Search Results (39)

The article suggests a simple one-step sol–gel method for synthesizing nanostructured zinc oxide films co-doped with copper and aluminum. It shows the possibility of forming hierarchical ZnO:Al:Cu nanostructures combining branches of different sizes and ranks and quasi-spherical fractal aggregates. It demonstrates the use of the synthesized samples as highly efficient photocatalysts providing the decomposition of toxic dyes (methyl orange) under the action of both ultraviolet radiation and visible light. It establishes the contribution of the average crystallite size, the proportion of zinc atoms in the crystalline phase, their nanostructure, as well as X-ray amorphous phases of copper and aluminum to the efficiency of the photocatalysis process. Full article

Carbon dioxide (CO₂) can be electrochemically, thermally, and photochemically reduced into valuable products such as carbon monoxide (CO), formic acid (HCOOH), methane (CH₄), and methanol (CH₃OH), contributing to carbon footprint mitigation. Extensive research has focused on catalysts, combining experimental approaches with computational quantum mechanics to elucidate reaction mechanisms. Although computational studies face challenges due to a lack of accurate approximations, they offer valuable insights and assist in selecting suitable catalysts for specific applications. This study investigates the electrocatalytic pathways of CO₂ reduction on cuprous oxide (Cu₂O) catalysts, utilizing the computational hydrogen electrode (CHE) model based on density functional theory (DFT). The electrocatalytic performance of flat Cu₂O (100) and hexagonal Cu₂O (111) surfaces was systematically analysed, using the standard hydrogen electrode (SHE) as a reference. Key parameters, including free energy changes (ΔG), adsorption energies (E_ads), reaction mechanisms, and pathways for various intermediates were estimated. The results showed that CO₂ was reduced to CO_(g) on both Cu₂O surfaces at low energies. However, methanol (CH₃OH) production was observed preferentially on Cu₂O (111) at ΔG = −1.61 eV, whereas formic acid (HCOOH) and formaldehyde (HCOH) formation were thermodynamically unfavourable at interfacial sites. The CO₂-to-methanol conversion on Cu₂O (100) exhibited a total ΔG of −3.38 eV, indicating lower feasibility compared to Cu₂O (111) with ΔG = −5.51 eV. These findings, which are entirely based on a computational approach, highlight the superior catalytic efficiency of Cu₂O (111) for methanol synthesis. This approach also holds the potential for assessing the catalytic performance of other transition metal oxides (e.g., nickel oxide, cobalt oxide, zinc oxide, and molybdenum oxide) and their modified forms through doping or alloying with various elements. Full article

Kesterite-based semiconductors, particularly copper–zinc–tin–sulfide (CZTS), have garnered considerable attention as potential absorber layers in thin-film solar cells because of their abundance, nontoxicity, and cost-effectiveness. In this study, we explored the synthesis of Ag-alloyed CZTS (ACZTS) materials via the sol–gel method and deposited them on a transparent fluorine-doped tin oxide (FTO) back electrode. A key challenge is the selection and manipulation of metal–salt precursors, with a particular focus on the oxidation states of copper (Cu) and tin (Sn) ions. Two distinct protocols, varying the oxidation states of the Cu and Sn ions, were employed to synthesize the ACZTS materials. The transfer from the solution to the precursor film was analyzed, followed by annealing at different temperatures under a sulfur atmosphere to investigate the behavior and growth of these materials during the final stage of annealing. Our results show that the precursor transformation from solution to film is highly sensitive to the oxidation states of these metal ions, significantly influencing the chemical reactions during sol–gel synthesis and subsequent annealing. Furthermore, the formation pathway of the kesterite phase at elevated temperatures differs between the two protocols. Structural, morphological, and optical properties were characterized via X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Our findings highlight the critical role of the Cu and Sn oxidation states in the formation of high-quality kesterite materials. Additionally, we studied a novel approach for controlling the synthesis and phase evolution of kesterite materials via molecular inks, which could provide new opportunities for enhancing the efficiency of thin-film solar cells. Full article

This study investigates the effects of varying CuO doping concentrations on the performance of titanium dioxide (TiO₂)-based or zinc oxide (ZnO)-based dye-sensitized solar cells (DSSCs). TiO₂ or ZnO mixed with CuO at different weight percentages (0–50 wt %) was employed as photoanodes in DSSCs, prepared via mechanical mixing. X-ray diffraction analysis revealed the structural changes, showing that as the CuO content increased in the hybrid, the CuO peaks (notably at 35.5° and 38.7°) became more prominent. Morphological and elemental characterizations were conducted using SEM and XRF, respectively. The solar cells were photosensitized by Vitis lasbrusca (V.L.) extract and N3 dye. The presence of anthocyanin molecules in the extracted V.L. was confirmed using UV-VIS and FTIR spectroscopy. The electrochemical characterization demonstrated optimal solar conversion efficiencies at a 20% doping level for both photosensitizers. Specifically, in the V.L. dye, TiO₂-CuO achieved a conversion efficiency of 7.18%, and ZnO-CuO reached 5.77%. In the N3 dye, TiO₂-CuO showed an efficiency of 11.34%, and ZnO-CuO, 9.55%. Notably, undoped photoanodes displayed a significantly lower photovoltaic performance: for V.L. dye, TiO₂ showed 1.12% and ZnO 0.87%; for N3 dye, TiO₂ showed 6.02% and ZnO 4.39%. Doping was therefore effective, yielding up to a seven-fold increase in performance in the case of V.L. with TiO₂, compared to undoped DSSCs. The results demonstrate that using the hybrid photoanode led to a considerable increase in performance compared to using only TiO₂ or ZnO photoanodes, highlighting the potential of DSSCs as sustainable energy sources. Full article

A new easy protocol to functionalize the middle layer of commercial surgical face masks (FMs) with Zn and Cu oxides is proposed in order to obtain antibacterial personal protective equipment. Zinc and copper oxides were synthesized embedded in a polydopamine (PDA) shell as potential antibacterial agents; they were analyzed by XRD and TEM, revealing, in all the cases, the formation of metal oxide nanoparticles (NPs). PDA is a natural polymer appreciated for its simple and rapid synthesis, biocompatibility, and high functionalization; it is used in this work as an organic matrix that, in addition to stabilizing NPs, also acts as a diluent in the functionalization step, decreasing the metal loading on the polypropylene (PP) surface. The functionalized middle layers of the FMs were characterized by SEM, XRD, FTIR, and TXRF and tested in their bacterial-growth-inhibiting effect against Klebsiella pneumoniae and Staphylococcus aureus. Among all functionalizing agents, Cu₂O-doped-ZnO NPs enclosed in PDA shell, prepared by an ultrasound-assisted method, showed the best antibacterial effect, even at low metal loading, without changing the hydrophobicity of the FM. This approach offers a sustainable solution by prolonging FM lifespan and reducing material waste. Full article

In this work, researchers synthesized copper–zinc oxide nanoparticles (NPs) of different shapes and sizes and tested their antibacterial and anticancer effects. The current research used a straightforward method to synthesize copper-doped zinc oxide nanoparticles (Cu-ZnO NPs). Next, the photocatalytic, antibacterial, and anticancer properties of the Cu-ZnO NPs were ascertained. Nanoparticles of Cu-doped ZnO were synthesized using co-precipitation technology. The physicochemical characterization was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible (UV-Vis) and Fourier-transform infrared (FTIR) spectroscopy, and other imaging techniques. The SEM analysis confirmed that the particles observed by SEM were found to be below 100 nm in size, which aligns with the results obtained from XRD. The size histogram in the figure inset shows that the nanoparticles are mostly round and have a size range of 5 to 50 nm. The XRD diffractograms revealed the classic structure of wurtzite-phase crystalline Cu-ZnO, and the crystallite size is 26.48 nm. Differences in the principal absorption peaks between the FTIR and UV-vis spectra suggest that varying ZnO NP morphologies might lead to spectrum shifts. We used the agar diffusion method to determine how effective Cu-doped ZnO NPs were against bacteria and the MTT assay to see how well they worked against cancer. The photocatalytic disintegration capacity of Cu-doped ZnO NPs was investigated by degrading crystal violet (CV) and methylene blue (MB) dyes under ultraviolet lamp irradiation. A value of 1.32 eV was recorded for the band gap energy. All peaks conformed to those of the Zn, O, and Cu atoms, and there were no impurities, according to the EDS study. Additionally, the nanoparticles had anticancer properties, indicating that the NPs were specifically targeting cancer cells by inducing cell death. At a 100 µg/mL concentration of the synthesized Cu-doped ZnO NPs, the cell availability percentages for the SW480, MDA-231, and HeLa cell lines were 29.55, 30.15, and 28.2%, respectively. These findings support the idea that Cu-doped ZnO NPs might be a new cancer treatment. Moreover, the results show the percentage of dye degradation over different time durations. After 180 h, the degradation of CV dye reached 79.6%, while MB dye exhibited a degradation of 69.9%. Based on these findings, Cu-doped ZnO NPs have the potential to be effective photocatalysts, antibacterial agents, and cancer fighters. This bodes well for their potential applications in the fields of ecology, medicine, and industry in the future. Full article

Recent developments in architectural materials emphasize the importance of antibacterial and thermal insulation functions due to the prevalence of diseases such as COVID-19 and influenza. There is a growing expectation for the implementation of constructed glass that possesses antibacterial properties. Low-emissivity (Low-E) glass, known for its ability to reduce infrared radiation penetration through windows, is a focal point of our ongoing research. In this study, we continued our preliminary investigations into the development of Low-E glass by preparing copper/aluminum-doped zinc oxide (Cu/AZO) films on glass substrates through in-line sputtering. Copper was incorporated to provide antibacterial functionality, while aluminum-doped zinc oxide was chosen for its high visible optical transmission, which is crucial for architectural glass, and its low electrical resistivity indicative of thermal insulation properties. A vacuum annealing process was subsequently applied to the Cu/AZO films on glass. The evaluation of these films involved measuring electrical resistivity that correlates with emissivity, as well as assessing average visible transmission and antibacterial effectiveness according to the JIS Z2801:2000 standard. The results of these tests reveal that the vacuum-annealed Cu/AZO films on glass exhibited commendable antibacterial and thermal insulation properties. Specifically, the antibacterial index (R) was determined to be 8.75; the emissivity, calculated from the measured electrical resistivity, was found to be 0.18; and the average visible transmission was recorded at 52.78%. These findings underscore the potential of Cu/AZO films in advancing the functionality of architectural glass. Full article

The paper breaks the general concepts and shows that pore formation is possible in anodic aluminum barrier oxide by anodizing of pure Al, and also presents the results of electrochemical anodizing in boric acid and citrate buffer aqueous solutions of homogeneous binary alloys AlCu (4 wt.%), AlZn (3 wt.%) and AlAg (5.2 wt.% and 16.2 wt.%). Barrier anodizing allowed obtaining Al₂O₃ thin films doped with copper, zinc and silver. The anodizing behavior and the effect of anodic current density on the charge were studied, and scanning electron microscopy, X-ray photoelectron spectroscopy and Auger electron spectroscopy analyses were performed. The doped alumina thin films, which are a mixture of Al₂O₃, Cu₂O, ZnO, Ag₂O, AgO and promising double metal oxides CuAlO₂, AgAlO₂ and ZnAl₂O₄, are promising for use as resistive switching, photoelectron, mechanical, photo-thermoelectric and fluorescence materials; sensors; and transparent conductive and photocatalyst films. Full article

This study investigated the effect of copper (Cu) doping content on zinc oxide with varied weight percentages and the dispersion of Cu-doped ZnO (CZO) by adding polyvinylpyrrolidone (PVP), coated on a glass substrate, through a physical assessment and optical property and thermal insulation testing. CZO NPs were synthesized by using the sol–gel method with a zinc acetate precursor. The powder X-ray diffraction (XRD) patterns of the CZO showed that the solid solubility limit was below 5 mol% without a secondary phase. A field-emission scanning electron microscopy (FE-SEM) micrograph demonstrated that the particle size of CZO was in nanoscale with the packing of a quasi-spherical shape. The UV-Vis-NIR reflectance spectra of the powder showed that 1 mol% CZO has the highest near-infrared (NIR) reflectivity in the wavelength 780–2500 nm, with great visible light transmission. The CZO NPs were loaded in acrylic copolymer in different weight percentages ranging from 25 wt% to 75 wt%, the film thickness of the coating was varied from 5 µm to 100 µm, and PVP was added into this nanocomposite polymer to disperse through an ultrasonication method. The results showed that the highest loading of CZO powder in a polymer at 75 wt% in 100 µm of thickness with polyvinylpyrrolidone (PVP) as a dispersant showed better sample dispersion and retained good transparency to the naked eye. Full article

Density functional theory (DFT) and coupled cluster theory (CCSD(T)) calculations are performed to investigate the geometric and electronic structures and chemical bonding of a series of Cu-doped zinc oxide clusters: Cu_nZn₃O₃ (n = 1–4). The structural evolution of Cu_nZn₃O₃ (n = 1–4) clusters may reveal the aggregation behavior of Cu atoms on the Zn₃O₃ cluster. The planar seven-membered ring of the CuZn₃O₃ cluster plays an important role in the structural evolution; that is, the Cu atom, Cu dimer (Cu₂) and Cu trimer (Cu₃) anchor on the CuZn₃O₃ cluster. Additionally, it is found that Cu_nZn₃O₃ clusters become more stable as the Cu content (n) increases. Bader charge analysis points out that with the doping of Cu atoms, the reducibility of Cu aggregation (Cu_n−1) on the CuZn₃O₃ cluster increases. Combined with the d-band centers and the surface electrostatic potential (ESP), the reactivity and the possible reaction sites of Cu_nZn₃O₃ (n = 1–4) clusters are also illustrated. Full article

B-doped zinc oxide/copper oxide composites prepared using a simple method showed high photocatalytic hydrogen production activity in the presence of aqueous sulfide solutions. Co-modification of the CuO composite with B-doping caused an increase in the charge separation efficiency and light absorption capacity. The sacrificial effect was thermodynamically enhanced by manipulating the composition of the sulfide solution. A maximum hydrogen production activity of 224 μmol g⁻¹ h⁻¹ was achieved under 450 nm light irradiation in a photocatalytic system with optimized B doping, a CuO composite, and a sulfide sacrificial agent concentration. Full article

In this study, Cu-doped ZnO was prepared via the facile one-pot solvothermal approach. The structure and composition of the synthesized samples were characterized by XRD (X-ray diffraction), TEM (transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy) analyses, revealing that the synthesized samples consisted of Cu-doped ZnO nanoparticles. Ultraviolet–visible (UV-vis) spectroscopy analysis showed that Cu-doping significantly improves the visible light absorption properties of ZnO. The photocatalytic capacity of the synthesized samples was tested via the disinfection of Escherichia coli, with the Cu-ZnO presenting enhanced disinfection compared to pure ZnO. Of the synthesized materials, 7% Cu-ZnO exhibited the best photocatalytic performance, for which the size was ~9 nm. The photocurrent density of the 7% Cu-ZnO samples was also significantly higher than that of pure ZnO. The antifungal activity for 7% Cu-ZnO was also tested on the pathogenic fungi of Fusarium graminearum. The macroconidia of F. graminearum was treated with 7% Cu-ZnO photocatalyst for 5 h, resulting in a three order of magnitude reduction at a concentration of 10⁵ CFU/mL. Fluorescence staining tests were used to verify the survival of macroconidia before and after photocatalytic treatment. ICP-MS was used to confirm that Cu-ZnO met national standards for cu ion precipitation, indicating that Cu-ZnO are environmentally friendly materials. Full article

Copper-doped zinc oxide films (Zn_1−xCu_xO) (x = 0, 2%, 4%, 6%) were fabricated on conductive substrates using the sol-gel process. The crystal structure, optical and resistive switching properties of Zn_1−xCu_xO films are studied and discussed. RRAM is made using Zn_1−xCu_xO as the resistive layer. The results show that the (002) peak intensity and grain size of Zn_1−xCu_xOfilms increase from 0 to 6%. In addition, PL spectroscopy shows that the oxygen vacancy defect density of Zn_1−xCu_xO films also increases with the increase in Cu. The improved resistive switching performance of the RRAM device can be attributed to the formation of conductive filaments and the destruction of more oxygen vacancies in the Zn_1−xCu_xO film. Consequently, the RRAM device exhibits a higher low resistance state to high resistance state ratio and an HRS state of higher resistance value. Full article

During the last few decades, major advances have been made in photovoltaic systems based on Cu(In,Ga)Se₂ chalcopyrite. However, the most efficient photovoltaic cells are processed under high-energy-demanding vacuum conditions. To lower the costs and facilitate high-throughput production, printing/coating processes are proving to be effective solutions. This work combined printing, coating, and chemical bath deposition processes of photoabsorber, buffer, and transparent conductive layers for the development of solution-processed photovoltaic systems. Using a sustainable approach, all inks were formulated using water and ethanol as solvents. Screen printing of the photoabsorber on fluorine-doped tin-oxide-coated glass followed by selenization, chemical bath deposition of the cadmium sulfide buffer, and final sputtering of the intrinsic zinc oxide and aluminum-doped zinc oxide top conductive layers delivered a 6.6% maximum efficiency solar cell, a record for screen-printed Cu(In,Ga)Se₂ solar cells. On the other hand, the all-non-vacuum-processed device with spray-coated intrinsic zinc-oxide- and tin-doped indium oxide top conductive layers delivered a 2.2% efficiency. The given approaches represent relevant steps towards the fabrication of sustainable and efficient Cu(In,Ga)Se₂ solar cells. Full article

This review addresses the importance of Zn for obtaining multifunctional materials with interesting properties by following certain preparation strategies: choosing the appropriate synthesis route, doping and co-doping of ZnO films to achieve conductive oxide materials with p- or n-type conductivity, and finally adding polymers in the oxide systems for piezoelectricity enhancement. We mainly followed the results of studies of the last ten years through chemical routes, especially by sol-gel and hydrothermal synthesis. Zinc is an essential element that has a special importance for developing multifunctional materials with various applications. ZnO can be used for the deposition of thin films or for obtaining mixed layers by combining ZnO with other oxides (ZnO-SnO₂, ZnO-CuO). Also, composite films can be achieved by mixing ZnO with polymers. It can be doped with metals (Li, Na, Mg, Al) or non-metals (B, N, P). Zn is easily incorporated in a matrix and therefore it can be used as a dopant for other oxidic materials, such as: ITO, CuO, BiFeO_3, and NiO. ZnO can be very useful as a seed layer, for good adherence of the main layer to the substrate, generating nucleation sites for nanowires growth. Thanks to its interesting properties, ZnO is a material with multiple applications in various fields: sensing technology, piezoelectric devices, transparent conductive oxides, solar cells, and photoluminescence applications. Its versatility is the main message of this review. Full article