Manganese-doped ZnO Research Articles

Manganese-doped Zinc Oxide recycled from spent alkaline batteries for photocatalysis and supercapacitor applications

In a sustainable future, recycling e-waste will offer an adequate solution to control the raw materials and energy crisis. Our study aims to obtain ZnO-based materials by recycling the alkaline batteries using mild and cost-effective methods. Manganese-doped ZnO materials were obtained through anodic paste annealing at different temperatures. In terms of morphology and structure, particles with rod shape, high crystallinity, and hexagonal symmetry were obtained. The annealing provides an atomic rearrangement ensuring the presence of isolated Mn2+ ions in the ZnO lattice, as evidenced by EPR spectroscopy. The sample defect evolution with the annealing temperature was highlighted by photoluminescence spectroscopy. The photocatalytic and energy storage applications of the obtained sample were investigated. The photocatalytic activity was tested on Rhodamine B and Oxytetracycline under visible light irradiation. The highest photocatalytic efficiency was obtained for Mn-doped ZnO annealed at 700 °C, and the proposed mechanism was based on reactive oxygen species generation correlated with scavengers’ tests, defect’s structure, and pores diameter. Additionally, the samples were used to design symmetric supercapacitors and tested using different electrochemical techniques to prove their energy storage features. As a result, the Mn-doped ZnO particles annealed at 800 °C showed increased specific capacitance of 182 F/g, energy density of 25.2 Wh/kg, and power density of 38.7 kW/Kg without the use of booster materials.

Monodispersed nanorod-shaped Mn-Co co-doped ZnO nanoparticles for enhanced photocatalytic and antibacterial activities

The present work deals with synthesizing the pure ZnO (PZ), manganese-doped ZnO (MZ), and manganese-cobalt co-doped ZnO (MCZ) nanoparticles by hydrothermal method. X-ray diffraction confirms their hexagonal wurtzite structure with varying crystallite sizes: 43.8 nm for PZ, 34.6 nm for MZ, and 27.6 nm for MCZ. The band gap values were calculated as 3.14 eV (PZ), 3.09 eV (MZ), and 2.89 eV (MCZ) from Tauc plot. FTIR analysis provided the evidence of metal–oxygen bonds and other characteristic functionalities. These nanoparticles exhibited potent antibacterial activity against both gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. In photocatalytic performance of MCZ has showed a higher rate of Crystal Violet dye degradation under visible light irradiation compared to other materials.

Enhancing apple shelf life: A comparative analysis of photocatalytic activity in pure and manganese-doped ZnO nanoparticles

This paper presents the hydrothermal synthesis of pure and manganese-doped ZnO nanoparticles with varying doping concentrations (1–5 %) for the purpose of examining photocatalytic activity and extending apple's shelf life. The structural, morphological, vibrational and optical characteristics of nanoparticles were investigated with the aid of XPS, XRD, SEM, FTIR, and PL. When tested for photocatalytic activity against methylene blue (MB), it was confirmed that Mn–ZnO NPs showed improved photocatalytic performance during MB degradation. Additionally, apples treated with synthesized nanoparticles were subjected to a variety of tests to determine influence of these NPs on the shelf life of apples, including those that measured weight loss over time, moisture content, ascorbic acid, and decay process. The current study is quite interesting because it correlates photocatalytic activity with Apple's shelf life. Moreover, Mn doped ZnO showed remarkable antifungal and antibacterial properties against Rosellinia necatrix and Fusarium spp. and Escherichia coli and Staphylococcus aureus.

Spectroscopic Probing Of Mn-Doped ZnO Nanowires Synthesized via a Microwave-Assisted Route

Dilute magnetic semiconductors such as transition-metal-doped ZnO are potential candidates for spintronic applications. Transition metals such as Mn, Fe, and Cu when doped in ZnO enable spin magnetic properties to conventional semiconductors. Although several techniques such as wet chemical and vapor deposition methods are employed to achieve homogeneous doping in ZnO, these methods have limits pertaining to solubility levels of dopant ion, morphology, competition between intrinsic and extrinsic defects and localization of the defect species. This manuscript is an addition to the vast knowledge of methods and protocols that present the synthesis of transition-metal-doped ZnO. In this report, manganese-doped ZnO is synthesized via a microwave-assisted hydrolysis technique. The defect structure of Mn-doped ZnO wires is investigated via electron paramagnetic resonance and photoluminescence techniques. The analysis indicates that Mn2+ substitutes the Zn ion and dominates the intrinsic defect species in ZnO.

Relationship between Physical Properties and Preparation Atmosphere of Manganese-doped ZnO–P2O5 Glasses

Relationship between Physical Properties and Preparation Atmosphere of Manganese-doped ZnO–P2O5 Glasses

Experimentally realization of dual nonlinear dielectric resonance and electromagnetic characteristics of Manganese-doped ZnO NPs in X-Band

In this paper, the electromagnetic details of Manganese-doped Zinc Oxide (Mn–ZnO) nanoparticles (NPs) were measured using the waveguide measurement method in the frequency range 8–12.5 GHz. The evaluations have been utilized by the Nicolson-Ross-Weir method for electromagnetic properties such as permittivity and permeability. The results indicate, dual nonlinear dielectric resonance in X-band at 9.446 and 10.47 GHz. The equivalent circuit and simulated waveguide structure are inserted to explain and verify the dual dielectric resonance. Consequently, Inductance-Capacitance properties are detected by the obtained impedance regarding the reaction of the NPs to the electromagnetic waves and, the outgoing power for the simulated waveguide has a sharp drop at around the two main resonance domains. The evaluated magnetic susceptibility quantity affirms that the Mn–ZnO NPs act as ferro and paramagnetic material at less and above than 10.39 GHz.

Vertically Aligned Manganese-doped ZnO Nanorods Synthesized on Glassy Carbon Electrode for Detection of Colorants in Soft Drinks

Vertically Aligned Manganese-doped ZnO Nanorods Synthesized on Glassy Carbon Electrode for Detection of Colorants in Soft Drinks

Role of Mn in biological, optical, and magnetic properties ZnO nano-particles

The properties of manganese-doped ZnO nano-particles fabricated by the sol-gel method were studied. The concentration of Mn in the ZnO was 1–4% w/w. The X-ray diffraction (XRD) confirmed wurtzite phase of ZnO. The results showed that Mn2+ ions substituted Zn2+ ions without altering the wurtzite structure of ZnO. Crystallite size was increased with increase in Mn doping percentage. Optical transmission recorded by UV–VIS–NIR spectrophotometer decreased with increase in Mn doping percentage. The optical band gap energy was quite low in the range 2.99–3.18 eV as compared to undoped ZnO and found to change with the increase in Mn percentage. Magnetic study displays that the Mn doped ZnO nanoparticles show ferro-magnetism at room temperature and the variation of the Mn percentage can tailor the ferromagnetic behavior of the nano-particles. Maximum coercivity of 228.07(Oe) is achieved for 2.5% Mn dopant and saturation magnetization is 0.03780 emu/g for 1.5% of Mn. Photo-catalytic activity was explored against methylene blue. 1% Mn contents have shown better photo-catalytic activity. It was discovered that ZnO nanoparticles with Mn doping displayed good antibacterial efficiency against Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) bacteria. The results displayed that the antibacterial activity of Mn doped ZnO nano-particles enhances with an increase in Mn percentage. Surface morphology is modified with an increase in Mn percentage. All thin films consist of nano-sized dispersed particles which are in agreement with the XRD results.

Photocatalytic Activities of Vertically Aligned Manganese-Doped ZnO Nanorods Synthesized on ITO Film by Electrochemical Technique

Photocatalytic Activities of Vertically Aligned Manganese-Doped ZnO Nanorods Synthesized on ITO Film by Electrochemical Technique

Comparative study on the physical properties of transition metal-doped (Co, Ni, Fe, and Mn) ZnO nanoparticles

Nano-crystalline of TM-doped ZnO with general formula Zn0.97TM0.03O (TM: Mn, Fe, Co, and Ni) was prepared using sol–gel method. The dependence of crystal structure, morphology, and optical and magnetic properties on the type of transition metals was investigated. The XRD investigation of pure and TM-doped ZnO nanoparticles samples confirms the formation of single-phase hexagonal wurtzite structure. The estimated crystallite sizes are found in the range of 17 and 38 nm for the doped and pure samples, respectively. The obtained data suggest that the dopant type plays a vital role in the physical properties of the investigated samples. The optical band-gap energy Eg has been calculated from near infrared (NIR) and visible (VIS) reflectance spectra using the Kubelka–Munk function. Minimum value of 2.398 eV and maximum one of 3.29 eV were obtained for Manganese-doped ZnO and pure ZnO, respectively. The analysis of XRD and VSM of the samples confirms that the observed room-temperature (RT) ferromagnetism can be attributed to an intrinsic property of doped material sample and not due to formation of any secondary phase. The magnetic results show that Mn is the most effective dopant for producing ferromagnetism in nanoparticles of ZnO.

Low temperature ammonia gas sensor based on Mn-doped ZnO nanoparticle decorated microspheres

Ammonia is a kind of colorless, pungent gas which is highly toxic to human health when inhaled above the moderate level. Detection of ammonia at low temperature is one of the most challenging tasks. In this work, low-temperature ammonia gas sensor using manganese-doped ZnO sphere as sensing material was successfully developed. Undoped ZnO nanorods and Mn-doped ZnO microsphere were successfully synthesized by the simple hydrothermal method and the structural, surface morphological, optical and gas sensing properties were investigated. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed that the Mn-doped ZnO has sphere like-morphology decorated with nanoparticles. X-ray photoelectron spectroscopy (XPS) analysis indicated that the Mn-doped ZnO sample is in the Mn2+ valence state. Mn-doped ZnO sphere showed enhanced selectivity towards ammonia compared to other gases at low temperature. Mn-doped ZnO (8 wt%) showed the higher response of 28.58. The response and the recovery time of the fabricated sensor towards 20 ppm ammonia are 4 and 10 s (s).

Influence of different precursors and Mn doping concentrations on the structural, optical properties and photocatalytic activity of single-crystal manganese-doped ZnO

Mn-doped ZnO single-crystal micronuts were synthesized via hydrothermal method in an hexamethylenetetramine aqueous solution. These micronuts are of wurtzite crystal structure. The effects of Mn doping amount and precursor concentration on the structural, optical properties and photocatalytic activity have been investigated. The synthesized Mn-doped ZnO was characterized by X-ray powder diffraction, field emission scanning electron microscopy (FESEM), UV–Vis absorption and photoluminescence spectroscopy. The structural analyses based on X-ray diffraction revealed the absence of Mn-related secondary phases. According to FESEM results, the length of ZnO micronuts was in the range of 5–8 μm. The band gap energy increased on increasing Mn doping concentration. The photocatalytic activity was studied by degradation of methyl orange aqueous solution, which showed that the Mn-doped ZnO micronuts prepared in precursor concentration of 0.1 M and 4% Mn doping had the highest photocatalytic activity. The effects of crystal defect and band gap energy on photocatalytic activity of Mn-doped ZnO samples were studied in different precursors and Mn doping amounts.

Structural and optical properties of ZnO and manganese-doped ZnO

The structural, morphological and optical properties of manganese oxides supported on commercial ZnO, prepared by impregnation with manganese nitrate, were investigated. The nominal compositions of Mn in the samples were 5, 10, 15 and 20%w/w.The X-ray diffraction (XRD) experiments revealed the presence of the ZnO wurtzite phase in all the samples, and ZnMnO3 was also found in the samples with 15 wt% and 20 wt% of Mn. X-ray photoelectron spectroscopy (XPS) showed the presence of Mn2+ and Mn4+ in the xMnZnO samples. The results showed that the Mn2+ ions had substituted the Zn2+ ions without changing the wurtzite structure of ZnO, while Mn4+ might be assigned to the ZnMnO3 impurity phase. The optical band gap was found to be 3.3 eV for undoped ZnO samples and 3.10 eV for Mn-doped samples. The lattice defect distribution was investigated using the positron annihilation method. The results revealed that the average lifetime is a function of the Mn concentration and the formation of the ZnMnO3 phase.

Microwave solvothermal synthesis and characterization of manganese-doped ZnO nanoparticles.

Mn-doped zinc oxide nanoparticles were prepared by using the microwave solvothermal synthesis (MSS) technique. The nanoparticles were produced from a solution of zinc acetate dihydrate and manganese(II) acetate tetrahydrate using ethylene glycol as solvent. The content of Mn2+ in Zn1−xMnxO ranged from 1 to 25 mol %. The following properties of the nanostructures were investigated: skeleton density, specific surface area (SSA), phase purity (XRD), lattice parameters, dopant content, average particle size, crystallite size distribution, morphology. The average particle size of Zn1−xMnxO was determined using Scherrer’s formula, the Nanopowder XRD Processor Demo web application and by converting the specific surface area results. X-ray diffraction of synthesized samples shows a single-phase wurtzite crystal structure of ZnO without any indication of additional phases. Spherical Zn1−xMnxO particles were obtained with monocrystalline structure and average particle sizes from 17 to 30 nm depending on the content of dopant. SEM images showed an impact of the dopant concentration on the morphology of the nanoparticles.

Dilute manganese-doped ZnO nanowires for high photoelectrical performance

This study developed dilute manganese-doped ZnO (D-(Zn,Mn)O) nanowires using a low temperature hydrothermal method.

First-principles investigations of Mn doped zinc-blende ZnO based magnetic semiconductors: Materials for spintronic applications

ZnO based magnetic semiconductors are intensively investigated because of showing strong potential as base materials for spintronic devices. In this study, full potential linearized augmented plane-wave plus local orbitals FP-L(APW+lo) scheme of computation is used to explore the structural, electronic and magnetic properties of Manganese-doped ZnO based magnetic semiconductors in zinc-blende (ZB) phase. For comprehensive understanding of Mn-doping effect on ZnO, several compositions of Mn:ZnO for 12.5%, 25%, 37.5%, 50%, 62.5%, 75% and 87.5% of Mn concentration are investigated. Our obtained results show a successful induction of the magnetic moment (MM) by Mn-doping into the ZnO matrix, without any geometrical deformation. However a marginal increase in the value of lattice constants is found up to 25% concentration of Mn for this system and for above compositions, it tends to decrease revealing the formation of secondary phases. It is also found that Mn:ZnO system favors ferromagnetic coupling for 12.5% and 25% of Mn contents that has been switched to anti-ferromagnetic coupling for higher Mn contents. The spin polarized electronic structure of Mn:ZnO system was calculated within the generalized gradient approximation (GGA). In addition, the Hubbard parameter was also employed to improve the electronic band structure calculations. The calculations performed at GGA+U level related to electronic band structures show zero energy gap for majority spin carriers, whereas a considerable energy gap is noted for minority spin carriers. This distinguished response of Mn:ZnO system to majority and minority spin carriers, in terms of resistivity and conductivity, highlights its importance for diverse applications as based material in spintronic devices like spin dependent transports, currents and other spin based electronic applications.

Preparation of manganese-doped ZnO thin films and their characterization

In this study, pure and manganese-doped zinc oxide (Mn:ZnO) thin films were deposited on quartz substrate following successive ion layer adsorption and reaction (SILAR) technique. The film growth rate was found to increase linearly with number of dipping cycle. Characterization techniques of XRD, SEM with EDX and UV–visible spectra measurement were done to investigate the effect of Mn doping on the structural and optical properties of Mn:ZnO thin films. Structural characterization by X-ray diffraction reveals that polycrystalline nature of the films increases with increasing manganese incorporation. Particle size evaluated using X-ray line broadening analysis shows decreasing trend with increasing manganese impurification. The average particle size for pure ZnO is 29·71 nm and it reduces to 23·76 nm for 5% Mn-doped ZnO. The strong preferred c-axis orientation is lost due to manganese (Mn) doping. The degree of polycrystallinity increases and the average microstrain in the films decreases with increasing Mn incorporation. Incorporation of Mn was confirmed from elemental analysis using EDX. As the Mn doping concentration increases the optical bandgap of the films decreases for the range of Mn doping reported here. The value of fundamental absorption edge is 3·22 eV for pure ZnO and it decreases to 3·06 eV for 5% Mn:ZnO.

Characterization of Manganese doped ZnO (MZO) thin films by Spin Coating Technique

Doping is a widely used to improve the structural and optical properties of semiconductors. However deposition route is also very important to get nanostructure with different properties. ZnO nanostructures doped with Mn having 5% doping concentrations by weight percentage have been synthesized in the laboratory using Spin coating technique. Scanning Electron Microscope (SEM) image shows the around one millimeter and X-ray diffractometer studies shows that the average diameter of the particles is 25 nm. From the UV-Vis studies the annealing temperature increases the crystal size decreases and the bandgap values increases accordingly.

Thermal properties of manganese-doped ZnO polycrystalline films

The thermal conductivity and heat capacity of manganese-doped zinc oxide polycrystals have been studied in the temperature range 30–300 K. A substantial influence of the secondary phase or MnO clusters formed as a result of doping on the temperature dependences of thermophysical properties of polycrystalline zinc oxide films has been shown.

Preparation and Characterization of Manganese Doped ZnO Varistors

In this paper, the influences of MnO2 and V2O5 on the varistor properties of ZnO- V2O5-based ceramics were examined. The results show that, the addition of MnO2 to the ZnO-V2O5-based ceramics was found to improve varistor properties. The sintered temperature was benefit to enhancing the growth of crystals of the samples and the non-ohomic coefficient can be improved. The samples have non-ohmic coefficient α=27.8 and varistor voltage U1mA=60.9V/mm when they are sintered at 1100°C with 2 hours.