ZnO Composites Research Articles

Synthesis and Characterization of Poly(2-vinylpyridine) and Poly(4-vinylpyridine) with Metal Oxide (TiO2, ZnO) Films for the Photocatalytic Degradation of Methyl Orange and Benzoic Acid.

In this study, composite material films of pyridine-based polymer and metal oxides (ZnO and TiO2) were successfully deposited by spin coating method for environmental remediation. Firstly, the polymers poly(2-vinylpyridine) P(2-VP), and poly(4-vinylpyridine) P(4-VP) were synthesized via solution polymerization. The analysis by grazing incidence X-ray diffraction (GIXRD) reveals semicrystalline nature and scanning electron microscopy (SEM) indicates that the poly(vinylpyridines) clusters of particles were observed on the surface of the films. It was also shown that the morphology of composite materials is completely dependent on the chemical nature of the oxide. In the case of P(2-VP)-TiO2 and P(4-VP)-TiO2, some channels or pathways of TiO2 on the surface of films were observed. However, the surface morphology of the polymer composites formulated with ZnO shows a homogeneous distribution in P(2-VP) and P(4-VP) matrix. The effectiveness of the composite materials in the photodegradation of methyl orange (MO) was evaluated by photocatalysis. According to the results, the P(4-VP)-ZnO composite exhibited the highest photodegradation of MO, allowing the separation of photogenerated species required for the photocatalytic reaction. The P(4-VP)-ZnO composite was also tested in benzoic acid (BA) photodegradation in water. The presence of some scavengers in the reaction system reveals that hydroxyl radicals (OH•), superoxide radicals (O2-•) and holes (h+) are responsible for the BA reduction by photocatalysis.

Designing of visible light active composites of CuS and ZnO for improved photocatalytic performance under solar light irradiation

Organic pollutants are considered to be very dangerous because of their bio-accumulative nature. They are responsible for many devastating diseases and environmental problems. Semiconductor photo catalysis being economic, non-toxic and sustainable technology exhibits great potential for removal of these pollutants. ZnO/CuS nanocomposites were fabricated by using template free hydrothermal route. XRD patterns confirm the successful fabrication of the composite. The morphology of prepared samples is explored through field emission scanning electron microscopy. UV–vis spectroscopy results indicate that samples of ZnO achieved visible light active upon composite formation, which not only reduces the bandgap but also retards the recombination time. The photocatalytic activity of ZnO is evaluated using methyl orange as a model pollutant. ZnO/CuS composite shows enhanced photocatalytic degradation ability as compared to pristine ZnO and CuS.

Visible light-activated ethanol sensor based on flower-like N3-loaded ZnO composites

Flower-like ZnO materials loaded by different amount of N3 dye were successfully synthesized via a facile one-step hydrothermal method. Several characterization techniques were applied to analyze the compositional, structural and morphological information of the products, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV−vis spectrophotometer (UV–vis). Ethanol sensing properties of sensors were tested for the N3-loaded ZnO composites under various light illumination conditions. Unusually, the sensor based on 0.10 wt. % N3-loaded ZnO exhibits the higher response, lower detect limit, shorter response time and more outstanding selectivity under green light illumination in comparison to those of sensors loaded with other N3 concentration as well as sensors illustrated by UV light or in dark condition. This study demonstrates that dye loading is an efficient and promising route in the development of high-performance gas sensors based on wide-band gap semiconductors with visible light irradiation.

Novel cubic heterojunction Fe2O3/ZnO composite for the photocatalyst application

Dye Sensitize Solar Cell (DSSC) gained attention as a replacement for silicon solar cells owing to operational and economic benefits. This study aims to synthesize the Fe2O3/ZnO composites using two different methods; Hydrothermal-calcination (HTC) and Hydrothermal (HT) method. The prepared samples structural properties were analysed using XRD, SEM/EDX, BET, FTIR, and TGA. It was found that the HT-Fe2O3/ZnO composite had a lower crystalline peak with a higher specific area of 34.855 m2/g than HTC-Fe2O3/ZnO composite as the formation of ZnO and Fe2O3 was well hybrid structure via atomic substitution mechanism. The particle characterization of HTC-Fe2O3/ZnO showed that Fe2O3 surrounding ZnO and had the composition of Fe, Zn and O of 16.71 wt%, 62.90 wt% and 20.39 wt%, respectively. HT-Fe2O3/ZnO showed a cubic structure with higher content ot Fe (47.63 wt%), lower content of Zn (34.89 wt%) and O (17.48 wt%). Both composites prepared from HT and HTC methods attained high absorbency in the ultra-violet and visible range, advantageously HT-Fe2O3/ZnO exhibits better absorbance in the visible light range, thus, resulting in a band gap energy is lower to 2.98 eV. Therefore, HT-Fe2O3/ZnO material is recommended for DSSC to achieve higher performance.

Structural, optical, morphological and electrochemical properties of ZnO and graphene oxide blended ZnO nanocomposites

A simple cost-effective co-precipitation method was adopted to prepare ZnO nanoparticles from a metal organic framework. The synthesized ZnO nanoparticles were blended with graphene oxide (GO) to prepare the ZnO-GO nanocomposite. The physicochemical properties of ZnO nanoparticles and ZnO-GO nanocomposite were analyzed via various techniques. The structural behavior of ZnO and ZnO-GO nanocomposite was studied by XRD and FT-IR analysis. The XRD profile confirms the hexagonal structure with an average crystallite size of 19.4 nm for ZnO and 16.2 nm for ZnO-GO nanocomposites. The functional groups and the vibration modes of the samples were examined through FT-IR. It confirms the metallic presence in the ZnO and ZnO-GO samples in the wavenumber range of 400–600 cm−1. The optical properties of ZnO and ZnO-GO were studied via UV–vis spectra. The surface morphology of the samples was recorded through FESEM, and the elemental presence in the samples was examined by EDX. It confirms that the prepared samples are spherical in shape with uniform size distributions. Cyclic voltammetry has been used to study the redox behavior of electroactive ZnO and ZnO-GO composites.

Electrochemiluminescence detection of Cu2+ ions by nitrogen-doped carbon quantum dots and zinc oxide composites

In this study, nitrogen-doped carbon quantum dots and ZnO (N-CQDs/ZnO) composites were prepared to improve the electrochemiluminescence (ECL) performance of carbon quantum dots (CQDs) for detecting copper ions. Nitrogen-doped carbon quantum dots (N-CQDs) were prepared by a pyrolysis method using glucosamine as a carbon source and urea as a nitrogen source. In addition, N-CQDs/ZnO composites were prepared using zinc acetate in the same way, and they were characterized by the ECL method. The ECL performance of composite ZnO materials with paper-based modified electrodes improved, and the principle of signal enhancement of the N-CQDs/ZnO composite material was demonstrated. The paper electrode was modified with the composite material to detect copper ions via the quenching reaction. The results show that the sensitivity and detection limit (6.13 × 10−9 M) of the paper ECL sensor improved across a wide linear detection range (1.0 × 10−8–1.0 × 10−3 M). Therefore, N-CQDs/ZnO composites prepared by this method have potential applications in ECL signal amplification.

Fabrication of amorphous carbon-based zinc oxide for efficient capture of intact Microcystis aeruginosa: Lysis in sedimentation process

The membrane integrity of harmful algae remains a major challenge for the safe and effective control of cyanobacterial blooms in drinking water sources. In this study, we used novel amorphous carbon-based ZnO (C@ZnO) nanoparticles to efficiently remove intact Microcystis aeruginosa cells. Different carbon-based ZnO composites were compared and characterized using XRD, Raman spectra, SEM, TEM, EDS, XPS and N2 adsorption/desorption. The results revealed that a high cyanobacterial cell capture efficiency was obtained by C@ZnO nanoparticles without damaging membrane integrity. The removal efficiency for cell density, OD680, and chlorophyll-a reached 98.4 ± 0.87%, 90.9 ± 1.04%, and 99.5 ± 0.39%, respectively, with the addition of 4.0 g L−1 C@ZnO in 19 min. The viability of algal cells was observed through K+ release, dissolved organic carbon release, and extracellular organic matrices during the removal process, thereby revealing the integrity of the cell structure. The optimal conditions (ZnO quantity of 333.80 mg and C@ZnO dosage of 3.48 g L−1) were verified via response surface methodology. The intracellular organic matter was released on day 2, although the floc could effectively adsorb part of the algal organic matter (AOM) released. This study developed novel amorphous C@ZnO nanoparticles materials for rapidly capturing intact cyanobacterial blooms to avoid secondary pollution and rovided theoretical guidance that the sludge should be quickly treated during cell removal using C@ZnO.

Au-modified spindle ZnO for high efficiency H2 sensors

With the rise of H2 production from water electrolysis, H2 fuel cell and other H2 industry, the development of H2 detection equipment is urgent. In this work, fusiform ZnO sensitive material was synthesized by hydrothermal and photodeposition method, and Au nanoparticles were loaded on its surface by photodeposition method. The size and length of the synthesized samples are about 1 μm and 5 μm, and Au nanoparticles are evenly distributed on the surface. The XRD, FESEM, TEM and XPS characterizations of the Au-loaded ZnO (AZO) composites were collected to investigate their compositions and structures. The as-synthesized materials were applied to fabricate sensors to study their gas sensing performance. After Au modification, the H2 sensing performance of the sensitive material is enhanced obviously. The response of AZO (Au-loaded ZnO) to 100 ppm H2 at 230 °C is 37.6, which is 4.5 times higher than that of pure ZnO. In addition, the cross response of AZO based gas sensor to different gases was evaluated, and its sensing performance was tested for one month. The results show that AZO sensitive materials have good selectivity and long-term stability for H2.

DFT based comparative study of pristine gCN and gCN-ZnO composite as a sensor for CO and CO2 gases

• Graphitic carbon nitride and ZnO composite (gCN-ZnO) is reported for CO and CO 2 sensing. • CO and CO 2 shows strong interaction with gCN-ZnO composite as compare to pristine gCN. • Adsorption energy for gCN-ZNO is −11.03 eV and −16.61 eV for CO and CO 2 respectively. • The adsorption energy for gCN-ZnO composite are 8 times (CO) and 12 times more (CO 2 ) than pristine gCN. In the present study sensing behavior of pristine gCN and gCN-ZnO composite towards CO and CO 2 gases has been analyzed using DFT. Structural and electronic properties such as adsorption energy, band structure and density of states (DOS) have been investigated. The study reveals that the sensing performance of gCN is enhanced by incorporating ZnO and hence gCN-ZnO composite is a better material for CO and CO 2 gas sensing.

Zinc additions in calcium phosphate system. Phase behavior, microstructural and mechanical compatibility during sequential heat treatments

The study investigates the structural and mechanical stability of the calcium phosphate - ZnO composites during sequential heat treatments. The composites were synthesized through a solution based co-precipitation technique by varying the precursor concentrations. The characterization results infer the Zn2+ insertion in calcium phosphate and moreover the isostructural phase of β-Ca3(PO4)2 → Ca19Zn2(PO4)14 is preserved until 1300 ℃. The upsurge in Zn2+ concentration ensure the presence of apatite trace at 1300 ℃. Zn2+ inclusion tends to the alter the calcium phosphate structure, mainly by delaying the allotropic β → α-Ca3(PO4)2 conversion until 1300 ℃. Zn2+ prefers to accommodate at Ca2+(4), and Ca2+(5) sites of Ca19Zn2(PO4)14 lattice, while the Zn2+ ions exceeding the saturation limit crystallize as ZnO. The structural distortion of PO4 bands due to the inclusion of Zn2+ concentration is verified from FTIR and Raman results. Zn2+ play a crucial role in the microstructural features and density of the resultant calcium phosphate system thus displaying the constant distribution of grains and resilient solidity in the system. Low ZnO content tends to boost the Youngs modulus and hardness while an inverse trend is noticed in case of high ZnO content.

Green Production and Interaction of Carboxylated CNTs/Biogenic ZnO Composite for Antibacterial Activity

Using biomolecule-rich plant extracts, the conversion of metal ions to metal oxide nanoparticles via abiogenic approach is highly intriguing, environmentally friendly, and quick. The inherent inclination of plant extracts function as capping agents in the insitu synthesis. In this study, biogenic zinc oxide nanoparticles (ZnO−NPs) were synthesized using an aqueous leaf extract from Moringaoleifera. The ZnO−NPs were then mixed with carboxylated carbon nanotubes (CNTs) to create a carboxylated CNTs/biogenic ZnO composite using asol–gel method. The CNTs/ZnO composite displayed 18 mm, 16 mm, and 17 mm zones of inhibition (ZOI) against Bacillus cereus, Pseudomonas aeruginosa, and Escherichia coli, respectively. In contrast with ZnO−NPs, the produced carboxylated CNTs/ZnO composite demonstrated a 13 percent elevation in ZOI as antibacterial activity against Bacillus cereus ATCC 19659, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853. The characterization of ZnO−NPs and the carboxylated CNTs/ZnO composite were performed via FTIR, UV/Vis spectroscopy, SEM, and XRD. The XRD pattern depicted a nano−sized crystalline structure (Wurtzite) of ZnO−NPs and a carboxylated CNTs/ZnO composite. The current work comprehends a valuable green technique for killing pathogenic bacteria, and gives fresh insights into the manufacture of metal oxide composites for future research.

Polyimide/ZnO composite cooperatively crosslinked by Zn2+ Salt-Bondings and hydrogen bondings for ultraflexible organic solar cells

High power conversion efficiency (PCE), operational stability and low cost are essential for the commercial application of ultraflexible organic solar cells (OSCs), but it is still challenging to realize these purposes simultaneously. Here, a high-performance polyimide (PI)/ZnO composite (PI-ZnO) was prepared via introducing ZnO nanocrystals to an elaborately designed PI with both hydrogen bondings and abundant carboxyl groups (PI-COOH), where the fabrication cost of the PI-COOH was reduced by using common solvent under air atmosphere. With the UV absorption of ZnO nanocrystals, Zn2+ salt-bondings (formed via carboxyl ligand exchanges) and strong hydrogen bondings integrated in the single material, the PI-ZnO showed outstanding solvent-resistant, mechanical, thermal, and UV filtering properties. An untraflexible OSC with an optimal PCE of 13.55 % (average of 13.42 %) was constructed based on the AgNWs semi-embedded ultrathin flexible transparent composite electrode (FTCE, ∼ 6 μm). The ultraflexible OSC showed outstanding mechanical stability (PCE decreased by less than 5 % after 4000 bending cycles at a small bending radius of 1 mm) and superior UV light stability (PCE decreased by only ∼3 % after UV light irradiation for 6 h). This work would provide a new approach for fabricating high-performance, stable and low-cost ultraflexible OSCs.

Interfacial charge transfers and ultrafast nonlinear optical response via constructing electronic structure-induced MoS2/ZnO heterostructure

The molybdenum disulfide (MoS 2 ) and ZnO composite system have reported as micro-nano photonic crystals in integrated optics. Based on interface engineering, their tunable nonlinear absorption (NLA) and photoelectric characteristics offer a flexible design strategies for saturation absorber and optical limiters. Nevertheless, the mechanism leading to the tunable NLA behavior has not been clearly elucidated, which were attribute to complex charge transfers and carrier regulation characteristics. In this article, MoS 2 /ZnO heterostructures with excellent nonlinear properties composed of ZnO nanorods (NRs) wrapped with MoS 2 nanosheets were prepared by magnetron sputtering (MS) synthesis of MoS 2 on highly stacked ZnO NRs. The MoS 2 /ZnO heterostructures exhibit an interesting brush-like morphology with abundant heterointerfaces base on optimizing sputtering time and temperature, which was beneficial to provide efficient charge transfer pathways. Due to the uneven distribution of the lowest nucleation free energy, MoS 2 nanosheets possess a hybrid mode of parallel (C // ) and perpendicular orientations (C ┴ ) on surface of ZnO NRs, which tends to form the bending and vertical growth of layered MoS 2 nanosheets. From electron-photon coupling effect, MoS 2 nanosheets, ZnO NRs and MoS 2 /ZnO heterostructures possess favorable saturation absorption (SA), reverse saturation absorption (RSA) and coexisting absorption behavior, respectively. In addition, a changeover from RSA to SA could be realized in MoS 2 /ZnO heterostructures by increasing the sputtering time. The NLA coefficient of MoS 2 /ZnO heterostructures are in the order of 10 −10 cm/W, which are about 2 times larger than those of the ZnO NRs. Thus, the MoS 2 /ZnO heterostructures with excellent NLA properties will be promising candidates in optoelectronic devices. • The interfacial charge transfers and carrier regulation characteristics of MoS 2 /ZnO composite have been studied. • The ultrafast nonlinear optical properties of MoS 2 /ZnO composite were analyzed. • The mechanism of growth and nonlinear absorption for MoS 2 /ZnO composite is analyzed.

Significant butanol gas sensor based on unique Bi2MoO6 porous microspheres and ZnO nanosheets composite nanomaterials

The heterostructure of metal oxide and other materials is one of the important ways for the development of electronic devices. The Bi 2 MoO 6 (BMO)/ZnO composites were synthesized by secondary hydrothermal method. The morphology and crystal structure of the compound were characterized by scanning electron microscopy, EDS mapping, X-ray photoelectron spectroscopy, transmission electron microscopy, nitrogen physical adsorption and X-ray diffraction. The synthesis technology and gas sensitivity of BMO and BMO/ZnO composites were discussed. The results showed that BMO and BMO/ZnO had better butanol gas sensitivity, faster response rate, lower working temperature, and good stability. Compared with methanol, benzene, methyl alcohol, ethanol, and acetone, BMO/ZnO sensor showed good selectivity to butanol at 270 ℃. The response time and recovery time for 100 ppm butanol were about 6 s and 33 s, respectively, the response value up to 128. The n-n type BMO/ZnO composites with unique microstructure has abundant diffusion channels, and the research work provides a valuable reference for the low-cost preparation of high-performance butanol sensors. The energy band, potential barrier and charge transfer of BMO/ZnO composites are discussed, and the optimization of their gas sensitivity is analyzed in detail. • The three-dimensional porous nanospheres Bi 2 MoO 6 were successfully synthesized. • The Bi 2 MoO 6 /ZnO composite were synthesized by hydrothermal method. • The Bi 2 MoO 6 /ZnO composite were employed as gas sensor for the detection of butanol gas.

Flower-like metal oxide composite as an efficient sulfur host for stable and high-capacity lithium-sulfur batteries

The major factors of the sulfur host are the high sulfur loading, ability to relieve the volume change, inhibition of the shuttle effect and electric conductivity for lithium-sulfur (Li–S) batteries. To improve the electrochemical performance of Li–S batteries in terms of specific capacity and steady cycling, a significant amount of time and effort has been paid to investigate in the search for new hosts. Because of their capability to prevent the shuttle effect and control the deposition of lithium sulfides, metal oxide materials have been the subject of substantial research and development in relation to their application as sulfur hosts in Li–S batteries. In this study, an advanced type of lithium-sulfur battery called a NiO–ZnO composite was used as a suitable sulfur host (NiO–ZnO/S). A high initial reversible capacity of 1326 mAh g−1 was achieved in NiO–ZnO/S at 0.1C, and the sulfur loading was 73.8 ​wt%. In addition, a great improvement in cycling stability in NiO–ZnO/S (77.6% capacity retention was maintained after 400 cycles at 0.2C) and rate performance (662 mAh g−1 at 5C) were achieved, benefiting from the strategy of anchor function from metal oxide composite (strong adsorption via physical and chemical interactions) and the unique flower-like structure of NiO–ZnO (relief of the volume change).

Electrically Conductive and Antimicrobial Agro-Food Waste Biochar Functionalized with Zinc Oxide Particles.

Carbonaceous materials derived from biomass have been used as sustainable platforms for the growth of ZnO particles aiming the production of functional composite fillers. Kidney-bean pods were pyrolyzed by applying an experimental design that demonstrates that the specific surface area (SBET) of biochar is improved with increasing pyrolysis temperature combined with a short air-oxidation time. Meanwhile, the graphitization degree and the electrical conductivity (EC) of biochars were negatively affected by increasing the air-oxidation time. The biochar sample with the higher EC and the one with the higher SBET were selected to be functionalized with ZnO particles by a solvothermal methodology, obtaining composites with an EC and SBET properties superior to the ZnO-rGO composite, in addition to a similar antibacterial activity. The developed ZnO-biochar composite structures, which are more ecological and biocompatible than the ZnO composites derived from graphene sheets, can be applied as electrically conductive and active fillers.

Depollution of Synthetic dyes From Waste Water Using Polyazomethine/TiO2 And Polyazomethine/ZnO Nanocomposites Via Photocatalytic Process

<p>We propose a simple method for synthesising Poly(azomethine), ZnO, TiO2, poly(azomethine)/TiO2, and poly(azomethine)/ZnO nanocomposites using an ultrasonication process, as well as the use of these nanomaterials for photocatalytic degradation of organic dyes (Methylene blue (MB), malachite green (MG), Bismarck brown (BB), alizarin red S (ARS), and (MO). Our findings show that precise control and optimization of ambient factors in the presence of natural sunlight can result in efficient tailoring of poly(azomethine)/TiO2 (PNT) and poly(azomethine)/ZnO (PNZ) nanocomposites. Compared to Poly(azomethine), ZnO, TiO catalysts, the PNT and PNZ composites exhibit better photocatalytic activity for MB, MG, BB, ARS, MO degradation, which could be attributed to the formation of special catalytically active structures on the nanocomposite surface. The synthesized PNT and PNZ composites had the maximum catalytic activity under circumstances of 500 mg photocatalyst dose, 5 h of sunlight exposure and 10 ppm dye concentrations. Under ideal conditions, MB degrades at a rate of 97 % after 5 h of sunlight exposure. The composites demonstrated selective dye degradation and have greater photocatalytic effectiveness for cationic dyes. This research could lead to the simple development of a high photocatalysts for the rapid removal of ecologically harmful dyes from aqueous solutions.</p>

High-energy ball milling synthesis of N-doped graphite/PbO and ZnO composites for lead-acid battery application

High-energy ball milling synthesis of N-doped graphite/PbO and ZnO composites for lead-acid battery application

Influence of nanofiller concentration on polypropylene nanocomposites for high voltage cables

Abstract Polymeric insulation for HVDC cable is attracting more attention in the modern power transmission system. Especially, the thermoplastic material is desirable for power cable insulation because of its recyclability and ease of processing. Thermoplastic material development is a good alternative to cross-linked polyethylene in the future. Polypropylene has the advantage of avoiding by-products during cable production, which can minimize space accumulation and degassing costs. Therefore, this study investigates the influence of nanofillers on the structural properties of isotactic polypropylene. In addition, the proposed composite material’s morphology, melting, dielectric permittivity, and breakdown strength are examined. Different weight percentages of inorganic nanofillers such as TiO2 and ZnO are used to make nanocomposite thin films. With increasing filler concentration, the dielectric constant of the nanocomposite thin film increases. Apart from that, the dielectric loss of the TiO2 nanocomposite thin film increases with weight percentage initially and it falls nearer to virgin material at a higher frequency. The breakdown strength of the nanocomposite materials shows a similar variation with filler concentration. TiO2 is more resistant to deterioration than ZnO composite. Based on the results of the complete investigation, the TiO2 nanocomposite is better suited for the insulation of HVDC cables.

Fe-doped MOF-derived N-rich porous carbon nanoframe for H2 S cataluminescence sensing.

Metal-doped porous carbon matrix composites are considered as outstanding H2 S cataluminescence sensing materials for their good sulfur tolerance and high cataluminescence activity. In this work, an Fe-doped MOF-derived N-rich porous carbon nanoframe was successfully fabricated using the pyrolysis of Fe-doped ZIF-8 in an Ar atmosphere at a temperature of 900°C, and used for H2 S cataluminescence sensing. Along with zinc volatilization, the obtained porous carbon nanoframe not only had high specific surface area and abundant voids, but also had well dispersed Fe species doped in the skeleton. Compared with Fe2 O3 /ZnO composites derived from the same precursor but different pyrolysis terms, this as-prepared Fe-doped N-rich porous carbon presented a three times increase in the cataluminescence intensity towards H2 S, attributed to the porous carbon skeleton that is indispensable for dispersing catalytic active sites and providing more absorptive surface and voids. Comparably, this proposed sensor demonstrated high sensitivity and good selectivity, with the detection range of 1.57-19.58 μg·ml-1 and detection limit of 0.13 μg·ml-1 towards H2 S. This work may provide a new pathway for preparing catalysts for cataluminescence sensing with better metal distribution, higher specific surface area, and richer pores than ever before.