Mn ZnO Research Articles

Crystalography and the behavior of optical band gap in transition metal-doped (Al+Mn) ZnO nanopowder

Crystalography and the behavior of optical band gap in transition metal-doped (Al+Mn) ZnO nanopowder

Band Energy Modulation in an Fe–Mn–ZnO Nanowire–Nanosheet Catalyst for Efficient Overall Water Splitting

Band Energy Modulation in an Fe–Mn–ZnO Nanowire–Nanosheet Catalyst for Efficient Overall Water Splitting

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.

Antimicrobial activities and neuroprotective potential for Alzheimer’s disease of pure, Mn, Co, and Al-doped ZnO ultra-small nanoparticles

Antimicrobial activities and neuroprotective potential for Alzheimer’s disease of pure, Mn, Co, and Al-doped ZnO ultra-small nanoparticles

Investigation on structural, photoluminescence and magnetic behavior of Mn–ZnO nanoparticles via solvothermal route

Mn doped ZnO (Zn: Mn) nanopowder is successfully synthesized using the solvothermal route with concentration (X = 2%–8%) and annealing at 450 °C. The resulting material is investigated using various techniques. XRD studies confirm the structure of hexagonal wurtzite and good crystallinity in nature. From FESEM analysis confirms the formation of nanoparticles and allows for evaluation of the particle size of the sample. UV–Vis studies are used to determine absorbance wavelength and energy bandgap values. PL and EPR spectra confirm of the existence of zinc vacancy defects and g values are calculated. Interestingly, magnetic measurements revealed that the low concentration exhibited superparamagnetic behavior, while the high concentration showed a soft ferromagnetic structure using VSM.

Rapid photodegradation of toxic organic compounds and photo inhibition of bacteria in the presence of novel hydrothermally synthesized Ag/Mn–ZnO nanomaterial

Purified water is the most concerning issue these days, and utmost conventional practices are allied with various downsides. Therefore, an ecologically benign and easily amicable therapeutic approach is the requirement. In this wonder, nanometer phenomena bring an innovative change to the material world. It has the potential to produce nanosized materials for wide-ranging applications. The subsequent research highlights the synthesis of Ag/Mn–ZnO nanomaterial via a one-pot hydrothermal route with an efficient photocatalytic activity against organic dyes and bacteria. The outcomes revealed that the size of the particle (4–5 nm) and dispersion of spherically shaped silver nanoparticles intensely affected by employing Mn–ZnO as a support material. Use of silver NPs as a dopant activates the active sites of the support medium and provides a higher surface area to upsurge the degradation rate. The synthesized nanomaterial was evaluated against photocatalytic activity using Methyl orange and alizarin red as model dyes and confided that more than 70% of both the dyes degraded under 100 min duration. It is well recognize that the modified nanomaterial recreates an essential role in every light-based reaction, and virtually produced highly reactive oxygen species. The synthesized nanomaterial was also evaluated against E. coli bacterium both in light and dark. The zone of inhibition in the presence of Ag/Mn–ZnO was observed both in light (18 ± 0.2 mm) and dark (12 ± 0.4 mm). The hemolytic activity shows that Ag/Mn–ZnO has very low toxicity. Hence, the prepared Ag/Mn–ZnO nanomaterial might be an effective tool against the depletion of further harmful environmental pollutants and microbes.

Structural and antibacterial properties of doped zinc oxide and their composites with hydroxyapatite

ZnO nanoparticles (NPs) doped by Mn2+ and Cu2+ ions at various doping levels and their hydroxyapatite (HA) composites are prepared by a facile hydrothermal and sol-gel method. The resultant doped ZnO NPs are of wurtzite crystal structure and nanorod morphology. The doping of transition metals in ZnO lattice structure offers feasible means to prepare effective antibacterial agent. The antibacterial property against gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus) shows that both Mn and Cu-doped ZnO NPs are more sensitive to S. aureus and revealed improved antimicrobial activity relative to pristine ZnO. 5% Mn and 10% Cu-doped ZnO NPs exhibited the best antibacterial property. Moreover, the composites by loading 10 wt% Mn-doped ZnO and 10 wt% Cu-doped ZnO on HA exhibit significant antibacterial activity. The CCK-8 experiments show that ZnO/HA composites are noncytotoxic and can promote osteosarcoma cell growth.

Fabrication of a biocompatible & biodegradable targeted theranostic nanocomposite with pH-Controlled drug release ability

Here we report synthesis and characterization of a biocompatible and biodegradable nanocomposite based on paramagnetic Mn–ZnO NPs as a tumor diagnostic agent, coated with polyacrylic acid, decorated and loaded with folic acid and doxorubicin, Mn–ZnO@PAA/FOA(Dox)load. The Mn–ZnO NPs were prepared under the coupled microwave-hydrothermal controlled conditions, leading to 42.00 ± 3.00 nm paramagnetic Mn–ZnO NPs, appropriating for theranostic applications. The several surface, solution, and electrochemical techniques approved successful fabrication of the nanocomposite. The application of nanocomposite was tested for A2780 cancer cells. In effect, the in-vitro MRI measurements, the drug release experiments, and the MTT assay, were performed, respectively, to show diagnostic efficiency, applicability of the nanocarrier as a pH-sensitive for Dox delivery, and the biocompatibility and also theranostic efficiency of the targeted nanocomposite system. The quantitative results obtained through in-vitro tests showed that the system has potential application as a contrast agent in MRI with relaxivity (r1) of 35 mM−1 s−1 for Mn–ZnO NPs in the Mn concentration range of 0.06–0.52, which are significantly improved, compared with our previous works. The Dox drug was released from the system more efficient and faster at pH 5.4 than 7.4, supporting the pH sensitivity of nanocarrier. The in-vitro biocompatibility studies showed that the Mn–ZnO@PAA/FOA NPs (having no Dox) are not toxic, while the Mn–ZnO@PAA/FOA(Dox)load NPs inhibited proliferation of the A2780 cancer cells more effectively, compared with HFFF2 normal cells. Based on the electrochemical impedance spectroscopy results, the Mn–ZnO@PAA/FOA(Dox)load NPs capture the A2780 cells significantly larger than the HFFF2 cells.

Benchmark assessment of performance indices of a selection of hybrid nanofluids in a hybrid photovoltaic/thermal system

Abstract This research is a study assessing the performance of hybrid nanofluids in hybrid photovoltaic (PV)–thermal systems. This study addresses 10 hybrid nanofluids applied to hybrid PV–thermal systems. The transition to carbon-free energy can mitigate the worst effects of climate change, ensuring that global sustainability is addressed. Clean energy is now responsible for one-third of the global capacity, of which 20% is attributed to solar energy. Renewables continue to be economically viable, with declining costs driving growth. This study aims to compare the yearly performances of a model hybrid PV–thermal system using 10 different hybrid nanofluids. Hybrid nanofluids constitute two or more dissimilar materials stably suspended in a base fluid (e.g. water). MATLAB and COMSOL Multiphysics® computational fluid dynamics software are employed together for the benchmarking assessment with good agreement observed. Various fluid inlet temperatures (Tin ∈ [300, 360] K), nanofluid volume concentrations (φ ∈ [0, 4]%) and storage-tank volumes (V ∈ [50, 300] L) were simulated. The meteorological data applied were those for Lagos, Nigeria (6° 27’ 55.5192” N, 3° 24’ 23.2128” E). The assessment based on analytical-numerical solutions reveals that the thermal enhancement by hybrid nanofluids ranges from 6.7% (graphene oxide [GO]—multiwalled carbon nanotube [MWCNT]/water) to 7% (ZnO—Mn–ZnFe2O4/water) for φ = 2% and V = 300 L. The yearly exergy efficiency ranges from 2.8% (ZnO—Mn–ZnFe2O4/water) to 2.9% (GO—MWCNT/water), also for φ = 2% and V = 300 L. These findings have implications for a vast range of industrial processes, expanding the knowledge that is critical to a sustainable future. A combined solar PV-thermal system that stores thermal energy using nanofluids is modelled. Hybrid nanofluids (two or more dissimilar materials stably suspended in a base fluid) are shown to enhance the annual electrical, thermal and exergetic outputs of the system.

Structural, optical and electrical properties of undoped and doped (Al, Al + Mn) ZnO nanoparticles synthesised by green combustion method using terminalia catappa seed extract

This paper presents the synthesis of undoped and doped (Al, Al + Mn) ZnO nanoparticles by green combustion method using Terminalia Catappa seed extract as a novel fuel and Zinc nitrate as a precursor, Aluminum nitrate and Magnesium chloride was used as dopant. Synthesized undoped and doped ZnO nanoparticles were characterized by XRD, FESEM, FTIR, UV-visible spectroscopy and impedance spectroscopy. The XRD study of undoped and doped (Al, Al + Mn) ZnO nanoparticles exhibits hexagonal wurtzite structure with high crystallinity. The crystallite size increases from 37.5 nm to 39 nm for Al doping and decreased to 30.5 nm for Al + Mn doped ZnO nanoparticles. Mean grain size of undoped ZnO nanoparticles was found to be 32.5 nm. For Al doped ZnO nanoparticles mean grain size increases (42.9 nm) and then decreases (21.25 nm) for Al + Mn doped ZnO nanoparticles. FTIR studies confirms the formation of Zn-O bond at 462, 455 and 439 cm−1 for both undoped and doped ZnO nanoparticles. The optical band gap was found to be 3.25, 3.2 and 2.54 eV for undoped and doped (Al , Al + Mn) ZnO nanoparticles respectively. The dielectric properties and conductivity studies were carried for undoped and doped (Al, Al + Mn) ZnO nanoparticles at various fixed temperatures (50 to 350 °C) by varying frequency from 10 Hz to 8 MHz. Dielectric constant increases with rise in temperature and, dielectric constant decreases with rise in frequency and remains constant at higher frequency. At lower frequencies AC conductivity was constant and increases as the frequency increases. Grain and grain boundary resistance for the synthesised ZnO nanoparticles were studied by complex impedance analysis and result exhibits a decrease in grain resistance with rise in temperature. The ZnO nanoparticles doped with Al shows improved microstructural properties, decreased optical band gap and activation energy. Hence these nanoparticles are suitable material for sensors and optoelectronics applications.

Fabrication of Mn–ZnO photoanodes for photoelectrochemical water splitting applications

Fabrication of Mn–ZnO photoanodes for photoelectrochemical water splitting applications

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.

Sol–gel synthesized ZnO/Mn–TiO2 core–shell nanocomposite and its elevated activity for methyl orange degradation

Photocatalysis is a new advanced oxidation process based on the irradiation of semiconductors such as TiO2 and ZnO for photodegradation of contaminants. In this process, the semiconductor absorbs the photon energy of ultraviolet radiation, generating highly reactive species for the degradation of organic compounds. It has been reported that doping of transition metals (e.g., Cu, Ni, Co, and Mn) into the structure of oxide semiconductors can reduce the band gap and expand their adsorption properties to the visible solar spectrum. Accordingly, a new hybrid photocatalyst of Mn-doped TiO2 / ZnO with an Mn content of 1 to 5 wt. % was synthesized via the sol–gel process followed by thermal calcinations in air at 500°C. The prepared photocatalyst powder was characterized in terms of crystalline structure, thermal property, surface morphology, and band gap energy level. Its photocatalytic performance was then assessed based on photodegradation of methylene orange under visible light irradiation. Compared with the pure TiO2 / ZnO, the lattice of Mn-doped TiO2 / ZnO was found to be more thermally stable, and thus phase transformation of anatase to rutile was postponed to a higher calcination temperature. The photocatalysis evaluation showed an increased activity of Mn–ZnO / TiO2 compared with pure TiO2 and TiO2 / ZnO under visible light irradiation. Accordingly, the highest degradation of 98% was obtained by the Mn–ZnO / TiO2 with 3 wt. % Mn.

Enhancing the structural, optical and electrical properties of ZnO nanopowders through (Al + Mn) doping

Abstract Undoped ZnO and Zn0.97−xAl0.03MnxO (x = 0, 1, 2 and 3%) nanopowders (NPs) were synthesized by co-precipitation method. They were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman, UV–visible, photoluminescence (PL) and impedance spectroscopies. All samples exhibit a single phase wurtzite type. The average crystallite size lying between 22 and 42 nm was found to increase for all doped ZnO samples. The optical transmission in the visible region was improved due to doping. The optical band gap is in the range of 3–3.4 eV and was found to decrease up to 2% of Mn content but slightly increases with further doping. All PL spectra exhibit two emission peaks in UV and visible regions. The deconvolution of the visible emission peak reveals different emissions for all samples. An additional yellow emission is noticed for (Al + Mn) ZnO doped samples suggesting that the incorporation of aluminum and manganese in the zinc oxide host lattice enhances luminescence properties of ZnO. The ac conductivity ( σ ac ) was found to follow Jonscher’s power law and was improved with doping. Cole-Cole plots of all samples were suitably fitted to a circuit consisting in a parallel combination of a resistance and a constant phase element (CPE).

Effects of ZnO/Mn Concentration on the Micro-structure and Optical Properties of ZnO/Mn–TiO2 Nano-composite for Applications in Photo-Catalysis

We successfully synthesized of ZnO/Mn–TiO2 (Mn–Ti) nano-composite for different ZnO:Mn (Zn-M) concentrations. These composites with high photo-catalytic activity derived from TiO2 and Zn-M nanoparticles elaborated by the sol–gel method. The SEM and TEM images indicated that samples reveals well-ordered and good size distribution of particles. In addition, the composite sample showed no aggregation in similitude with the anatase TiO2 sample. The study of optical properties of nano-composites shows that Zn-M nanoparticles caused to increase the optical activity of Mn–Ti composites samples and it established by UV–Vis, photo-luminescence, and photo-catalytic tests. The XRD study exhibited that in ours composites samples with increasing the Zn-M concentration, the particle size increased from 10 to 27 nm. PL measurements suggest that co-emission of a strong luminescence, high yellow emission at 563 nm, at 640 nm and at 774 nm is observed from the Mn–Ti composites samples. The photo-catalytic activity of the prepared nano-composite was examined for the degradation of methyl-orange (MO) by the irradiation of UV light.

Microstructure and luminescence properties of ZnO:Mn nano-particles and ZnO:Mn/TiO2 nano-composite synthesized by a two-step chemical method

The present study is determined on the fabrication and the characterization of Mn-doped ZnO (Mn/ZnO), TiO2 nano-particles and ZnO:Mn/TiO2 (Mn–O–Ti) nano-composite. The microstructure and luminescence properties were analyzed by XRD, SEM, TEM, optical reflectance and photo-luminescence. The particle sizes of nano-particles and nano-composites have been varied from 12 to 22 nm. The photo-luminescence measurements of the as-prepared Mn/ZnO nano-particles exhibit broad visible emissions, while the Mn–O–Ti composite samples have yellow emission. The Mn–O–Ti nano-composite exhibits considerably ameliorated photo-catalytic activities for the degradation of methyl orange (MO) under the visible light irradiation. The introduction of Mn/ZnO nano-particles to TiO2 confirm that the internal micro-structure, thus obtained will make the stability of nano-composite allowing an improvement of physical properties and catalytic features of TiO2.

Single-Doped and Multidoped Transition-Metal (Mn, Fe, Co, and Ni) ZnO and Their Electrocatalytic Activities for Oxygen Reduction Reaction.

The electrochemical oxygen reduction reaction (ORR) is the limiting half-reaction of fuel cells, which is mediated by using platinum-based catalysts. Hence, the development of low-cost, active ORR catalysts is highly required to make fuel cell technology commercially available. In this report, transition-metal (TM; Mn, Fe, Co, and Ni) single-doped and multidoped (MD) ZnO nanocrystals (ZNs) were prepared for use as ORR catalysts using a simple precipitation method. The effects of single doping and multidoping on the structure, morphology, and properties of the TM-doped ZNs were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence, X-ray photoelectron microscopy, electron paramagnetic resonance, and Raman and photoluminescence (PL) spectroscopies. The XRD results reveal that synthesized ZnO samples retained a pure hexagonal wurtzite crystal structure, even at high levels of multidoping (nominal 20%). SEM analyses show that the morphology of the prepared ZNs varies with the doping elements, doping mode, and amounts of doping. The observation of peak shifting and peak intensity changes in Raman studies confirms the presence of dopants in ZnO. The PL investigation reveals that the incorporation of dopants into the ZnO structure increases the oxygen vacancies within the materials. The highest oxygen vacancies were present in Mn-doped ZnO and 15% MD ZnO among the single-doped and MD samples, respectively. Linear-sweep voltammetry studies conclude that doped ZnO shows enhanced ORR activity compared to the undoped samples. The Mn-doped ZnO and 15% MD ZnO exhibited the highest ORR activity among the prepared single-doped and MD ZN samples, respectively. In comparison, single doping showed better ORR activity than the multidoping system. The enhanced ORR activity of the synthesized ZN materials correlates with the amount of oxygen vacancies present in the samples. The enhanced activity of TM-doped ZnO suggests that these materials can be used as potential, low-cost electrocatalysts for ORR in fuel cell technology.

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.

Structure and magnetic properties of (Co, Mn) co-doped ZnO diluted magnetic semiconductor nanoparticles

The ZnO, Zn0.96Mn0.04O, Zn0.95Mn0.04Co0.01O, Zn0.94Mn0.04Co0.02O and Zn0.92Mn0.04Co0.04O nanoparticles were synthesized by simple chemical precipitation technique. The effects of co-doping on the structure and magnetic properties of these nanoparticles were studied. The X-rays diffraction (XRD) scans were performed in the 2θ range of 20°–80°. The XRD patterns, at 300 K, of all the pure and co-doped ZnO samples confirmed the formation of wurtzite-type structure. X-ray diffraction and transmission scanning electron microscope analysis indicated that the high spin Co2+ and Mn2+ ions were substituted for the Zn2+ ions at tetrahedral sites. The average size of the nanoparticles were increased from 17 to 24 nm with the increase of dopants concentration. Moreover, Energy Dispersive X-ray spectroscopy (EDX) confirmed the synthesis results. All Zn0.96−xMn0.04Co x O (x = 0.0, 0.1, 0.2 and 0.4) nanoparticles samples were observed to be paramagnetic below 300 K. However, a large increase in the magnetization was observed below 40 K. This behavior, along with the negative value of the Curie–Weiss constant obtained from the linear fit to the susceptibility data below room temperature, indicated the ferromagnetic nature of the samples. The origin of ferromagnetism is likely to be the intrinsic characteristics of the Co and Mn doped samples. The high magnetization was noted for the 1 wt% Co co-doped Mn–ZnO annealed samples as compared to other samples with Co concentration above and below this threshold concentration.

Dependence of the magnetic properties of the dilute magnetic semiconductor Zn1−xMnxO nanorods on their Mn doping levels

The effects of Mn doping on the ferromagnetic properties of the dilute magnetic semiconductor Zn1−xMnxO nanorods (NR’s) having the nominal composit-ions x=0, 0.01, 0.03, 0.04 and 0.05 grown by a low temperature hydrothermal method are studied. Energy dispersive X-ray (EDX) is used to determine the actual amounts of the elements in each NR’s. X-ray diffraction, scanning electron microscopy, photoluminescence and vibrating sample magnetometer measurements are used to observe the effects of the Mn substitution on the properties of the doped ZnO and to relate the changes in the properties to changes in the defect content. It is observed that the saturation magnetization of the Mn ions in the wurtzite structure varies from 0.0210µB/Mn2+ to 0.0234µB/Mn2+ reaching a high of 0.0251µB/Mn2+ as the Mn concentrations is varied from 0.9 to 7.36atomic%. It is argued that the changes in the saturation magnetization are due to the competition between the direct Mn-Mn exchange interaction and the indirect Mn-O-Mn exchange interaction in the doped Mn ZnO NP’s.