Mn-doped ZnO Nanorods Research Articles

Highly sensitive magnetic field sensor based on uniform core fiber using Mn doped ZnO nanorods as cladding

Highly sensitive magnetic field sensor based on uniform core fiber using Mn doped ZnO nanorods as cladding

Photoluminescence, Optical Energy Gap and Electrical properties of Mn-Doped ZnO Nanorods Synthesized by CBD Method

In this work, un-doped and Manganese doped Zinc Oxide Nanorods (NRs) thin films were grown on the glass substrates using chemical bath deposition method (CBD) at 80 °C temperature. The effect of Mn content (0, 2 and 4%) on the structural, morphology, optical and photoluminescence characteristics of ZnO NRs films was investigated. The XRD patterns of un-doped and Mn-doped ZnO NRs demonstrate sharp and strong peaks together with high crystalline structure. The FESEM images showed that the nanorods of ZnO and Mn:ZnO were well-aligned and distributed throughout the films. The absorption edge was observed to be blue-shifted and the optical energy gap was found to be widening from (3.21, to 3.31) eV with increased Mn content. The photoluminescence spectrum (PL) of Mn-doped samples was examined, at room temperature, and revealed of highly UV emission, whereas the green-yellow wavelengths emissions were enhanced with increased Mn content. Current-voltage (I-V) characteristics showed that the photocurrents of all prepared samples are enhanced and the Mn doped samples showed a good response, under UV light.

Electrochemical Detection of Ascorbic Acid in Citrus Juices using Mn-doped ZnO nanorods modified graphene oxide

Electrochemical Detection of Ascorbic Acid in Citrus Juices using Mn-doped ZnO nanorods modified graphene oxide

The Enhancement of Visible Photodetector Performance based on Mn doped ZnO Nanorods by Substrate Architecting

ZnO is one of the most fascinating and cost-effective materials for numerous applications, especially optoelectronics. To improve its properties and performance, many techniques have been developed, in which doping and surface engineering are usually of interest. Recently, combining techniques for further enhancement has got significant attention but not fully explored. In this study, a new combination to widen the light absorbance of ZnO nanorods (NRs) is introduced. This combination is based on (i) doping of Mn and (ii) substrate architecting. Patterned substrates are formed with master molds as digital video disc (DVD) and lotus leaf through polydimethylsiloxane (PDMS) molding. Mn-doped ZnO NRs were then hydrothermally grown on them at low temperatures. For investigate their morphology, structure and optical properties, scanning electron microscopy (SEM), X-ray diffraction (XRD), and ultraviolet-visible spectroscopy (UV-Vis) were employed. The obtained results show that the Mn-doped ZnO samples with the patterned substrates own a remarkable increase (> 40%) in the visible light absorbance as compared to that with the flat substrate due to an increment of light scattering. Besides, a photodetector is fabricated based on the optimized patterning PDMS substrate with the active material of Mn doped ZnO NRs. The results show that the photocurrent of patterning device is 3.8 time higher than that of flat substrate. Overall, our approach for growing Mn-doped ZnO NRs on 3D patterned structures at low temperature is promising for optical applications such as flexible and stretchable optoelectronic devices.

One step synthesis of vertically grown Mn-doped ZnO nanorods for photocatalytic application

Pure and Mn-doped ZnO nanorods thin films on glass substrates were successfully synthesized by a one-step hydrothermal route. It was confirmed from XRD data that pure and Mn-doped ZnO samples show hexagonal (wurtzite) structures and the particle size was found to be in the range 27–31 nm. From XRD data it was clearly found that vertical growth along (002) plane after Mn-doping into ZnO lattice. Functional groups and chemical species were detected using FT-IR spectra. Diameter and length of ZnO nanorods were determined by TEM which is in the range 350 nm, 1–4 μm respectively. UV–Vis results exhibit red shift with increasing Mn concentration in ZnO lattice. The 5% Mn-doped ZnO sample exhibits higher fluorescence intensity in visible region with surface defects. The electrical resistance of pure and Mn-doped ZnO nanorods was demonstrated by I–V characteristics. It was explicitly outlined from Raman spectra E 2 high mode was shifted towards the higher wavenumber from 439 to 440 cm−1 owing to Mn doping in ZnO lattice. The average surface area, pore volume, and pore diameter were measured by using the BET isotherm. The photocatalytic activity of pure and Mn-doped ZnO was evaluated by the degradation of methylene blue (MB) under UV–Vis light irradiation which indicates that 5% Mn-doped ZnO nanorods have better photocatalytic activity than other samples.

Preparation and Characterization of Mn Doped ZnO Nanorods

Mn doped ZnO nanorods were prepared by chemical precipitation method. The micro-structural and structural properties of the nanorods were calculated from the X-ray diffraction technique. The formed nanorods was seen in the scanning electron microscopy. The purity of the sample was confirmed by the energy dispersive X-ray analysis (EDX). The optical properties were studied using UV-Vis spectroscopy and photoluminescence. In the photoluminescence spectrum, the peaks due to recombination of free electrons, oxygen vacancy and intrinsic defects were observed. The magnetic properties were studied using vibrating sample magnetometer (VSM) and the paramagnetic nature of the material was confirmed.

Mn-doping-induced photocatalytic activity enhancement of ZnO nanorods prepared on glass substrates

Mn-doped ZnO nanorods were synthesized on glass substrates via a two-steps process of ultrasonic spray pyrolysis and hydrothermal methods with four different concentrations Mn-doping (0, 1, 3, and 7 mol%). Introduction of Mn into ZnO is known could enhance the photocatalytic activity owing to the increase in the defect sites that effectively suppress the recombination of free electrons and holes. In this study, results show that Mn-doping has effectively modified the nucleations and crystal growth of ZnO, as evidenced by the increasing in the diameter, height, and the number of nanorods per unit area, besides slightly reduced the band gap and increased the oxygen vacancy concentrations in the ZnO lattice. This condition has successfully multiplied the photocatalytic performance of the ZnO nanorods in the degradation of methylene blue (MB) compared to the undoped-ZnO sample where in the typical process the MB can be degraded approximately 77% within only 35 min under a UV light irradiation.

Preparation and characterization of Mn doped ZnO nanorods -=SUP=-*-=/SUP=-

AbstractMn doped ZnO nanorods were prepared by chemical precipitation method. The micro-structural and structural properties of the nanorods were calculated from the X-ray diffraction technique. The formed nanorods was seen in the scanning electron microscopy. The purity of the sample was confirmed by the energy dispersive X-ray analysis (EDX). The optical properties were studied using UV-Vis spectroscopy and photoluminescence. In the photoluminescence spectrum, the peaks due to recombination of free electrons, oxygen vacancy and intrinsic defects were observed. The magnetic properties were studied using vibrating sample magnetometer (VSM) and the paramagnetic nature of the material was confirmed.

The effect of cation doping on the morphology, optical and structural properties of highly oriented wurtzite ZnO-nanorod arrays grown by a hydrothermal method

Undoped and C-doped (C: Mg2+, Ni2+, Mn2+, Co2+, Cu2+, Cr3+) ZnO nanorods were synthesized by a hydrothermal method at temperatures as low as 60 °C. The effect of doping on the morphology of the ZnO nanorods was visualized by taking their cross section and top SEM images. The results show that the size of nanorods was increased in both height and diameter by cation doping. The crystallinity change of the ZnO nanorods due to each doping element was thoroughly investigated by an x-ray diffraction (XRD). The XRD patterns show that the wurtzite crystal structure of ZnO nanorods was maintained after cation addition. The optical Raman-active modes of undoped and cation-doped nanorods were measured with a micro-Raman setup at room temperature. The surface chemistry of samples was investigated by x-ray photoelectron spectroscopy and energy-dispersive x-ray spectroscopy. Finally, the effect of each cation dopant on band-gap shift of the ZnO nanorods was investigated by a photoluminescence setup at room temperature. Although the amount of dopants (Mg2+, Ni2+, and Co2+) was smaller than the amount of Mn2+, Cu2+, and Cr3+ in the nanorods, their effect on the band structure of the ZnO nanorods was profound. The highest band-gap shift was achieved for a Co-doped sample, and the best crystal orientation was for Mn-doped ZnO nanorods. Our results can be used as a comprehensive reference for engineering of the morphological, structural and optical properties of cation-doped ZnO nanorods by using a low-temperature synthesis as an economical mass-production approach.

Controllable Mn-doped ZnO nanorods for direct assembly of a photoelectrochemical aptasensor.

A label-free photoelectrochemical (PEC) aptasensor for K+ was first constructed by direct self-assembly of the K+ aptamer onto the electrodeposited Mn-doped ZnO nanorods. In the presence of K+, the conformation of G-quadruplex changes to a K+-stabilized conformation, which can efficiently prevent the quercetin electron donor from reaching the functionalized photoanode, thus proportionately affecting the quercetin-enhanced photocurrent response. Under the optimal experimental conditions, the fabricated biosensor exhibited a linear response in the K+ concentration range of 0.012 to 12.32 nmol L-1, with a detection limit of 4.0 pmol L-1, which was 3-5 orders of magnitude lower than that of most of the recently reported methods. The presence of other ions did not interfere with the detection of K+, and the results in serum samples agreed well with those obtained by ICP-MS. Using K+ as the detection model, this novel PEC aptasensor exhibited a good performance in terms of ultrasensitivity, selectivity and simplicity, and it was economical. As regards the electrode modification, this work provided a convenient direct self-assembly strategy that did not require the use of ionic polymers such as PDDA as a binder. Thus, this study paves the way for the immobilization of molecular probes for label-free PEC aptasensing.

A Novel Vible-Light Photodetector Based on Chlorophyll-Modified ZnO Nanoparticles

This paper reports a new material for visible-light detection based on chlorophyll-modified ZnO nanoparticles. ZnO nanoparticles were synthesized via a hydrothermal process. Chlorophyll was extracted from Katuk (Sauropus androgynus) leaves, an Indonesian vegetable which has many benefits for health. ZnO nanopartcles were mixed with the extracted chlorophyll, later to be formed into a film onto ITO coated glass substrate by the casting method. The hybrid chlorophyll-modified ZnO nanoparticle film was characterized for its optical absorption and current-voltage (I-V) property. A visible-light response of the hybrid chlorophyll-modified ZnO nanoparticle film can be seen on the I-V curves as well as a dynamic response. Full Text: PDF References D.J. Sornalatha, S. Bhuvaneswari, S. Murugesan, P. Murugakoothan, "Solochemical synthesis and characterization of ZnO nanostructures with different morphologies and their antibacterial activity", Optik 126, 63 (2015). CrossRef K.L. Foo, M. Kashif, U. Hashim, M.E. Ali, "Sol–gel derived ZnO nanoparticulate films for ultraviolet photodetector (UV) applications", Optik 124, 5373 (2013). CrossRef M. Procek, T. Pustelny, "A study of gas sensing properties of ZnO nanostructures activated by UV light", Phot. Lett. Poland 7, 50 (2015). CrossRef J. A. Anta, E. Guille?n, R. Tena-Zaera, "ZnO-Based Dye-Sensitized Solar Cells", J. Phys. Chem. C 116, 11413 (2012). CrossRef V. Sanna, N. Pala, V. Alzari, D. Nuvoli, M. Carcelli, "http://dx.doi.org/10.1016/j.matlet.2015.10.031", Mat. Lett. 162, 257 (2016). CrossRef C.O. Chey, X. Liu, H. Alnoor, O. Nur, M. Willander, "Fast piezoresistive sensor and UV photodetector based on Mn-doped ZnO nanorods", Phys. Status Solidi RRL 9(1), 87 (2015). CrossRef A. Kondapi, "Development of chlorophyll-protein complex nanoparticles for light harvesting and solar cell application", Int. J. Nanoparticles 7(3/4), 307 (2014). CrossRef S. Ashoka, G. Nagaraju, C.N. Tharamani, G.T. Chandrappa, "http://dx.doi.org/10.1016/j.matlet.2009.01.054", Mat. Lett. 63, 873 (2009). CrossRef J.B. Zvezdanovic, D.Z. Markovic, S.M. Milenkovic, "Zinc(II) and copper(II) complexes with pheophytin and mesoporphyrin and their stability to UV-B irradiation: Vis spectroscopy studies", J. Serb. Chem. Soc. 77(2), 187 (2012). CrossRef X. Lian, Y. Li, D. An, Y. Zou, Q. Wang, N. Zhang, "Synthesis of porous ZnO nanostructures using bamboo fibers as templates", Mat. Science-Poland 32(3), 514 (2014). CrossRef S. Wein, J. Zhao,W. Du, "Synthesis, characterization and acetone-sensing properties of bristlegrass-like ZnO nanostructure", Ceramics Internat. 41, 769 (2015). CrossRef

Improving color rendering index of Mn-doped ZnO nanorods on silicon-based substrate

Porous silicon pillar array (PSPA) samples which are ideal substantial materials with dominant electronic and luminescence properties were prepared by surface etching method. ZnO nanorods with or without Mn doping grown uniformly and aligned onto PSPA regardless of lattice matching show various photoluminescence (PL) properties. The doped Mn ions in ZnO nanorods were directly observed by X-ray photoelectron spectroscopy (XPS), and ZnO structures were detected by X-ray diffraction (XRD). As the doping concentration increases, XRD peaks of ZnO nanorods shift to low angle. The influences of doping Mn ions on luminescence properties of ZnO nanorods were investigated. Except for the ultraviolet (UV) PL band, the broad PL band is observed at visible region. The band could be divided into three separate bands (orange, green and red) by Lorentzian deconvolution. The intensity of orange PL band firstly increases then decreases, and then gets the maximum at the doping Mn-to-Zn molar ratio of 2.0:100.0 which is the most effective doping concentration. The green PL band is attributed to zinc vacancy of ZnO, the orange PL band to Mn ions recombination of itself, and the red PL band to oxygen vacancy of ZnO, respectively. As the Mn-doped ZnO nanorods could emit yellow green luminescence excited by UV radiation, and doped Mn ions could improve the color rendering index of the luminescence, the nanorods could be used as promising white-light emitters in the future.

Magnetic and optical properties of Mn-doped ZnO vertically aligned nanorods synthesized by hydrothermal technique

In this paper we have reported the synthesis of high quality vertically aligned undoped and Mn-doped ZnO single crystalline nanorods arrays on Si (100) substrates using two steps process, namely, initial slow seed layer formation followed by solution growth employing wet chemical hydrothermal method. The shapes of the as grown single crystalline nanorods are hexagonal. The diameter and length of the as grown undoped ZnO nanorods varies in the range of 80-150 nm and 1.0 - 1.4 μm, respectively. Along with the lattice parameters of the hexagonal crystal structure, the diameter and length of Mn doped ZnO nanorods are found to increase slightly as compared to the undoped ZnO nanorods. The X-ray photoelectron spectroscopy confirms the presence of Mn atoms in Mn2+ state in the single crystalline ZnO nanorods. The recorded photoluminescence spectrum contains two emissions peaks having UV exciton emissions along with a green-yellow emission. The green-yellow emissions provide the evidence of singly ionized oxygen vacancies. The magnetic field dependent magnetization measurements [M (H)] and zero field cooled (ZFC) and field cooled (FC) magnetization [M(T)] measurements have been carried out at different isothermal conditions in the temperature range of 5-300 K. The Mn doped ZnO nanorods clearly show room temperature ferromagnetic ordering near room temperature down to 5 K. The observed magnetization may be attributed to the long range ferromagnetic interaction between bound magnetic polarons led by singly charged oxygen vacancies.

Optical and structural properties of Mn-doped ZnO nanorods grown by aqueous chemical growth for spintronic applications

The effect of Mn-doping on the structural, morphological, optical and magnetic properties of the ZnO:Mn nanorods (NRs) synthesized by aqueous chemical process is reported. Grown ZnO:Mn NRs are shown to have hexagonal end facets and the diameters increasing with nominal Mn content. Optical absorption measurements show a decrease in optical band gap with increase of Mn concentration. Raman spectroscopy revealed significant modification of the lattice vibrational properties of the ZnO matrix upon Mn doping. The additional Mn-related vibrational mode, intensity of which increases with amount of Mn can be regarded as an evidence of Mn incorporation into the host lattice of the ZnO. At high Mn concentrations, coexistence of hexagonal Zn1−xMnxO phase along with the secondary phases of ZnMn2O4 cubic spinel is revealed. Magnetic properties of ZnO:Mn NRs are studied by combinatorial atomic force microscopy and magnetic force microscopy imaging, and obtained clear magnetic contrast at room temperature provides a strong evidence of ferromagnetic behavior.

Effect of Mn doping on microstructural and optical behavior of Zn(1−x)MnxO nanorod by simple auto-combustion method

Mn doped ZnO nanorods with different doping concentrations (0, 0.02, 0.05, 0.1, 0.15, and 0.2) were synthesized by simple auto-combustion method. The structural, morphological and optical behaviors of Zn(1−x)MnxO were investigated by X-ray diffraction (XRD), field-emission microscopy (FE-SEM) and diffuse reflectance spectroscopy (DRS). The structural properties of un-doped and Mn doped ZnO nanorods exhibit hexagonal wurtzite structure with no secondary phase. From scanning electron micrographs results it can be evidenced that, both crystallite size and surface morphology are significantly affected by Mn doping concentrations. From the optical studies, the reflectance in UV region of doped samples was decreased in comparison to undoped one and the optical band gap varies between 3.33 and 2.81eV. Photoluminescence spectra shows large emission band originated at 388nm and a weak band centered on 495nm. The present study reveals about the influence of Mn2+ ions on morphological and optical properties of Zn(1−x)MnxO.

Defect-assisted saturable absorption characteristics in Mn doped ZnO nano-rods

After reaching a threshold doping level of Mn, it is possible to alter from two photon absorption to saturable absorption in ZnO nanorods.

Back Cover: Fast piezoresistive sensor and UV photodetector based on Mn-doped ZnO nanorods (Phys. Status Solidi RRL 1/2015)

Back Cover: Fast piezoresistive sensor and UV photodetector based on Mn-doped ZnO nanorods (Phys. Status Solidi RRL 1/2015)

Fast piezoresistive sensor and UV photodetector based on Mn-doped ZnO nanorods

A low cost hydrothermal synthesis method to synthesize Mn-doped ZnO nanorods (NRs) with controllable morphology and structure has been developed. Ammonia is used to tailor the ammonium hydroxide concentration, which provides a source of OH– for hydrolysis and precipitation during the growth instead of HMT. The morphological, chemical composition, structural, and electronic structure studies of the Mn-doped ZnO NRs show that the Mn-doped ZnO NRs have a hexagonal wurtzite ZnO structure along the c-axis and the Mn ions replace the Zn sites in the ZnO NRs matrix without any secondary phase of metallic manganese element and manganese oxides observed. The fabricated PEDOT:PSS/Zn0.85Mn0.15O Schottky diode based piezoresistive sensor and UV photodetector shows that the piezoresistive sensor has pressure sensitivity of 0.00617 kPa–1 for the pressure range from 1 kPa to 20 kP and 0.000180 kPa–1for the pressure range from 20 kPa to 320 kPa with relatively fast response time of 0.03 s and the UV photodetector has both relatively high responsivity and fast response time of 0.065 A/W and 2.75 s, respectively. The fabricated Schottky diode can be utilized as a very useful human-friendly interactive electronic device for mass/force sensor or UV photodetector in everyday living life. This developed device is very promising for small-size, low-cost and easy-to-customize application-specific requirements. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

Low Temperature Mn Doped ZnO Nanorod Array: Synthesis and Its Photoluminescence Behavior

The present study focused on low temperature synthesis of Mn doped ZnO nanorod array film via chemical bath deposition method on glass substrates. Microstructural, morphological, and optical properties of Mn doped ZnO nanorods were investigated. X-ray diffraction patterns showed sharp and intense peaks, indicating the highly crystalline nature of the film. Energy dispersive X-ray (EDAX) results confirmed the presence of Mn ions in ZnO nanorods. Scanning electron microscopy (SEM) pictures suggested Mn doped ZnO nanorods were well aligned and distributed throughout the surface. Vibrational analysis has been carried out by Fourier transform infrared and Raman spectroscopy. Room temperature photoluminescence (PL) exhibited the presence of one broad defects related band in the visible region ranging 440–640 nm. Blue shifting in the absorption edge with Mn doping was observed in absorption spectra.

Synthesis and characterization of Mn-doped ZnO nanorods grown in an ordered periodic honeycomb pattern using nanosphere lithography

We report a study of the structural, optical and magnetic properties of undoped and Mn-doped ZnO nanorods grown by chemical bath deposition in a periodic honeycomb lattice formation. Mn-doping is accomplished by a diffusion process at a constant time of 8h for different temperatures of 500°C, 600°C and 700°C. Undoped and Mn-doped ZnO nanorods had a hexagonal wurtzite structure with a (002) preferred orientation. From SEM results, it was seen that Mn-doped ZnO nanorods grew vertically in the honeycomb lattice with lengths of 0.8μm. XPS results showed that Mn3+ ions was successfully incorporated in the ZnO matrix by substituting for Zn2+ ions and that Mn-doping increased the number of oxygen vacancies in ZnO compared to undoped ZnO. This result was also supported by photoluminescence data at 10K. Magnetic data showed that all the samples exhibited ferromagnetic character. Although the origin of undoped ZnO is related to oxygen vacancy-induced d0 ferromagnetism, bound magnetic polarons are responsible from the ferromagnetism of Mn-doped ZnO samples which have Tc values above the room temperature.