splitting

Highly efficient water splitting reaction on hematite photoelectrode has been encumbered by its low photovoltage and photocurrent in a water splitting cell. In this work, a nanostructured hematite photoanode was prepared via a hydrothermal method, and its water oxidation activity was greatly enhanced by the synergetic application of uniform in-situ cobalt-doping and surface modification with fine cobalt iron oxide nanoparticles electrocatalyst. As a result, its remarkable low onset potential of 0.55 VRHE for water oxidation allows the construction of tandem cell with a novel metal oxide photocathode CuBi2O4, which has already proven reasonably robust photoactivity for water reduction reaction. The photocurrent and long-term stability of this metal oxides based device in alkaline electrolyte for unassisted overall water splitting reaction were investigated. A solar to hydrogen efficiency of 0.15% was measured accordingly on this spontaneous hydrogen production device, without the involvement of precious metal components.

Hydrothermal Synthesis, Structural and Catalytic Studies of CuBi2O4 Nanoparticles

In the present work CuBi2O4 nano-spinel has been synthesized via mild hydrothermal method at 180°C for 10 h. The synthesized nanomaterials were characterized by several techniques to emphasis the structure and properties of produced materials. The crystal structure was investigated by X-ray powder diffraction method and the values of refined unit cell volume and the structure properties were studied by using the Rietveld analysis is done using fullprof program. The results shew the formation of tetrahedral structure with space group P4/ncc for this sample. Also, the morphologies of the synthesized materials were figured out by field emission scanning electron microscope (FE-SEM). According to the FESEM images, several nano cubic form particle grew on micro spherical particles. As well, the catalytic performance of obtained CuBi2O4 was studied in Biginelli reaction. The reaction conditions of this study optimized by experimental design method. This experiment stablished high catalytic performance of copper bismuth oxide in compare with some other metal oxide catalysts.Also, the results shew this product is reusable homogenous catalyst.

Hydrothermal synthesis and crystal structure of a new lithium copper bismuth oxide, LiCuBiO4

A new lithium copper bismuth oxide, LiCuBiO4 was prepared by hydrothermal reaction using NaBiO30.1*4H2O. The crystal structural model of this compound was refined by using synchrotron X-ray powder diffraction data. This bismuthate has the LiCuSbO4 related structure with the orthorhombic cell (Space group: Pnma) of a=10.9096(9), b=5.8113(5) and c=5.0073(4)Å, and the final R-factors were Rwp=4.84 and Rp=3.58%. This compound is the first example of a lithium copper bismuthate containing Bi5+. An antiferromagnetic ordering of Cu2+ moment was observed at 6K.