Synthesis, Analysis, and Photocatalysis of Mg-Doped ZnO Nanoparticles (original) (raw)
Related papers
2015
Mg2+ doped hexagonal ZnO nanoparticles with different Mg2+contents (0%, 1%, 2%, 3%,4%, 5%, 10%, 15%, 20% and 25%) were prepared from oxalate precursors synthesized by direct reaction in the solid state between oxalic acid dihydrate (H2C2O4.2H2O), nitrate salts of zinc (Zn(NO3)2.6H2O) and magnesium (Mg(NO3)2.6H2O) at 150 °C. The resulting precursors were subsequently calcined at 500 °C to produce the corresponding oxides. In addition, the oxalates of the single metals were also prepared by heating at 180 °C to dehydrate the complexes, before using TGA thermal gravimetric analysis to determine the temperature range of the decomposition. The obtained oxides were characterized using X-ray Diffraction (XRD), Brunauer–Emmett–Teller technique (BET), transmission electron microscopy (TEM) and tested as photocatalysts in the degradation of methylene blue (MB) under UV irradiation. The results show a segregation of phases starting at an Mg2+ content of 10%. The crystallites' sizes, calcul...
Mg-Doped ZnO Nanoparticles for Efficient Sunlight-Driven Photocatalysis
ACS Applied Materials & …, 2012
Magnesium-doped ZnO (ZMO) nanoparticles were synthesized through an oxalate coprecipitation method. Crystallization of ZMO upon thermal decomposition of the oxalate precursors was investigated using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. XRD studies point toward a significant c-axis compression and reduced crystallite sizes for ZMO samples in contrast to undoped ZnO, which was further confirmed by HRSEM studies. X-ray photoelectron spectroscopy (XPS), UV/vis spectroscopy and photoluminescence (PL) spectroscopy were employed to establish the electronic and optical properties of these nanoparticles. (XPS) studies confirmed the substitution of Zn 2+ by Mg 2+ , crystallization of MgO secondary phase, and increased Zn−O bond strengths in Mg-doped ZnO samples. Textural properties of these ZMO samples obtained at various calcination temperatures were superior in comparison to the undoped ZnO. In addition to this, ZMO samples exhibited a blue-shift in the near band edge photoluminescence (PL) emission, decrease of PL intensities and superior sunlight-induced photocatalytic decomposition of methylene blue in contrast to undoped ZnO. The most active photocatalyst 0.1-MgZnO obtained after calcination at 600°C showed a 2-fold increase in photocatalytic activity compared to the undoped ZnO. Band gap widening, superior textural properties and efficient electron−hole separation were identified as the factors responsible for the enhanced sunlight-driven photocatalytic activities of Mg-doped ZnO nanoparticles.
Materials Science in Semiconductor Processing, 2015
A series of Zn 1 À x Mg x O nanoparticles with x ¼ 0 to 0.15 were prepared by auto combustion method using citric acid as the fuel and chelating agent. Structure, luminescence and photocatalytic properties were systematically investigated by means of X-ray diffraction, scanning electron microscopy, photoluminescence spectra, ultraviolet-visible absorbance measurement and photochemical reactions etc. The samples retained hexagonal wurtzite structure of ZnO and single phase below x ¼ 0.13, and the sizes of the nanoparticles were 60-70 nm. The photoluminescence spectroscopy demonstrated blue shift of ultraviolet emission with increasing Mg doping concentration. Both optical measurements of the as grown and Mg doped ZnO nanoparticles showed that the optical band gap could be modified from $ 3.28 eV to 3.56 eV as the Mg content x increased from 0 to 0.13. The photocatalytic activities of the samples were evaluated by photocatalytic degradation of methyl orange, and the results showed that the doping of Mg into ZnO nanoparticles could enhance photocatalytic activity compared to the undoped ZnO nanoparticles, which was attributed to increased band gap and superior textural properties. In addition, according to the PL and photocatalytic studies, the critical doping content of effective Mg in ZnO is up to 0.09.
Nanoscale research letters, 2018
In this research, a facile co-precipitation method was used to synthesize pure and Mg-doped ZnO nanoparticles (NPs). The structure, morphology, chemical composition, and optical and antibacterial activity of the synthesized nanoparticles (NPs) were studied with respect to pure and Mg-doped ZnO concentrations (0-7.5 molar (M) %). X-ray diffraction pattern confirmed the presence of crystalline, hexagonal wurtzite phase of ZnO. Scanning electron microscope (SEM) images revealed that pure and Mg-doped ZnO NPs were in the nanoscale regime with hexagonal crystalline morphology around 30-110 nm. Optical characterization of the sample revealed that the band gap energy (E) decreased from 3.36 to 3.04 eV with an increase in Mg doping concentration. Optical absorption spectrum of ZnO redshifted as the Mg concentration varied from 2.5 to 7.5 M. Photoluminescence (PL) spectra showed UV emission peak around 400 nm. Enhanced visible emission between 430 and 600 nm with Mg doping indicated the defe...
2023
Herein this study, pure and manganese-(Mn-) doped ZnO (2 wt. %) nanoparticles have been synthesized using the chemical precipitation method and characterized for the photodegradation of methyl green (MG) pollutant dye under natural sunlight. The structural analysis via XRD patterns has revealed that both intrinsic and Mn-doped ZnO (2 wt. %) samples have hexagonal wurtzite structures with appropriate phase purity, clearly indicating the absence of any external impurity. The incorporation of Mn in the host ZnO lattice has decreased the crystallite size (21.10 → 18.76 nm), and nanoparticle-type surface features with sizes in the 50-100 nm range have been observed through FESEM-based surface morphological studies. Both aforementioned observations have merit in providing more active area and a high surface area to volume ratio for photocatalytic reaction. The investigation of photophysical properties indicates that in Mn-doped ZnO nanoparticles, the absorption peak is blue-shifted by 5 nm (365 → 360 nm), due to the widening of the bandgap. The degradation kinetics of MG dye follow the pseudo-second-order kinetics, and the degradation efficiency has been observed to be 62.78% mediated by pure ZnO and 66.44% by Mn-doped ZnO (2 wt. %) photocatalyst under 60 minutes of sunlight irradiation. Specifically, the rate of photocatalytic reaction (K)~0.01792 min-1 and R 2~0 .97992 has been achieved for pure ZnO, whereas slightly higher (K)~0.02072 min-1 and R 2~0 .97299 have been observed for Mn-doped ZnO, respectively. Conclusively, the synergistic interactions with multiple charge transfer pathways, improvement of e − /h + pair charge separation, improved surface area, and efficient generation of hydroxyl radicals are supposed to be responsible for the highly efficient photocatalytic activity of the Mn-doped ZnO photocatalyst for MG dye.
Catalysts
Doping ZnO with appropriate foreign metal and/or non-metal ions is one of the most promising ways to improve both the extension of ZnO photosensitization to the visible region and the separation of charge carriers. Herein, Mn-doped ZnO nanoparticles were synthesized using a precipitation method. The effect of the Mn amount on the physico-chemical properties of these nanomaterials was investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, UV–visible diffuse reflectance spectroscopy, photoluminescence spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The photocatalytic properties of the synthesized nanomaterials were assessed through methyl orange (MO) under visible light. The obtained results showed that the structural and optical properties of the synthesized Mn-ZnO nanomaterials depended greatly on the Mn amount. It was found that the substitution of Zn2+ by Mn2+/Mn3+ within the lattice of ZnO occurred. The phot...
In this study pure and Ni doped ZnO nanoparticles were fabricated by using sol-gel method. The morphology and the microstructure of the pure and doped samples have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The results revealed that the samples were crystalline hexagonal wurzite structure and the absorption spectra were observed under the UV-visible spectroscopy. The effect of pH on the rate of degradation is important and it has to be considered .In order to investigate the effect of pH on pure and doped ZnO nanoparticles photocatalytic activity of the water degradation of methyl orange was also studied with different pH values and it is observed that the absorption of the dye on ZnO and Nickel doped ZnO nanoparticles surface is strongly dependent on the pH of the solution and which plays an important role in photocatalytic degradation also the dopant studies shows a greater efficacy value under pH 6.
Photocatalytic activity of manganese-doped ZnO nanocrystalline powders
2009
ZnO nanocrystalline powders doped with up to 5 at% manganese were synthesized and their photocatalytic activity was studied. Doped ZnO powders were prepared using a sol-gel process. The crystal structure and grain size of the particles were characterized by X-ray diffractometry and optical properties were studied using UV-Vis spectroscopy. The photoactivity of undoped and doped ZnO nanocrystalline powders was evaluated by monitoring the photo-bleaching of the aqueous solutions of Rhodamine B dye in the presence of ZnO under simulated sunlight. The results showed that up to 3 at% manganese were successfully doped into the nanocrystalline ZnO and that manganese-doping reduced the photocatalytic activity of ZnO.
PHOTOLUMINESCENCE AND PHOTOCATALYTIC ACTIVITY OF Mn- DOPED ZnO NANOPARTICLES
2013
Nanocrystalline ZnO particles doped with Mn(II) ions were prepared by a forced hydrolysis method of zinc acetate dihydrate and manganese acetate tetrahydrate, under reflux, in buthanol. The precipitate obtained was separated by centrifugation at 9.000 rpm and purified by refluxing in water. The dopant percentage was 1, 2.5 and 5%. The qualitative composition of the nanopowder has been evidenced in the elemental EDS maps. Optical investigation shows that the Mn doping in ZnO lattice leads to a decrease in the near band edge position due to the introduction of new unoccupied states by Mn 3d electrons. The luminescence of ZnO is quenched by increasing the dopant ions percentage. At doping rate of 1% Mn in the ZnO lattice a tenfold decrease in intensity of luminescence was observed, along with modification of the luminescence pattern. Further increases of dopant percent from 1% to 5% had as result a decrease of only 30% in the luminescence intensity. The photocatalytic activity was inve...