Search Results (11)

In this study, we explored the formation of CuO nanoparticles, NiO nanoflakes, and CuO-NiO nanocomposites using saponin extract and a microwave-assisted hydrothermal method. Five green synthetic samples were prepared using aqueous saponin extract and a microwave-assisted hydrothermal procedure at 200 °C for 30 min. The samples were pristine copper oxide (100C), 75% copper oxide–25% nickel oxide (75C25N), 50% copper oxide–50% nickel oxide (50C50N), 25% copper oxide–75% nickel oxide (25C75N), and pristine nickel oxide (100N). The samples were characterized using FT-IR, XRD, XPS, SEM, and TEM. The XRD results showed that copper oxide and nickel oxide formed monoclinic and cubic phases, respectively. The morphology of the samples was useful and consisted of copper oxide nanoparticles and nickel oxide nanoflakes. XPS confirmed the +2 oxidation state of both the copper and nickel ions. Moreover, the optical bandgaps of copper oxide and nickel oxide were determined to be in the range of 1.29–1.6 eV and 3.36–3.63 eV, respectively, and the magnetic property studies showed that the synthesized samples exhibited ferromagnetic and superparamagnetic properties. In addition, the catalytic activity was tested against para-nitrophenol, demonstrating that the catalyst efficiency gradually improved in the presence of CuO. The highest rate constants were obtained for the 100C and 75C25N samples, with catalytic efficiencies of 98.7% and 78.2%, respectively, after 45 min. Full article

Individual (FTO/Cu₂O and FTO/CuCo₂O₄) and heterostructured (FTO/BiVO₄/Cu₂O, FTO/BiVO₄/CuCo₂O₄, and FTO/CuCo₂O₄/Cu₂O) electrodes were successfully formed using the electrodeposition method on copper-containing compounds. The morphology of the synthesized electrode systems, which affect the electrochemical properties, was determined. A comparative study of the electrochemical and photoelectrochemical properties of the individual and heterostructured electrodes showed that the modification of the BiVO₄ electrode surface with Cu₂O and CuCo₂O₄ oxides led to a significant increase in its efficiency as a photoanode. The deposition of Cu₂O nanoclusters onto CuCo₂O₄ nanoflakes increased the electrochemical stability of the electrode while maintaining its high capacitance. Full article

The ever-increasing energy demands have prompted researchers to develop innovative charge-storage devices. Here, aluminum-doped copper-oxide nanoflakes were fabricated via a simple co-precipitation method to investigate the electrochemical properties, which depicted a novel dominant battery-type charge-storage mechanism, manifested by the porous morphology of the electrodes to enhance the diffusion-controlled process. Copper oxide was chosen as the electroactive material due to its low cost, easy processability, environmental friendliness, and multiple oxidation states, all of which are very important for practical applicability in charge-storage devices. Additionally, aluminum was chosen as a dopant due to its elemental abundance, non-toxicity, and energetically favorable ionic radius for substitutional doping. A maximum 272 C/g (@1 A/g current-density) specific capacity was observed for 5 wt% Al-doped CuO. Evidently, higher Al-doping provided increased defects and doping sites to enhance the redox activity in order to improve the supercapacitive performance. A combinatorial battery−capacitor charge-storage mechanism was proposed in terms of the accumulation and intercalation of charges at the inner electroactive sites of the nanoflakes through a large number of voids and cavities in order to contribute towards dominant battery-type diffusion capacitance, while optimum Al-doping created considerable redox-active sites to promote surface-controlled pseudocapacitance. The optimized Al-CuO electrode revealed extraordinary long-term cycling stability with 99% capacity retention over 5000 charge/discharge cycles. A hybrid two-electrode device, made up of a battery type Al-CuO positrode and capacitor-type activated-carbon negatrode, demonstrated a remarkable energy-power performance with a maximum energy density of 30 Wh/kg and a maximum power density of 7.25 kW/kg, with an excellent cycle life (98% capacity retention over 5000 cycles). This work demonstrates a novel strategy to fabricate high-performance hybrid supercapacitors for the next generation charge-storage devices. Full article

In this work, the extraction of vanadium (V) ions from an alkaline solution using a commercial quaternary ammonium salt and the production of metal vanadates through precipitation stripping were carried out. The crystallization of copper vanadates from the extracts was performed using a solution containing a copper(II) source in concentrated chloride media as a stripping agent. In an attempt to control growth, a stabilizing polymer (polyvinylpyrrolidone, PVP) was added to the stripping solution. The structural characteristics of the crystallized products, mainly copper pyrovanadate (volborthite, Cu₃V₂O₇(OH)₂·(H₂O)₂) nanoflakes and nanoflowers and the experimental parameter influencing the efficiency of the stripping process were studied. From the results, the synthesis of nanostructured vanadates is a simple and versatile method for the fabrication of valuable three-dimensional structures providing abundant active zones for energy and catalytic applications. Full article

Designing highly active material to fabricate a high-performance noninvasive wearable glucose sensor was of great importance for diabetes monitoring. In this work, we developed Cu_xO nanoflakes (NFs)/Cu nanoparticles (NPs) nanocomposites to serve as the sensing materials for noninvasive sweat-based wearable glucose sensors. We involve CuCl₂ to enhance the oxidation of Cu NPs to generate Cu₂O/CuO NFs on the surface. Due to more active sites endowed by the Cu_xO NFs, the as-prepared sample exhibited high sensitivity (779 μA mM⁻¹ cm⁻²) for noninvasive wearable sweat sensing. Combined with a low detection limit (79.1 nM), high selectivity and the durability of bending and twisting, the Cu_xO NFs/Cu NPs-based sensor can detect the glucose level change of sweat in daily life. Such a high-performance wearable sensor fabricated by a convenient method provides a facile way to design copper oxide nanomaterials for noninvasive wearable glucose sensors. Full article

In this study, Cu and Cu₂O hybrid nanoparticles were synthesized onto the WO₃ nanoflake film using a one-step electrodeposition method. The critical advance is the use of a heterojunction consisting of WO₃ flakes and Cu₂O as an innovative stack design, thereby achieving excellent performance for CO₂ photoreduction with water vapor under visible light irradiation. Notably, with the modified Cu nanoparticles, the selectivity of CH₄ increased from nearly 0% to 96.7%, while that of CO fell down from 94.5% to 0%. The yields of CH₄, H₂ and O₂ reached 2.43, 0.32 and 3.45 mmol/g_cat after 24 h of visible light irradiation, respectively. The boosted photocatalytic performance primarily originated from effective charge-transfer in the heterojunction and acceleration of electron-proton transfer in the presence of Cu nanoparticles. The S-scheme charge transfer mode was further proposed by the in situ-XPS measurement. In this regard, the heterojunction construction showed great significance in the design of efficient catalysts for CO₂ photoreduction application. Full article

Designing and modifying nanoporous metal foils to make them suitable for supercapacitor and catalysis is significant but challenging. In this work, Cu_xO nanoflakes have been successfully in situ grown on nanoporous Cu foil via a facile electrooxidation method. A Ga-assisted surface Ga-Cu alloying–dealloying is adopted to realize the formation of a nanoporous Cu layer on the flexible Cu foil. The following electrooxidation, at a constant potential, modifies the nanoporous Cu layer with Cu_xO nanoflakes. The optimum Cu_xO/Cu electrode (O-Cu-2h) delivers the maximum areal capacitance of 0.745 F cm⁻² (410.27 F g⁻¹) at 0.2 mA cm⁻² and maintains 94.71% of the capacitance after 12,000 cycles. The supercapacitor consisted of the O-Cu-2h as the positive electrode and activated carbon as the negative electrode has an energy density of 24.20 Wh kg⁻¹ and power density of 0.65 kW kg⁻¹. The potential of using the electrode as oxygen evolution reaction catalysts is also investigated. The overpotential of O-Cu-2h at 10 mA cm⁻² is 394 mV; however, the long-term stability still needs further improvement. Full article

The morphology, chemical composition, and doping process of metal oxides and sulfides play a significant role in their photocatalytic performance under solar light illumination. We synthesized Cu²⁺-doped ZnO–SnS nanocomposites at 220 °C for 10 h, using hydrothermal methods. These nanocomposites were structurally, morphologically, and optically characterized using various techniques, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible absorption spectroscopy. Their photocatalytic activity (PCA) on methylene blue (MB) pollutant dye was examined under 150 W solar light illumination. Mixed-phase abundances with hexagonal ZnO and orthorhombic SnS structures were observed. TEM micrographs showed changes in morphology from spherical to nano-flake structures with an increasing doping concentration. XPS indicated the chemical states of the constituent elements in the nanocomposites. UV-visible absorption spectroscopy showed a decrease in the bandgap with an increasing doping concentration. Strong PCA was observed due to the separation of charge carriers, a change in bandgap, and a high light absorption ability under solar light irradiation. The measured photodegradation efficiency of the MB dye was approximately 97% after 2 h. The movement of the charge carriers and the bandgap alignment of the synthesized composites are briefly discussed. Full article

Among chemical water pollutants, Cr(VI) is a highly toxic heavy metal; solar photocatalysis is a cost-effective method to reduce Cr(VI) to innocuous Cr(III). In this research work, an efficient and economically feasible ZnO/CuO nanocomposite was grafted onto the polyester fabric ZnO/CuO/PF through the SILAR method. Characterization by SEM, EDX, XRD, and DRS confirmed the successful grafting of highly crystalline, solar active nanoflakes of ZnO/CuO nanocomposite onto the polyester fabric. The grafting of the ZnO/CuO nanocomposite was confirmed by FTIR analysis of the ZnO/CuO/PF membrane. A solar photocatalytic reduction reaction of Cr(VI) was carried out by ZnO/CuO/PF under natural sunlight (solar flux 5–6 kW h/m²). The response surface methodology was employed to determine the interactive effect of three reaction variables: initial concentration of Cr(VI), pH, and solar irradiation time. According to UV/Vis spectrophotometry, 97% of chromium was removed from wastewater in acidic conditions after four hours of sunlight irradiation. ZnO/CuO/PF demonstrated reusability for 11 batches of wastewater under natural sunlight. Evaluation of Cr(VI) reduction was also executed by complexation of Cr(VI) and Cr(III) with 1, 5-diphenylcarbazide. The total percentage removal of Cr after solar photocatalysis was carried out by AAS of the wastewater sample. The ZnO/CuO/PF enhanced the reduction of Cr(VI) metal from wastewater remarkably. Full article

The treatment of organic dye contaminants in wastewaters has now becoming more imperative. Fenton-like degradation of methylene blue (MB) and methyl orange (MO) in aqueous solution was investigated by using a nanostructure that a layer of CuCl₂ nanoflake film grown on the top surface of nanoporus anodic alumina substrate (nano-PAA-CuCl₂) as catalyst. The new nano-PAA-CuCl₂ composite was fabricated with self-assembly approach, that is, a network porous structure film composed of CuCl₂ nanoflake grown on the upper surface of nanoporous anodic alumina substrate, and the physical and chemical properties are characterized systematically with the X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HRTEM), Energy Dispersive Spectrometer (EDS), X-ray photoelectron spectroscopy (XPS). The experimental results showed that the nano-PAA-CuCl₂ catalyst presented excellent properties for the degradation of two typical organic pollutants such as MB and MO, which were almost completely degraded with 8 × 10⁻⁴mol/L nano-PAA-CuCl₂ catalyst after 46 min and 60 min at reaction conditions of H₂O₂ 18 mM and 23 mM, respectively. The effects of different reaction parameters such as initial pH, H₂O₂ concentration, catalyst morphology and temperature were attentively studied. And more, the stability and reusability of nano-PAA-CuCl₂ were examined. Finally, the mechanism of MB and MO degradation by the nano-PAA-CuCl₂/H₂O₂ system was proposed, based on the experimental data of the BCA and the temperature-programmed reduction (H₂-TPR) and theoretical analysis, the reaction kinetics belonged to the pseudo-first-order equation. This new nanoporous composite material and preparation technology, as well as its application in Fenton-like reaction, provide an effective alternative method with practical application significance for wastewater treatment. Full article

A magnesium hydroxide (MH)-modified calcined fly ash (CFA) nanocomposite (CFAMH) with core-shell structure was obtained with a heterogeneous nucleation method, and its application for removal of copper, zinc and nickel ions from aqueous acidic solution was studied. The microstructure and surface properties of CFA, CFAMH and MH powders were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller specific surface area (BET), X-ray diffraction (XRD) and Fourier translation infrared spectroscopy (FTIR), respectively. The preparation mechanism of CFAMH was discussed based on zeta potential and FTIR data. The results showed that nano-flake MH with thickness 13.4 nm was well coated on the surface of CFA. The specific surface area was increased from 2.5 to 31.0 m²/g. Si-O-Mg-OH bonds formed from the condensation of Si-OH and Mg-OH. The removal efficiency of heavy metals on CFAMH nanocomposite is higher than that of CFA and MH and follows an order of Cu²⁺ > Zn²⁺ > Ni²⁺. Solubility product constant (Ksp) is an important constant for the removal order of heavy metals on FA, CFAMH and MH. CFAMH nanocomposite can be a cheap material for removing heavy metal ions from acidic wastewater. Full article