Copper Cobaltite Research Articles

Design of novel Z-scheme g-C3N4/TiO2/CuCo2O4 heterojunctions for efficient visible light-driven photocatalyic degradation of rhodamine B

One of the most important environmental challenges that needs to be resolved is the industrial discharge of synthetic dyes. Graphitic carbon nitride (g-C3N4), Titanium dioxide (TiO2) and flower-like copper oxide (CuO)/copper cobaltite (CuCo2O4) nanocomposites were synthesized in order to synthesis an effective visible light driven photocatalyst that could degrade Rhodamin B (Rh.B) dye under simulated solar light irradiation. The SEM and TEM results verifies that the flower-like CuO/CuCo2O4 (CCO) structure and g-C3N4/TiO2 (g-CN/TO) generated a smart hybrid structure with superior g-CN distribution. According to the photocatalytic studies, g- C3N4/TiO2/CuO/CuCo2O4 (g-CN/TO/CCO) shows good photodegradation of Rh.B dye (99.9%) in minmal times (1 h) in CCO: g-CN/TO (2:1) ratio by Z-Scheme mechanism. The enhanced visible light absorption and effective electron-hole pair separation provided by the synergistic dispersion of CuO/CuCo2O4 and g-C3N4 can be attributed to the improved photocatalytic performances. These novel insights into g-CN/TO/CCO based photocatalysts are useful for treating industrial effluent.

Synthesis and improved optical, electrical, and dielectric properties of PEO/PVA/CuCo2O4 nanocomposites

This study investigates the development of novel nanocomposite films based on a blend of polyethylene oxide (PEO) and polyvinyl alcohol (PVA) loaded with varying weight percentages of copper cobaltite nanoparticles (CuCo2O4 NPs). The primary objective was to fabricate these nanocomposites using a solution casting technique and explore the influence of CuCo2O4 content on their structural, optical, electrical, and dielectric properties. Spinel-type CuCo2O4 NPs were synthesized via the hydrothermal method and incorporated into the PEO/PVA blend. X-ray diffraction (XRD) analysis revealed the transformation of the polymer matrix towards an amorphous state with increasing CuCo2O4 content. UV–Vis spectroscopy studies demonstrated a decrease in both the direct and indirect band gaps of the nanocomposites, suggesting potential applications in optoelectronic devices. Impedance spectroscopy measurements revealed a significant enhancement in ionic conductivity (three orders of magnitude higher than the pristine blend) for the nanocomposite film containing 1.8 wt% CuCo2O4. The real permittivity (ε′) and imaginary permittivity (ε″) of the polymer nanocomposites exhibited a decrease with increasing frequency due to the interplay of various polarization mechanisms. Notably, incorporating 1.8 wt% CuCo2O4 nanoparticles led to a remarkable improvement in energy density compared to the pristine blend. Additionally, a significant decrease in the potential barrier was observed. These findings demonstrate the successful fabrication of PEO/PVA-CuCo2O4 nanocomposite films with enhanced optical, electrical, and dielectric properties. The observed improvements suggest promising applications for these materials in energy storage devices and potentially in optoelectronic devices like light-emitting diodes.

PVA/PEG/CuCo2O4/PANi/x wt% MWCNTs blended polymers: Improved the physical properties for energy storage devices and optoelectronic applications

The current investigation aims to enhance the optical and dielectric properties of poly (vinyl alcohol) (PVA)/polyethylene glycol (PEG) blended polymers via loading with copper cobaltite (CuCo2O4), polyaniline (PANi), and x wt% multi-walled carbon nanotubes (MWCNTs) for potential applications in optoelectronics and capacitive storage. The fabrication of PVA/PEG/CuCo2O4/PANi/x wt% MWCNTs blended polymers was carried out via casting and hydrothermal methods. Characterization of the blended polymer's structure and morphology was conducted using X-ray diffraction and scanning electron microscopy techniques. The impact of various fillers on the linear and nonlinear optical properties of the host blend was analyzed. The loaded blends demonstrated efficacy in blocking UVA, UVB, and UVC spectra, making them suitable absorbers for solar cells. The lowest values for direct and indirect optical band gap energy (Eg), of 5.34 eV and 4.44 eV were attained at x = 0.02. The blend with x = 0.01 displays the highest refractive index at λ = 600 nm. The optical conductivity exhibited nonmonotonically growth until peaking at x = 0.01. Analysis of chromaticity diagrams in CIE 1931 color space reveals that all blends emit blue-violet hues with slight variations in intensity. The fluorescence (FL) intensity of the doped blend is notably lower compared to the undoped counterparts. The doped blend (x = 0.03) showcases superior dielectric constants and ac conductivity values. The maximum energy density was achieved at 1 kHz for the host blend incorporating CuCo2O4/PANi. Overall, the observed characteristics indicate that PVA/PEG/CuCo2O4/PANi/x wt% MWCNTs blended polymers represent promising hybrid nanomaterials suitable for diverse applications.

Phytotoxic and electrochemical properties of mixed Cu-Ni cobaltite nanoflowers: Environmental and energy storage applications

Herein, the flower-like mixed Cu-Ni cobaltite spinels Cu1−xNixCo2O4 (x = 0, 0.05, 0.15, and 0.25) were successfully synthesized via simple hydrothermal approach followed by annealing process. Copper cobaltite flowers were characterized using XPS, XRD, FT-IR, SEM, TEM, EDAX, BET, and UV–Vis analysis. The photodegradation efficiency (PDE) of the cobaltite photocatalysts was determined by the degradation of rhodamine 6 G (Rh6G), methylene green (MG), and mixed dye effluents (Rh6G+MG, 1:1 v/v) upon visible-light radiation. The PDE of the CNC 3 catalyst was found to be 90%, 83%, and 86% for degradation of Rh6G, MG, and mixed dye effluents, respectively, and it retained 87% of photocatalytic efficiency even after four cycles. The phytotoxic analysis of control, untreated, and treated Rh6G dye solutions was examined in Phaseolus vulgaris for real-time applications. The electrochemical characteristic was investigated by CV, GCD, and EIS. The CNC 3 electrode showed excellent electrochemical performance (315 Fg−1 at 0.5 Ag−1), and the capacity reached 93% of its initial capacitance after 3000 cycles. The b values of oxidative and reductive currents were determined to be 0.67 and 0.68, respectively. The capacitance contribution was 56% at 10 mVs−1, indicating a mixture of surface capacitive and diffusion controlled behavior in charge/discharge processes. The two-electrode symmetric cell was fabricated using CNC 3 as the positive and negative electrodes for real-life applications. CNC 3 cell delivered a significant energy density (13.47 Wh/kg) and a power density (251.01 W/kg) at 0.5 Ag−1.

Decisive role of Cu/Co interfaces in copper cobaltite derivatives for high performance CO2 methanation catalyst

Thermo-catalytic bio-SNG (CH4) production is one of the useful tools for converting waste to gaseous fuels through CO2 conversion. To abundant properly, however, efficient, robust and cost-effective catalysts would be required. Bimetallic systems based on transition metals seem to be promising candidates for this task. The CoCu bimetallic system with in-situ generated interfaces was synthesized and used as a catalyst for CO2 methanation. The in-depth analysis of the structure-activity-selectivity relationships involving XRD, (NAP-)XPS, EXAFS and TEM-EDX revealed that the co-existence of Co0, CoO, and Cu0 in the proper distribution on the surface can ensure the selective production of methane. To fine-tune the surface composition of the bimetallic systems, a systematic alteration of the Cu:Co ratio in the precursor spinel structures must be performed. Cu0.4Co2.6O4 derivative, stabilizing subsurface Cu(I)–O specimen, showed the best performance with high activity (12,800 nmol g–1 s–1) and a remarkable selectivity of 65–85% for methane in a wide temperature range (250–425 °C). In studying the mechanistic aspects of methanation, it has been shown that the hydrogenation of active carbon at the surface or below the surface is the key step for the production of methane. So far, this cobalt-catalyzed sub-step has been proposed in catalytic Fischer-Tropsch syntheses.

Investigation on copper cobaltite (CuCo2O4) and its composite with activated carbon (AC) for supercapacitor applications

Energy storing devices plays a major role in the development of technology. We synthesized carbon-based nanocomposites through a physical method and CuCo2O4 nanocomposites through a sol–gel technique calcined at 600 °C. From X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) confirmed the formation of CuCo2O4 nanocomposites which also shows some impurity phase of CuO nanoparticle. The average crystalline size found to be 45 nm. According to optical absorption analysis, the particles show maximum absorption in 256 nm and 369 nm in the UV region, while copper cobaltite doped with activated carbon (AC) shows broad absorption compared with copper cobaltite alone. Morphology studies shows agglomerate image in AC composites and hexagonal structures was formed in CuCo2O4 nanoparticles with average particle size of 100 nm. Atomic and weight percentages were recorded using energy dispersive X-ray analysis (EDAX). A good specific capacitance can be found from CV analysis, using electrochemical impedance spectroscopy (EIS), nanoparticles are shown to have different interface properties at the surface of electrodes. Using CuCo2O4 and its composite as positive and negative electrodes in cyclic voltammetry (CV) studies shows excellent electrochemical properties. In addition, CuCo2O4 with activated carbon is promising as a low-cost and good supercapacitor material.

Investigating the photocatalytic properties of copper cobaltite and copper cobaltite-reduced graphene oxide composites for organic dye removal under sunlight irradiation

ABSTRACT Scientists are researching new catalysts that can be used in the photocatalytic degradation of water pollution caused by organic dyes. The challenges of photocatalysis are the high recombination rate and low conductivity of photogenerated electrons (e−) and photogenerated holes (h+). To address these issues, the synthesis of hetero-structured composites can provide a solution. Reduced graphene oxide (rGO) can enhance the photocatalytic properties of hetero-structured composite when used together in a composite material. The combination of these materials can lead to improved performance in the degradation of organic dyes, such as methyl blue (MB), in wastewater treatment. In this study, the preparation of copper cobaltite (CuCo2O4) and copper cobaltite-reduced graphene oxide (CuCo2O4-rGO) composites was carried out using an economical chemical method, resulting in a high-performing photocatalyst. The structural, morphological and functional properties of the composites were characterised using X-ray Diffractometry (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), and Fourier Transform Infrared Spectroscopy (FTIR). Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-vis DRS) revealed the optical band gap 1.52 eV and 1.44 eV for CuCo2O4 and CuCo2O4-rGO composites respectively. Photoluminescence Spectroscopy (PL) of CuCo2O4-rGO showed peak with decreased intensity as compared to CuCo2O4, which is indicative of low recombination rate. Brunauer-Emmett-Teller (BET) analysis showed that CuCo2O4-rGO has high surface area 125.479 m2/g and large pore volume 0.03850 cc/g. Narrow arc radius of Nyquist plot of CuCo2O4-rGO obtained by Electrochemical Impedance Spectroscopy (EIS) demonstrated better charge separation than CuCo2O4. The findings of this study demonstrated that both synthesised photocatalysts exhibit exceptional photocatalytic activity for the degradation of dye under solar irradiation but rGO incorporated CuCo2O4 showed more improved photocatalytic behaviour as compared to CuCo2O4. This improvement is credited to large surface area and high electrical conductivity of rGO, which facilitated the transfer of photogenerated electrons from CuCo2O4 to rGO, reduced the chance of recombination and increased the overall efficiency.

Design and development of copper cobaltite (CuCo2O4) nanoparticle for antibacterial anticancer and photocatalytic activity

In this paper, hydrothermal technique has been utilized for the fabrication of spinel-type copper cobaltite nanoparticles (CuCo2O4 NPs). The prepared nanoparticle was characterized using FT-IR, SEM, XRD and EDAX techniques. The XRD spectra of CuCo2O4 show the formation of a cubic spinel-type CuCo2O4 nanocomposite. The FTIR graph determines the existence of metal-oxygen bonds. SEM images reveal the morphology of the nanoparticles. The synthesized materials were tested against the pathogens using agar-well diffusion method. The CuCo2O4 nanoparticles shows that have potent bactericidal properties. MTT assay was done to evaluate the cytotoxic activity of CuCo2O4 NPs against a cervical cancer cell (HeLa) with an IC50 value of 0.72 μg/ml. Addition to these biological applications, the nanoparticle also degrade toxic dyes under direct sunlight.

Electronic tuning of Ni-Fe-Co oxide/hydroxide as highly active electrocatalyst for rechargeable Zn-air batteries.

As a bifunctional oxygen electrocatalyst (oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)), spinel copper cobaltite (CuCo2O4) is attracting significant research interest owing to the tailored Co, Cu electronic structure and ease of adjusting the electrochemically active area. However, its poor OER performance (>300 mV at 10 mA cm-2) limits its practical application for rechargeable zinc-air batteries. Therefore, we construct a CuCo2O4/NiFe LDH oxide/hydroxide interface to tune the properties of Ni, Fe and Co for enhancing OER activity and decreasing the charging overpotential of rechargeable zinc-air batteries. The obtained electrocatalysts show a low overpotential of 251 mV (10 mA cm-2), which is 91 mV lower than the overpotential (342 mV) of CuCo2O4. By in situ Raman, XPS and electrochemical analyses, we ascribe the enhanced OER activity to the increasing Ni/Fe oxidation state triggered by the charge transfer of Ni/Fe and Co, which prompts CuCo2O4/NiFe LDH to rapidly form an active surface layer. Benefiting from enhanced OER performance, zinc-air batteries with a CuCo2O4/NiFe LDH electrode display a high round-trip efficiency with a low voltage gap of ∼0.78 V (10 mA cm-2) due to the obvious decrease in the charging overpotential. These results suggest the importance of tuning the charge transfer on interfaces for designing high-efficiency electrocatalysts.

Hierarchical and ultra-porous copper cobaltite flakes with honeycomb-like physiognomies for highly efficient non-enzymatic glucose sensing

We present here a novel and facile synthesis of ultra-porous CuCo2O4 in our effort to increase the selectivity and sensitivity of innovative structured multi-metal oxides for electrochemical non-enzymatic sensing of glucose.

Modulating Direct Growth of Copper Cobaltite Nanostructure on Copper Mesh as a Hierarchical Catalyst of Oxone Activation for Efficient Elimination of Azo Toxicant.

As cobalt (Co) has been the most useful element for activating Oxone to generate SO4•-, this study aims to develop a hierarchical catalyst with nanoscale functionality and macroscale convenience by decorating nanoscale Co-based oxides on macroscale supports. Specifically, a facile protocol is proposed by utilizing Cu mesh itself as a Cu source for fabricating CuCo2O4 on Cu mesh. By changing the dosages of the Co precursor and carbamide, various nanostructures of CuCo2O4 grown on a Cu mesh can be afforded, including nanoscale needles, flowers, and sheets. Even though the Cu mesh itself can be also transformed to a Cu-Oxide mesh, the growth of CuCo2O4 on the Cu mesh significantly improves its physical, chemical, and electrochemical properties, making these CuCo2O4@Cu meshes much more superior catalysts for activating Oxone to degrade the Azo toxicant, Acid Red 27. More interestingly, the flower-like CuCo2O4@Cu mesh exhibits a higher specific surface area and more superior electrochemical performance, enabling the flower-like CuCo2O4@Cu mesh to show the highest catalytic activity for Oxone activation to degrade Acid Red 27. The flower-like CuCo2O4@Cu mesh also exhibits a much lower Ea of Acid Red 27 degradation than the reported catalysts. These results demonstrate that CuCo2O4@Cu meshes are advantageous heterogeneous catalysts for Oxone activation, and especially, the flower-like CuCo2O4@Cu mesh appears as the most effective CuCo2O4@Cu mesh to eliminate the toxic Acid Red 27.

Nanocubic copper cobaltite for methyl orange degradation through photocatalytic process

In this study, cubic spinel structured CuCo2O4 (Copper cobaltite) nanospheres were fabricated by thermal decomposition method. The visible light degradation of organic contaminant methyl orange (MO) was focused in this study using the synthesized pure CuO, Co3O4 and CuCo2O4 with different weight ratios of raw materials (90:10, 75:25 and 50:50). It could be well realized that after the characterization techniques, the synthesized CuCo2O4 materials resembled cubic spinel structure as confirmed by X-ray diffraction (XRD) investigation. Meanwhile, all the synthesized materials through transmission electron microscopy (TEM) have showed cubic shaped particles and among the CuCo2O4 materials, CuCo2O4 (50:50) expressed not as much of crystallinity due to the agglomerated nanospheres. On the other hand, well crystalline CuCo2O4 (75:25) displayed higher surface area than the other materials when analysed through Brunauer-Emmett-Teller (BET) method. The Fourier transform infra-red (FTIR) spectrum has evinced the formation of CuCo2O4 nanostructures. In addition, the cubic spinel structured CuCo2O4 provided positive results over visible light irradiation. Finally, the CuCo2O4 (75:25) sample has scored high as much of 85% MO degradation compared with others. This sample was progressed with repetitive recycling tests and presented the best photocatalytic degradation efficiency. The upgraded results of CuCo2O4 sample have been linked with the developed synergistic effects during the formation of binary metal oxides. Also, the interfacial electron-hole formation leads to the migration and hindering of charge carriers for visible light activity.

Highly efficient photocatalytic degradation of malachite green dye over copper oxide and copper cobaltite photocatalysts under solar or microwave irradiation

• Copper oxide and Copper Cobaltite have been successfully synthesized using Co-precipitation method. • Both prepared oxides show efficient photocatalytic activity in the degradation of malachite green dye under solar or microwave irradiation. • Photocatalyst amount and dye concentration significantly affected the rate of MG photodegradation. Advanced Oxidation Processes (AOPs) have been developed in the field of environmental technologies. The aim of this study was to verify the efficiency of heterogeneous photocatalysis in the AOPs for the degradation of organic pollutants. The photocatalytic degradation processes were carried out under sunlight and microwave irradiation in remediation of malachite green (MG) dye taken as model organic pollutant. The copper oxide and copper-cobalt bimetallic oxide (Cu-500 and CuCo-500) were prepared by a simple coprecipitation method and calcined at 500 °C. The synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDX), and Diffuse Reflectance Spectroscopy (DRS) analysis for optical properties (band gap of 1.49 and 1.44 eV for Cu-500 and CuCo-500, respectively). Thereafter, the catalytic activities of the prepared photocatalysts for MG photodegradation were investigated. The influence of different parameters on the photocatalytic reactions, such as photocatalyst mass, initial dye concentration, and irradiation source, was studied. The results reveal the efficiency of the synthesized photocatalysts in the photodegradation of MG with higher rate and good reusability. Hence, the monometallic Cu-500 photocatalyst exhibited better catalytic performance compared to bimetallic CuCo-500.

Engineering the Structural Defects of Spinel Oxide Nanoneedles by Doping of V for a Highly Efficient Oxygen Evolution Reaction.

Rational design of multi-structural defects in the transition-metal oxides is a very alluring and challenging strategy to significantly improve its oxygen evolution reaction (OER) performance. Herein, a simple and promising element doping approach is demonstrated to fabricate a poor-crystalline V-doping CuCo2O4 (V-CuCo2O4) nanoneedle with rich oxygen vacancies (Vo), partially amorphous phase, and Co2+ defects on the carbon fiber (CF) (V-CuCo2O4/CF). The results indicate that the V doping could further weaken the crystallinity of V-CuCo2O4, providing the thoroughfares for the convenience of electrolyte penetration and the exposure of active sites. Meanwhile, [CoO6] octahedron in the V-CuCo2O4 lattice is gravely distorted due to a strong electronic interaction between the doped V and Co atoms, creating more Co2+ active species. With the merits of these multiple structural defects, V-CuCo2O4/CF exhibits rich active sites, and its intrinsically electrocatalytic activity is significantly enhanced. The optimized V-CuCo2O4/CF electrocatalyst has a significantly enhanced OER activity with a required low overpotential of ∼204 and ∼246 mV at a current density of 100 and 300 mA cm-2, respectively, a small Tafel slope of 40.7 mV dec-1, and excellent stability in an alkaline medium. Furthermore, the results from the projected partial density of states calculation not only demonstrate that the 3-fol-coordinated Co near Vo bonded with Cu and V sites (Cu-Co(surf-Vo)-V) exhibits an enhanced electronic transfer activity but also reveal that the doped V could protect the Co sites from the deactivation by intermediates overbinding on the V sites. This work provides new insights into structure engineering of spinel phase copper cobaltite, resulting in significantly boosting electrocatalytic OER activity.

Copper-Cobalt-Based Sulfides: Strategy To Boost Energy Storage Performance Utilizing the Synergistic Effect of a Double Metal Ion

The copper cobaltite chalcogenides were designed and developed via a simple and economically effective electrochemical route followed by the hydrothermal anion-exchange process without altering the morphological features. The systematic synthetic approach provided spinel crystalline-structured copper cobalt sulfide (CuCo2S4) through in situ co-deposition and copper sulfide/cobalt sulfide composite (CuS/CoS) via layer-by-layer deposition. Obtained high-resolution scanning electron microscopy explains the unique dendrite morphology of copper cobalt sulfide (CuCo2S4) with a primary midrib followed by secondary and tertiary trunks, whereas CuS/CoS governs a distinct CuS dendrite covered with thin CoS sheets homogeneously. Furthermore, the CuCo2S4 electrode material governed a superior charge storage property in supercapacitor application with a capacitive value of 966–676.8 C g–1 at a current density ranging from 10 to 40 A g–1 with a 70.15% retention value, whereas CuS/CoS delivered only 455.3–278.8 C g–1 at current densities with 61.23% retention. The promising faradaic behavior of the as-prepared material was attributed by the stable charge-discharge profile at different applied current densities as 10, 20, 30, 40, and 10 A g–1 for 5000 cycles for CuCo2S4 and CuS/CoS electrodes, respectively. To evaluate real-time charge storage behavior, an asymmetric device was assembled by coupling the CuCo2S4 electrode with activated carbon electrode using a 3 M KOH aqueous electrolyte. The fabricated device delivered 126.8 and 81.45 C g–1 at 10 and 50 A g–1, respectively. Moreover, the device demonstrated excellent cycling stability up to 5000 cycles at 50 A g–1 with 96.70% capacitive retention. Thus, the present work demonstrates the most effective strategy to exploit the synergistic effect of bimetal ions to boost the charge storage properties of a ternary chalcogenide electrode.

Boosting the Electrochemical Performance of Mn-doped CuCo2O4/CuO Heterostructures for All-Solid-State Asymmetric Battery-type Supercapacitors

The introduction of Manganese (Mn) ions (2+ ⇋ 3+ ⇋ 4+) to transition metal oxides proved to be a potential strategy to tailor the redox behavior of these materials for energy storage. We fabricate a lower electronegative element (i.e., Mn) doped copper cobaltite and copper oxide (CuCo2O4/CuO; CCO) heterostructures electrodes through the hydrothermal synthesis route. The ensued electrodes have a more than 2-fold improvement in specific capacity (382.9 C g−1) than the undoped CCO electrode (120.8 C g−1) at 1 A g−1. The all-solid-state asymmetric supercapacitor (ASC) practical device is constructed with higher Mn-doped CCO heterostructures as the positive electrode and activated carbon (AC) as the negative electrode. With a voltage window of 1.5 V, the fabricated ASC device has a high specific energy of 52.6 Wh kg−1 and specific power of 774.3 W kg−1. The long-term cyclic stability of 92% capacity retention after 5000 cycles at the current density of 4 A g−1. Additionally, two ASC devices are series-connected that can power up a red light-emitting diode (LED) display for more than 150 s, demonstrating the device’s efficient power delivery.

Novel S-doped polyaniline@CuCo2O4–carbon composites and optimization of their weight ratios on the basis of their electrochemical activities

ABSTRACT Polyaniline–acetylene black–copper cobaltite-based ternary composites were synthesized with different weight ratios of aniline, acetylene black, and copper cobaltite. Electrochemical testings of all the systems were executed by cyclic voltammetry, charging–discharging, and electrochemical impedance spectroscopy. The optimized weight ratio was found to be 4:1:2 (aniline:acetylene black:copper cobaltite). In three- and two-electrode configurations, polyaniline–acetylene black–copper cobaltite having a weight ratio of 4:1:2 based system showed the highest specific capacitances of 771.03 F/g and 240.11 F/g, respectively, at 5 mV/s. The system had a low charge transfer resistance of 2.8 Ω. It could retain 89.8% of the capacitance after 5000 cycles. At 4:1:2 ratio, the fabricated system exhibited the highest specific power and energy of 125 W/kg and 34.41 Wh/kg, respectively, at 1 mA current.

Ultrasonic-assisted degradation of a methylene blue using CuCo2O4 as a heterogeneous Fenton-like catalyst

In this study, a copper cobaltite nanostructure was prepared as a non-ferrous heterogeneous Fenton catalyst using a one-step solvothermal method. The prepared nanocatalyst was characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), infrared spectroscopy (FT-IR) and energy-dispersive X-ray spectroscopy (EDS). The prepared CuCo2O4 exhibited outstanding activity for the degradation of methylene blue (MB) in aqueous solutions under ultrasonic irradiations. The degradation efficiency of MB was only 27.4 % in the absence of catalyst, whereas it reached more than 95.0 % in the presence of the CuCo2O4 after 60 min of ultrasonic irradiation. The trapping experiments with two radical scavengers (tert-butanol and chloroform) showed that both hydroxyl and superoxide radicals are generated during the decomposition of H2O2 and played important roles in oxidation of MB. The prepared nanocatalyst demonstrated good catalytic stability over three successive runs, without any remarkable decrease in catalytic activity.

Fabrication of copper cobaltite films by drop-on-demand inkjet printing

Inkjet printing has become an efficient and scalable technique for materials deposition using digital patterning. We report the use of inkjet printing as an alternative for the preparation of copper cobaltite films, with control over the pattern definition and film thickness from 180 nm to 815 nm by adjusting the drop spacing for an optimized ink and jetting voltage. The inkjet-printed films are formed by nanoparticles with size ~100 nm and the principal crystalline phase corresponds to copper cobaltite with the overall stoichiometry Cu0.92Co2.08O4. The films are characterized by a dark-brown color showing absorption in the range from 400 nm to 800 nm, and present a cathodic photocurrent under simulated solar illumination in an inert aqueous solution (pH 5.3).

Effect of Mo-doping on the structure, magnetic and optical characteristics of nano CuCo2O4

The changes in the properties of the supercapacitor electrode material copper cobaltite, prepared by a simple hydrothermal procedure, were investigated upon doping with Mo with different ratios (CuCo1-xMoxO4, x = 0.0, 0.1, 0.2). The effect of doping on the structural, microstructural parameters, cation distribution was studied using Rietveld analysis for x-ray diffraction patterns. Results evidenced the incorporation of Mo6+ ions substitutionally for Co3+ ions, which is confirmed by the vibrational bands obtained from Fourier transform infrared spectrometry and by the vibrating sample magnetometer measurements. The particle morphology and size distribution of the samples were investigated using high-resolution transmission electron microscope (HRTEM) imaging. The influence of Mo-doping on the absorbance behavior of copper cobaltite was examined utilizing measured absorbance diffused spectra; the bandgap structure of doped samples was greatly affected. The changes that occurred in the optical band gap upon doping were explained using the Burstein–Moss shift effect. The photoluminescence intensity was affected by the amount of Mo doping. The samples emitted violet, blue, and yellow colors depending on the amount of doping.