Surface Of ZnO Nanoparticles Research Articles

Evaluation of copper(I)-doped zinc oxide composite nanoparticles on both gram-negative and gram-positive bacteria

Antibiotic resistance is a serious problem all over the world. Inorganic metal oxide nanoparticles are suitable substitutional treatments for organic antibiotic-resistant bacterial infections. Various copper dopped ZnO nanocomposites were prepared with chemical deposition method in aqueous solution. X-ray diffraction (XRD) coupled with energy dispersive spectroscopy results reveals that cuprous oxide is uniformly doped on the surface of ZnO nanoparticles, forming Cu2O/ZnO nanocomposites. In addition, from Transmission electron microscopy (TEM) and scanning electron microscopy analysis, the average size of prepared Cu2O/ZnO composite is about 30 nm. The antibacterial activity of the Cu2O/ZnO composite was examined on two bacteria strains: Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). When the doping amount of Cu2O reaches more than 5%, a 3.58 log-reduction of S. aureus growth under visible light within 30 mins treatment was observed. The antibacterial activity of Cu2O/ZnO is 2.7-fold higher than pure ZnO and killing bacteria on E. coli with a 1.0 log-reduction in viability. Meanwhile, the bacteriological properties of Cu doped ZnO composites with different valence states (Cu2+, CuO, Cu2O, and Cu0) were compared. Furthermore, the antibacterial mechanism was further discussed in this paper.

Facile one-pot solid-state fabrication of a novel binary nanocomposite of commercial ZnO and commercial PbCrO4 with enhanced photocatalytic degradation of Rhodamine B dye

Lead chromate, PbCrO4, is a semiconductor material exhibiting narrow bandgap energy indicating its promising visible-light-driven photocatalytic activity. However, very few papers reported the utilization of PbCrO4 as a photocatalyst. Herein, we report a simple one-pot room-temperature method that was employed for the synthesis of a novel PbCrO4/ZnO binary nanocomposite, for the first time, based on solid-state mixing of commercial Zinc oxide nanoparticles and commercial PbCrO4 nanorods to enhance the optical properties and photocatalytic performance of ZnO. The as-synthesized nanocomposite was characterized by FE-SEM, XRD, FTIR, DRS, and PL. The results confirmed that the anchoring of PbCrO4 nanorods on the surface of ZnO nanoparticles achieved a significant enhancement in their optical properties such as decreasing the bandgap energy and reducing the e-h recombination rate as well as the enhanced photocatalytic performance toward Rhodamine B photodegradation. Finally, the mechanism of the enhanced photocatalytic performance of the as-synthesized novel PbCrO4/ZnO nanocomposite was suggested.

Comparative effects of zinc oxide nanoparticles over the interfacial properties of low concentrations of ionic surfactants at interfaces

Nanoparticles (NPs) are well-known for their surface activities and recently their use in petroleum industry is on rise which call for better understanding of implications of interactions of NPs and surfactants. Furthermore, this study can provide additional benefits because zinc oxide nanoparticles (ZnO NPs) are widely used in the industrial products and are therefore of special importance. Surfactants, on the other hand are also industrial chemicals and almost an essential constituent of every other formulation with or without the presence of nanoparticles. The self-assembling properties of surfactants on the interface and remarkable surface activities of nanoparticles led to the studies of interactions between nanoparticles and surfactants in a hope to tune the interfacial properties. The surface of ZnO NPs is charged and therefore they can electrostatically interact with ionic surfactants molecules as well as their self-assembled structures such as monolayers at the interfaces and micelles in solutions. This work is set to find how and to what degree, the self-assembling properties of surfactants are affected by ZnO NPs interactions under the influence of change in pH, and ionic strength using sodium chloride which is commonly used among many other ions to simulate “low salinity environment”. Surface tension (ST), dynamic light scattering technique with hydrodynamic size (Dh) and zeta potential (ζ) measurements were used to characterize the possible interactions of nanoparticles with surfactants. Commercially important sodium dodecyl sulfate (SDS) and cetrimonium bromide (CTAB) were chosen ionic surfactants for their interactions with ZnO NPs. The study concluded that the interactions of particles with surfactants, due to change in pH, and ionic strength have an appreciable impact on the activities of SDS and CTAB at the air-water (A/W) and n-hexane (oil)-water (O/W) interfaces. The effect of electrolytes was found more prominent in the case of CTAB+ZnO NPs system, while the effect of pH was more pronounced for SDS+ZnO NPs system i.e., in case of both A/W and O/W interfaces. The study will help to improve the understanding and use of ZnO NPs in combination with surfactants and similar systems in enhanced oil recovery and many other processes of industrial importance.

Cinnamic acid-functionalized ZnO nanoparticles for constructing UV-shielding and mechanically robust polyvinyl butyral composites

Biomolecule cinnamic acid (CNA) was chemically grafted on the surface of ZnO nanoparticles (ZnO Nps) via (3-Aminopropyl) trimethoxysilane (KH550) as the linkage to obtain a novel UV-shielding material CNA-mZnO. It was found that CNA-mZnO exhibits stronger UV absorption property than pure ZnO. Moreover, CNA-mZnO could be homogeneously dispersed in polyvinyl butyral (PVB) matrix. As expected, the introduction of CNA-mZnO gives a positive effect on the UV-shielding performance and mechanical properties of PVB matrix. Particularly, the PVB with 2 wt% CNA-mZnO achieved a dramatically improved UV-shielding performance with UV-shielding efficiency more than 99% below 370 nm, along with satisfactory visible transmittance. Meanwhile, the maximum tensile strength of PVB/CNA-mZnO composite were approximately 50% enhancement than pure PVB. More importantly, the PVB/CNA-mZnO composites also possess the excellent anti-UV aging performance and exhibit high retention of mechanical properties after UV exposure for 96 h. This work proposed a new strategy to prepare UV-shielding and mechanically robust composites by introducing natural biomolecule-functionalized ZnO Nps, which may greatly promote their applications in packing, intelligent windows and optical devices.

Raman and X-ray photoelectron spectroscopic investigation of solution processed Alq3/ZnO hybrid thin films

In this study, we characterize the solution processed tris-(8-hydroxyquinoline)aluminum(Alq3)/ZnO hybrid thin films using Raman and X-ray photoelectron spectroscopic (XPS) techniques. Raman studies reveal the sol–gel derived spin-coated ZnO thin film has hexagonal wurtzite structure. The incorporation of Alq3 molecules in the hybrid film results in the formation of bonding onto the surface of highly crystalline ZnO nanoparticles. The XPS confirms the incorporation of Alq3 in the hybrid thin films and corroborates that the Alq3 molecules may be adsorbed onto the surface of ZnO nanoparticles (chemisorption), showing the existence of chemical interaction between Alq3 and ZnO in the hybrid films. These studies support that the chemisorbed Alq3 molecules onto the ZnO nanoparticles may facilitate the charge transfer (non-radiative) between Alq3 and ZnO in the hybrid thin films which will be useful to enhance the optical and electrical properties for the optoelectronic device applications.

Self-Assembly of Porphyrin Nanofibers on ZnO Nanoparticles for the Enhanced Photocatalytic Performance for Organic Dye Degradation.

Synthesizing novel photocatalysts that can effectively harvest photon energy over a wide range of the solar spectrum for practical applications is vital. Porphyrin-derived nanostructures with properties similar to those of chlorophyll have emerged as promising candidates to meet this requirement. In this study, tetrakis(4-carboxyphenyl) porphyrin (TCPP) nanofibers were formed on the surface of ZnO nanoparticles using a simple self-assembly approach. The obtained ZnO/TCPP nanofiber composites were characterized via scanning electron microscopy, X-ray diffraction analysis, and ultraviolet–visible absorbance and reflectance measurements. The results demonstrated that the ZnO nanoparticles with an average size of approximately 37 nm were well integrated in the TCPP nanofiber matrix. The resultant composite showed photocatalytic activity of ZnO and TCPP nanofibers concomitantly, with band gap energies of 3.12 and 2.43 eV, respectively. The ZnO/TCPP photocatalyst exhibited remarkable photocatalytic performance for RhB degradation with a removal percentage of 97% after 180 min of irradiation under simulated sunlight because of the synergetic activity of ZnO and TCPP nanofibers. The dominant active species participating in the photocatalytic reaction were •O2– and OH•, resulting in enhanced charge separation by exciton-coupled charge-transfer processes between the hybrid materials.

Turning Toxic Nanomaterials into a Safe and Bioactive Nanocarrier for Co-delivery of DOX/pCRISPR.

Hybrid bioactive inorganic-organic carbon-based nanocomposites of reduced graphene oxide (rGO) nanosheets enlarged with multi-walled carbon nanotubes (MWCNTs) were decorated to provide a suitable space for in situ growth of CoNi2S4 and green-synthesized ZnO nanoparticles. The ensuing nanocarrier supplied π-π interactions between the DOX drug and a stabilizing agent derived from leaf extracts on the surface of ZnO nanoparticles and hydrogen bonds; gene delivery of (p)CRISPR was also facilitated by chitosan and alginate renewable macromolecules. Also, these polymers can inhibit the potential interactions between the inorganic parts and cellular membranes to reduce the potential cytotoxicity. Nanocomposite/nanocarrier analyses and sustained DOX delivery (cytotoxicity analyses on HEK-293, PC12, HepG2, and HeLa cell lines after 24, 48, and 72 h) were indicative of an acceptable cell viability of up to 91.4 and 78.8% after 48 at low and high concentrations of 0.1 and 10 μg/mL, respectively. The MTT results indicate that by addition of DOX to the nanostructures, the relative cell viability increased after 72 h of treatment; since the inorganic compartments, specifically CoNi2S4, are toxic, this is a promising route to increase the bioavailability of the nanocarrier before reaching the targeted cells. Nanosystems were tagged with (p)CRISPR for co-transfer of the drug/genes, where confocal laser scanning microscopy (CLSM) pictures of the 4',6-diamidino-2-phenylindole (DAPI) were indicative of appropriate localization of DOX into the nanostructure with effective cell and drug delivery at varied pH. Also, the intrinsic toxicity of CoNi2S4 does not affect the morphology of the cells, which is a breakthrough. Furthermore, the CLSM images of the HEK-293 and HeLa cell displayed effective transport of (p)CRISPR into the cells with an enhanced green fluorescent protein (EGFP) of up to 8.3% for the HEK-293 cell line and 21.4% for the HeLa cell line, a record. Additionally, the specific morphology of the nanosystems before and after the drug/gene transport events, via images by TEM and FESEM, revealed an intact morphology for these biopolymers and their complete degradation after long-time usage.

Green Synthesis of ZnO Nanoparticles using Eryngium Billardieri Leaf Extract: Characterization and its Anti-Diabetic Properties

The present study developed the green synthesis approach to prepare ZnO nanoparticles (ZnONPs) with the aid of Eryngium billardieri leaf extract as an efficient stabilizer. The properties of the fabricated nanoparticles were determined by TEM, FE-SEM, XRD, EDX, FT-IR, TGA, and UV-vis DR spectra techniques. The results obtained from FE-SEM and TEM images displayed that the size of ZnONPs synthesized in the presence of the leaf extract in compared to the chemically fabricated sample was decreased. According to the results from UV-vis DRS spectra, EDX, FTIR, and TG analyses, presence of some bio-molecules from the plant extract on the surface of ZnONPs was confirmed. The green synthesis of nanoparticles using extracts and their potential applications as anti-diabetic agents has attracted a great attention in recent years. Anti-diabetic activity of the prepared sample was detected by treating alloxan-induced diabetic rats compared with those treated with the E. billardieri leaf extract and insulin. The pre and post treatments, levels of fasting blood sugar, total cholesterol, insulin, high-density lipoprotein, and total triglyceride were determined. Analysis in the diabetic rats displayed an increase in high-density lipoprotein and a significant decrease in fasting blood sugar levels in all groups under treatment. Furthermore, cholesterol reduction was observed in the group treated by ZnO powder prepared in the presence of the extract. The anti-diabetic results indicated that the green ZnONPs have an excellent efficiency in overcoming diabetic rats.

Ligand-Protected Ultrasmall Pd Nanoclusters Supported on Metal Oxide Surfaces for CO Oxidation: Does the Ligand Activate or Passivate the Pd Nanocatalyst?

Herein, we report on the synthesis of ultrasmall Pd nanoclusters (∼2 nm) protected by L-cysteine [HOCOCH(NH2 )CH2 SH] ligands (Pdn (L-Cys)m ) and supported on the surfaces of CeO2 , TiO2 , Fe3 O4 , and ZnO nanoparticles for CO catalytic oxidation. The Pdn (L-Cys)m nanoclusters supported on the reducible metal oxides CeO2 , TiO2 and Fe3 O4 exhibit a remarkable catalytic activity towards CO oxidation, significantly higher than the reported Pd nanoparticle catalysts. The high catalytic activity of the ligand-protected clusters Pdn (L-Cys)m is observed on the three reducible oxides where 100 % CO conversion occurs at 93-110 °C. The high activity is attributed to the ligand-protected Pd nanoclusters where the L-cysteine ligands aid in achieving monodispersity of the Pd clusters by limiting the cluster size to the active sub-2-nm region and decreasing the tendency of the clusters for agglomeration. In the case of the ceria support, a complete removal of the L-cysteine ligands results in connected agglomerated Pd clusters which are less reactive than the ligand-protected clusters. However, for the TiO2 and Fe3 O4 supports, complete removal of the ligands from the Pdn (L-Cys)m clusters leads to a slight decrease in activity where the T100% CO conversion occurs at 99 °C and 107 °C, respectively. The high porosity of the TiO2 and Fe3 O4 supports appears to aid in efficient encapsulation of the bare Pdn nanoclusters within the mesoporous pores of the support.

Zinc oxide nanoclusters and nanoparticles as a drug carrier for cisplatin and nedaplatin anti-cancer drugs, insights from DFT methods and MC simulation

ABSTRACT In this work, we study the ability of (Zno) n (n = 2–5 and 12) nanoclusters and ZnO nanoparticles to act as a drug carrier for cisplatin and nedaplatin drugs by DFT methods and MC simulation. Binding energies in both gas and water phases are calculated, the bonds formed between (ZnO)n (n = 2–5 and 12) and cisplatin and nedaplatin drugs are studied and computed using QMAIM. The binding energy in water is lower than that in gas, which supports that the partially covalent and partially electrostatic bonding nature. Also, binding energies in the state of (ZnO) n -cisplatin complexes are lower than those in the (ZnO) n -nedaplatin complexes in both gas and water phases. Also, the adsorption of cisplatin and nedaplatin drugs on ZnO nanoparticles surface (different sizes and shapes) was studied by Monte Carlo simulation. We find that increasing the ZnO size dose not significantly influences on the adsorption energies of cisplatin and nedaplatin drugs for all studied nanoparticles shapes. All adsorption energies obtained by MC calculations are negative which revealed that the adsorption of the cisplatin and nedaplatin molecules on ZnO surfaces is exothermic, spontaneously and energetically favourable. So, ZnO nanoclusters and nanoparticles can act as a drug carrier for cisplatin and nedaplatin anticancer drugs. Abbreviations: Density Functional Theory; MC simulation: Monte Carlo simulation; QMAIM: quantum mechanics atoms in molecules

Ag-nanoparticle enhanced photodegradation of ZnO nanostructures: Investigation using photoluminescence and ESR studies

Ag-nanoparticle/ZnO nanostructures were synthesized using a room-temperature sol-gel method, followed by the thermally activated process at 500℃ under 4☓10-3 Torr. The nanostructures were elucidated the results of HR-TEM, FE-SEM, and XRD. ESR and PL spectra revealed defects, including Oi'', VZn'', VO∙∙,and Zni∙∙, which were the main factors to enhance the chemi-degradation reactivity and the photodegradation efficiency of the Ag-nanoparticle/ZnO nanostructures. The Ag nanoparticles formed on the ZnO nanoparticle surfaces significantly influenced the intensities of PL and ESR signals, which extended the free-carrier lifetime and confirmed the high degradation efficiency and the large reaction coefficient of the Ag-nanoparticle/ ZnO nanostructures. Photodegradation results reveal that the efficiency and reaction rate coefficient of the Ag-nanoparticle/ZnO nanostructures were 3.6 and 15 times higher than those of pristine ZnO nanostructures. According to multi-run photodegradation tests, the Ag-nanoparticle/ZnO nanostructure exhibited stable photodegradation efficiencies of more than 99 % and reaction rate coefficients of 0.06−0.07 min−1, indicating that the Ag-nanoparticle/ZnO nanostructure had stable and reliable photodegradation efficiency.

Is the electrochemical or the “green chemistry” method the optimal method for the synthesis of ZnO nanoparticles for applications to biological material? Characterization and SERS on ZnO

This work developed ecological procedures for the synthesis of stable, uniform, and pure ZnO nanoparticles for biological and medical applications. Nanoparticles were synthesized on two synthesis pathways: (i.) electrochemical zinc dissolution in a solution free of surfactants (ZnONPs) and (ii.) from banana skin (ZnONPs-GS) by a green synthesis – a cheap method that allows efficient use of waste from plant products. ATR-FTIR, Raman, and UV-Vis confirmed the formation of ZnO nanoparticles. XRD showed a high crystalline hexagonal structure, whereas TEM and DLS confirmed that nanoparticles are pure, well dispersed, and have a rather uniform size and spherical shape. ZnO nanoparticles were evaluated for their ability to adsorb selected amino acids and to promote the SERS effect. SERS spectra on the surface of ZnO nanoparticles were compared with SERS spectra on the surface of Zn. The obtained data show that (i.) with the use of specific marker bands SERS allows us to distinguish between amino acids and to determine the state of zinc surfaces (distinguish between Zn and ZnONPS and ZnONPs-GS), (ii.) ZnONPs-GS obtained from “green chemistry” are more friendly to biological material than those obtained using the electrochemical method because their surface is free from hydroxyl groups, which easily form reactive oxygen species, and (iii.) considering the view in the literature that metal surface type and metal roughness/nanoparticle size influence adsorption, the obtained results supplement the current understanding of amino acid adsorption on various metal surfaces.

Target synthesis of dense C-coated ZnO for advanced lithium storage via a facile and cost-effective approach

Herein, ZnO@C composite is synthesized through a facile, time saving, and ecofriendly chemical vapor deposition approach. Very thin and dense carbon layer is well coated on the surface of ZnO nanoparticles. As anode, the ZnO@C composite delivers a high reversible lithiation capacity of 685 mA h g−1 at 0.2 A g−1 and good rate performance (still high as 225 mA h g−1 at 5 A g−1) together with high initial Coulombic efficiency of ~ 72%, which are much better than that of bare ZnO.

An in-depth study of photocathodic protection of SS304 steel by electrodeposited layers of ZnO nanoparticles

Thin layers of ZnO nanoparticles were deposited potentiostaticly on the surface of stainless steel 304 (SS304) at various potentials (−0.7 V, −1.0 V, −1.3 V, −1.6 V) to study the effect of photo-generated cathodic protection on the substrate. Electrochemical methods of open circuit potential (OCP), potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) were employed to investigate the electrochemical behaviors of ZnO-covered SS304 system (ZnO/SS304) in 3.5 wt% NaCl solution under the conditions with and without UV illumination. It is found that the ZnO nanoparticles deposited at −1.0 V was in the shape of hexagonal nanorods, which caused a negative shift to lowest OCP upon UV illumination. Polarization curves were also performed on ZnO/ITO glass system to reveal the photoelectrochemical behavior of ZnO nanoparticles only. Possible anodic and cathodic reactions on the ZnO/SS304 and ZnO/ITO systems at the absence and presence of light illumination have been analysed and discussed in detail. It is found that traditional Tafel extrapolation of the polarization curves cannot be used to get the free corrosion current density of ZnO/SS304 system under light illumination due to the superposition of photo-generated current density. The charge transfer resistance obtained from EIS also includes the influence from the photo-generated reactions on the ZnO/SS304 system. Long-term immersion of the ZnO/SS304 in NaCl solution indicates that the ZnO nanorods underwent morphological transitions to nanotubes at 5 days and finally to needles and thin plates at 10 days. Correspondingly, the photocathodic protection of the ZnO layer decreases with the extension of immersion time. The transformation in morphology is postulated to be caused by the attack of Cl− ions on the surface of ZnO nanoparticles.

Lifetime and dynamics of charge carriers in carbon-incorporated ZnO nanostructures for water treatment under visible light: Femtosecond transient absorption and photoluminescence study

The fabrication of high performance photocatalysts working under visible light to fully degrade the organic pollutants is one of ultimate goals in environmental applications. We fabricated very high active carbon-incorporated ZnO nanowire-based photocatalyst by a simple low temperature (300 °C) annealing process involved zinc acetate precursor and poly vinyl pyrrolidone (PVP). This novel carbon-incorporated ZnO nanowires decomposed 98% of MB only within 90 min under sun-simulated irradiation. To understand the reason of this high activity, the effect of carbon content on dynamics and lifetime of charge carriers were investigated by Femtosecond transient absorption and Photoluminescence spectroscopy besides using SEM, XRD, UV–vis, BET, and FTIR to probe structural and physical properties. The femtosecond transient absorption spectroscopy revealed that there are four decay components for each of pure ZnO and carbon-incorporated ZnO photocatalyst. The different lifetimes can be assigned for electron-hole recombination at different levels. The fastest component in pure ZnO (τ1 = 50 ps) represents the first stage of recombination of shallow-trapped electrons on the surface of the pure ZnO nanoparticles with holes in the valence band. This component is slower in the case of carbon-incorporated ZnO (τ1 = 90 ps), indicating longer residence time of the electrons in the conduction band. The PL spectroscopy exhibited that interstitial oxygen and interstitial zinc are very abundant in carbon-incorporated ZnO samples and the FTIR spectroscopy showed that fragments of acetate and PVP are responsible for good adsorption of organic pollutants and also surface modification of ZnO surface.

Formation of surface defects by thermal shock method for the improved photocatalytic activity of ZnO nanoparticles

ABSTRACTSurface-modified ZnO photocatalysts with enhanced UVA-light-driven and visible-light-driven activities were synthesized by the thermal shock method with Cu(NO3)2 at different thermal shock temperatures (300 – 600°C). The influences of thermal shock temperatures on the crystal structure, morphology, surface functional groups and surface composition of modified catalysts were investigated by XRD, TEM, Raman and XPS spectra, respectively. Their photocatalytic activity was evaluated via the degradation of methylene blue under both UVA and visible light irradiation. According to the results, by combining the thermal shock method and an agent with low thermal stability such as Cu(NO3)2, we did not modify the crystal structure, phase composition nor the morphology of ZnO nanoparticles, but successfully modified the surface of ZnO nanoparticles with the migration of zinc ions, leading to the creation of new environments of Zn2+ and O2 – ions as well as the formation of surface zinc vacancies. These evolutions were found to be able to enhance the photocatalytic performance in the UVA light region and also in the visible light region.

Study of Time-dependent Interaction of ZnO Nanoparticles with Sucrose and Honey Molecules for Biomedical Applications

Background: Nanoparticles are in the forefront of research due to their unique properties that find possible applications from optoelectronics to medical technology. It is also reported that nanoparticles can interact with the living cells and can selectively destroy the cells. Researchers are thus interested to find a way by which the drugs will be attached to the nanoparticles, go to the target site and destroy the infected cells. Before that, it is very much important to understand the interaction of nanoparticles with the blood, plasma and other biological cells that exists in the blood. It is also very essential to understand how the nanoparticles interact with the absorbed sucrose in the cell. Objective: Our objective in this research is to investigate the interaction of ZnO nanoparticles with sucrose and honey sugar to understand the basic interaction mechanism. It will also enable us to find a way of stabilizing body sucrose and glucose level. Methods: We have followed a simple chemical synthesis method to prepare ultrafine ZnO nanoparticles. Then the interaction of ZnO nanoparticles with sucrose and honey sugar was investigated as a function of time using UV-visible spectroscopy to understand the basic interaction mechanism. Results: Well grown ZnO nanoparticles were found to form of crystallite size ~38 nm. The band gap was calculated from the absorption spectra and was found to be ~ 3.9 eV. This band gap enhancement indicates that the sizes of the nanoparticles are very small. The decrease of absorption with time indicates that the ZnO nanoparticles interact with the sugar molecule. Sucrose molecules are polar. Hence there is electrostatic attraction between the sucrose molecules and ZnO molecules resulting in the sucrose-ZnO composite system. On increasing the interaction time more and more sucrose molecules will cover the ZnO nanoparticles by forming ZnO-sucrose corona. The interaction time constant i.e., the binding time of sucrose molecule with the surface of ZnO nanoparticles, t1 was found to be 27.7127 min and is 29.59 min for honey. The results indicate an association process to form corona of ZnO nanoparticles with sucrose and honey molecules. Conclusion: We have successfully synthesized ultrafine ZnO nanoparticles of high band gap. The synthesized nanoparticles interact with the sucrose and honey molecules and form corona. This study is very important in understanding the interaction mechanism on nanoparticles with the biomolecules for possible drug delivery applications.

Fabrication and characterization of superhydrophobicity ZnO nanoparticles with two morphologies by using stearic acid

In this work, ZnO nanoparticles (NPs) with two morphologies (ZnO nanospheres and ZnO nanorods) were prepared by wet chemical method, and superhydrophobic materials were synthesized by stearic acid modification. The effects of parameters such as time, temperature and molar mass fraction of stearic acid on the superhydrophobic properties of the composites were systematically studied, and the optimal reaction conditions were determined. The microstructure, chemical composition, surface topography, and water contact angle (CA) of the two morphologies of superhydrophobic ZnO materials have been measured by x-ray diffractometer (XRD), fourier transform infrared spectrum (FT-IR), field emission scanning electron microscope (FESEM) and water CA apparatus. The results showed that the hydroxyl groups on the surface of ZnO NPs modified by stearic acid were replaced by carboxyl groups of stearic acid, and existed on the surface of ZnO NPs in the form of coordination adsorption. The hydrophobic group (–CH3) of stearic acid was grafted onto the surface of ZnO NPs, which made it superhydrophobic. By studying the SEM and water CA of two morphologies of ZnO NPs modified by stearic acid, we found that the surface of ZnO nanospheres were easier to form micro-nano rough structure than that of ZnO nanorods, which also reveals the reason why the hydrophobic property of ZnO nanospheres modified by stearic acid was better than that of ZnO nanorods.

Microwave-assisted particle size-controlled synthesis of ZnO nanoparticles and its application in fabrication of PLED device

ZnO nanoparticles were synthesised in diethylene glycol (DEG) with different ZnO molar precursor concentration (1 mmol, 2 mmol, 4 mmol and 8 mmol) in a microwave reactor for 15 minutes up to 250 °C. Zinc acetate dihydrate was used as the precursor for ZnO nanoparticles and oleic acid as a capping agent. It was found that different mmol precursor concentration yielded in different nanoparticle sizes. The crystallinity and particle size was analysed by XRD and the optical properties of the nanoparticles were studied by UV-Vis and PL. Oleic acid forms a layer around the ZnO nanoparticle surface. This layer helps in preparing nanocomposite solution by dispersing the ZnO nanoparticles in MEH-PPV solution. Further, the nanocomposite solution is deposited as a thin-film by spin-coating and this forms the emissive layer of the fabricated PLED device. The diode characteristics were analysed by studying the I-V and EL graphs.

Synthesis of Zn2SiO4@ZnO core-shell nanoparticles and the effect of shell thickness on band-gap transition

A combined sol-gel and annealing method was used for the synthesis of Zinc Silicate-Zinc Oxide (Zn2SiO4@ZnO) core-shell nanoparticles with high bandgap value. First, different thicknesses of ZnSiO3 shell were successfully coated on to ZnO nanoparticle surfaces by varying the Na2SiO3/ZnCl2 precursor concentrations. Then, by applying a relatively low annealing temperature (780 °C), the amorphous ZnSiO3 reacted with ZnO to form crystalline Zn2SiO4 shell. The structure and elements of the core-shell nanoparticles were characterized by TEM, XRD, EDS, and the band gap values were measured by UV–Vis spectroscopy. The Zn2SiO4@ZnO nanoparticles showed mostly spherical core-shell morphology and high band gap value (Eg = 5.5 eV) at high Zn2SiO4 loading, which are promising for semiconductor and luminescent applications.