Solvothermal Synthesis of In2−xCoxO3 (0.05 ≤ x ≤ 0.15) Dilute Magnetic Semiconductors: Optical,Magnetic, and Dielectric Properties

Highly crystalline and monophasic nanoparticles of In_2?xCo_xO₃ (0.05 ≤ x ≤ 0.15) were successfully synthesized by the solvothermal method through an oxalate precursor route. Collective evidence from X‐ray diffraction and reflectance measurements suggest that the Co²⁺ is incorporated into the In₂O₃ lattice site. Effect of cobalt dopant on the growth and morphology of indium oxide was studied by transmission electron microscopy. It has been observed that particle size decreases from 23 to 9 nm on increasing the Co concentration. High surface area has been obtained, with values ranging between 66 and 151 m²/g, respectively. Values for the dielectric constant were around 40. All these solid solutions show paramagnetic behavior with weak antiferromagnetic interactions.     

Green synthesized zinc oxide nanoparticles: Effect of polyethylene glycol and chitosan on structural,optical and morphological analysis

The use of plant extracts in the synthesis of nanoparticles has several advantages over traditional chemical-based synthesis methods. The synthesis of ZnO, Polyethylene Glycol ZnO (PEG), and Chitosen (Chit) ZnO nanoparticles using moringa oleifera leaf extracts as an effective reducing agent is described in this report. The colour of the reaction mixture changes from yellowish brown to white as nano metal oxide forms. Surface modifying agents for ZnO nano oxide included polyethylene glycol and chitosan. UV–Vis and FTIR spectroscopy were used to investigate the optical characteristics of produced nano oxides. The structural, elemental analysis, and morphology of nano oxides were studied using XRD, FESEM, EDAX, and HRTEM techniques. XRD validated the hexagonal wurtzite structure, and the average crystallite size of the ZnO, PEG-ZnO, and Chit-ZnO nanoparticles were 35 nm, 32 nm, and 28 nm, respectively. The band gaps of ZnO, PEG-ZnO, and Chit-ZnO nanoparticles were found to be 3.12 eV, 3.18 eV, and 3.14 eV, respectively, using UV–Visible analysis. ZnO, PEG-ZnO, and Chit-ZnO nanoparticles were found to be generally spherical and nano in size, according to SEM and TEM examination. According to the findings, moringa oleifera leaf extract-assisted ZnO-based nanoparticles are promising materials for various applications.     

Polyol Synthesis and Investigation of Ce1−xRExO2−x/2 (RE = Sm,Gd, Nd,La, 0 ≤ x ≤ 0.25) Electrolytes for IT‐SOFCs

In this study, we aimed to examine the effect of dopant type and concentration on the ionic conductivity of ceria‐based electrolytes. Ceria electrolytes doped with samarium (SDC), gadolinium (GDC), neodymium (NDC), and lanthanum (LDC) for solid oxide fuel cells were prepared through the polyol process. Acetate compounds of cerium and dopants were used as starting materials, and triethylene glycol was used as a solvent. Prepared powders and pellets were characterized by TG/DTA, XRD, FTIR, SEM, EIS, and EDS techniques. The results of the TG/DTA and XRD indicated that a single‐phase fluorite structure formed at the relatively low calcination temperature of 500°C. The relative densities of the pellets were higher than 90% and these finding were supported by the SEM images. The lattice parameters of the samples increased with the dopant concentration. According to the electrochemical analysis results, the samples with maximum conductivity values were SDC‐20, GDC‐15, NDC‐15, and LDC‐15. The results of the impedance spectroscopy revealed that the SDC‐20 sample exhibited the highest ionic conductivity with a value of 4.29 × 10^?2 S/cm at 800°C in air.     

Nanoparticles of ZnO and Mg-doped ZnO: Synthesis,characterization and efficient removal of methyl orange (MO) from aqueous solution

Nanoparticles of zinc oxide and of ZnO doped with MgO in different concentrations (1, 2 and 4 mol%) were synthesized in a controlled and reproducible way, using the Pechini polymer precursor method. To determine the physicochemical and structural characteristics of the synthesized nanoparticles, Fourier transform IR (FTIR), X-ray diffraction (XRD), UV–Vis spectroscopy and transmission and scanning electron microscopy (TEM and SEM) were used. Characterization revealed the particles obtained to be nanometric in size (<50 nm) and with a deformed hexagonal morphology. Taking into account the doping percentage, the energy gap value varied between 3.3 eV for pure ZnO and 3.45 eV for ZnO with 4 mol% of Mg, which indicates that the optical properties of these nanoparticles were affected by dopant concentration. The effect of doping with Mg²⁺ on the capacity for removal of pollutant molecules by ZnO, for different working conditions, was evaluated by studying the removal of methyl orange (MO) in aqueous solution. Irradiation of the compounds led to a greater removal of MO from the solution such that all ZnO samples doped with MgO showed higher photoactivity than ZnO. The ZnO nanoparticles doped with 2% Mg were the most efficient in removing MO, achieving a removal percentage of ~73% after 2 h of testing and a totally transparent solution after 3 h of treatment. The kinetics of removal of MO promoted by this sample was best represented by pseudo-first-order kinetics. The results of this work showed that on combining a photosensitive semiconductor, ZnO, with a wide band gap insulator, MgO, Zn–Mg solid solutions are obtained that showed adequate capacity to remove contaminating organic molecules, specifically MO.     

Insight of structural,dielectric and spectroscopic characteristics of Ba0.6Sr0.4-xYbxFe12-yCoyO19 M-type hexaferrite

Ba_0.6Sr_0.4-xYb_xFe_12-yCo_yO₁₉, (0.0≤x ≤ 0.125, 0.0≤y ≤ 1.25) M-type hexaferrite were synthesized using the auto combustion sol-gel process. The synthesized samples were then sintered at 1200 °C for 5 h in a muffle furnace. XRD, FTIR, Raman, and Photoluminescence spectroscopies were used to analyse all the samples. XRD technique was used for structural examination of Ba_0.6Sr_0.4-xYb_xFe_12-yCo_yO₁₉. The XRD patterns of Yb–Co co-substituted M-type hexaferrites revealed the pure single phase of synthesized samples. Change in Yb–Co concentration influenced lattice parameters and unit cell volume. The variations in lattice constants "a" and "c" values are 5.891–5.862 and 23.180–23.317. FTIR spectroscopic data graphs revealed the formation of several absorption bands from 430 cm^?1 to 3000 cm^?1. The strain in the unit cell produced by substitution changes in Raman spectra which is also confirmed by XRD. Many 630 nm–700 nm emissions were observed in the PL spectra of Ba_0.6Sr_0.4-xYb_xFe_12-yCo_yO_19. Furthermore, a bandgap of 1.961–1.875 eV was observed for the pure sample. The substitution improves the dielectric losses and Ac conductivity. The Maxwell-Wagner theory was used to investigate the changing trends of characteristics regarding dielectric parameters. The findings show that the samples with the appropriate cationic substitution can be used in microwave and high-frequency applications.     

Physical Properties of La1−xEuxPO4,0 ≤ x ≤ 1, Monazite‐Type Ceramics

Synthetic La_1?xEu_xPO₄ monazite‐type ceramics with 0 ≤ x ≤ 1 have been characterized by ultrasound techniques, dilatometry, and micro‐calorimetry. The coefficients of thermal expansion and the elastic properties are, to a good approximation, linearly dependent on the europium concentration. Elastic stiffness coefficients range from 182(1) to 202(1) GPa for c₁₁ and from 53.8(7) to 61.1(4) GPa for c₄₄. They are strongly dependent on the density of the sample. The coefficient of thermal expansion at 673 K is 8.4(3)  × 10^?6 K^?1 for LaPO₄ and 9.9(3)  × 10^?6 K^?1 for EuPO₄, respectively. The heat capacities at ambient temperature are between 101.6(8) J·(mol·K)^?1 for LaPO₄ and 110.1(8) J·(mol·K)^?1 for EuPO₄. The difference between the heat capacity of LaPO₄ and the Eu‐containing solid solutions is dominated by electronic transitions of the 4f‐electrons at temperatures above 75 K.     

In vitro anticancer activity and comparative green synthesis of ZnO/Ag nanoparticles by moringa oleifera,mentha piperita,and citrus lemon

This study proposes a simple, effective, and environmentally friendly approach for the synthesis of zinc oxide/silver nanoparticles (ZnO/Ag NPs) using three different plant extracts. The plants used in this study were moringa oleifera (MO), mentha piperita (MP), and citrus lemon (CL). Characterizations of ZnO/Ag NPs were done using ultraviolet–visible spectroscopy (UV vis), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) along with energy dispersive spectroscopy (EDX), and fourier transform infrared spectroscopy (FTIR). In accordance with size distribution findings, ZnO/Ag NPs synthesized with MO have a narrow size distribution, with the average particle size being 119 ± 36 nm. Among these three reducing agent MO act as the best reducing agent. Moreover, the anticancer activity of silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs) and ZnO/Ag NPs synthesized with MO were demonstrated in human cervical cancer cells (HeLA). The results revealed that ZnO/Ag NPs demonstrate in vitro cell viability of 72%, 81%, and 84% using 2.5, 5, and 10 μgml^?1of ZnO/Ag NPs for 24 h. While Ag NPs and ZnO NPs prepared with MO showed 50% and 60% cell viability using 2.5 μgml^?1concentration for 24 h. This showed that the ZnO/Ag NPs act as a strong anticancer agent compared to Ag NPs and ZnO NPs. Overall, this research proposes a green synthesis approach for ZnO/Ag NPs with a wide range of potential uses, particularly in biomedicine.     

Enhanced photocatalytic degradation of Acid Blue 1 using Ni-Decorated ZnO NPs synthesized by sol-gel method: RSM optimization approach

In this research, the synthesis of pure and Ni-decorated ZnO nanoparticles was carried out successfully by sol-gel method. The morphology, structure, chemical bonding, and absorption spectrum of the synthesized nanoparticles were investigated using FESEM, TEM, XRD, EDX and elemental mapping, FT-IR, and UV–Vis techniques. After Ni decoration, the spherical structure of ZnO nanoparticles almost changed to uniform hexagonal nanoparticles. The synthesized nanoparticles were used for Acid Blue 1 dye degradation through a photocatalysis procedure under UV light (6 w). The influence of four factors, including metal (Ni) percentage, dye concentration, catalyst dosage, and pH, on the photocatalytic activity of the synthesized photocatalysts, was studied. The experiments were evaluated by means of the response surface methodology (RSM) based on the central composite design (CCD). The experimental results indicated dye concentration = 10 mg/L, pH = 7.77, Ni percentage = 1.117% and catalyst dosage = 1.07 g/L as the optimum values for variables. At optimum conditions, CCD estimated the degradation rate equal to 90.23% which is close to the experimental efficiency, 89.13%, (R² = 0.9877 and adjusted R² = 0.9762). The results confirmed the reliability of the CCD to predict the amount of dye removal. Additionally, the Ni-decorated ZnO nanoparticles had more activity in the visible area than the pure ZnO sample. According to the UV–Vis spectra, the band gap decreased from 3.13 to 2.97 eV by adding Ni to ZnO. Furthermore, the Ni-decorated ZnO sample represented a significant redshift compared to the pure sample.     

Temperature Dependence of Electrical Resistivity (4–300 K) in Aluminum‐ and Boron‐Doped SiC Ceramics

Al‐ and B‐doped 3C–SiC ceramics were prepared by hot‐pressing powder compacts containing submicrometer‐sized β‐SiC, precursors of 5 wt% nanosized β‐SiC, and an optional additive (Al or B) in an Ar atmosphere. Electron probe microanalysis (EPMA) investigation on the obtained specimens revealed that a portion of the doped Al and B atoms substituted the zinc blende lattice sites. The temperature‐dependent electrical resistivity data of the Al‐ and B‐doped SiC specimens were measured in the 4–300 K range and compared with those of an undoped specimen. The Al‐ and B‐doped SiC specimens exhibited resistivities that were as high as ~10³ Ω cm at room temperature and ~10⁵ and ~10⁴ Ω cm, respectively, below 100 K. These values are larger than those of the undoped SiC specimen by a factor of ~10⁴. Such high resistivities of the impurity‐doped specimens are attributable to the carrier compensation by the Al‐ and B‐derived acceptors located well above the valence‐band edge of 3C–SiC. Photoluminescence investigation revealed that the Al‐ and B‐doped specimens exhibited emission profile below 2 eV, implying the existence of the acceptors.     

Structural,optical, morphological and electrochemical properties of ZnO and graphene oxide blended ZnO nanocomposites

A simple cost-effective co-precipitation method was adopted to prepare ZnO nanoparticles from a metal organic framework. The synthesized ZnO nanoparticles were blended with graphene oxide (GO) to prepare the ZnO-GO nanocomposite. The physicochemical properties of ZnO nanoparticles and ZnO-GO nanocomposite were analyzed via various techniques. The structural behavior of ZnO and ZnO-GO nanocomposite was studied by XRD and FT-IR analysis. The XRD profile confirms the hexagonal structure with an average crystallite size of 19.4 nm for ZnO and 16.2 nm for ZnO-GO nanocomposites. The functional groups and the vibration modes of the samples were examined through FT-IR. It confirms the metallic presence in the ZnO and ZnO-GO samples in the wavenumber range of 400–600 cm^?1. The optical properties of ZnO and ZnO-GO were studied via UV–vis spectra. The surface morphology of the samples was recorded through FESEM, and the elemental presence in the samples was examined by EDX. It confirms that the prepared samples are spherical in shape with uniform size distributions. Cyclic voltammetry has been used to study the redox behavior of electroactive ZnO and ZnO-GO composites.     

Concentration dependence of physical properties of low temperature processed ZnO quantum dots thin films on polyethylene terephthalate as potential electron transport material for perovskite solar cell

Colloidal Zinc oxide quantum dots (ZnO QDs) prepared with varying concentrations through precipitation method were deposited on flexible ITO/PET substrates using spin-coating technique. Various characterization tools were utilized to investigate the morphological, structural, electrical and optical properties of the films. The crystallinity of the films was found to improve with increasing ZnO QD concentration (ZQ_C) as evident from the X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) studies. Crystallographic and optical parameters were evaluated and explained in depth. The average nanograin size and bandgap were increased and decreased respectively, from ～5 nm to ～8 nm and 3.29 eV–3.24 eV with an increase in ZQ_C from 10 mg/mL to 70 mg/mL. Columnar structure growth of the films is revealed by AFM results. The films showed decent optical transparency up to 81%. All the ZnO films exhibited n-type semiconducting property as indicated by the electrical measurements with carrier mobility and low resistivity of 12.21–26.63 cm²/Vs and 11.84 × 10^?3 to 13.16 × 10^?3 Ω cm respectively. Based on the experimental findings, ZnO QD nanostructure film grown at 50 mg/mL is envisaged to be a potential candidate for flexible perovskite photovoltaic application.     

Biosynthesized Ag–ZnO nanohybrids exhibit strong antibacterial activity by inducing oxidative stress

We report facile biosynthesis of Ag–ZnO nanohybrids consisting of Ag nanoparticles decorated ZnO nanobullets prepared by decorating wet chemically synthesized ZnO nanobullets with Ag nanoparticles through bioreduction of Ag ⁺ ions with aqueous extract of Piper nigrum fruits. The prepared nanomaterials were well characterized by FESEM, TEM, HRTEM, EDX, XRD, XPS, PL and UV–vis spectroscopy. FESEM and TEM analyses on the nanohybrids revealed ∼18 nm Ag nanoparticles decorating ZnO nanobullets with average size ∼48 nm. XRD results revealed hexagonal wurtzite ZnO with 22.4 nm crystallite size and FCC Ag with 18.7 nm crystalline size. Ag–ZnO nanohybrids exhibited strong antibacterial action against Escherichia coli, Bacillus oceanisediminis and Pseudomonas entomophila and efficiently inhibited their growth at 100 μg/mL, 50 μg/mL and 125 μg/mL, respectively. The molecular basis of antibacterial action of Ag–ZnO nanohybrids against E. coli was investigated using different biochemical and molecular assays. Addition of antioxidant histidine suppressed the antibacterial action of Ag–ZnO nanohybrids towards E. coli due to its ROS scavenging action. Bradford assay results showed enhanced protein leakage from Ag–ZnO nanohybrids treated E. coli, while TBARS assay results confirmed lipid peroxidation triggered by ROS. SEM on Ag–ZnO nanohybrids treated E. coli confirmed significant damage to the cell wall leading to morphology change. The antibacterial activity of Ag–ZnO nanohybrids against E. coli is mainly due to the ROS-induced oxidative stress, which caused enhanced lipid peroxidation, cell wall damage leading to significant protein leakage and DNA fragmentation.     

Enhanced optoelectronic properties of Ti-doped ZnO nanorods for photodetector applications

We report the effect of Ti-doping on structural, morphological, photoluminescence, optical and photoconductive properties of ZnO thin films. Pure and Ti(1, 3 and 5%)-doped ZnO thin films are deposited by the successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction analysis revealed the single-phase hexagonal wurtzite ZnO structure of all the films. Scanning electron microscope images suggest the formation of rod shaped particles in Ti-doped ZnO thin films. Photoluminescence spectra of all the films show emission peaks centered at 398 nm, 413 nm, 438 nm, 477 nm and 522 nm wavelengths. Optical properties support the semiconducting nature of all the films. The optical bandgap values are estimated to be 3.29 eV, 3.26 eV, 3.19 eV and 3.23 eV for ZnO, ZnO:Ti(1%), ZnO:Ti(3%) and ZnO:Ti(5%) thin films, respectively. Photoconductivity study indicates that ZnO:Ti(3%) thin film exhibits high responsivity, external quantum efficiency and detectivity of 0.30 AW^-1, 97% and 5.49 × 10¹⁰ Jones, respectively, among all the films. The enhanced photoconductivity of Ti-doped ZnO thin films make them useful for optoelectronic applications.     

Size‐dependent optical properties of transparent,spin‐coated polystyrene/ZnO nanocomposite films

Zinc oxide (ZnO) nanoparticles are synthesized using a simple chemical method at room temperature. A variation in molar concentration of the precursor, potassium hydroxide, from 0.25 to 0.01 mol L^?1 is accompanied by a decrease in the average size of the nanoparticles. These nanoparticles are used for the preparation of polystyrene/ZnO nanocomposite films using the spin‐coating technique. These films are found to be highly transparent throughout the visible region and absorb UV light in the region from 395 to190 nm, almost covering the near and middle UV ranges (400 to 200 nm). This observation highlights the possible prospects of these films in UV shielding applications. The wavelength corresponding to the onset of UV absorption is found to be blue shifted with a decrease in size of the ZnO particles in the composite films due to confinement effects. The photoluminescence spectra of the composite films also change as a function of particle size. The emissions at longer wavelength due to defects and impurity‐related states in ZnO are almost quenched as a result of surface modification by the polymer matrix. The observed band‐gap enlargement with a decrease in size of the ZnO particles in the composite films is significant for band‐gap engineering of nanoparticles for various applications. Copyright © 2011 Society of Chemical Industry     

Structural,optical and electrical properties of low temperature grown undoped and (Al,Ga) co-doped ZnO thin films by spray pyrolysis

Aluminum and gallium co-doped ZnO (AGZO) thin films were grown by simple, flexible and cost-effective spray pyrolysis method on glass substrates at a temperature of 230 °C. Effects of equal co-doping with aluminum (Al) and gallium (Ga) on structural, optical and electrical properties were investigated by X-ray diffraction (XRD), UV–vis–NIR spectrophotometry and Current–Voltage (I–V) measurements, respectively. XRD patterns showed a successful growth with high quality polycrystalline films on glass substrates. The predominant orientation of the films is (002) at dopant concentrations ≤2 at% and (101) at higher dopant concentrations. Incorporation of Al and Ga to the ZnO crystal structure decreased the crystallite size and increased residual stress of the thin films. All films were highly transparent in the visible region with average transmittance of 80%. Increasing doping concentrations increased the optical band gap, from 3.12 to 3.30 eV. A blue shift of the optical band gap was observed from 400 nm to 380 nm with increase in equal co-doping. Co-doping improved the electrical conductivity of ZnO thin films. It has been found from the electrical measurements that films with dopant concentration of 2 at% have lowest resistivity of 1.621×10⁻⁴ Ω cm.     

Sodium‐Doped ZnO Nanowires Grown by High‐pressure PLD and their Acceptor‐Related Optical Properties

Sodium‐doped ZnO (ZnO:Na) nanowires were grown with a high‐pressure pulsed‐laser deposition process on silicon substrates using sputtered gold particles as catalysts. The introduction of sodium dopants into ZnO nanowires was confirmed by both X‐ray diffraction spectrum and X‐ray photoelectron spectroscopy. The morphology and microstructural changes in ZnO nanowires due to sodium doping were investigated with scanning electron microscope, high‐resolution transmission electron microscope, and Raman spectrum. Detailed photoluminescence studies of ZnO:Na nanowires revealed characteristic sodium acceptor‐related peaks, for example, neutral acceptor‐bound exciton emission (A⁰X, 3.356 eV), free‐to‐neutral‐acceptor emission (e, A⁰, 3.314 eV), and donor‐to‐acceptor pair emission (DAP, 3.241 eV). This indicated that sodium doping induces stable acceptor level with a binding energy of 133 meV in ZnO:Na nanowires.     

Comparative investigation on the structural,morphological, optical,and magnetic properties of CoFe2O4 nanoparticles

Herein, we report a sustainable production of magnetic cobalt ferrite nanoparticles by conventional (CHM) and microwave heating (MHM) method. Hibiscus rosa-sinensis extract was used as both reducing and stabilizing agent. Using plant extracts to synthesize nanoparticles has been considered as an eco-friendly method, since it avoids noxious chemicals. The plethora of plant extract mediated nanoparticles were compared by techniques, such as XRD, Rietveld, FT-IR, SEM, EDX, UV-Visible DRS, PL and VSM were carried out to analyze and understand their crystallite size, functional groups, morphology, optical and magnetic properties. The crystalline structure of cobalt ferrite nanoparticles revealed the cubic structure and the microwave heating of nanoparticles showed smaller crystallite size compared to the conventional heating, which was then confirmed by XRD analysis. To analyze the presence of functional groups and the phytochemical involvement of the plant extract was confirmed by FT-IR studies. Spherical morphology with less than 100 nm sized particles was confirmed by SEM and EDX analysis confirm the existence of Co, O, and Fe elements present in the samples. UV-Visible DRS studies were carried out to calculate the band gap of the as-synthesized nanoparticles, estimated from the Kubelka-Munk function, as 2.06, and 1.87 eV for CHM and MHM, respectively. Photoluminescence emission spectrum of the nanoparticles showed two different bands at 494 and 620 nm, which explores the optical properties of the nanoparticles, due to the quantum confinement effect. VSM analysis showed better ferromagnetic behavior, which can be used for magnetic applications.     

Enhanced dielectric stability and coercivity of band gap tuned Ba–Al Co-doped bismuth ferrite: An experimental and DFT+U investigation

Employing a modified sol-gel combustion technique, BiFeO₃ and Bi_0.85Ba_0.15Fe_1-xAl_xO₃ (x = 0, 0.025 and 0.050) nanoparticles were synthesized, and the effects of these dopants were investigated analyzing the experimental findings and adopting the DFT + U approach. Rietveld analysis of XRD revealed a deformed perovskite rhombohedral structure for all the Ba–Al co-doped nanoparticles, which was also validated by theoretical study. Suppression of the low-frequency dispersion promoting outstanding dielectric stability was observed due to Al³⁺ doping, and the least dielectric constant along with the highest resistivity was reported for BBFAO-2.5. The band gap of co-doped nanoparticles (x = 2.5 & 5) decreased to 1.95 eV and 1.98 eV, respectively, compared to 2.06 eV, and 2.09 eV for BBFAO-0 and pure BFO. The average particle size of all the co-doped nanoparticles was below the repeat length of the cycloid structure, which is favorable for improved magnetic properties. Remanent magnetization, coercivity, and squareness increased as the motion of domain walls is inhibited by the smaller-sized nanoparticles. DFT + U study further endorses the findings of the experimental study. Analysis of DOS revealed the emergence of shallow impurity states around VBM due to doping, which can operate as active trap centers and impede carrier recombination. Thus, it can be inferred that, Ba–Al co-doped nanoceramics with intriguing dielectric, optical, and magnetic properties are a promising candidate for high-frequency microwave devices, magnetic memory and storage devices, near UV-detector, and solar photocatalysis applications.     

Enhancement in the photocatalytic and antimicrobial properties of ZnO nanoparticles by structural variations and energy bandgap tuning through Fe and Co co-doping

In this study, pure ZnO and iron (Fe) and cobalt (Co) co-doped ZnO nanoparticles were synthesized by varying Fe and Co concentrations using the co-precipitation method. The physical properties of as-prepared samples were investigated through XRD, FTIR, SEM, and UV–vis spectroscopy. X-ray diffraction confirmed the strong influence of Fe and Co ions on structural parameters without disturbing the basic ZnO hexagonal structure. The microstructural study was executed by using the Scherrer, W–H, and SSP methods. FTIR confirmed the presence of Zn–O, and Zn–M–O (M = Fe, Co) vibrational modes, which further confirmed the successful incorporation of dopants ions. The energy bandgap (E_g) extracted from UV–vis spectra has shown red-shift (3.37–2.7 eV) for decreasing Fe contents, whereas blue-shift (3.37–3.39 eV) for increasing Co concentration. SEM was used to investigate surface morphology, which represents the high rate of agglomeration. The photocatalytic test was performed on grown samples against various dyes and also observed the effects of varying concentrations of Fe and Co ions. The maximum degradation efficiency (98.8%) at 6%Fe and 4%Co under direct sunlight in 60 min against methylene blue (MB) was achieved. The photocatalytic activity of optimized concentration (6%Fe and 4%Co) was further tested against cresol red (CR), methyl orange (MO), safranin-O (SO), rhodamine-B (RhB), and methyl red (MR) dyes. The maximum degradation efficiency against MR dye (96.0%) was observed. The antibacterial test against Staphylococcus aureus and Klebsiella pneumoniae bacterial strains have shown that co-doped ZnO nanoparticles have a higher activity as compared to pristine ZnO, and furthermore, the sample with 6%Fe and 4%Co concentration exposed the highest antibacterial actively for both bacterial strains.     

Garcinia xanthochymus mediated green synthesis of ZnO nanoparticles: Photoluminescence,photocatalytic and antioxidant activity studies

Green synthesis of multifunctional zinc oxide nanoparticles (ZnO Nps) was achieved employing water extract of Garcinia xanthochymus by solution combustion synthesis. The structure and morphology were determined by XRD, UV–visible and scanning electron microscopy studies. The ZnO Nps were evaluated for photoluminescence (PL), photocatalytic and antioxidant properties. The water extract was found to comprise significantly high amounts of polyphenols and flavonoids. Powder XRD studies indicate the formation of pure wurtzite structure with absorption maximum of 370 nm corresponding to band gap energy of 3.33 eV. SEM studies reveal the formation of spongy cave like structures. The PL spectra exhibited 4 emission edges at 397, 436, 556 and 651 nm upon excitation at 325 nm because of oxygen deficiencies and zinc interstitials. Nps exhibit remarkable photodegradation of methylene blue (MB) in presence of UV and sun light. They exhibit antioxidant activity by inhibiting the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. Therefore, the study reveals an efficient, ecofriendly and simple method for the green synthesis of multifunctional ZnO Nps.