Cu-doped Samples Research Articles

Substoichiometric La0.8MnO3-based nanocomposites for PGM-free activation of CH4: Ni or Cu? Surface or bulk?

Methane is a renewable fuel when derived from biogas upgrading or by CO2 capture and utilization, with the possibility of fully replacing natural gas in the already established gas infrastructure and engines. However, being a potent greenhouse gas, its use as fuel demands a sustainable activation procedure, to convert any residual traces of unburned CH4 into CO2, a challenging reaction especially at near-stoichiometric conditions typical of Three-Way Catalytic systems (TWC). To avoid expensive noble metals, we developed cheaper alternative catalysts: A-site deficient LaMnO3-based nanocomposites incorporating Ni and Cu. These elements were introduced either as B-site dopants in the perovskite lattice or deposited via Ammonia-driven Deposition-Precipitation (ADP) on the perovskite surface, in both cases yielding metal nanoparticles (NPs) after a reductive treatment. Characterization encompassed various techniques: XRD, N2 physisorption, SEM-EDX, XPS, H2-TPR, HAADF STEM-EDX. CH4 oxidation to CO2 under stoichiometric O2 served as the probe reaction, as model for TWC conditions in methane-fed engines. The LaMn-perovskite itself displayed a promising activity thanks to favourable morphological and redox features (50 % and 90 % CH4 conversion at 581 °C and 678 °C, respectively); further improvements could be obtained upon Ni and Cu loading. The best performances were achieved by: i) the catalyst prepared by Ni-ADP (50 % and 90 % CH4 conversion at 517 °C and 635 °C), featuring high Ni surface concentration and NPs density and a synergy with the perovskite support, as opposed to the low Ni surface concentration on B-site doped samples; ii) the reduced Cu-doped catalyst (50 % and 90 % CH4 conversion at 508 °C and 645 °C), thanks to the high activity of reduced Cu species, the low NPs size and good metal-support interaction, in contrast to the strong NPs agglomeration of the Cu-ADP catalyst. Among the two most active catalysts, a better long-term stability was retained by the Cu-doped sample. This work laid the foundation for the development of alternative CH4 oxidation catalysts at the stoichiometric air-to-fuel ratio, cheaper than commercial Pd-based ones.

Microstructure and properties of Cu-doped β-Ga2O3 rod prepared with liquid metallic gallium

One-dimensional β-Ga2O3 is expected for potential applications in electronics, sensors, and optoelectronics. Gallium hydroxide (GaO(OH)) with different Cu doping was prepared via the hydrothermal method using liquid metallic gallium and copper chloride dihydrate (CuCl2·2H2O) as the starting materials. The material was then transformed to β-Ga2O3 after calcination at 800 °C. SEM images reveal that the obtained powders are well dispersed and have a uniform rod morphology with a length of 13–14 μm and a width of approximately 500 nm. The addition of Cu ion significantly improves the surface morphology of the rod and effectively inhibits the generation of intrinsic oxygen vacancies. And the relative Fermi energy level of Cu-doped β-Ga2O3 undergoes a notable shift from 2.81 eV to 1.25 eV, suggesting the formation of p-type conductivity. Meanwhile, the PL spectra of the Cu-doped samples exhibit emission peaks in the red wavelength range, which is expected for new applications.

Combine Improvement for Dye-Sensitized Solar Cells

Dye Sensitized-Solar Cells (DSSC) represent a third-generation solar cell technology based on photoelectrochemical principles. This study explores the use of Clitoria ternatea (butterfly pea) extract as an organic dye for DSSCs, focusing on its ability to absorb sunlight effectively. Excitation of electrons triggered by light in photocatalysis is strongly influenced by the position of the band gap. To be effective as a photocatalyst, the material must have a conduction band with a high positive potential compared to the electron accepting potential. Doping metal oxides such as CuO, MgO, Fe2O3, and ZnO into TiO2 can change the band edge properties or surface states which can increase light absorption. This research presents the synthesis of TiO2 nanoparticles as photoanodes doped using metal oxides to evaluate characteristic that can influence DSSC performance. TiO2 nanoparticles doped with metal oxide were synthesized using the solvothermal method and characterized by XRD, SEM-EDX, FTIR, and UV-Vis. Comprehensive analysis of samples doped with metal oxides significantly affects the crystal structure, morphology, elemental composition, and optical properties of the material. The results showed that Cu-doped TiO2 samples allowed for the most significant performance improvement in DSSC, followed by Fe-doped TiO2, Mg-doped TiO2, and Zn-doped TiO2, with pure TiO2 having the lowest performance potential. These results provide important insights into material optimization to improve DSSC efficiency.

Grain Manipulation by Annealing Treatment Realizes High-Performance N-Type Bi2Te2.4Se0.6 Thermoelectric Material and Device.

Bi2Te3-based materials play a crucial role in solid cooling and power generation, but the rapidly deteriorated ZT with rising temperatures above 450 K severely limits further applications. Here, this paper reports a novel preparation method of annealing treatment for molten ingot, which can enhance the thermoelectric performance of n-type Bi2Te2.4Se0.6 in a wide temperature range. Instead of conventional halides, copper is adopted to regulate the carrier concentration and grain size to optimal levels. During the process of annealing at 573 K for 4h, the number of twins significantly increases and the grains of Cu-doped samples become larger and more oriented. These optimizations lead to higher carrier mobility with similar carrier concentration compared with the sample without heat treatment. The synergistic effects of Cu doping and annealing treatment realize a high average ZT of 0.89 within 300-600 K in n-type Cu0.02Bi2Te2.4Se0.6. Combined with p-type (Bi,Sb)2Te3, the fabricated thermoelectric device exhibits a high conversion efficiency of 6.9% at a temperature difference of 300 K. This study suggests that annealing treatment is a simple and effective scheme to promote the applications of n-type Bi2(Te,Se)3 in a wide temperature range.

Biogenically Synthesized ZnO and Cu-Doped ZnO Nanoparticles: Effect of Cu-Dopent Concentration and Annealing on Morphology and Optical Properties

In this work, ZnO nanoparticles and Cu-doped ZnO nanoparticles were biogenically synthesized using precipitation method in <i>Cissus quadrangularis</i> plant extract medium. The influence of Cu dopant on the crystalline structure, optical properties, and morphology of ZnO was investigated. The samples were characterized by XRD, FTIR, UV–vis spectroscopy and SEM. XRD patterns confirmed the wurtzite formation of doped and undoped ZnO nanoparticles. The average crystallite size of the neat and Cu-doped samples was ~18 nm irrespective of the amount of dopant. The annealing process enhanced the size of both the neat and Cu-doped samples. However, the influence on the size is less prominent in the Cu-doped sample than in the neat sample. The UV-visible spectral analysis shows that all the synthesized doped and undoped nano zinc oxides absorb at ~400nm. The band gap energy of Cu-doped ZnO particles was greater for unannealed samples whereas it was appreciably lowered on annealing for Cu-doped samples. SEM analysis shows rod-like morphology for the unannealed and annealed undoped zinc oxides. It is changed to flower-like morphology with the addition of 5mM Cu<sup>2+</sup> and then to nano sheet-like structure with the incorporation of higher amount of Cu<sup>2+</sup> ions. Annealing of zinc oxide samples leads to the smoothening of the surfaces with a change in morphology for the ZnO nanoparticles.

Exploring structural and optical properties of Cu-doped and Fe-doped sodium borate glasses

This study investigated the structural and optical properties of Cu-doped and Fe-doped sodium borate glasses. X-ray diffraction (XRD) patterns confirmed that both samples were amorphous, with no sharp peaks. However, differences in the width and center of the high-intensity humps suggested variations in atomic packing and field strength between the two samples. Fourier transform infrared (FTIR) spectra showed wider vibrational modes and stronger absorption in the Fe-doped sample, confirming its higher atomic packing and field strength. Luminescence spectra indicated that the Cu-doped sample had a higher ratio of Cu2+:Cu3+ than the Fe-doped sample of Fe2+:Fe3+, resulting in greater UV–visible region absorption. Optical parameters such as absorbance, transmittance, and reflectance supported these findings, with the Fe-doped sample exhibiting higher absorbance band edges. Quality factor (Q.F.) analysis revealed that the Fe-doped sample had a larger Q.F. than the Cu-doped sample, indicating lower energy losses. Furthermore, the optical conductivity of both samples increased with photon energy, with the Cu-doped sample dominating in all energy regions. Finally, both samples exhibited high effective atomic numbers, suggesting potential applications in radiation shielding, with the Cu-doped sample having a wider radiation shielding window. Finally, the findings unique structural and optical properties suggests the Cu-doped and Fe-doped sodium borate glasses to a lot of potential applications in various fields including radiation shielding, optics, electronics, and energy storage.

Cu-Doped TiO2 Thin Films by Spin Coating: Investigation of Structural and Optical Properties

Cu-doped TiO2 films were synthesized directly on FTO glass with a spin coating method. With a variation in copper amount, samples were prepared with 0%, 1%, 2%, 4% and 8% of dopant concentrations. Morphological and structural characterization of undoped and Cu-doped TiO2 samples were investigated and the obtained results showed the small, spherical shapes of the nanoparticles forming a thin film on top of FTO glass and their preferred orientation of TiO2 anatase (101), which is the same for each sample. However, this peak exhibited a slight shift for the 2% sample, related to the inflation of the microstrain compared to the other samples. For the optical properties, the 4% sample displayed the highest transmittance whereas the 2% sample exhibited the lowest band gap energy of 2.96 eV. Moreover, the PL intensity seems to be at its highest for the 2% sample due to the present peaking defects in the structure, whereas the 8% sample shows a whole new signal that is related to copper oxide. These properties make this material a potential candidate to perform as an electron transport layer (ETL) in solar cells and enhance their power conversion efficiency.

Bulk photovoltaic effect in Cu-doped LiNbO3 single crystals with controlled oxidation state

We investigate the bulk photovoltaic (PV) effect of Cu-doped LiNbO3 single crystals with various oxidation states of Cu. The Cu-doped samples exhibit the PV response under below-bandgap excitation, and the onset of photocurrent shifts depending on partial oxygen pressures (pO2) during the annealing treatment. Open-circuit voltages (V oc) under simulated sunlight (AM 1.5 G) illumination are changed by pO2, and crystals annealed at pO2 = 1.0 × 10−10 atm exhibit the highest V oc of 1700 V. Moreover, density functional theory (DFT) calculations for Cu-doped LiNbO3 cells with Cu2+ on the Li site and the Nb site indicate that half-filled gap states derived from 3d orbitals of Cu are formed within the bandgap. Based on Glass coefficients obtained by the analyses of polarization angle-dependent photocurrent densities and the DFT calculations, we consider that Cu2+ on the Li site is the major active site for the generation and separation of electron–hole pairs under visible light at hν = 2.4 eV.

Multifunctional assessment of copper-doped ZnO nanoparticles synthesized via gliding arc discharge plasma technique: antioxidant, antibacterial, and photocatalytic performance.

In this paper, undoped and copper-doped ZnO nanoparticles (NPs) were successfully synthesized using a gliding arc discharge (GAD) plasma technique, which is a sustainable, cost-effective, and scalable method. This method offers several advantages over traditional synthesis methods. The synthesized NPs were characterized by various techniques to understand their physicochemical properties. XRD analysis confirmed the presence of characteristic peaks of pure ZnO, while doped samples exhibited additional peaks corresponding to CuO crystal planes, indicating the successful incorporation of Cu into the lattice. As obvious, bare ZnO showed absorption peak at 378 nm corresponding to the band gap of 3.21 eV. The band gap of Cu-doped samples increased systematically, i.e., 3.35 eV for 2% Cu, 3.47 eV for 4% Cu, and 3.66 eV for 6% Cu. SEM images revealed aggregation and increase in particle size with the increasing in Cu concentration. EDAX analysis revealed a decrease in the weight percentage of oxygen and zinc with the increase in Cu concentration, suggesting structural changes within the lattice. Furthermore, the antibacterial activity against Gram-positive and Gram-negative bacteria, antioxidant activity, and photocatalytic activity against three different organic dyes such as Brilliant Cresyl Blue (BCB), Methylene Blue (MB), and Congo Red (CR) was studied. It is found that the photocatalytic activity of ZnO NPs varies with Cu concentration, leading to a decrease in its performance. The antibacterial activity of the NPs was also assessed, with undoped ZnO NPs showing dose-dependent effects against bacteria, while the Cu-doped ZnO NPs exhibited decreased efficacy. Interestingly, Cu doping significantly enhanced the antioxidant activity of the NPs compared to the undoped ZnO.

Impact of Cu and Ce on the electrochemical, antibacterial, and wear properties of 316 L stainless steel: Insights for biomedical applications

This study provides a comprehensive investigation of the tribological, electrochemical, and antibacterial characteristics of austenitic stainless steel, type 316 L, doped with Ce and Cu. The samples were doped with varying concentrations of Ce (0.5, 1.5, and 3 wt%) and Cu (1.5, 2.5, and 3.5 wt%). The initial measurements focused on determining the final density values of each sample. Subsequently, friction wear tests were conducted under both dry and wet conditions, shedding light on the wear resistance of the materials. In addition, electrochemical polarization tests were employed to assess the influence of Ce and Cu on the corrosion resistance of AISI 316 L. Furthermore, antibacterial assessments were conducted against bacterial cultures of Staphylococcus aureus (ATCC 29213) and Escherichia coli (ATCC 25922). The findings of this study illuminate several noteworthy outcomes. Namely, the results showed that all Ce and Cu-doped samples exhibited an increase in final density values when compared with the as-received AISI 316 L. The wear test results revealed that samples doped with 0.5 wt% Ce and 2.5 wt% Cu exhibited the highest wear resistance, in both dry and wet environments. Polarization curve analysis indicated that Ce was more effective in enhancing the corrosion resistance of AISI 316 L than Cu. Notably, Ce and Cu modifications endowed the material with antibacterial properties, effectively inhibiting bacterial growth in both S. aureus and E. coli cultures. In summary, this study demonstrates that the addition of even trace amounts of Ce and Cu to AISI 316 L leads to noticeable improvements in the material's tribological, electrochemical, and antibacterial performance, underscoring its potential for diverse biomedical applications. The enhanced mechanical strength, corrosion resistance, and antibacterial activity make the doped material promising for use in various medical devices, implants, and other biomedical applications.

Correlation between phase composition and physicochemical properties in Cu-, Mo-, and W- doped bismuth vanadate

We report a detailed study about the correlation between the physicochemical properties of solvothermally synthesized pristine and 1 %, 2.5 %, and 5 % Cu, Mo, and W-doped bismuth vanadate (BiVO4, BVO) with its phase composition. The effect of the dopant and the duration of synthesis (8 h and 20 h) on the physicochemical properties of BVO allowed us to tune the ratio of monoclinic scheelite to tetragonal zircon phase in BVO powders. This approach helped us to establish the relationship between the presence of monoclinic scheelite or tetragonal zircon phase with structural, morphological and optical properties of BVO powders, obtained by different physicochemical methods (e.g. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Diffuse Reflectance Spectroscopy (DRS) and Photoluminescence spectroscopy (PL)). The results indicated that, in addition to XRD, Raman, and DRS, several other methods could distinguish between the two phases. For example, SEM analysis revealed that monoclinic scheelite BVO exhibits either elongated assemblies of cube-like particles or prismatic particles with sizes ∼500 nm. In contrast, tetragonal zircon BVO exclusively exhibited porous spherical particles with diameter ∼2 μm. DRS and Raman spectroscopy indicated that there is a possibility of distinguishing between the two phases if their shares are large enough. For instance, monoclinic BVO showed band gap values in the range of 2.35–2.52 eV, while tetragonal zircon BVO exhibited values in the range of 2.80–3.00 eV. XPS showed a correlation between phase composition and surface chemistry of BVO only for Cu-doped samples, revealing the presence of Cu+ in monoclinic BVO and the presence of both Cu+ and Cu2+ in tetragonal zircon BVO. PL showed that monoclinic scheelite BVO displayed decreased charge recombination compared to tetragonal zircon BVO. Deeper insight into the correlation between the physicochemical properties and phase composition of Cu, Mo, and W-doped bismuth vanadate (BiVO4, BVO) was based on water/pentanol medium (2:1 vol%) as a novel synthesis pathway. This may open new avenues for the broader methodological exploration of surface chemistry, particle size, and morphology of BVO particles through the use of diverse functionalization agents. Finally, the established links between phase composition and structural, morphological, and other physicochemical properties provide new and more predictable opportunities for further improvement of BVO properties for various applications.

Synthesis, structural, molecular docking, and in vitro biological activities of Cu-doped ZnO nanomaterials

Copper-doped ZnO nanoparticles with the formula Zn1−x(Cu)O, where x = 0.0, 0.03, 0.05, and 0.07 were produced using the co-precipitation process. Physical, chemical, and structural properties were properly examined. Powdered X-ray diffraction (P-XRD) patterns revealed the formation of hexagonal wurtzite crystal structure in all samples, through atomic substitutional incorporation in the Cu-doped ZnO lattice. The presence of Cu ions and their dissolution in the host ZnO crystal structure was supported by FT-IR spectra. HR-TEM images were used to assess the average size, morphology, and shape regularity of the synthesized samples. The form and homogeneity of the ZnO changed when Cu ions were substituted, as evidenced by FE-SEM/EDX analysis. The presence of copper signals in the Cu-doped samples indicates that the doping was successful. The decrease in zeta potential with an increased copper doping percentage designates that the nanoparticles (NPs) are more stable, which could be attributed to an increase in the ionic strength of the aqueous solution. The synthesized NPs were evaluated for their substantial in vitro antioxidant properties. In addition, the antimicrobial efficacy of the materials was tested against pathogenic microorganisms. Regarding the anti-diabetic activity, the 7Cu ZnO sample showed the highest inhibitory effect on the α-amylase enzyme. No variations were observed in the activities of the acetylcholinesterase enzyme (AChE) and proteinase enzymes with ZnO and samples doped with different concentrations of Cu. Therefore, further studies are recommended to reveal the in-vitro anti-diabetic activity of the studied doped samples. Finally, molecular docking provided valuable insights into the potential binding interactions of Cu-doped ZnO with α-amylase, FabH of E. coli, and Penicillin-binding proteins of S. aureus. These outcomes suggest that the prepared materials may have an inhibitory effect on enzymes and hold promise in the battle against microbial infections and diabetes.

Photocatalytic Degradation of Crystal Violet on Cu, Zn Doped BiVO4 Particles.

Fabrication of codoped photocatalysts is a developing area of research. Herein, we explore the visible light photocatalytic properties of Cu, Zn codoped BiVO4 particles. Doping lower valent cations (Cu and Zn) makes the BiVO4 surface more acidic and enables us to target the basic crystal violet (CV) dye. The adopted hydrothermal protocol of synthesis results in the formation of Cu-Zn codoped monoclinic BiVO4 particles. Undoped monoclinic BiVO4, prepared by the same protocol, showed significant formation of oxygen vacancies. XPS analyses confirm the coexistence of Cu2+/Cu+ and Zn2+ dopants. Increased dopant percentage reduced oxygen vacancies. XRD indicates that Cu2+/Cu+ or Zn2+ dopants generally substitute Bi3+ in BiVO4. All photocatalysis activities for CV degradation are reported under near-neutral pH conditions. A typical codoped BiVO4 photocatalyst with 1% Zn and 2% Cu demonstrated the best CV degradation photocatalytic activity. The activity of this Zn, Cu codoped photocatalyst is better than that of pure, Zn-doped, and Cu-doped BiVO4 samples. Active species trapping experiments indicated the possible photocatalysis mechanism. The photocatalysts exhibited appropriate recyclability and photostability.

Cu-doping induced tuning of magnetic properties and phase transformation in MnBi alloys

This study investigates the effect of Cu doping on the magnetic properties of MnBi alloy at sub-ambient temperatures. The Curie temperatures (Tc) were observed at 175.2 and 161.6 K for Mn52Bi45Cu3 and Mn51Bi45Cu4 alloys, respectively. The Mn55Bi45 sample demonstrates a notable saturation magnetization (Ms) of 72 emu/g, reaching 90% of the theoretical value, indicating the successful synthesis of high-purity ferromagnetic low-temperature phase MnBi. Compared to Mn55Bi45, all Cu-doped samples exhibit higher coercivity (Hc) within the temperature range of 10–200 K. In particular, the sample with 4 at. % Cu exhibits an Hc of 7.4 kOe at 10 K, which is 37 times higher than that of the MnBi sample (0.2 kOe), and it remains significantly higher than that of the 0–3 at. % Cu-doped samples, even at 200 K. Further details of this investigation are presented in this paper.

Boosted visible light dye-decontamination and colossal dielectric constant features of Bi2O3: Role of In, Cu and Li-dopants

This study focused on improving the optical, dielectric properties, and photocatalytic efficiency of Bi2O3, a prominent photocatalyst with challenges like limited visible light absorption and rapid electron-hole pair recombination. Using an adapted sol-gel technique, pure Bi2O3, In, Cu and Li-doped Bi2O3 visible-light-driven photocatalyst were synthesized. X-ray diffraction (XRD) confirmed monoclinic Bi2O3 formation. The inclusion of In, Cu, and Li ions into the Bi2O3 lattice was evidenced by alterations in diffraction peak intensities, lattice parameters, and changes in average crystallite size. Vibrational spectra corroborated the formation of pure α-Bi2O3 with slight shifts in transmittance bands, aligning with the XRD findings. Morphological investigation via scanning electron microscopy (FE-SEM-EDX) confirmed the purity of the synthesized nanocompositions and unveiled that the doping induces distinct morphological changes in Bi2O3 nanoparticles, resulting in increased porosity and formation of round and needle-like shapes (In-doped), coalescence of particles (Cu-doped), and fused agglomerates with altered particle size distribution (Li-doped). Optical analysis demonstrated a red shift in the band gap energy of α-Bi2O3 (initially 2.90 eV), with In, Cu, and Li doping, resulting in band gaps of 2.77 eV, 2.78 eV, and 2.88 eV, respectively, accompanied by high refractive indices exceeding 2.0, rendering them suitable for optical applications. Both Cu and Li doping led to enhanced relative permittivity (εʹ) values, with the Li-doped sample displaying remarkable εʹ values at low frequencies (up to 1000 Hz). The In, Cu and Li doping has the effect of reducing PL (photoluminescence) emission intensity while simultaneously diminishing radiative recombination and promoting the separation of photogenerated charge carriers. The doped samples demonstrated superior degradation performance, with In-doped and Cu-doped samples achieving degradation efficiencies of 99% and 91%, respectively, within 180 min. This remarkable performance can be attributed to their visible-light-responsive band gaps, increased electron-hole trapping sites, and distinct morphological features.

Cu-doped LiCl scintillator for thermal neutron detection

Photoluminescence and scintillation properties of Cu-doped LiCl single crystals synthesized by the Bridgman-Stockbarger method were evaluated. Under UV and X-ray irradiation, two emission bands were observed at 325 and 400 nm, and these emissions would be due to 3d94s1-3 d10 transition of Cu+ and Cu+ perturbed by near OH−, respectively. From pulse height spectra under 252Cf neutron irradiation, the 0.1% Cu-doped sample showed the highest light yield (LY) of 5600 photons/neutron among all the samples and the energy resolution of 8.3 %. The LY and the energy resolution of 0.1% Cu-doped LiCl single crystal were comparable with those of commercial Li-glass (GS20). Furthermore, Cu-doped LiCl was not sensitive to γ-ray, and neutron-γ discrimination performance of 0.1% Cu-doped LiCl single crystal was better than that of GS20.

Probing analysis of Cu-doping on the structural, optical, morphological and magnetic properties of hematite nanoparticles and their antibacterial activity

The present study describes the synthesis of pure and Cu doped α-Fe2O3nanoparticles (with various concentrations of Copper 1, 3, 6, and 9 wt%) by conventional chemical precipitation technique and examines their structural, morphological, optical, magnetic, and antibacterial capabilities. The XRD pattern of pure and Cu-doped α-Fe2O3 nanoparticles exhibit rhombohedral structure and the estimated crystalline sizes were ranged from 39 to 58 nm. It is discovered that the estimated density dislocations linked to the agglomeration/cluster formations diminish when interstitial vacancies are filled with copper. The obtained bandgap from Tauc’s plot, 2.07 eV of pure α-Fe2O3 is found to less than Cu doped α-Fe2O3 nanoparticles (2.9–3.4 eV), due to the structural changes and the tailing of localised states into deep bandgap energy levels. The intense blue emission bands (410–490 nm) arised due to the movement of trapped electrons from the donor level to the valance band and broad green emission bands (522–560 nm) are due to deep level CuO defect to the Fe2O3. The fundamental stretching of Fe-O vibrations and the presence of Cu in prepared samples were identified in FTIR and Raman spectra. SEM micrograph shows the uniform distribution of spherical nanoparticles with size ranged from 39 to 61 nm, which is in good accord with XRD studies. Further, the magnetic characteristics of the pure and Cu-doped α-Fe2O3 samples were assessed using a vibrating sample magnetometer (VSM); the ensuing hysteresis loop of the Cu-doped α-Fe2O3 displays weaker ferromagnetic behaviour. In the present investigations, the disc diffusion technique has been used to examine the antibacterial activity. Thus, the results of antibacterial activities demonstrated that at concentrations of 200 and 500 μg/ml of pure and Cu-doped α-Fe2O3 NPs, the highest zone of inhibition was found against gram (+ve) positive bacteria and was followed by the gram (–ve) negative bacteria’s.

Synergistic effect of ZnO nanoparticles with Cu2+ doping on antibacterial and photocatalytic activity

The nanoparticles (NPs) of ZnO and Cu-doped ZnO samples were prepared using a chemical precipitation method specifically aimed at enhancing photocatalytic and antibacterial activity. The structural, morphological, phase constitutional, functional, elemental, and optical properties have been studied using Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM), Ultra Violet diffused reflectance spectroscopy (UV-DRS), Fourier-transform infrared (FTIR) spectroscopy, and Thermogravimetric analysis (TGA). The crystallite size was calculated by using Debye Scherrer formula and the obtained average crystallite size of pure ZnO, ZnO-Cu2.5%, ZnO-Cu5%, and ZnO-Cu10% sample is 24.31 ± 0.12 nm, 25.72 ± 0.47 nm, 26.83 ± 0.39 nm, and 26.94 ± 0.29 nm, respectively. High-resolution Transmission Electron Microscope (HR-TEM) was used to calculate the d-spacing. The values of d-spacing for ZnO, ZnO-Cu2.5%, ZnO-Cu5%, and ZnO-Cu10% samples were measured as 0.248 nm, 0.266 nm, and 0.273 nm, respectively and corresponds to (101), (002) and (100) planes of ZnO, respectively which are well associated with the PXRD data (JCPDS card no. 36–1451). It was found that the doping concentration affects the crystallinity of the ZnO nanoparticles. The average grain size of ZnO, ZnO-Cu2.5%, ZnO-Cu5%, and ZnO-Cu10% is 35.75 ± 1.91 nm, 38.55 ± 2.31 nm, 45.39 ± 1.78 nm, and 50.65 ± 2.23 nm, respectively as determined from TEM images by using the ImageJ software. Further, photo-catalytic dye degradation was studied to understand the photocatalytic behavior of synthesized nanoparticles. The UV–Vis adsorption study has revealed that optimum doping of Cu is mandatory to get the highest degradation of methylene blue (MB) dye. It was observed that 5% Cu-doped ZnO NPs have the optimum photocatalytic activity. Furthermore, the antibacterial activity of various formulations on the gram-negative, facultative anaerobic, coliform bacterium Escherichia coli (E. coli) was studied to establish zone of inhibition (ZOI) values for ZnO and Cu-doped ZnO NPs. The current research indicated that 5% Cu-doped ZnO NPs have shown maximum inhibition and may be used for various antibacterial applications.

Copper-doping induced hierarchically porous metal-organic framework for enhanced adsorption of cefradine antibiotic

Development of hierarchically porous materials is important for adsorptive removal of antibiotic with large molecular size. Herein, we proposed a novel strategy for constructing hierarchically porous metal-organic frameworks (MOFs), via introducing low-coordination-number copper in zirconium-oxygen clusters. Compared with UiO-66 (UiO, University of Oslo), the Cu-doped sample exhibits larger specific surface area and importantly, abundant defects and large rhombus-like window. Benefited from that, cefradine is easily diffused into the cages of UiO-66. The resultant UiO-66-Cu owns much higher adsorption capacity (325.1 mg g−1) for this antibiotic than Cu-absence sample does (102.0 mg g−1), which is also superior to those reported adsorbents. Besides, adsorption equilibrium was obtained at ∼600 min. It is found that the adsorption behavior can be well described by Langmuir isotherm model and pseudo-second-order model. The adsorption is gradually enhanced along with the increasing pH (2.0–8.0). Co-existing ions including Na+, K+, Ca2+, Mg2+, Cl-, NO3- and SO42- commonly have negligible effects on the adsorption. Finally, the adsorbent can be well regenerated by using ethanol as the eluent. Mechanism investigation indicates that cefradine adsorption in UiO-66-Cu is driven by electrostatic, hydrogen bond and coordination interactions. Thus, our work provides an effective adsorbent for cefradine and meanwhile proposes a new approach to construct hierarchically porous MOFs.

Reduction of Typical Diesel NOx Emissions by SCR-NH3 Using Metal-Exchanged Natural Zeolite and SBA-15 Catalysts

In this work, the catalytic performance of clinoptilolite (CLIN) and SBA-15 catalysts, doped with Fe and Cu, was evaluated in the selective catalytic reduction of NO using NH3 as a reducing agent (SCR-NH3). Both Cu-CLIN and Fe-CLIN were obtained by ion-exchange using natural clinoptilolite zeolite originating from the Hrabovec deposit (northeast Slovakia region). Cu-SBA-15 and Fe-SBA-15 were prepared by impregnation into SBA-15 mesoporous synthesized silica. Standard catalytic activity tests were carried out on a bench-scale laboratory apparatus using a reaction mixture of a standard test. GHSV of 48,000 h−1 was adopted based on the space velocity of a real NH3-SCR catalyst for diesel vehicles (100–550 °C). All Cu-doped samples showed better NO conversion values than Fe-doped samples. Clinoptilolite catalysts were more active than those based on SBA-15. Maximum NO conversions of about 96% were observed for Cu-CLIN and Fe-CLIN at 350–400 °C, respectively. Moreover, Fe-CLIN also showed higher stability in the presence of SO2 and water steam at 350 °C. These results demonstrate the potential of metal-doped natural clinoptilolite to be used as cost-effective catalysts applied to the abatement of NOx emissions generated in automotive combustion processes.