Surface Modification Of ZnO Nanoparticles Research Articles

Effect of combined zinc oxide nanoparticles using citric acid and microwave heating on the quality of animal fat

The processing method of animal fat as a non-negligible food resource has attracted attention. ZnO nanoparticles (ZnONPs) are a widely studied inorganic antimicrobial agent. In this paper, citric acid modified ZnO nanoparticles (CA-ZnO) were prepared using citric acid for surface modification of ZnO nanoparticles. The surface modification reduced the agglomeration of ZnONPs in the water, and the particle size of CA-ZnO particles was reduced by about 4 times compared to the ZnONPs after dispersion in the water. CA-ZnO also showed a good inhibitory effect against Bacillus cereus, Escherichia coli, and Staphylococcus aureus at the concentration of 0.05 g/kg. Microwave heating combined with CA-ZnO (MCCZ) had a good bactericidal effect and disrupted the integrity of bacterial cell membrane leading to leakage of cell materials and altering the secondary structure of bacterial proteins such as the reduction of α-helix. Using this method for sterilization of animal fats (a mix of same amount of chicken oil and lard), the sterilization rate of animal fats reached 99.97% after 90 s of MCCZ treatment. And MCCZ resulted in less flavor change and quality deterioration compared to traditional high temperature treatment. Therefore, MCCZ could be used as a new method to preserve the product quality of mixed chicken oil and lard.

Surface functionalization of ZnO nanoparticles by Schiff base oriented tetrapodal ligands at room temperature and their photocatalytic applications: A comparative account on effect of structure directing agent on photocatalysis

Surface modification of ZnO nanoparticles at room temperature and their photocatalytic activity • Synthesis of surface modified ZnO NPs i.e. P-ZnO, Q-ZnO, R-ZnO and S-ZnO by ligands P , Q , R and S respectively at room temperature of different shape and size. • Photocatalytic efficiency of P-ZnO, Q-ZnO, R-ZnO and S-ZnO towards photocatalytic degradation of Rh B dye in 90 min is ∼92%, 80%, 89% and 79% respectively. • ZnO nanoparticles modified by tetrapodal ligands having urea linker moieties (P-ZnO and R-ZnO) have shown very high photocatalytic degradation (∼89-92%). ZnO is very popular and extremely sought after semiconductor material and more so as in the nanocrystalline form. It is biocompatible having a tunable band gap (3-3.7 eV) at room temperature and popular for several optical properties of interest in many fields. Nanoparticles have a lot of surface defects which affect their stability, properties and applications. We use structure directing agents to control the morphology of ZnO nanoparticles and also to control surface defects. We utilised four Schiff base oriented tetrapodal ligands (P, Q, R and S) as the structure directing agents for synthesis of surface modified ZnO nanoparticles i.e. P-ZnO [nanospheres (50-55 nm)], Q-ZnO [nanorods of length (∼1-2 µm) and breadth (∼130-170 nm)], R-ZnO [fibrous/entangled mesh] and S-ZnO [nanorods of length (30-40 nm) and breadth (5-20 nm)] at room temperature i.e. 30-40°C. The application of P-ZnO, Q-ZnO, R-ZnO and S-ZnO are further explored for photocatalytic degradation of Rhodamine B dye under UV lamp (90 min). The efficiency of P-ZnO, Q-ZnO, R-ZnO and S-ZnO towards photocatalytic degradation of Rhodamine B dye was ∼92%, ∼80%, ∼89% and ∼79% respectively.

Ethanedithiol treatment on zinc oxide films for highly efficient quantum dot light-emitting diodes by reducing exciton quenching

Surface modification of ZnO nanoparticles with ethanedithiol (EDT) has been studied to minimize exciton loss at the ZnO/quantum dots (QDs) interface and to improve the efficiency of QD light-emitting diodes (QLEDs). The EDT treatment has been demonstrated to fill oxygen vacancies and reduce carboxylate and hydroxyl ligands on the surface of the ZnO nanoparticles from the x-ray photoelectron spectroscopy analysis. The reduction of oxygen vacancies makes the ZnO films more hydrophobic and maintains the optical bandgap under ambient conditions. EDT treatment shifts the energy level up by 0.47 eV by modifying the surface of ZnO. Non-radiative recombination processes at the ZnO/QDs interface such as interfacial charge transfer and energy transfer are reduced through the upshifted energy level and reduced surface defects. The brightness of the QLED with EDT treatment on ZnO was improved by more than 330% having a maximum luminance of 59 , 500 c d / m 2 compared to the QLED with pristine ZnO. The maximum current efficiency of the QLEDs has been improved from 54.3 cd/A to 73.4 cd/A, which is 35% higher than ZnO-based QLEDs.

A new method to prepare superhydrophobic cotton fabrics by post-coating surface modification of ZnO nanoparticles

Abstract A new, simple and low cost method for the preparation of superhydrophobic cotton fabric by post-coating surface modification of zinc oxide nanoparticles (ZnO NPs) is developed. The method includes synthesis of ZnO NPs, their coating on fabric by padding dry cure technique and post deposition surface modification of the nanoparticles and of the fabric with hexadecyltrimethoxysilane (HDMS). The synthesized ZnO NPs and surface modified cotton fabrics were fully characterized. The ZnO coated and HDMS modified cotton fabric showed very high water contact angle of 152°. The high contact angle was maintained even after several washing cycles.

Low‐Temperature Modification of ZnO Nanoparticles Film for Electron‐Transport Layers in Perovskite Solar Cells

An electron-transport layer (ETL) that selectively collects photogenerated electrons is an important constituent of halide perovskite solar cells (PSCs). Although TiO2 films are widely used as ETL of PSCs, the processing of TiO2 films with high electron mobility requires high-temperature annealing and TiO2 dissociates the perovskite layer through a photocatalytic reaction. Here, we report an effective surface-modification method of a room-temperature processed ZnO nanoparticles (NPs) layer as an alternative to the TiO2 ETL. A combination of simple UV exposure and nitric acid treatment effectively removes the hydroxyl group and passivates surface defects in ZnO NPs. The surface modification of ZnO NPs increases the power conversion efficiency (PCE) of PSCs to 14 % and decreases the aging of PSCs under light soaking. These results suggest that the surface-modified ZnO film can be a good ETL of PSCs and provide a path toward low-temperature processing of efficient and stable PSCs that are compatible with flexible electronics.

A role of ZnO nanoparticle electrostatic properties in cancer cell cytotoxicity.

ZnO nanoparticles (NPs) have previously been shown to exhibit selective cytotoxicity against certain types of cancerous cells suggesting their potential use in biomedical applications. In this study, we investigate the effect of surface modification of ZnO NPs on their cytotoxicity to both cancerous and primary T cells. Our results show that polyacrylic acid capping produces negatively charged ZnO NPs that are significantly more toxic compared to uncapped positively charged NPs of identical size and composition. In contrast, the greatest selectivity against cancerous cells relative to normal cells is observed with cationic NPs. In addition, differences in NP cytotoxicity inversely correlate with NP hydrodynamic size, propensity for aggregation, and dissolution profiles. The generation of reactive oxygen species (ROS) was also observed in the toxicity mechanism with anionic NPs generating higher levels of mitochondrial superoxide without appreciably affecting glutathione levels. Additional experiments evaluated the combined effects of charged ZnO NPs and nontoxic cationic or anionic CeO2 NPs. Results show that the CeO2 NPs offer protective effects against cytotoxicity from anionic ZnO NPs via antioxidant properties. Altogether, study data indicate that surface modification of NPs and resulting changes in their surface charge affect the level of intracellular ROS production, which can be ameliorated by the CeO2 ROS scavenger, suggesting that ROS generation is a dominant mechanism of ZnO NP cytotoxicity. These findings demonstrate the importance of surface electrostatic properties for controlling NP toxicity and illustrate an approach for engineering NPs with desired properties for potential use in biological applications.

Thermo‐Optical Properties of Amino Acid Modified ZnO‐PVA Colloidal Suspension Under CW Laser Illumination

SummaryIn this paper, we present synthesis of amino acids (l‐arginine and l‐alanine) assisted surface modification of ZnO nanoparticles (NPs) using chemical precipitation method. Study emphasizes the utility of l‐arginine over l‐alanine in the synthesis process and ZnO NPs with average particle size of 18 nm have been successfully obtained using l‐arginine. Structural properties were evaluated using powder X‐ray diffraction (XRD) pattern, energy dispersive X‐ray spectroscopy (EDAX) and transmission electron microscopy (TEM) that confirmed the purity, surface morphology and hexagonal wurtzite crystal structure of ZnO NPs. Linear optical studies using ultraviolet‐visible (UV‐vis) spectroscopy and Fourier transform infra‐red (FT‐IR) spectroscopy indicated the blue shift of excitons absorption wavelength and surface modification by amino acids. Blue shifting is more prominent for l‐arginine and optical band gap of 3.48 eV has been achieved in the present case. Third order nonlinearity (nonlinear refraction and absorption) of ZnO NPs embedded in polyvinyl alcohol (ZnO‐PVA colloidal suspension) was studied by Z‐scan technique at wavelength 632.8 nm in continuous wavelength regime which shows negative nonlinearity with self‐defocusing effect. Large value of n2 and β were obtained in case of ZnO NPs passivated by l‐arginine and effect was attributed to thermal lensing. Thermally stimulated third order nonlinear susceptibility (x(3)) for ZnO‐PVA colloids have also been calculated and presented.

Surface Site Modulations by Conjugated Organic Molecules To Enhance Visible Light Activity of ZnO Nanostructures in Photocatalytic Water Splitting

Surface modification of ZnO nanoparticles is identified as a method of modulating surface sites advantageously. ZnO nanoparticles of two different sizes are surface modified with a conjugated organic moiety to enable electron conduction and transfer. Enhanced H2 evolution from water–methanol mixtures was observed in the composite systems compared to pristine ZnO under visible light irradiation without any cocatalyst. The system is also marginally active in water splitting in pure water without any sacrificial agents. Photophysical characterization indicates that even though reducing size into the nanoregime affects the band gap detrimentally, modifications by simple conjugated organic molecules assist in enhanced visible light activity. The experimental observations are corroborated with computational studies, which also point to a localization of valence band maximum of the interface on the organic moiety and conduction band minimum on ZnO.

Surface modification of ZnO nano-particles with Trimetoxyvinyl Silane and Oleic Acid and studying their dispersion in organic media

Zinc oxide nano-particles with the average diameter of about 25 nm were modified with different mole ratios of trimetoxyvinyl silane (TMVS) and oleic acid, as coupling agents, in order to modify their surface properties and render them more hydrophobic. Then, dispersibility of the surface modified nano-particles was examined in some monomers with different levels of hydrophobicity, including methyl methacrylate (MMA), butylacrylate (BuA), and styrene with low, medium and high hydrophobicity, respectively. The modified ZnO nanoparticles were characterized using elemental analysis (EA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM). Findings revealed that the surface modified ZnO nano-particles were more dispersible in the examined organic media indicating better compatibility. TMVS behaved more efficient than Oleic acid, as coupling agent, to make compatibility with MMA; Whereas, ZnO modified with oleic acid exerted more compatibility with styrene. The mixed coupling agent (50/50 Wt% TMVS/oleic acid) showed better compatibility with BuA.

Spectroscopic studies on photoelectron transfer from 2-(furan-2-yl)-1-phenyl-1H-phenanthro[9,10-d]imidazole to ZnO, Cu-doped ZnO and Ag-doped ZnO.

The 2-(furan-2-yl)-1-phenyl-1H-phenanthro[9,10-d]imidazole [FPI] has been designed and synthesized as fluorescent sensor for nanoparticulate ZnO. The present work investigates the photoelectron transfer (PET) from FPI to ZnO, Cu-doped ZnO and Ag- doped ZnO nanoparticles using electronic and life time spectral measurements. Broad absorption along with red shift indicates the formation of charge-transfer complex [FPI-Nanoparticles]. The photophysical studies indicate lowering of HOMO and LUMO energy levels of FPI on adsorption on ZnO due to FPI- ZnO interaction. The obtained binding constant implies that the binding of FPI with nanoparticles was influenced by the surface modification of ZnO nanoparticles with Cu and Ag.

Surface treatment of nano ZnO using 3,4,5,6-tetrabromo-N-(4-hydroxy-phenyl)-phthalamic acid as novel coupling agent for the preparation of poly(amide–imide)/ZnO nanocomposites

Technological developments during the last century have led to the use of materials that inhibit or resist the spread of fire, because modern world with the increase in electronic products presents a greater risk of fire dangers. In line with this goal, a novel modifier containing bromine elements with flame retardancy potential for the surface modification of ZnO nanoparticles was produced from the reaction between tetrabromophthalic anhydride and p-aminophenol. For the synthesis of nanocomposites (NCs), the modified ZnO was embedded in the poly(amide–imide) (PAI) matrix under ultrasonic conditions. Samples were characterized by Fourier transform infrared, thermogravimetric analysis (TGA), X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy and UV-visible (UV/Vis) techniques. TGA results indicated that the addition of modified ZnO into the PAI matrix increases in the thermal decomposition temperatures of the obtained NCs and that the UV/Vis absorbance of NCs was examined and displayed better UV-protection property than the pure PAI.

Novel Surface Modification of ZnO Nanoparticles by Fluidized-Bed Jet Mill

Novel Surface Modification of ZnO Nanoparticles by Fluidized-Bed Jet Mill

Use of response surface methodology for optimization of the photocatalytic degradation of ampicillin by ZnO/polyaniline nanocomposite

ZnO/polyaniline nanocomposite was obtained by surface modification of ZnO nanoparticles with conducting polyaniline, synthesized by polymerization of aniline monomers. The ZnO/polyaniline nanocomposite was characterized by use of UV–visible spectroscopy, TEM, and XRD, and was used for removal of the antibiotic ampicillin, an important water pollutant, from aqueous solution. The effects of initial concentration of ampicillin, reaction time, and solution pH on efficiency of removal by 10 mg/L ZnO/polyaniline nanocomposite were determined and optimized by use of response surface methodology. Predicted and experimental values of the degradation efficiency were in good agreement (R 2 = 0.9763). Maximum degradation was achieved under the optimum conditions: initial ampicillin concentration 4.5 mg/L, reaction time 120 min, and solution pH 5.

Influence of surface modification by 2-aminothiophenol on optoelectronics properties of ZnO nanoparticles

In this study, a precipitation method was used to synthesise ZnO nanoparticles using suitable precursors. An efficient surface modification method was proposed in order to reduce the agglomeration among synthesised small sized ZnO nanoparticles using 2-aminothiophenol as a capping agent. This article briefly investigated the effects of capping agent like 2-aminothiophenol on the optoelectronic properties of ZnO nanoparticles. The modified effectivity of 2-aminothiophenol has been examined on the nanosized ZnO nanoparticle for fluorescence and UV–visible (UV–vis) studies. The mechanism was studied for ZnO nanoparticles light emitting capability under different conditions. By facilitating the capping of ZnO with 2-aminothiophenol, fluorescence emission of the surface defects vanishes and ultraviolet (UV) emission increases. Surface capping by 2-aminothiophenol effectively covers most of the surface defects of ZnO and results in quenching of the visible region. The UV–vis absorption spectra of modified ZnO nanoparticles has been influenced by modified ZnO nanoparticles as a result of surface modification; where marked blue shift in absorption edge results. By surface modification of ZnO nanoparticles, change in optoelectronics properties has opened the new scope and possibilities to explore and fine tune the optical character of the modified ZnO for various optoelectronics applications such as UV laser.

Effect of Nano-ZnO on Thermal, Mechanical, UV Stability, and Other Physical Properties of Wood Polymer Composites

Wood polymer nanocomposite (WPNC) was prepared by impregnation of styrene-acrylonitrile copolymer (SAN) of 2:3 molar ratio, vinyl trichlorosilane (VTCS) modified ZnO nanoparticles and glycidyl methacrylate (GMA) as a cross-linking agent into cellular structure of wood. The surface modification of ZnO nanoparticles and the properties of the WPNC were investigated by XRD, FTIR, TGA, SEM and TEM. The mechanical properties including modulus of rupture (MOR), tensile strength and hardness, and multifunctional properties involving UV resistance, water resistance, dimensional stability and thermal stability were studied. The nano-ZnO particles dispersed uniformly in the polymer filled in the porous structure of wood, as evidenced by SEM-EDX and FTIR, respectively. TEM study showed the homogeneous dispersion of ZnO nanoparticles on the cell wall of wood with SAN polymer matrix.

On the interesting optical properties of highly transparent, thermally stable, spin‐coated polystyrene/zinc oxide nanocomposite films

AbstractIn the present work, polystyrene/zinc oxide (PS/ZnO) nanocomposite films are prepared by simple mixing followed by film deposition, using spin‐coating technique. Although there are a few reports on the UV‐shielding properties of PS/ZnO nanocomposite films, these reports deal with rather thick films obtained by solution casting. Spin coating is a more advantageous technique where one can control the film thickness by suitably adjusting the viscosity of the solution and the spinning speed and get homogeneous films with thickness around a few hundreds of nanometers. These aspects provide the motivation for the present work where emphasis is given to investigating the optical properties of PS/ZnO nanocomposite films obtained by spin coating and analyzing the effects of each component of the composite (PS/ZnO) on the properties of the other. The nanocomposite films are found to be highly transparent throughout the visible region and the thermal stability is better compared with PS. The optical absorption of the composite films in the UV region is quite high, and this aspect highlights the prospects of applications of these films in UV shielding. The PS matrix brings about considerable surface modification of ZnO nanoparticles, resulting in the reduction of defect states within ZnO and facilitating sharp, near band edge photoluminescence emission. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Surface Modification of ZnO Nanoparticles

The synthesis and surface modification of ZnO nanoparticles, achieved through a controlled precipitation reaction using NaOH as precipitating agent with a 0.2 molar ratio were studied. The surface modification was carried out through a chemical hydrolysis reaction at 80°C for 6 h, in order to promote better adhesion between inorganic particles and a polymer matrix when they were used in composite materials. Both 3-aminopropyltrimethoxysilane (APTMS) and difunctional alcohol spiroorthocarbonate (SOC DIOL) were used as modifying agents in a 0.5:1 ratio with respect to ZnO nanoparticles. According to x-ray diffraction (XRD), electron transmission microscopy with scanning modulus (STEM) and infrared spectroscopy (FTIR), the ZnO crystalline structure did not change after treatment. Surface modification was performed in order to subsequently use ZnO nanoparticles in medical antimicrobial devices.

Toxicological Effect of ZnO Nanoparticles Based on Bacteria

Streptococcus agalactiae and Staphylococcus aureus are two pathogenetic agents of several infective diseases in humans. Biocidal effects and cellular internalization of ZnO nanoparticles (NPs) on two bacteria are reported, and ZnO NPs have a good bacteriostasis effect. ZnO NPs were synthesized in the EG aqueous system through the hydrolysis of ionic Zn2+ salts. Particle size and shape were controlled by the addition of the various surfactants. Bactericidal tests were performed in an ordinary broth medium on solid agar plates and in liquid systems with different concentrations of ZnO NPs. The biocidal action of ZnO materials was studied by transmission electron microscopy of bacteria ultrathin sections. The results confirmed that bactericidal cells were damaged after ZnO NPs contacted with them, showing both gram-negative membrane and gram-positive membrane disorganization. The surface modification of ZnO NPs causes an increase in membrane permeability and the cellular internalization of these NPs whereas there is a ZnO NP structure change inside the cells.

Synthesis and surface modification of ZnO nanoparticles

ZnO precursor was prepared by direct precipitation from zinc acetate and ammonium carbonate. ZnO nanoparticles were synthesized by calcination of the precursor at 450 degrees C for 3 h and the calcination after the heterogeneous azeotropic distillation of the precursor, respectively. The synthesized ZnO nanoparticles were characterized by FT-IR, XRD and TEM. It is concluded that the heterogeneous azeotropic distillation of the precursor effectively reduced the formation of hard agglomerates. The surface modification of synthesized ZnO nanoparticles was conducted by capping with oleic acid, and the existence of organic layer can be confirmed by the FT-IR spectra. The lipophilic degree of surface modified ZnO nanoparticles was measured. The ZnO nanoparticle surface was also modified by SiO2, coating. The FT-IR spectrum and XPS clearly showed the formation of an interfacial chemical bond between ZnO and SiO2. In addition, photocatalytic degradation of methyl orange in aqueous solution was performed using ZnO nanoparticles or ZnO/SiO2 nanoparticles as photocatalyst, respectively. The results showed that the ZnO/SiO2 nanoparticles have reduced catalytic activity than that of ZnO nanoparticles. (c) 2006 Elsevier B.V. All rights reserved.