Doped Zinc Oxide Research Articles

Synthesis and characterization (optical and antibacterial) of silver doped zinc oxide nanoparticles

In the present work, Zn1-xAgxO (x = 0, 0.03, 0.05, and 0.07) nanoparticles were synthesized by the sol-gel synthesis method. Microstructural, morphological, optical, and antibacterial characterizations were performed. The wurtzite crystalline structure was confirmed through XRD analysis. The maximum crystallite size was found for Zn0.93Ag0.07O (∼22.36 nm). Rietveld refinement was performed to understand better crystal symmetry. The optical band gap property exhibited a decremental pattern with the increasing Ag content. The lowest band gap was achieved by Zn0.93Ag0.07O (∼3.26 eV). The Fourier transform infrared spectroscopy (FTIR) analysis ensured the bond stretching of Zn–O and Ag–O near the absorbance band of 490 cm−1. Further, the Thermogravimetric analysis (TGA) was performed to determine the samples' weight loss, and the minimum weight loss was observed for Zn0.93Ag0.07O (∼9–11%). Finally, the antibacterial characterization was performed using Escherichia coli (gram-negative bacteria), and again Zn0.93Ag0.07O exhibited better performances than other synthesized nanoparticles.

Structural, optical and magnetic characteristics of iron doped zinc oxide thin films

Zn1-xFexO films with x = 0, 5, 10, 15 and 20 at.% were prepared under high vacuum by the electron beam gun evaporation. The impact of Fe doping concentration on the films' structural, optical and magnetic characteristics has been taken into account. The patterns of XRD for all films at various Fe concentrations showed wurtzite-type structures. The results show that the size of nano-films reduces from 24 nm (0%) to 11 nm (0.20%) with elevating Fe content, which is owing to the difference between the ionic radii of Zn and Fe. Peaks associated with the elements to be seen were visible in the XPS spectra of undoped and 10% Fe-doped ZnO nanoparticles produced by the precipitation process: zinc (Zn), iron (Fe), and oxygen (O). The optical constants (n, k) of the Zn1-xFexO films were obtained by the SE measurements by an ellipsometric model, allowing for the verification of the Fe3+ ions in Fe-doped ZnO. With the addition of Fe, the energy band gap decreased from 3.44 eV to 3.28 eV. M-H measurements revealed room-temperature ferromagnetism in Fe-doped ZnO thin film. As the Fe concentration rises, the magnetization increases until it reaches a concentration of 15%, at which point it starts to decrease. This decrease in magnetization was attributable to the spinel phase, which was seen in the XRD spectra. These findings imply that Fe-doped ZnO is a highly suggested material for the creation of spintronic and optoelectronic devices.

Comparative efficacy of Parthenium hysterophorus (L.) derived biochar and iron doped zinc oxide nanoparticle on heavy metals (HMs) mobility and its uptake by Triticum aestivum (L.) in chromite mining contaminated soils

In this study we investigated the efficacy of a novel material parthenium weed (Parthenium hysterophorus L.) biochar (PBC), iron doped zinc oxide nanoparticles (nFe-ZnO), and biochar modified with nFe-ZnO (Fe-ZnO@BC) to adsorb heavy metals (HMs) and reduce their uptake by wheat (Triticum aestivum L.) in a highly chromite mining contaminated soil. The co-application of the applied soil conditioners exhibited a positive effect on the immobilization and restricted the HMs uptake below their threshold levels in shoot content of wheat. The maximum adsorption capacity was because of large surface area, cation exchange capacity, surface precipitation, and complexation of the soil conditioners. The scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) showed porous smooth structure of parthenium weed derived biochar that helped in HMs adsorption, increase the efficiency of soil fertilizers and nutrients retention which help in the enhancement soil condition. Under different application rates the highest translocation factor (TFHMs) was obtained at 2 g nFe-ZnO rate followed the descending order: Mn > Cr > Cu > Ni > Pb. The overall TFHMs was found <1.0 indicating that low content of HMs accumulation in roots from soil slight transferred to shoot, thus satisfying the remediation requirements.

Role of dual doping in zinc oxide for optimizing thermoelectric performance

In this study, we have investigated the effect of dual doping on the thermoelectric performance of zinc oxide (ZnO). Pure ZnO is a wide band-gap semiconductor with a very low carrier concentration in its intrinsic form. Doping ZnO by trivalent impurity ions is considered a viable approach to improve its electrical conductivity by enhancing the concentration of charge carriers in the material. However, the above enhancement in the carrier concentration can also increase the electronic component of the system's thermal conductivity, thereby limiting its thermoelectric performance. It is expected that the dual doping of ZnO can decrease its thermal conductivity without adversely affecting its electrical conductivity. To test the above hypothesis, we doped ZnO with four different pairs of dopants (In/B, In/Al, In/Ga, and In/Bi) and compared the thermoelectric performance of the resulting materials over the temperature range of 350 K–773 K. For the above comparison, Seebeck coefficient, electrical conductivity, and thermal conductivity of the samples were measured, and corresponding power factors (PF) and figure of merits (ZT) were determined. Among all the samples investigated in the study, the In/Bi-doped ZnO exhibited the highest ZT value of 0.37 at 773 K.

Hydrothermal-assisted synthesis of Co-doped ZnO nanoparticles catalyst for sodium borohydride dehydrogenation and photodegradation of organic pollutants in water

In recent years, studies on dye removal and hydrogen energy have gained momentum. However, these studies are still not in the desired position. Existing biological and physical methods for dye removal are quite inadequate. In hydrogen production, the efficiency is very low when a catalyst is not used. It is important to obtain inexpensive catalysts for both purposes. For this purpose, Cobalt doped Zinc oxide nanoparticles (Co-doped ZnO NPs) were synthesized using a one-pot flash combustion approach. The photocatalytic activity and hydrolysis process of the produced catalyst on NaBH4 were evaluated. The photocatalytic activity of Co-doped ZnO NPs was investigated for decolorization against certain dyes under sunlight irradiation. Co-doped ZnO NPs were analyzed for hydrogen production from NaBH4 hydrolysis. It has been determined that the nanomaterial has a superior catalytic activity with Turnover frequency (TOF) of 1682.3 min−1, 32.45 kJ/mol enthalpy (∆E),-158.4 J/mol.K entropy (∆S), and 34.94 kJ/mol activation energy (EA) obtained as a result of the hydrolysis reaction of Co-doped ZnO NPs. Their reusability was found to be 72.5% at the 4th cycle. The photocatalytic activity of the Co-doped ZnO NPs was found 81.22% (120 min) and 86.98% (90 min) against RhB and MB dyes, respectively. According to the results obtained, it has been seen that Co-doped ZnO NPs are reusable catalysts with high catalytic activity for hydrogen production as a clean energy source. At the same time, it was emphasized that a photocatalyst with high catalytic activity was obtained for wastewater treatment.

Synthesis and Characterization of Cadmium Doped Zinc Oxide Nanoparticles for Visible Light Driven Catalytic Removal of MB and RhB Dye: Experimental and Computational Analysis

Synthesis and Characterization of Cadmium Doped Zinc Oxide Nanoparticles for Visible Light Driven Catalytic Removal of MB and RhB Dye: Experimental and Computational Analysis

Development of AZO TCOs with ALD for HEMT and HJSC Solar Cell Applications

Transparent Conductive Oxide (TCO) films are widely used in optoelectronic devices, such as solar cells, LEDs, and Lasers. Utilization of these contacts directly affects the device efficiencies. Purpose of this study is to produce and optimize properties of Aluminum doped Zinc Oxide (AZO) using a vapor phase technique, Atomic Layer Deposition (ALD) for (n+) a-Si:H surface of silicon Heterojunction Solar Cells (HJSCs) and High Electron Mobility Transistor (HEMT) applications. This study is focused on the effect of the deposition temperature and aluminum atomic concentration on structural, electrical and optical properties of ALD grown AZO ohmic contact films. The results show that as-deposited films have 80-90% transmittance in the visible spectra, low resistance (2.04x10-3 ohm.cm) and mobility value of 5.25 cm2/V.s.

Aluminium doped ZnO nanostructures for efficient photodegradation of indigo carmine and azo carmine G in solar irradiation

Aluminium doped zinc oxide (AZO) nanomaterials (AlxZn1-xO) with x fraction varying as 0.02 and 0.04 were synthesized using the auto-combustion method using glycine as a fuel. The synthesized catalysts were characterized with X-ray diffraction (XRD), UV–Visible Spectroscopy (UV–Vis), Raman spectroscopy, Photoluminescence (PL) spectroscopy, and High Resolution Transmission Electron Microscopy (HR-TEM). XRD results showed that synthesized materials possessed good crystallinity, while UV–VIS was employed to find the band gaps of synthesized materials. Raman was used to determine the vibrational modes in the synthesized nanoparticles, while TEM analysis was performed to study the morphology of the samples. Industrial effluents such as indigo carmine and azo carmine G were used to test the photodegradation ability of synthesised catalysts. Parameters such as the effect of catalyst loading, dye concentration and pH were studied. The reduction in crystallite size, band gap and increased lattice strain for the 4% AZO was the primary reason for the degradation in visible irradiation, degrading 97 and 99% equimolar concentrations of indigo carmine and azo carmine G in 140 min. The Al doped ZnO was found to be effective in faster degradation of dyes as compared to pure ZnO in presence of natural sunlight.

Structural, morphological, and non-linear optical properties of thermally evaporated neodymium doped zinc oxide thin films

The thermal evaporation procedure has been used in the current work to synthesize various compositions of neodymium-doped zinc oxide thin films with varied thicknesses on glass substrates. The Films have a hexagonal wurtzite structure, according to x-ray Diffraction (XRD) study, and the structure has not changed after doping of Neodymium. Raman spectroscopy revealed peaks at 100.49, 331, 434,574, and 581 cm−1 that supported the ZnO phase, and the intensity of the peaks reduced as the number of dopants rose. FTIR analysis verified that Nd had completely dispersed in ZnO. The calculations of the bandgap (Eg) and absorption coefficient (α) are done using absorption spectra. The Z-Scan method has been employed to assess nonlinear optical characteristics for all Nd-doped ZnO thin films. The samples show the change from saturable absorption (SA) to reverse saturable absorption (RSA), the process of focusing to self-defocusing, and vice versa. This is due to the fact that the two-photon process is more potent than the one-photon process. The acquired value of the third-order optical non-linear susceptibility χ (3) is of the order of 10−5 to 10 −6 (e.s.u.) that makes the samples suitable for use in various photonic applications like using as an optical limiter and/or optical switch due to higher values of optical non-linear parameters.

Advanced Morphological, Structural, and Optical Study of Pure and Doped Zinc Oxide Thin Films for Transparent Electronics Applications

Advanced Morphological, Structural, and Optical Study of Pure and Doped Zinc Oxide Thin Films for Transparent Electronics Applications

Reaction mechanisms of pristine and Cu-doped ZnO clusters with ethanol using Evans–Polanyi principle

The interaction and adsorption of pristine and copper (Cu)-doped zinc oxide (ZnO) nanoparticles of ethanol (C2H6O) and several other gases are calculated. These gases include carbon dioxide (CO2), carbon monoxide (CO), ammonia (NH3), ozone (O3), nitrogen dioxide (NO2) and sulfur dioxide (SO2). Most of these gases are air pollutants. Zinc oxide wurtzoid clusters are used to represent zinc oxide nanoparticles. The Gibbs free energy and enthalpy of reactions are evaluated. The Evans–Polanyi principle is used to evaluate the activation energy that gives the best fit to the Arrhenius equation of the reaction. The results of solving the reaction rate equations are used to compare with experimental findings. The reaction of gases with air before reaching the sensor surface is included. A comparison of the calculated response time (10.5 s), recovery time (470 s) and reaction rate with available experimental results is performed (9 and 420 s, respectively) for 50 parts per million ethanol at room temperature. As these results show, the Evans–Polanyi principle combined with Arrhenius equation can give acceptable results. The response time is inversely proportional to the gas concentration, while the recovery time is linearly proportional to the gas concentration. A correlation factor can relate the reaction rate with the response.

Batch and Continuous Flow Treatment Studies of Trichloroethylene Contaminated in Water by Silver and Cerium Doped Zinc Oxide Adsorption and Photocatalysis

The development of photocatalytic treatment in continuous flow systems to be more practical is challenging. This research aimed to study batch and continuous flow treatment of trichloroethylene (TCE) contaminated in water by silver and cerium doped zinc oxide (0.005Ag-0.005Ce-ZnO) visible light driven photocatalyst. This catalyst was selected to represent the green route synthesis with simplicity and ease of upscaling. The 0.005Ag-0.005Ce-ZnO powder was synthesized using sticky rice flour as a template. Mechanical coating of the 0.005Ag-0.005Ce-ZnO powder on activated alumina (Al2O3) beads was done to improve the appropriate packing in the fixed bed columns. Characterization of 0.005Ag-0.005Ce-ZnO showed a higher response to visible light and smaller crystallite size compared to zinc oxide synthesized with the same method. Using sticky rice starch as a template increased the uniform distribution of the elements. The photocatalytic batch test over 0.005Ag-0.005Ce-ZnO powder, 0.30 g/100 mL, could remove TCE up to 80% in 180 min. The decrease of TCE via photocatalysis compared to volatilization, adsorption, and photolysis presented the predominance of photocatalysis. Langmuir-Hinshelwood kinetics described that the decrease of TCE more depended on the reaction than adsorption. In addition, the TCE degradation steadily remained at 80-90% along the run of 0.005Ag-0.005Ce-ZnO@Al2O3 photocatalysis under visible light from both warm white lamps and sunlight in the continuous flow system. Besides photocatalysis, TCE adsorption on 0.005Ag-0.005Ce-ZnO@Al2O3 packed in the columns showed significant results. Our findings presented the possibility of applying the photocatalytic continuous flow system to remove TCE in industrial wastewater.

Recent Progress in Solution Processed Aluminum and co-Doped ZnO for Transparent Conductive Oxide Applications.

With the continuous growth in the optoelectronic industry, the demand for novel and highly efficient materials is also growing. Specifically, the demand for the key component of several optoelectronic devices, i.e., transparent conducting oxides (TCOs), is receiving significant attention. The major reason behind this is the dependence of the current technology on only one material-indium tin oxide (ITO). Even though ITO still remains a highly efficient material, its high cost and the worldwide scarcity of indium creates an urgency for finding an alternative. In this regard, doped zinc oxide (ZnO), in particular, solution-processed aluminum doped ZnO (AZO), is emerging as a leading candidate to replace ITO due to its high abundant and exceptional physical/chemical properties. In this mini review, recent progress in the development of solution-processed AZO is presented. Beside the systematic review of the literature, the solution processable approaches used to synthesize AZO and the effect of aluminum doping content on the functional properties of AZO are also discussed. Moreover, the co-doping strategy (doping of aluminum with other elements) used to further improve the properties of AZO is also discussed and reviewed in this article.

SILAR-deposited manganese doped zinc oxide thin films for NO2 gas detection applications

ABSTRACT The structural, optical and gas detection characteristics of Mn-doped ZnO thin films synthesised by the Successive Ionic Layer Adsorption and Reaction (SILAR) process with varied doping concentrations (4, 6 and 8%) were examined. X-ray diffraction data was used to investigate the structural properties and confirm the hexagonal wurtzite crystal structure. The surface morphology and the existence of all elements were verified using a field emission scanning electron microscope and energy dispersive X-ray spectroscopy, respectively. To explore the vibrational bands present in Mn-doped ZnO films, we used FTIR spectra at ambient temperature. Ultraviolet-visible analysis reveals the absorption edge, which is found in the ultraviolet area, with a minor shift towards high wave length, whereas the energy bandgap decreases as Mn concentrations increase. At 200°C operating temperature, the gas sensing properties of Zn0.92Mn0.08O showed good sensitivity, selectivity and shorter response time when compared to other prepared films.

Impact of deposition time and working pressure on delay of ice formation on aluminum doped zinc oxide thin films

Thin films of aluminum doped Zinc Oxide were synthesized on glass substrate by RF magnetron sputtering. The thin films' structural, optical, wettability and anti-icing properties were studied as a function of deposition time and sputtering pressure. X-Ray Diffraction patterns showed an increase in the intensity of (002) peak when the deposition time was increased and when pressure was decreased. The roughness and average grain size also increased with an increment in deposition time and decreased with an increase in working pressure. Transmittance and band gap energy observed in the wavelength range of 350-800 showed that the average transmittance was 83 to 73% and 3.24-2.88 eV. The contact angle and anti-icing properties observed during the investigation demonstrated that the synthesized coating is hydrophobic with the highest water contact angle of 125.5° and the formation of ice was delayed by 4.36 times when compared to the uncoated substrate.

Investigation of UV photodetector properties of zirconium (Zr)-doped zinc oxide (ZnO)

Investigation of UV photodetector properties of zirconium (Zr)-doped zinc oxide (ZnO)

Comparative Studies on Synthesis, Characterization and Photocatalytic Activity of Ag Doped ZnO Nanoparticles.

In this work, silver (Ag) doped zinc oxide (ZnO) nanoparticles were synthesized using zinc chloride, zinc nitrate, and zinc acetate precursors with (0 to 10) wt % Ag doping by a simple reflux chemical method. The nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet visible spectroscopy, and photoluminescence spectroscopy. The nanoparticles are studied as a photocatalyst for visible light driven annihilation of methylene blue and rose bengal dyes. The 5 wt % Ag doped ZnO displayed optimum photocatalytic activity toward methylene blue and rose bengal dye degradation at the rate of 13 × 10-2 min-1 and 10 × 10-2 min-1, respectively. Here we report antifungal activity for the first time using Ag doped ZnO nanoparticles against Bipolaris sorokiniana, displaying 45% efficiency for 7 wt % Ag doped ZnO.

A numerical analysis of ZnTe/AZO as tunnel junction in CdTe/Si tandem solar cell

Recently, interest has shifted towards developing multijunction or tandem solar cells due to their high potential to generate higher efficiency than traditional single-junction solar cells. Cadmium telluride (CdTe) and silicon (Si) solar cell materials have demonstrated significant potential in photovoltaic energy generation as tandem structures if fully developed. One approach for optimising CdTe/Si is to develop an effective tunnel junction that can electrically and optically interconnect the cadmium telluride and silicon cells with minimal loss. The wxAMPS 3.0 numerical simulation was used in this work to develop CdTe/Si tandem using zinc telluride/aluminium doped zinc oxide (ZnTe/AZO) as a tunnel junction (TJ). The result obtained shows an optimum efficiency of over 36 % with Voc = 1.945 V, Jsc = 21.519 mA/cm2, and FF = 86.823 % utilising the optimal 200 nm CdTe and Si absorber thickness of 300 μm. An analysis of the demonstrated results suggests that ZnTe/AZO tunnel junction will significantly contribute to the realisation of the CdTe/Si tandem solar cell. Hence, upon inserting a 40 nm highly doped ZnTe/AZO tunnelling junction to a CdTe/Si tandem configuration, the solar cell’s performance was enhanced by 48.190%.

Synthesis and characterization of rare earth-doped zinc oxide nano structures

Pure and rare earth metal [cerium (Ce) and thorium (Th)-doped zinc oxide (ZnO)] nanostructures were prepared by solution combustion synthesis by making use of metal nitrates and glycine as precursors in alkaline medium. The average crystal size was examined using Powder X-Ray Diffraction (PXRD) which showed sizes of 45 nm for pure ZnO sample,17.9 nm and 20 nm for Ce and Th-doped ZnO samples respectively. Accordingly, the synthesized samples were confirmed to be polycrystalline from High-Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED) and X-Ray Diffraction (XRD) analyses. Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectroscopy (FESEM / EDX) confirmed the existence of the respective components in the synthesized samples. The Ultra Violet – Visible - Near Infra-Red (UV – Vis - NIR) Spectroscopy showed the characteristic absorption spectra of the samples. The surface topography of the prepared samples was studied by Atomic Force Microscopy (AFM). To further confirm the chemical composition and binding energy, X-Ray Photoelectron Spectroscopy (XPS) was employed.

Review on structural, magnetic, optical properties of manganese doped zinc oxide nanoparticles

Due to its distinctive features and potential applications, the ZnO nanostructure has received extensive attention in recent years. The addition of a transition metal allows ZnO optical and magnetic characteristics to be tuned, which enhances the applicability. Mn doped ZnO has received the significant attention among all transition metals due to notable improvement in ZnO magnetic behaviour at ambient temperature. The magnetism in ZnO is quite controversial and still needs a proper justification, but substitution of magnetic ions undoubtedly enhances the magnetic nature of ZnO. In this review, we have summarised the properties and applications of ZnO and explored the possible mechanism to enhance its property to make it more applicable. Overviews of the ZnO synthesis procedure, uses, and dopant impacts on the structural, magnetic, and optical characteristics of ZnO nanoparticles are provided in this work. The effect of Mn doping concentration on both magnetic and optical behaviour is assessed and justified appropriately. This work will help the novice researcher to observe the applicability of Mn doped ZnO for optoelectronic devices.