Fe-doped CuO Research Articles

Machine Learning Allowed Interpreting Toxicity of a Fe-Doped CuO NM Library Large Data Set─An Environmental In Vivo Case Study.

The wide variation of nanomaterial (NM) characters (size, shape, and properties) and the related impacts on living organisms make it virtually impossible to assess their safety; the need for modeling has been urged for long. We here investigate the custom-designed 1-10% Fe-doped CuO NM library. Effects were assessed using the soil ecotoxicology model Enchytraeus crypticus (Oligochaeta) in the standard 21 days plus its extension (49 days). Results showed that 10%Fe-CuO was the most toxic (21 days reproduction EC50 = 650 mg NM/kg soil) and Fe3O4 NM was the least toxic (no effects up to 3200 mg NM/kg soil). All other NMs caused similar effects to E. crypticus (21 days reproduction EC50 ranging from 875 to 1923 mg NM/kg soil, with overlapping confidence intervals). Aiming to identify the key NM characteristics responsible for the toxicity, machine learning (ML) modeling was used to analyze the large data set [9 NMs, 68 descriptors, 6 concentrations, 2 exposure times (21 and 49 days), 2 endpoints (survival and reproduction)]. ML allowed us to separate experimental related parameters (e.g., zeta potential) from particle-specific descriptors (e.g., force vectors) for the best identification of important descriptors. We observed that concentration-dependent descriptors (environmental parameters, e.g., zeta potential) were the most important under standard test duration (21 day) but not for longer exposure (closer representation of real-world conditions). In the longer exposure (49 days), the particle-specific descriptors were more important than the concentration-dependent parameters. The longer-term exposure showed that the steepness of the concentration-response decreased with an increased Fe content in the NMs. Longer-term exposure should be a requirement in the hazard assessment of NMs in addition to the standard in OECD guidelines for chemicals. The progress toward ML analysis is desirable given its need for such large data sets and significant power to link NM descriptors to effects in animals. This is beyond the current univariate and concentration-response modeling analysis.

Investigation of structural and optical properties of TM-doped CuO NPs: Correlation with their photocatalytic efficiency in sunlight-induced pollutant degradation

The presence of non-biodegradable, toxic, and harmful organic pollutants in various environmental mediums poses significant threats to ecosystems and human health. This study investigates the impact of transition metal (TM) doping on the photocatalytic performance of copper oxide nanoparticles (CuO NPs) in degrading methylene blue (MB) dye under sunlight irradiation. CuO NPs are synthesized using the co-precipitation method. X-ray diffraction (XRD) analysis revealed a monoclinic structure with space group C2/c for undoped and TM–doped CuONPs, with crystalline sizes ranging from 13 nm for undoped to 36 nm for Zn-doped CuO. Based on UV–Visible Spectroscopy data, the band gap energies and the nature of electronic band transitions are determined using a new simplified calculation method. Accordingly, direct band gap energy exhibits a slight red-shift as a result of doping with Ni, Mn or Fe, from 1.427 eV for undoped to 1.402 eV for Fe-doped CuO. While Co or Zn doping, induces a trivial blue-shift to 1.468 eV and 1.434 eV respectively. The CuO particles show a heterogenous distribution size and shape. The mean grain size raised from 34.3 nm for undoped to about 100 nm for TM-doped CuONPS, excluding the Co-doped CuO for which the mean grain size reached 154.532 nm with highest standard deviation heterogeneity of 125.737 nm. Furthermore, photocatalytic experiments demonstrated that TM-doping significantly enhanced the degradation rate of MB dye under sunlight irradiation. Co-doped CuO is the most efficient catalyst. This makes TM-doping a promising pathway for the use of CuO NPs in wastewater decontamination applications.

Synthesis and characterization of Fe-doped CuO nanoparticles: Catalytic efficiency in crystal violet dye degradation and exploration of electrical properties

In recent times, environmental pollution has become a pressing issue. Different methods have been developed to detach hazardous materials from H2O bodies. Among these techniques, photo-catalysis has emerged as a low-cost and advanced method. However, finding a potent photocatalyst has been a topic of considerable research. Our study prepared CuO from copper acetate using hydrothermal treatment in an autoclave at 170 ºC for 14 hours. We introduced various quantities of Fe by adding FeSO4 mixture to Cu (CH3COO)2, following the identical method for preparing CuO. The resulting precipitate was cleaned with deionized H2O and dried at 100 °C. The prepared substance was then heated at 450 ºC in a muffle furnace for 60 minutes. We characterized the manufacture of photocatalysts utilizing various techniques such as Ultraviolet (UV), FT-IR, SEM, EDX, and XRD. Our Ultraviolet (UV) spectrum analysis helped us recognize the adsorption spectroscopic analysis of un-doped and doped CuO with various ratios of Fe. FTIR spectroscopic analysis helped us identify functional groups in CuO NPs. Our XRD study showed the monoclinic composition of copper oxide nanoparticles. The SEM picture suggested that NPs exist in a spherical shape. We studied the catalytic activity of synthesized NPs concerning crystal violet (CV) colorant degradation below a direct ray of light irradiation. Our results showed that the degradation productiveness, as compared to CV colorant, was about 93.52% in 180 min. This research is of great importance in the quest for effective and sustainable solutions to environmental problems. The examination of electrical properties highlighted the promising aspects of Fe-doped CuO, particularly at 6% doping. This variant demonstrated superior dielectric parameters, lower tangent loss, semiconductor-like impedance behavior, and enhanced electrical conductivity, emphasizing its potential for applications in electrical and energy storage domains.

Electron redistribution and proton transfer induced by atomically fully exposed Cu-O-Fe clusters coupled with single-atom sites for efficient oxygen electrocatalysis

Single-atom catalysts have garnered significant attention by showing sparkling performance in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the air cathode side of energy devices such as metal-air batteries and fuel cells. This work presents a novel catalyst, AC-CuFe-NC, that incorporates Fe-doped CuO atomic clusters (CuOFe) synergistically with single-atom sites. The AC-CuFe-NC demonstrates outstanding ORR performance (half-wave potential of 0.92 V) and an oxygen overpotential gap between ORR and OER as low as 0.61 V, which is among the top reported performances. Combined with in situ ATR-SEIRAS and DFT calculations, it is shown that the synergistic CuOFe atomic clusters are effective in inducing the electronic structure redistribution of the Fe single-atom site, modulating oxygen adsorption energy, and lowering ORR barriers. More importantly, it is revealed that the synergistic adsorption of clusters and single-atom sites establishes hydrogen bonds between the oxygenated intermediates and the electrolyte H2O molecules. The constructed hydrogen bond can provide a pathway for efficient proton transport as supported by kinetic isotope experiments, leading to a substantial enhancement in reaction kinetics. Additionally, the oxygenated intermediates are stabilized, and the Fe-O bond is elongated during the final step of ORR, thereby facilitating the desorption of OH*. The excellent bifunctional electrocatalytic performance of AC-CuFe-NC enable it to show promising application in rechargeable Zn-air batteries. The innovative catalyst structure and synergistic mechanism demonstrated in this study shed light on the development of high-performance catalysts in energy devices.

Highly Selective and Reversible Detection of Simulated Breath Hydrogen Sulfide Using Fe-Doped CuO Hollow Spheres: Enhanced Surface Redox Reaction by Multi-Valent Catalysts.

The precise and reversible detection of hydrogen sulfide (H2S) at high humidity condition, a malodorous and harmful volatile sulfur compound, is essential for the self-assessment of oral diseases, halitosis, and asthma. However, the selective and reversible detection of trace concentrations of H2S (≈0.1ppm) in high humidity conditions (exhaled breath) is challenging because of irreversible H2S adsorption/desorption at the surface of chemiresistors. The study reports the synthesis of Fe-doped CuO hollow spheres as H2S gas-sensing materials via spray pyrolysis. 4 at.% of Fe-doped CuO hollow spheres exhibit high selectivity (response ratio ≥ 34.4) over interference gas (ethanol, 1ppm) and reversible sensing characteristics (100% recovery) to 0.1ppm of H2S under high humidity (relative humidity 80%) at 175 °C. The effect of multi-valent transition metal ion doping into CuO on sensor reversibility is confirmed through the enhancement of recovery kinetics by doping 4 at.% of Ti- or Nb ions into CuO sensors. Mechanistic detailsof these excellent H2S sensing characteristics are also investigated by analyzing the redox reactions and the catalytic activity change of the Fe-doped CuO sensing materials. The selective and reversible detection of H2S using the Fe-doped CuO sensor suggested in this work opens a new possibility for halitosis self-monitoring.

Melt-Blown nonwovens coated with Fe-doped CuO and CuO for antibacterial applications

Melt-Blown nonwovens coated with Fe-doped CuO and CuO for antibacterial applications

An investigation on structural, dielectric and optical properties of pure and Fe-doped CuO nanoparticles for optoelectronic device applications

An investigation on structural, dielectric and optical properties of pure and Fe-doped CuO nanoparticles for optoelectronic device applications

Effects of transition metals (Fe, Co) on the physical and photoelectrochemical hydrogen generation properties of copper oxide nanoparticulate films

The composites of some transition metal oxides are currently attracting interesting roles in various fields of technology and industry. The present work attempts to tune the properties of copper oxide (CuO) for hydrogen energy generation. Iron (Fe) and cobalt (Co) were intentionally doped at precise contents into CuO thin films. X-ray diffraction (XRD) indicated that the successful substitution of Fe and Co on the Cu sites created induces pressure (tensile) stress in the lattice. Fe doping deteriorated the films' crystallinity and increased the dislocation density from 1.82 × 10−3 to 4.36 × 10−3 nm−2, while Co codoping displayed unsystematic behavior. The scanning electron microscope (SEM) images showed that the films have smooth surfaces comprising a huge number of particles/unit area with a narrow size distribution. The energy-dispersive X-ray (EDX) analysis confirmed the presence of both Fe and Co with almost the pre-calculated ratios. The optical measurement showed that increasing the Fe contents increases the absorption coefficient of CuO and narrows its optical band gap from 1.7 to 1.55 eV. The photoluminescence (PL) intensity increases for Fe-doped CuO films whereas quenched when doped with Co. A series of photoelectrochemical (PEC) measurements were conducted to evaluate the performance of the prepared films in the production of solar hydrogen. The CuO–6%Fe film showed high photocatalytic performance for H2 generation from H2O splitting over a wide wavelength range of sunlight with long-term photostability. The photocurrent density of CuO–6%Fe film is about 155 times more than those obtained from pure CuO film. The incident photon-to-current efficiency (IPCE) and the solar-to-hydrogen efficiency (ηSTH) of CuO–6%Fe film were 5.98 % at 307 nm and 0.94 % under Xenon illumination, respectively. Hence, this work proposed an efficient and reasonable technique to enhance the performance of a CuO-based photoelectrode for solar hydrogen production.

Transition metal-doped CuO nanosheets for enhanced visible-light photocatalysis

Herein, we report a comprehensive investigation of Zn- and Fe-doped CuO nanosheets as promising photocatalysts for the degradation of organic dyes. These nanosheets were synthesized via a hydrothermal process and thoroughly characterized through spectroscopic and microscopic techniques. Photocatalytic degradation experiments using methylene blue (MB) and malachite green (MG) revealed a marked increase in efficiency within the doped CuO nanosheets when compared to their undoped counterparts. The degradation kinetics showed MB following a zero-order model and MG following a first-order model. In particular, Zn and Fe-doped CuO nanosheets outperformed undoped CuO, degrading 66% and 73% of MB and 85% and 90% of MG within specific timeframes, while undoped CuO achieved 62% and 76% degradation, respectively. Computational analysis conducted with Gaussian 09 software pinpointed reactive sites susceptible to radical and electrophilic attacks in the dyes. The enhanced performance is credited to transition metal doping, which induces a red shift in the optical band gap, thereby improving visible light absorption and diminishing electron-hole recombination. This study underscores the potential of transition metal doping in bandgap engineering for efficient visible light-assisted photocatalytic remediation.

H2 gas sensing applications of undoped and Fe-doped CuO thin films grown by USP

H2 gas sensing applications of undoped and Fe-doped CuO thin films grown by USP

Structural, Electrical and Optical Properties of Fe-doped CuO Deposited by Spray Pyrolysis TechniqueStructural, Electrical and Optical Properties of Fe-doped CuO Deposited by Spray Pyrolysis Technique

Our work consists in depositing the copper oxide Fe doped CuO films by spray obtained from the solution of copper chloride CuCl2 and FeCl2 with a percentage of 2, 4; 6 and 8%, on glass substrates at a temperature of 3500c. The thin films obtained are characterized by X-ray diffraction, visible UV spectroscopy and the four-point technique.With X-ray diffraction, high peak intensity is obtained for the preferential orientations of (002) and (111), this intensity increases as the doping rate increases and gives us a more crystalline structure for a doping rate of 8%, also a grain size were estimated. The transmission of our films varies between 55% and 75% with a high absorption in the visible domain, the resistivity of our films increase with the increase of doping rate and the gap energy varies between 4.00 and 1.47 eV

Fe Doping Enhances the Peroxidase-Like Activity of CuO for Ascorbic Acid Sensing

Although significant advances have been witnessed in the application of nanozymes in recent years, exploring new strategies to enhance the enzyme-like activity of nanozymes is of urgent importance. Herein, we investigate the feasibility of accelerating the peroxidase-like reaction rate of CuO nanostructures through Fe doping. The coprecipitation method was used to synthesize Fe-doped CuO (Fe-CuO) nanozymes, and the results indicate that the diversified valence of Fe benefits the redox reaction driven by CuO-based nanozymes. With the improved peroxidase-like activity, the Fe-CuO nanozyme enables the significant chromogenic oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB), facilitating the construction of a visual sensing platform for the sensitive and selective determination of ascorbic acid. Under optimal conditions, the absorbance at 652 nm decreases linearly with the concentration of ascorbic acid in the range of 5–50 μM, with a limit of detection as low as 4.66 μM. This work exemplifies the activity enhancement for peroxidase-mimicking nanozymes with a metal-doping strategy and provides a broad prospect for the design of more high-performance nanozymes for biosensing applications.

Design of a Flexible Enzyme‐less Glucose Sensor Based on Non‐woven Fabric and Fe‐Doped CuO Nanocomposite

AbstractAmong various enzyme‐free sensors, transition metals and their oxides have been used as suitable modifiers for the design of glucose electrochemical sensors due to their availability and low cost. In the present study, a flexible, enzyme‐less, nonwoven fabric‐based glucose sensor was developed. We synthesized the Fe‐doped CuO (Fe/CuO) chemically and used it as a modifier to the carbon paste to achieve this. A working electrode was created by stabilizing the paste on a nonwoven fabric. The fabric used did not require any pre‐preparation except cleaning. The synthesized Fe/CuO was characterized using scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), electrochemical impedance spectroscopy (EIS), diffuse reflectance spectroscopy (DRS), and X‐ray diffraction (XRD). The electrochemical properties of the Fe/CuO nanocomposite on the textile electrode were investigated using cyclic voltammetry, amperometry, and electrochemical impedance spectroscopy. In the proposed enzyme‐free sensor, Fe/CuO catalyzed the oxidation of glucose on the electrode surface. The sensor has high sensitivity, a wide linear range (2.5×10−3–6.57 mM), a low detection limit (8.0×10−4 mM), long‐term stability, and good selectivity. Finally, the sensor was used to determine the amount of glucose in a human sweat sample.

Effect of ageing on electrical properties of Fe-doped CuO thin films deposited by spin coating technique

Effect of ageing on electrical properties of Fe-doped CuO thin films deposited by spin coating technique

Fe-Doped CuO/MWCNT as a Sensing Material for Electrochemical Detection of Nitrite

With unique electrical and catalytic properties, CuO has been ubiquitously employed in many applications including electrochemical sensors. Enhanced electrocatalytic performance of CuO can be achieved through doping. This work explored the potential of 3 mol% Fe-doped CuO/multi-walled carbon nanotube (MWCNT) composite for nitrite detection. The undoped CuO and 3 mol% Fe-doped CuO powders, prepared using a solution combustion technique, had average particle sizes lower than 100 nanometres. Particle refinement and enhancement of the specific surface area were observed in 3 mol% Fe-doped CuO. CuO/MWCNT and 3 mol% Fe-doped CuO/MWCNT composites, prepared using the hydrothermal impregnation technique, were tested for their electrocatalytic activities in the presence of nitrite. Cyclic voltammetry results revealed reduction reaction at an applied voltage of approximately −0.4 V. Superior peak currents were evident in the 3 mol% Fe-doped CuO/MWCNT composite. With acceptable sensitivity, limit of detection, selectivity, reusability, and recovery percentage, the 3 mol% Fe-doped CuO/MWCNT composite demonstrated potential capability in the detection of nitrite.

Structural, nonlinear optical and antimicrobial properties of sol-gel derived, Fe-doped CuO thin films

Undoped and Fe-doped CuO thin films with different weight ratios (3, 6, and 9 wt.% of Fe) were deposited onto glass substrates using the sol-gel spin coating technique. X-ray diffraction analysis of these samples indicated that all the films were polycrystalline, and crystallite size decreased with doping concentration. As revealed by scanning electron microscopy, Fe doping increased average particle size and improved size distribution in films. The bandgap of undoped CuO thin film was tuned from 3.48 to 2.79 by the addition of 9 wt.% Fe, and reasonable explanations have been presented. Optical parameters, such as refractive index, extinction coefficient, dielectric constant, and optical conductivity, were calculated for optoelectronic applications. Finally, antimicrobial properties were measured for their possibility to be used as disinfectants, and the antifungal activity of Fe-doped CuO thin films was shown to be more effective.

Rapid organic dye degradation and wavelength dependent sensing study in Cu1-xFexO

Cu1-xFexO (x = 0, 0.0156, 0.0234 and 0.0312) nanoparticles have been synthesized by using a simple sol-gel route. A pure monoclinic phase (space group c2/c) was observed from XRD studies. A Rietveld analysis of the XRD spectra using GSAS software helped evaluate the variations of lattice constant, lattice strain and bond length/angles. With Fe doping, while the indirect bandgap could be nominally tuned from ∼1.40 eV to ∼1.46 eV, the Fe-doping seems to improve carrier concentration, mobility, and lattice regularity than pure CuO. The photocatalytic degradation of toxic methylene blue (MB) dye could be enhanced from 0.91%/min for the pure CuO to 1.48%/min for 3.125%-Fe-doped CuO. This property has been correlated to the carrier properties of the materials. The UV and visible photoresponse of Cu1-xFexO nanoparticles was investigated. A drastic reduction in both UV and visible light-sensitivity with Fe-doping was observed and correlated with carrier properties.

Investigation of Doping Effect on Structural, Optical, Antibacterial and Toxicity Properties of Iron Doped Copper Oxide Nanostructures Prepared By Co-Precipitation Route

In this work, pure copper oxide and Fe-doped copper oxide nanostructures [Cu1-x FexO where 0 ≤ x ≤ 0.08 in steps of 0.02] were synthesized using co-precipitation method. Iron nitrate nano-hydrate and copper nitrate trihydrate as precursors and NaOH was used as precipitating agent. The samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and UV-visible spectroscopy for their structural, morphological and optical properties, respectively. The effect of iron concentration on antibacterial activity and hemolysis were also investigated for Escherichia coli and Bacillus Subtilis. The XRD pattern showed the single-phase monoclinic structure of CuO nanoparticles. The average crystallite size of pure copper oxide was found to be 39 nm whereas average crystallite size of Fe-doped CuO was found to be in the range 39-44 nm. It was observed that average crystallite size was increased with increasing iron concentration in CuO. Scanning electron microscopy analysis showed the spherical like morphology and EDS confirmed the presence of iron and copper with proper composition. UV-vis spectroscopy results showed that band gap was decreased with increasing iron concentration. Samples prepared with higher concentration of iron exhibited high E. coli and B. subtilis antibacterial activity. Low hemolytic is safer to be used in various applications such as drug delivery.

Experimental investigation of Co and Fe-Doped CuO nanostructured electrode material for remarkable electrochemical performance

The current research work presents a facile and cost–effective co-precipitation method to prepare doped (Co & Fe) CuO and undoped CuO nanostructures without usage of any type of surfactant or capping agents. The structural analysis reveals monoclinic crystal structure of synthesized pure CuO and doped-CuO nanostructures. The effect of different morphologies on the performance of supercapacitors has been found in CV (cyclic voltammetry) and GCD (galvanic charge discharge) investigations. The specific capacitances have been obtained 156 (±5) Fg−1, 168(±5) Fg−1 and 186 (±5) Fg−1 for CuO, Co-doped CuO and Fe-doped CuO electrodes, respectively at scan rate of 5 mVs−1, while it is found to be 114 (±5) Fg−1, 136 (±5) Fg−1 and 170 (±5) Fg−1 for CuO, Co–CuO and Fe–CuO, respectively at 0.5 Ag-1 as calculated from the GCD. The super capacitive performance of the Fe–CuO nanorods is mainly attributed to the synergism that evolves between CuO and Fe metal ion. The Fe-doped CuO with its nanorods like morphology provides superior specific capacitance value and excellent cyclic stability among all studied nanostructured electrodes. Consequently, it motivates to the use of Fe-doped CuO nanostructures as electrode material in the next generation energy storage devices.

Core–shell behavior and exchange bias of Fe-doped CuO nanoparticles

Cu1−xFexO nanoparticles were prepared using a freeze-drying process followed by heat treatment. The particles were then characterized using Mössbauer spectroscopy and magnetization techniques. The results revealed complex magnetic behavior, which can be attributed to the presence of two different magnetic regions: the particle core, which has antiferromagnetic fluctuations, and the particle shell, where uncompensated spins are responsible for their superparamagnetic characteristics. At low temperatures, the moments freeze, revealing a ferromagnetic order for the shells and a dipolar magnetic interaction among the nanoparticles. In addition, an exchange-bias field revealed magnetic interactions between the core and the shell of the nanoparticles. The ferromagnetism observed in this system suggests that antiferromagnetic oxide matrices can be used for diluted magnetic semiconductor applications, if suitably doped.