Surface Of ZnO Nanoparticles Research Articles

Synthesis of Pd-decorated ZnO nanocomposites with improved gas-sensitive properties for acetone detection

ZnO/Pd nanocomposites containing 0.5–3.0 mol.% palladium and possessing improved gas-sensitive properties for VOC’s detection were prepared using solvothermal synthesis. The synthesised powders have been characterised using various methods of physicochemical analysis (DSC/TGA, XRD, SET/TEM, XPS). It is shown that Pd@PdO nanoparticles (4–7 nm in diameter) are localised on the surface of ZnO nanoparticles (40–50 nm in size). According to the combined XRD and XPS data, it was found that palladium is in partially oxidised state, and the nanocomposite has a structure close to "core@shell": Pd@PdO. The influence of palladium concentration in the ZnO/Pd composite on the complex of chemoresistive gas-sensitive properties was studied. It is shown that at 250 °C the obtained nanocomposites demonstrate a high (up to 57.8 a.u.) response to 100 ppb–20 ppm acetone, which can be used as a part of supersensitive devices for noninvasive diagnostics of diseases.

Bio-based materials in tribology: New salicylate ionic liquid+ZnO nanolubricant of PLA and PLA nanocomposite

ZnO nanoparticles have been dispersed (in 0.05; 0.5 and 1.0 wt% proportions) in the protic ionic liquid bis(2-hydroxyethyl) ammonium salicylate (DSa) to obtain new (DSa+ZnO) nanofluids. A non-Newtonian behavior was found for ZnO concentrations lower than 1 wt%. The Newtonian DSa+ 1 wt%ZnO nanofluid was selected as lubricant of polylactic acid (PLA) and as 5 wt% additive to obtain the new PLA+ (DSa+ZnO) nanocomposite. PLA+ZnO was also studied as a reference. The excellent friction-reducing and antiwear behavior of PLA+ (DSa+ZnO) is attributed to the porosity that promotes self-lubrication and to synergy due to interactions between the salicylate anion in DSa and the surface of ZnO nanoparticles. Electron microscopy (SEM and TEM), Raman spectroscopy, thermal analysis (DSC and TGA) and profilometry techniques were used.

Zinc Oxide:Gold Nanoparticles (ZnO:Au NPs) Exhibited Antifungal Efficacy Against Aspergillus niger and Aspergillus candidus

Fungal pathogens are a major health issue that threatens the era of antifungal drugs commonly used in the treatment of infections. An effective approach of biosynthetic nanoparticles can be used as antifungal agents owing to their intrinsic features such as their simplicity, non-toxic, and physicochemical properties. Therefore, this study was aimed to molecularly ascertain Aspergillus species known to cause aspergillosis and investigate the potency of zinc oxide:gold nanoparticles (ZnO:Au NPs) against the fungal pathogens. Two Aspergillus strains retrieved with potato dextrose agar (PDA) culture media from commercial food products in South Africa were molecularly identified using calmodulin (CaM) gene region. DNA sequence phylogeny of the gene showed that the strains were A. niger and A. candidus. ZnO:Au (1%) NPs were synthesised and characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Two distinct peak plasmon bands for ZnO and ZnO:Au NPs were 390 nm and 565 nm, respectively. FE-SEM images demonstrated the presence of Au on the surface of ZnO nanoparticles in the ZnO:Au nanocomposites. The ZnO:Au NPs antifungal activity of 10 µg/mL and 50 µg/mL concentrations were evaluated against the two Aspergillus spp. ZnO:Au NPs at 50 µg/mL exhibited a maximum antifungal activity against A. candidus and A. niger, with zones of inhibition (ZoI) of 31.2 ± 0.15 mm and 25.0 ± 0.06, respectively. When the ZoI was observed by SEM, major morphological damages on the conidia were observed for both strains, indicating that the antifungal activity may have been enhanced by the ZnO:Au NPs. Therefore, due to these outstanding properties, ZnO:Au NPs can be utilised as potential antifungal agents to inhibit the proliferation of fungal pathogens.

Field emission properties of LIG/ZnO heterojunction prepared by ultrafast laser direct writing

The facile in situ synthesis of graphene-coated metal-oxide nanoparticles and their potential applications in optoelectronic devices are highly anticipated. In this study, we prepared three-dimensional graphene flakes decorated with ZnO nanoparticles (LIG/ZnO) using femtosecond laser-induced zinc salt-containing cork. The LIG/ZnO heterojunction was formed by carbonizing the cork and decomposing the zinc salt in situ to coat LIG during laser irradiation. The correlation between the zinc salt concentration and the morphology, structure, and field-emission characteristics of LIG/ZnO was systematically investigated. The optimized LIG/ZnO-5 emitters demonstrate a decreased threshold electric field (Eth) of 1.07 V/μm, an enhanced field enhancement factor (β) value of 20,559, and a maximum current density of 18.07 mA/cm2 at 1.96 V/μm, representing the most superior performance reported to date. The enhanced field-emission performance of LIG/ZnO can be attributed to the larger number of effective emission sites from ZnO nanoparticles and LIG edges, as well as to the energy band variation induced by the heterostructures. Density functional theory (DFT) calculations show the migration of electrons from the LIG to the ZnO after the formation of the heterojunction, which elevates the Fermi level of emitters. In addition, the accumulation of electrons on the surface of ZnO nanoparticles in the presence of a strong electric field results in a downward shift of the energy band, thereby enhancing the likelihood of electron-vacuum tunneling.

Ni-doped ZnO nanoparticles derived by the sol–gel method: structural, optical, and magnetic characteristics

A simple sol–gel route was used for preparation of Ni doped ZnO nanoparticles (Ni:ZnO) with 0, 3, 5, 7 and 9 wt% of Ni to Zn precursor salts. Structural, optical and room temperature magnetic properties were studied. The prevailing structural arrangement that observed in all the examined samples is the wurtzite structure of ZnO. Nevertheless. The orderly development of NiO rock-salt phase on at the surfaces of ZnO nanoparticles upon Ni doping is confirmed by Rietveld refinements. The ZnO wurtzite structure is dominant in all the samples as confirmed by both XRD and Raman results. The average crystallite size showed almost no change upon Ni doping. RTFM behavior is being exhibited for all Ni:ZnO nanoparticles that is demonstrating using of ZnO as the host structure allowed for the efficient formation of DMS. The Near-infrared solar reflectance (RNIR) and the visible solar reflectance (RVis) values reduced with increasing of the Ni content as a result of the rising in density of trap states upon Ni doping of the samples. Kubelka-Munk method was used to determine the energy band gap (Eg) and band Urbach energy (EU) tails from diffused reflectance (DRS) results. The obtained energy gap values were very close in all studied samples with an average value of energy gap is 3.164 eV. The EU values raise from 123 to 173 meV upon increasing of Ni content in the samples in agreement with lower values of RNIR and RVis and their effect on optical performance of the investigated samples in applications.

Synthesis and characterization of ZNO: CU and AG bimetallics nanoparticles by sol gel method

Different weight ratios of Cu-silver-doped and non-doped ZnO nanoparticles were created, By using XRD, FTIR, UV-visible spectroscopy, FESEM, and EDS the presence of nanoparticles in the sol-gel (ZnO) and (ZnO: Ag and Cu) techniques was confirmed, the JCPDS standard card for Zn (01-080-0074) validated the hexagonal ZnO structure by X-ray diffraction for (ZnO) and (ZnO:Ag and Cu). we calculated the average crystal size of all the produced samples, and we observe that the crystal size grows as the ratio of copper and silver doping rises. According to the FTIR data, O-H expansion is responsible for the expected distinctive absorption band in the vicinity of (3090-3665 cm). Because KBr quickly absorbs CO, it is possible that the peaks in the range (1550-1630 cm) are caused by the KBr utilized. These peaks are related to the stretching vibrations of C=O that are symmetric and asymmetric. The stretching vibration of the ZnO bond can be seen in the form of a prominent peak in the (350–780 cm) range. When Ag and Cu are entered to the doped ZnO samples, the peak strength declines, indicating the start of Ag and Cu clusters on the surface of ZnO nanoparticles. The bond position was shifted as a result of alteration in bond length brought about by the substitution of Ag+ ions at the ZnO lattice sites. According to the UV-VIS measurements, pure ZnO has a peak at 370 nm that becomes red at 569 nm. With increasing concentrations of Ag and Cu, the nanocomposites show high absorption in the visible region because the peaks shift monotonously to longer wavelengths and cause the energy gap value to decrease by 3, 2.958, 2.76, 2.74, 2.69, and 2.5 eV, respectively. According to the FESEM data from IMAGE J, the nanoparticles have a spherical or nearly spherical form. Zn, Ag, and Cu elements may be seen in the EDS data.

Investigation of the Lubrication Performance of γ-Al2O3/ZnO Hybrid Nanofluids for Titanium Alloy

Titanium alloys are difficult to machine and have poor tribological properties. This paper investigates the lubricating performance of γ-Al2O3/ZnO hybrid nanofluids for Ti-6Al-4V. Pure and hybrid nanofluids are compared, and the effects of γ-Al2O3/ZnO ratios are studied. The results show that γ-Al2O3/ZnO hybrid nanofluids outperform pure nanofluids in terms of lower friction coefficients and better surface quality. Moreover, the hybrid nanofluid with a mass ratio of Al2O3 to ZnO of 2:1 demonstrates the best lubrication performance with a reduced friction coefficient of up to 22.1% compared to the base solution, resulting in improved surface quality. Al2O3 nanoparticles can adhere to the surface of ZnO nanoparticles and work as a coating, which further enhances the lubrication performance of the water-based nanofluid.

Defect structures and (ferro)magnetism in Zn1-xFexO nanoparticles with the iron concentration level in the dilute regime (x = 0.001 – 0.01) prepared from acetate precursors

Zn1-xFexO nanoparticles with the iron concentrations level in the dilute regime (x = 0.001–––0.01) were produced by a sol–gel route from acetate precursors along with an un-doped and 3 at.% Fe-doped reference. The X-ray diffraction of the un-doped and 0.1–1 at.% Fe-doped samples reveal the reflections for only the ZnO wurtzite structure. Fe doping enhances the a-axis lattice constant, the unit cell volume and the microstrain. Iron doping reduces the average crystallite/particle size (confirmed by Scanning Electron Microscopy), improving the surface-to-volume ratio or the concentration of defective surface sites. XPS identifies the iron in both Fe3+ and Fe2+ states. XPS and 57Fe Mossbauer spectroscopy indicate a broad distribution (distortion) of Fe3+ sites on the surface of ZnO nanoparticles. The blue shift and broadening of the UV emission, and quenching of defect-related photoluminescence in the Fe-doped samples verify the presence of iron in the ZnO lattice and surface intrinsic defects. 0.1–1 at.% Fe-doped ZnO show room temperature ferromagnetism, RTFM, characteristic of dilute magnetic semiconductors, DMS. The magnetization measurements with temperature evidence an antiferromagnetic alignment and an increase of ferromagnetic contribution with Fe doping up to 1 at.%. Zn0.97Fe0.3O reference is a superparamagnetic ZnO/ZnFe2O4 nanocomposite with a blocking temperature of 20 K; HRTEM shows (ultra)fine ZnFe2O4 particles at the surface of ZnO nanoparticles. The analysis of experimental data of 0.1–1 at.% Fe-doped ZnO was done in terms of iron coupling with intrinsic defects, which can generate surface Fe3+ states with geometries similar to the Fe3+ in inverse spinel ZnFe2O4. The superexchange interaction (resembling that in the inverse spinel ZnFe2O4) between the Fe3+ sites with distorted configuration resulting in ferrimagnetism was hypothesised as a possible mechanism of RTFM. Experimental (structural, local chemical, magnetic, optical) and interpretation results can be used to optimize the processing conditions for Fe-doped ZnO to serve as an effective DMS, e.g. for spintronic applications.

Decoration of ZnO surface with tiny sulfide-based nanoparticles for improve photocatalytic degradation efficiency

Modifying wide band gap ZnO nanoparticles surface by combine narrow bandgap semiconductors is a novel route to promote the ZnO to diverse applications. Herein, different metal sulfides (CdS, Ag2S and Bi2S3) were decorated on ZnO surface using facile a chemical route for photocatalytic application. Crystal structure, surface morphology and optical changes for the surface modified ZnO were studied by using various characterization techniques. The XRD spectra exhibited mixed phase of decorated metal sulfide nanoparticles along with strong pattens of hexagonal structure ZnO. The SEM images were confirmed that tiny CdS, Ag2S and Bi2S3 sulfide nanoparticles are well decorated on ZnO hexagonal rods surface. Band gap of the ZnO was tuned into visible region by modifying the surface by the sulfide nanoparticles. Textile industry-based crystal violet (CV) dye was used as a model pollutant to evaluate the photocatalytic activity of sulfides decorated well-crystalline ZnO photocatalysts under natural sunlight. Among the three catalysts, the Ag2S decorated ZnO achieved greatest photodegradation efficiency of 94.1% for degradation of the CV dye with rate constant value of 0.050. The highest catalytic activity may be related to Ag2S acting a significant part in reducing bandgap and boosting hole, superoxide radical, and hydroxyl radical formation, which inhibits recombination, hence enhancing the photocatalyst's efficacy, activity, and also stability.

Influence of the filling ratio of vial in chemical surface and physicochemical properties of ZnO nanoparticles obtained by planetary ball milling process

The production of nanoparticles (Np) is an important sector in current technological development. Processes such as high‐energy grinding are among the most promising because of their high efficiency and low energy cost. In this sense, the filling ratio of vial (FRV) is one of the most interesting and poorly studied process variables that can optimize the production of Np on a large scale. In the present work, dry ZnO Np are produced, with different FRV values (40%, 38%, 23%, and 10%), as well as wet samples. The results show that the variation of the FRV allows to generate an energetic increase of the grinding, modifying the morphology, the particle size, and the surface area of the ZnO powders, without generating structural or chemical changes. The X‐ray diffraction (XRD) results show the presence of the zincite phase (hexagonal) with a variation in crystallinity depending on the FRV, which is due to the deformation of the Np during the process. The XPS results showed a slight chemical shift (variation in binding energy) as a function of grinding because of the activation shown by deformation. UV–VIS analyses showed a marked increase in the magnitude of absorbed intensity for all analyzed samples compared with the commercial powder. These results confirm that FRV is a sensitive parameter in the process of obtaining ZnO Np by the planetary mill technique, which allows efficient control of its characteristics for a given application.

IMPROVING THE PERFORMANCE OF ZNO NANOPARTICLES FOR EOR IN HIGH-TEMPERATURE AND HIGH SALINITY CARBONATE RESERVOIRS

The main challenge of the application of nanofluids for enhanced oil recovery (EOR) in carbonate reservoirs is to maintain colloidal stability under reservoir conditions with high salinity and high temperature. In this study, we address this issue by increasing the stability and hydrophilicity of ZnO nanoparticles by adding TTIP. Adding TTIP on the surface of ZnO nanoparticles results in an increase in the hydrophilic heads in the final product. Then, these nanoparticles are used to coat carbonate rock surfaces to change their wettability. The coated rock plates are obtained by aging them in nanofluids. The modified ZnO-based coatings show to be more effective for wettability alteration purposes compared to the conventional ZnO coating. The un-coated rock plate is strongly oil-wet, where the water and n-heptane droplets contact angles on this surface are 168° and 0°, respectively. After aging the rock samples in nanofluids, superhydrophilic coatings form on the superhydrophobic surfaces. The rock surface before and after treatment, as well as the synthesized nanoparticles, are characterized by scanning electron microscope (SEM), x-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analyses. Results of this study indicate the possibility of using the materials for wettability alteration of oil-wet carbonate rock in the EOR process. The results of core flooding tests demonstrate that the oil recovery enhances significantly through the nanofluid flooding.

Natural sunlight driven photocatalytic performance of Ag/ZnO nanocrystals

Herein, spherical-shaped ZnO nanoparticles of an average size of about 10 nm were successfully synthesized through a soft chemical approach. We further prepared the Ag/ZnO nanocrystals by varying the loaded amounts of metallic silver nanoparticles (1, 3, and 5 wt%) without using any reducing and stabilizing agent. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the transformation of Ag ions into metallic Ag and the interaction between Ag and ZnO nanoparticles. High resolution-transmission electron microscopy (HR-TEM) images revealed that Ag nanoparticles of an average size of about 4.6 nm are present on the surface of spherical ZnO nanoparticles. UV-visible absorption spectra showed that the appropriate amount of Ag loading with ZnO shifted the band gap from UV to the visible region. Photoluminescence spectrum reveals the inclusion of Ag in ZnO and minimizes the recombination of electron-hole pairs. These synthesized Ag/ZnO nanocrystals were investigated for its potential applications in photocatalytic degradation of methylene blue dye under UV and sunlight irradiation and compared their efficiency with pure ZnO. Interestingly, it is seen that ZnO nanocrystals that are UV active become visible active when loaded with 1 and 5 wt% of metallic Ag. ZnO loaded with 1 wt% of metallic Ag completely degraded the methylene blue within 3 h under natural sunlight. Under UV light, 3 wt% of Ag in ZnO exhibits higher photocatalytic performance than the others. Thus, incorporating metallic Ag in ZnO nanoparticles shows excellent photocatalyst performance and recycling capability. Furthermore, the participation of different reactive species in the photocatalysis degradation mechanism was studied using four scavengers and the results indicate that superoxide and singlet oxygen are the dominant reactive species. We report heterostructure of Ag/ZnO nanocrystals and explored their efficiency for photocatalytic degradation of dye under visible light irradiation. • Synthesis of Ag/ZnO nanocrystals without any reducing and stabilizing agent. • Transformation of band gap from UV to Visible by incorporation of appropriate amount of Ag in ZnO. • Excellent photocatalytic performance and recycling capability for degradation of dye under UV and natural sunlight. • These nanocatalysts can be for further use for inhibition of bacteria pathogens.

In-situ polymerization of polycarbazole-zinc oxide nanocomposite: An in silico docking model and in vitro antibacterial biomaterial

The current study focuses on the synthesis of polycarbazole-zinc oxide (PCz/ZnO) nanocomposite and its application as an in vitro antibacterial biomaterial as well as an in silico docking model. The synthesized pristine polymer, polycarbazole (PCz) and its nanocomposite PCz/ZnO were characterized by Fourier transform infrared (FT-IR), Thermo-gravimetry/Differential Thermo-gravimetry (TG-DTG), X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Brunauer-Emmett-Teller (BET), Energy-dispersive X-ray (EDX), Raman and X-ray photoelectron spectroscopic (XPS) techniques. FT-IR, XRD, FE-SEM, and XPS studies revealed that the polymerization of Cz has been successfully achieved on the surfaces of ZnO nanoparticles, indicating the strong interfacial interaction between PCz and ZnO nanoparticles. However, TG-DTG studies revealed that the nanocomposite, PCz/ZnO, proved thermally more stable compared to the pristine polymer, PCz. Further, the pristine PCz and PCz/ZnO nanocomposite were evaluated for antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. The nanocomposite PCz/ZnO showed the highest zone of inhibition against K. Pneumoniae (17 mm), followed by P. aeruginosa (16 mm), then S. aureus (14 mm) and E. coli (19 mm) at 80 mg ml−1. Significantly, the in silico molecular docking predicts the modes of interactions of PCz and PCz/ZnO with B-DNA. Briefly, the results obtained from in silico molecular docking studies of the pristine PCz and PCz/ZnO nanocomposite with negative free binding energies (-7.1 kcal mol−1 of PCz and −6.23 kcal mol−1 of PCz/ZnO) imply an excellent and favourable binding affinity vis-à-vis interaction modes of both pristine PCz and PCz/ZnO nanocomposite (drugs) with B-DNA bases (target).

Enhancing the structural, optical and electrical conductivity properties of ZnO nanopowders through Dy doping

• Doping ZnO nanopowders with different Dy percentages was successfully achieved with the co-precipitation method. • XRD analysis reveals a decrease in the lattice parameters and cell volume of the ZnO lattice due to stress relaxation induced by the formation of Dy 2 O 3 secondary on the surface of the nanoparticles. • Crystalline quality was improved on Dy doping. • The optical band gap was decreased on Dy doping where the disorder increased. • Electrical conductivity of ZnO was enhanced by increasing Dy doping concentration up to an optimum doping concentration of 4% and then lowered significantly. In this work, pure ZnO and Dy-doped ZnO nanopowdres (NPs) with varying doping concentration of Dy from 1 to 5 % were successfully synthesized by the co-precipitation method. The effect of Dy doping on the structure, morphology, optical and electrical conductivity of ZnO has been studied. XRD analysis shows that Dy-doped ZnO nanostructures exhibit primary wurtzite structure and a cubic Dy 2 O 3 secondary phase. The average crystallite sizes were found to be 20.14 nm for pure ZnO and in the range of 24–33 nm for Dy-doped NPs. Crystallite size of Dy-doped ZnO NPs increases with increasing Dy concentration from 1 % to 3 % and then decreases as Dy increases. The decrease in crystallite size was explained by the formation of Dy - O - Z n bonds on the surface of ZnO. Lattice parameters ( a and c ) and unit cell volume ( V ) decrease as Dy content is initially increased up to 2 % then increase for further increase in Dy content. The initial decrease in a , c and V is due to strain relaxation stresses resulting from the formation of Dy 2 O 3 secondary phase. FTIR spectra indicate the formation of the secondary phase and confirm the successful incorporation of Dy 3 + ions into Zn 2 + sites in ZnO structure. Optical band gap of pure and Dy-doped ZnO nanoparticles was evaluated from diffuse reflectance spectroscopy (DRS) spectra and found to be reduced in Dy-doped samples. Optical band gap decreases from 3.269 eV to 3.226 eV for the 1 % Dy-doped sample then increases on further increasing Dy concentration up to 4 % (3.252 eV) and slightly decrease again at 5 % (3.247 eV). PL emission spectra of Dy-doped samples, show the enhancement of the orange-red emission and the appearance of emission band at around 580 nm which may be assigned to the electrical dipole transition of Dy 3 + ions. The electrical conductivity was enhanced by increasing Dy concentration up to an optimum doping concentration of 4 %, then decreases significantly due to scattering of charge carriers caused by the excess of the secondary phase on the surface of ZnO nanoparticles.

Surface engineering of ZnO nanoparticles with diethylenetriamine for efficient red quantum-dot light-emitting diodes

SummaryDue to the outstanding electron injection/transport capability of ZnO nanoparticles (NPs), quantum-dot light-emitting diodes (QLEDs) are commonly constructed by employing a hybrid device structure with ZnO electron-transporting layer and organic hole-transporting layer. However, the emission quenching of quantum dots and excessive electron injection induced by ZnO NPs also limits the device efficiency and operational stability. Here, diethylenetriamine (DETA) molecules as the ligands are introduced to modify the surface of ZnO NPs, which not only passivate the surface defects of ZnO but also suppress the overwhelming electron injection in the QLED. As a result, the device based on the DETA-modified ZnO NPs exhibits a peak external quantum efficiency of 23.7%, corresponding to an enhancement factor of 129% in comparison with that of the device with as-synthesized ZnO as the electron-transporting layer. The easy and feasible strategy may also be applicable to other photoelectric devices, such as solar cells and photodetectors.

UV-shielding and strong poly(vinyl alcohol) composite films reinforced with zinc oxide@polydopamine core-shell nanoparticles

Zinc oxide@polydopamine (ZnO@PDA) core-shell nanoparticles (NPs) were prepared by depositing PDA on the surface of ZnO NPs via the self-polymerization of dopamine (DA) in alkaline solution. It was found that ZnO@PDA exhibits lower photocatalytic activity and higher UV absorbance than pure ZnO. Moreover, ZnO@PDA NPs could be homogenously dispersed in poly(vinyl alcohol) (PVA) matrix and form strong hydrogen bonding interaction with PVA molecular chains. As a result, the prepared PVA/ZnO@PDA composite films display excellent UV-shielding, mechanical and anti-UV aging properties. Particularly, the PVA composite film added with 2.0 wt% ZnO@PDA is able to shield 96.1% UV irradiation (200–400 nm) and exhibits superior tensile strength (66.3 Mpa) than pure PVA film. Moreover, the result of UV aging tests indicate that ZnO@PDA also give a positive effect on the UV stability of PVA matrix, while PVA/ZnO composite film shows serious degradation. This work proposed a facile and rational strategy to design the ZnO-based UV-shielding agent with reduced photocatalytic activity and enhanced UV absorbance, which may provide an inspiration to construct high performance UV-shielding composites.

High‐Efficiency Adsorptive Removal of Phenol from Aqueous Solution Using Natural Red Clay and ZnO Nanoparticles

AbstractPhenol, a highly toxic compound, is a common hazardous chemical. Hence, eco‐friendly and cost‐effective technology for phenol elimination is required. The present study presents a comprehensive study to eliminate phenol compounds via an adsorption technique using ZnO nanoparticles and natural red clay as adsorbents. X‐ray diffraction (XRD), X‐ray fluorescence (XRF), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and Burnauer‐Emmett‐Teller (BET) analyses were conducted for adsorbent surfaces characterization. The impacts of various effects, such as pH and the adsorbent dose on the phenol removal efficiency are described. The results reveal that both ZnO and clay adsorbents removed 99.4 % of phenol at the optimum adsorbent dose of 0.6 g\L and 1 g\L with pH 8 and 2, respectively. The isotherm adsorption data for phenol fitted into Langmuir for the two adsorbents. Yet, the ZnO nanoparticle surface showed a higher capacity (342.72 mg\g) than the natural clay surface (84.01 mg\g). ZnO nanoparticles removed phenol from polluted water at a smaller dose (0.6 g\L) than natural clay (1 g\L). In conclusion, the two adsorbents showed high efficiency in the phenol compound removal.

Structural, morphological, optical and electrochemical characterization of Ag2O/ZnO and ZnO/Ag2O nanocomposites

In this paper, well-crystalline Ag2O/ZnO and ZnO/Ag2O nanocomposites were prepared by a facile chemical method. Structural, morphological and optical properties of the nanocomposite were studied using various advanced characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), UV-Visible (UVVis) and photoluminescence (PL) spectroscopy. The Ag2O and ZnO were clearly identified in the composite from SEM and TEM. Significant shifting observed in the both UV-Vis and PL spectroscopy. In addition, electrocatalytic activity of the Ag2O/ZnO and ZnO/Ag2O nanocomposites studied by an electrochemical workstation. The ZnO/Ag2O nanocomposites showed better optical and electrochemical properties due to decorating the low-band gap Ag2O on the surface of hexagonal structure ZnO nanoparticles.

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.