Aluminum-doped Zinc Oxide Nanoparticles Research Articles

Construction of an electrochemical platform with carbon nanotubes and aluminium doped zinc oxide nanoparticles for the sensitive determination of sunset yellow

AbstractSunset yellow, a synthetic colorant and used to improve the texture and the appearance of food samples, can adversely affect humans. The development of a sensitive method to analyse food products for the accurate determination of sunset yellow is of importance for the level of risk to human health and thus food safety. The present study aimed to prepare a voltammetric method for the precise detection of sunset yellow content in a commonly consumed powdered beverage and pharmaceutical products. For this purpose, a sensitive method utilizing a voltammetric platform was constructed by modifying a glassy carbon electrode (GCE) with carbon nanotubes (MWCNTs) and aluminium doped zinc oxide (AZO). Cyclic voltammetry (CV) and electrochemical impedance spectroscopic (EIS) measurements indicated that the proposed voltammetric platform (GCE/MWCNTs/AZO) possessed high electro‐active surface area and lower value of charge transfer resistance (Rct) and therefore, could serve as a promising sensing material. The GCE/MWCNTs/AZO system improved voltammetric behaviour of sunset yellow at an accumulation time of 210 s and indicated good electrocatalytic activity due to high synergistic effect between MWCNTs and AZO nanoparticles. This method of analysis exhibited a dynamic working range from 4.0×10−9 to 7.5×10−6 M with a limit of detection (LOD) of 9.5×10−10 M for sunset yellow. The GCE/MWCNTs/AZO system was successfully utilized for the electroanalysis of beverages and pharmaceuticals for detection of sunset yellow. Voltammetric measurements indicate that the GCE/MWCNTs/AZO system enables good accuracy and high precision for the determination of sunset yellow.

Aluminum oxide, cobalt aluminum oxide, and aluminum-doped zinc oxide nanoparticles as an effective antimicrobial agent against pathogens

Since the clock of antimicrobial resistance was set, modern medicine has shed light on a new cornerstone in technology to overcome the worldwide dread of the post-antimicrobial era. Research organizations are exploring the use of nanotechnology to modify metallic crystals from macro to nanoscale size, demonstrating significant interest in the field of antimicrobials. Herein, the antimicrobial activities of aluminum oxide (Al2O3), cobalt aluminum oxide (CoAl2O4), and aluminum doped zinc oxide (Zn0.9Al0.1O) nanoparticles were examined against some nosocomial pathogens. The study confirmed the formation and characterization of Al2O3, CoAl2O4, and Zn0.9Al0.1O nanoparticles using various techniques, revealing the generation of pure nanoscale nanoparticles. With inhibition zones ranging from 9 to 14 mm and minimum inhibitory concentrations varying from 4 mg/mL to 16 mg/mL, the produced nanoparticles showed strong antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Meanwhile, the bactericidal concentrations ranged from 8 mg/mL to 40 mg/mL. In culture, Zn0.9Al0.1O NPs demonstrated a unique ability to inhibit the development of nosocomial infections with high bactericidal activity (8 mg/mL). Transmission electron microscope images revealed changes in cell shape, bacterial cell wall morphology, cytoplasmic membrane, and protoplasm due to the introduction of tested nanoparticles. These results pave the way for the use of these easily bacterial wall-piercing nanoparticles in combination with potent antibiotics to overcome the majority of bacterial strains' resistance.

Investigation of Ethanol gas sensing properties of pristine and Al doped ZnO nanoparticles synthesized by Sol-gel method

Pure and Aluminum-doped Zinc Oxide nanoparticles were prepared by using a simple Sol–gel method. Al contents were varied with 1 wt% and 3 wt% at a fixed concentration of pure ZnO. Synthesized samples were calcinated at 400 °C for 2 h. The results of x-ray diffraction (XRD) confirm that the synthesized nanoparticles have a Hexagonal Wurtzite structure. The average crystallite size of the nanoparticles shows variation from 16 nm to 21 nm. Grain size and surface morphology were investigated with the help of a Field Emission Scanning Electron Microscope (FESEM). Functional groups present in the prepared samples were analyzed by using Fourier Transform Infra-red spectroscopy (FTIR). The percentage response of the fabricated sensor, containing Al-doped ZnO nanoparticles, was examined with exposure to the toxic gas Ethanol. It was observed that percentage response changes due to various sensing parameters like response time and percentage response which, were calculated at 100 ppm and 200 ppm concentrations of toxic Ethanol gas. It was found that with an increase in Al concentration as well as Ethanol ppm level the percentage response of synthesized samples is increased. The maximum percentage response of 17.82 and 20.91 at 100 and 200 ppm with 3 wt% of Al-doped ZnO nanoparticles was observed respectively, which is greater than that of pure ZnO. Also, the same sample shows the lowest response time of 215 s and 120 s at 100 ppm and 200 ppm, respectively. Thus, aluminum doping enhanced the gas sensing response of pristine zinc oxide nanoparticles.

Aluminum-doped zinc oxide nanoparticles prepared via nanosecond Nd: YAG laser ablation in water: optoelectronic properties

Aluminum-doped zinc oxide nanoparticles prepared via nanosecond Nd: YAG laser ablation in water: optoelectronic properties

Synthesis and characterization of aluminum doped zinc oxide nanoparticles via a novel and low cost aqueous chemical process

Pure and Aluminum doped Zinc Oxide Nanoparticles (AZO NPs) with various doping concentrations were synthesized using an original aqueous chemical process under atmospheric pressure and moderate temperature, using only deionized water as a solvent with a filtration step followed by heat treatment.The X-Ray Diffraction (XRD), Raman and Field Emission Scanning Electron Microscopy- Energy-Dispersive X-ray Spectroscopy (FESEM-EDS) analysis of nanoparticles reveals a hexagonal wurtzite structure, with a size around 60 nm and the presence of aluminum in our samples. Optical investigations demonstrate that the material is of high quality, with few deep structural defects, since Photoluminescence (PL) is largely dominated by excitonic emission at low temperatures.

Interfacial Engineering of a PCBM/AZO Electron Transport Bilayer for Efficient and Stable Inverted Perovskite Solar Cells

AbstractThe reduced hysteresis index and low‐temperature processed fabrication of inverted p‐i‐n perovskite solar cells (PSC) have attracted substantial attraction for achieving higher photovoltaic performance through interfacial engineering. Despite having certain limitations, fullerene‐based electron transport layers have been used frequently utilized in mixed halide inverted perovskite solar cells. The energy level mismatch between PCBM and metal electrode creates a hindrance in efficient electron extraction and thus a limiting factor in attaining higher device performances. In this work, we report an efficient interlayer of aluminum‐doped zinc oxide (AZO) nanoparticles in‐between PCBM and the metal electrode to suppress interfacial recombination. The PCBM/AZO electron transport bilayer can effectively mitigate the imperfections of the PCBM layer alone. The PCBM/AZO electron transport bilayer with an optimal concentration of 2% Al dopant exhibited greatly improved power conversion efficiency (PCE) of 18.63%, VOC of 1.13 V, and FF of 73% with negligible hysteresis index of 0.04. Further, the optimal device exhibited remarkable stability by retaining 91% of the initial PCE after 200 hours confirming the suitable insertion of the AZO bilayer. The improved photovoltaic performance using PCBM/AZO bilayer can be attributed to higher electron transfer efficiency, suppressed interfacial recombination, and smooth surface morphology of AZO nanoparticles atop the PCBM layer.

Dye-sensitized solar cells with aluminum-doped zinc oxide nanoparticles-loaded electrolyte: A breakthrough solution for recombination and hysteresis suppression

Dye-sensitized solar cells (DSCs) suffer from reduced power conversion efficiency due to electron recombination with triiodide (I3−) ions at the photoanode/electrolyte interface. Organic additives are conventionally used in electrolyte to reduce recombination and improve the efficiency of the device. These additives react covalently with iodine (I2) in the electrolyte, leading to a reduction in the concentration of I3− ions. Other inorganic oxides, such as silica (SiO2), titania (TiO2), and magnesia (MgO), have been shown to improve the efficiency of the solar cell. These oxides can adsorb heavy ions to some extent. In this study, we investigated aluminum-doped zinc oxide nanoparticles (AZO NPs) as an inorganic additive with ionic adsorption properties towards I− and I3− anions in the electrolyte. We confirmed the ionic adsorption of AZO NPs through zeta potential and electrochemical impedance measurements. We observed a significant decrease in recombination between photogenerated electrons and electrolyte ions after adding AZO NPs, which resulted in an increase in open circuit voltage (VOC) and fill factor (FF) values. Furthermore, the incorporation of AZO NPs reduced the compelled hysteresis caused by the mismatch in current density-voltage curves for the forward and reverse scan direction. Mott-Schottky analysis confirmed the increase in VOC due to the negative shift in the Fermi level of the TiO2 photoanode. Additionally, open circuit voltage decay measurements indicated a longer electron lifetime at the TiO2/electrolyte interface in AZO NPs loaded electrolyte. Our findings suggest that AZO NPs have potential as an effective inorganic additive for improving the performance of DSCs.

Novel DAZO Film with a Negative Temperature Coefficient Effect and Its Application Prospects for the Thermal Runaway Warning System in Batteries

A novel dopamine- and aluminum-doped zinc oxide (DAZO) sensing film was prepared by blending DAZO nanoparticles with silicone latex; this film has promising applications for the thermal runaway warning system of new energy batteries. The DAZO nanoparticles were generated by the coprecipitation–calcination method through the structure-orienting modification of eco-friendly polydopamine biomaterials, followed by the doping of aluminum and nitrogen into the zinc oxide lattice. Dopamine was used as a nitrogen source; it easily self-polymerizes to form polydopamine, which is then pyrolyzed and doped into the zinc oxide lattice. The negative temperature coefficient (NTC) effects of the DAZO film and the aluminum-doped zinc oxide (AZO) film below 150 °C were tested and compared. The results showed that the DAZO film had a more pronounced NTC effect than the AZO film because of the doped nitrogen element. DAZO films exhibited good recyclability and thermal stability during the high-low temperature NTC cycle test. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry/mass spectrometry (TG–MS), and energy dispersive X-ray spectroscopy were performed to characterize the fabrication of the synthesis mechanism of the DAZO nanoparticles. The NTC effects of DAZO films with varying aluminum doping amounts, varying dopamine doping amounts, and different pH values were investigated. Nitrogen doping in the conventional AZO nanoparticles enhanced the sensitivity and low-temperature NTC effect; this is because of the increase in the DAZO grain size due to doping and the structure–orientation of polydopamine, which further leads to the increase in the height of the grain boundary potential barrier. On the basis of the test results, an alarm response device at different temperatures was initially established, and its alarm response at different temperatures was simulated and tested, which showed the possibility of the application of the DAZO film to the runaway warning system for the new energy batteries.

AZO Nanoparticles-Decorated CNTs for UV Light Sensing: A Structural, Chemical, and Electro-Optical Investigation

Nanocomposites formed by aluminum-doped zinc oxide nanoparticles (AZO-NP) and multiwall carbon nanotubes (CNT) are proposed here as a promising material for UV light sensing applications, with the great advantage of operating in air, at room temperature, and at low voltage. Nanocomposite layers were prepared with different AZO:CNT weight ratios by a simple methodology at room temperature. They were characterized by means of UV-Vis spectroscopy, scanning and transmission electron microscopies (SEM and TEM), and X-ray photoelectron spectroscopy (XPS). The interaction between the two nanomaterials was demonstrated by comparing the properties of the nanocomposite with the ones shown by the AZO-NPs. Dense AZO-CNT nanocomposite layers were deposited between two metal electrodes on a SiO2/Si substrate, and the electrical properties were investigated in dark condition and under UV light irradiation. The electrical response to the UV light was a sudden current increase that reduced when the light was switched off. Several UV on/off cycles were performed, showing good repeatability and stability of the response. The mechanisms involved in the electrical response are discussed and compared to the ones previously reported for ZnO-CNT nanocomposites.

In Situ Synthesis of AZO-Np in Guar Gum/PVOH Composite Fiber Mats for Potential Bactericidal Release.

Since the number of antibiotic-resistant bacterial infections is growing and cases are getting worse every year, the search for new alternative bactericidal wound dressing treatments is becoming crucial. Within this context, the use of polysaccharides from plants and seeds in innovative biopolymer technologies is of key importance. In this work, bio-nano-composite guar gum/polyvinyl alcohol (PVOH) membranes loaded with aluminum-doped zinc oxide nanoparticles were produced via electrospinning. Citric acid was added to the mixture to increase spinnability. However, depending on the pH, zinc oxide nanoparticles are partially dissociated, decreasing their bactericidal efficiency. Thus, a second successful alkaline thermo-chemical regrowth step was added to the process to treat the obtained fibers. This alkaline thermo-chemical treatment reconstituted both the nanoparticles and their bactericidal properties. The Staphylococcus aureus antibacterial assay results show that the membranes obtained after the alkaline thermo-chemical treatment presented a 57% increase in growth inhibition.

High-performance electrically conductive adhesives with aluminum-doped zinc oxide (AZO) for various flexible electronic devices

Electrically conductive adhesives (ECAs) are a kind of attractive alternative to tin solders in microelectronics. However, fabricating high-performance, low-cost ECAs remains challenging due to the need for high-content metal fillers. This work reported a facile preparation of cost-effective ECAs composed of aluminum-doped zinc oxide (AZO) nanoparticles and silver (Ag) micro-flakes. The AZO nanoparticles could serve as a “bridge” to connect neighboring Ag micro-flakes to significantly improve the ECAs′ conductivity (from 1638.8 × 10-5 Ω⋅cm to 8.5 × 10-5 Ω⋅cm). After the aging and bonding performance tests, prototyped applications of the as-prepared ECAs for three flexible electronic devices were demonstrated sequentially: (Ⅰ) The resistance of flexible conductive film showed excellent dynamic stability after being folded for 1000 cycles, bent/released within 6 mm radius for more than 2000 cycles, or applied with 1000 kPa pressure; (Ⅱ) The coil antenna achieved fast transmission of radio frequency signal for near field communication (NFC) system; (III) The flexible heater performed efficient thermal management at 0.4–1.4 V input voltages. Therefore, the fabricated ECAs are expected to provide new opportunities for the development of novel flexible electronic devices for future applications.

Aluminum Doped Zinc Oxide Nanoparticles Loaded Electrolyte: An Effective Recombination and Hysteresis Suppressant in Dye Sensitized Solar Cell

Aluminum Doped Zinc Oxide Nanoparticles Loaded Electrolyte: An Effective Recombination and Hysteresis Suppressant in Dye Sensitized Solar Cell

Microfluidic electrogenerated chemiluminescence cells using aluminum-doped zinc oxide nanoparticles as an electron injection layer

We demonstrated highly luminescent microfluidic electrogenerated chemiluminescence (ECL) cells using aluminum-doped zinc oxide nanoparticles (AZO NPs) as an electron injection layer (EIL). The 5-μm-thick electro-microfluidic device, in which an approximately 1.6-μm-thick AZO NPs layer was embedded, was fabricated by microelectromechanical systems processes and a vacuum ultraviolet-assisted direct bonding technique. A tris(2,2′-bipyridine)ruthenium(II) solution was used as an orange-red emitter. A luminance and a half-lifetime were measured to be 161 cd/m2 at 3.3 V and 30 s at 3.0 V, respectively, which were 2.5 times higher and 4.3 times longer than those of the device without EIL. We also compared the EIL performance of the AZO NPs with that of titanium dioxide NPs. Furthermore, 2-μm-thick microfluidic ECL cell with the AZO NPs layer was fabricated by the same process, and the maximum luminance increased up to 240 cd/m2. We expect that the developed microfluidic device will be highly attractive for solution-based display applications.

Characterization and Optimization of AZO Nanoparticles as Coatings for Flexible Substrates toward High IR Reflectivity.

Energy consumption by air-conditioning is expansive and leads to the emission of millions of tons of CO2 every year. A promising approach to circumvent this problem is the reflection of solar radiation: Rooms that would not heat up by irradiation will not need to be cooled down. Especially, transparent conductive metal oxides exhibit high infrared (IR) reflectivity and are commonly applied as low-emissivity coatings (low-e coatings). Indium tin oxide (ITO) coatings are the state-of-the-art application, though indium is a rare and expensive resource. This work demonstrates that aluminum-doped zinc oxide (AZO) can be a suitable alternative to ITO for IR-reflection applications. AZO synthesized here exhibits better emissivity to be used as roofing membrane coatings for buildings in comparison to commercially available ITO coatings. AZO particles forming the reflective coating are generated via solvothermal synthesis routes and obtain high conductivity and IR reflectivity without the need of any further post-thermal treatment. Different synthesis parameters were studied, and their effects on both conductive and optical properties of the AZO nanoparticles were evaluated. To this end, a series of characterization methods, especially 27Al-nuclear magnetic resonance spectroscopy (27Al-NMR) analysis, have been conducted for a deeper insight into the particles' structure to understand the differences in conductivity and optical properties. The optimized AZO nanoparticles were coated on flexible transparent textile-based roofing membranes and tested as low-e coatings. The membranes demonstrated higher thermal reflectance compared with commercial ITO materials with an emissivity value lowered by 16%.

Synthesis, structural, morphological, optical and electrical conductivity properties of aluminium doped ZnO/POLY (o-TOLUIDINE) (Al-ZnO-POT) nanocomposites

Aluminium doped Zinc oxide (Al-ZnO) nanoparticles synthesized by chemical precipitation method. Chemical oxidative polymerization ofo-toluidine monomer for the synthesis of Poly (o-toluidine) (POT)polymer and its nanocomposites with Al-ZnO nanoparticles(Al-ZnO-POT)employing ammonium persulfate as an oxidizing agent in aqueous medium.Synthesized nanoparticles, polymer and nanocomposites were characterized with XRD studies, FTIR, SEM, EDAX, UV-Vis and PL analysis.The XRD pattern confirms an amorphous structurein Al -ZnO-POTnanocomposities.The FTIR pattern confirmsfunctional group and chemical bonding present in the synthesiszedsamples.SEM images confirm the nanorod shapeof nanoparticles. EDAX images confirm the elemental composition of the synthesized samples.The optical property of the particles wasanalysedby UV-Visible and PL Spectra.Incorporation of nanoparticles, polymer and nano composites showed a significant difference inelectrochemical conductivity properties were analysed by using four probe DC electrical conductivity instrument from room temperature 32°C to higher temperature 120°C.

Effect of ink formulation on the inkjet printing process of Al–ZnO nanoparticles

This study focuses on the inkjet printing of aluminum-doped zinc oxide (AZO) spherical and platelet nanoparticle-based nanoflakes with typical sizes ranging from 700 to 800 nm. The AZO nanoparticles were synthesized by aqueous precipitation. The preparation of the solvent-based inks was performed with the control of the viscosity, ink stability, and nanoparticle dispersion. The results showed that the viscosity for nanoparticle dispersions slightly changes (from 6.9 to 8.7 cPs) when the nanoparticles mass concentration increases from 1.8 to 10%. In order to achieve thin films of AZO nanoparticles, we optimized the printing process by real-time monitoring of drop velocity with a stroboscopic camera. This technology involves direct patterning of a functional material by tiny MEMS-jets on a flexible and rigid substrate at specific locations. The lowest concentration of AZO nanoparticles corresponding to 1.8% enables printing several times during the nanoparticle dispersions and the clogging of printhead nozzles is less pronounced. In our conditions, the optimum voltage value is 25 V to achieve a drop velocity from 7 to 9 m/s. In the case of nanospheres with 10% of AZO nanoparticles, for a large dropspace (90 $$\mu$$ m), the individual printed droplets appear as a sequence of linear dots. When the drop spacing decreases to 75 $$\mu$$ m, isolated drops start to overlap and merge. Further decrease in the drop spacing eliminates scalloping and leads finally to a regular and continuous layer at 55 $$\mu$$ m.

Synthesis and Characterization of Aluminum Doped Zinc Oxide Nanostructures by Nd:YAG Laser in Liquid

Aluminum doped zinc oxide nanoparticles (AZO) with different doping concentrations were prepared by Nd-YAG laser ablation of target in deionized water. The characterization of these nanoparticles was performed using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and photoluminance spectroscopy (PL). FTIR spectra confirmed the formation of vibrational bonds for ZnO NPs and AZO NPs. SEM images illustrated that the size and shape of the NPs changed with changing the number of laser pulses. Photoluminescence peaks exhibited two emission peaks, one at the UV region and the second in the visible region, which were modified as the number of laser pulses and doping concentration were changed.

Infrared emission characteristic and microwave loss property of aluminum doped zinc oxide nanoparticles

Aluminum doped zinc oxide (AZO) nanoparticles with different doping concentrations were prepared by a simple one-step hydrothermal synthesis method. The crystal structure, morphology, infrared absorption, infrared emission and microwave loss properties of the AZO nanoparticles were analyzed in detail. With the increase of the aluminum doping concentration, the crystal plane spacing does not change much, while the grain size increases gradually, and the thickness of the flakes and the average size of the particles have no significant change. With the increase of the Al doping concentration, the infrared emissivity of AZO tends to decrease first and then increase, among which the AZO infrared emissivity with Zn-ion ratio of 95:5 is the lowest. The electromagnetic parameters of AZO with a mole doping ratio of 93:7 were carried out at a frequency range of 2–18 GHz, the real part (ε′) and imaginary part (ε″) of the complex permittivity varies between 4.3-4.5 and 0.2–0.4, respectively, the dielectric loss tangent (tanδ) varies between 0.04 and 0.09.

Synthesis, Characterization and Evaluation of Anti-bacterial, Anti-parasitic and Anti-cancer Activities of Aluminum-Doped Zinc Oxide Nanoparticles

The preparation of nanoparticles by utilizing laser ablation in liquid has gained extensive attention as a reliable, simple, fast, efficient and environmental friendly method. In the present study, zinc oxide nanoparticles (ZNO NPs) and aluminum-doped ZNO nanoparticles (Al ZNO NPs) were produced via laser ablation in deionized water. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), UV–Vis spectroscopy, field emission scanning electron microscopy (FESEM) and energy dispersive spectrum (EDS) analyses. ZNO NPs showed that the particle size increased with the increase in the number of laser pulses, while the shape changed from nanoplate to nanowire, along with the presence of small agglomerated spherical nanoparticles. The results confirmed the formation of Al ZNO NPs with Wurtzite hexagonal phase where the shape being modified from nanowire to spherical, along with high agglomeration. The EDS analysis showed that all peaks had conformity with the peaks of Zn, O, and Al atoms, with no impurities. The antibacterial activity test revealed a largest inhibition zone in Staphylococcus aureus as compared to Escherichia coli, with a more potent effect for Al ZNO NPs when compared with ZNO NPs alone. The same effects were recorded against Leishmania tropica and L. donovani, with stronger activity against the former parasite. The nanoparticles also showed anticancer activities against MDA-MB-231 cells, suggesting that cancer cells were targeted by the NPs through induction of cell death. Consequently, these investigations reveal that the prepared particles may be useful for the development of anti-cancer drugs, including those used for breast cancer therapy.

Application of bimetallic Al-doped ZnO nano-assembly for heavy metal removal and decontamination of wastewater.

In the present study, bimetallic aluminium doped zinc oxide (AZO) nano-assemblies were synthesized for heavy metal removal and disinfection of wastewater. These bimetallic nanoparticles (NPs) were prepared by a simple co-precipitation method and characterized using field emission transmission electron microscopy (FETEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), a Litesizer, and energy dispersive X-ray spectroscopy (EDS). The AZO NPs was tested for lead removal at various environmental conditions and optimized at pH 4 and 25 °C. The kinetic data were well fitted to the pseudo-second-order model and the process consisted of both surface adsorption and intraparticle diffusion. Al doping enhanced the surface charge of AZO NPs four fold as compared to ZnO, which improved colloidal stability and contributed towards its reusability. AZO NPs exhibited excellent removal efficiency of 86% over three adsorption-desorption cycles. The adsorption was found to be an exothermic and physicochemical process. The prepared AZO NPs were also used to treat a real wastewater sample and found to effectively remove Pb(II) and kill all the bacteria present.