CuO ZnO Research Articles

A Copper(I) oxide-zinc oxide nano-catalyst hybrid: Brief characterization and study of the kinetic of its photodegradation and photomineralization activities toward methylene blue

In this study, as-prepared coupled copper(I) oxide-zinc oxide (Cu2O–ZnO) nanoparticles were briefly characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), diffuse reflectance spectroscopy (DRS), and scanning electron microscope/energy-dispersive X-ray methods, followed by testing their photocatalytic activity toward the photodegradation and photomineralization of methylene blue (MB). The cubic phase of Cu2O and the hexagonal wurtzite ZnO crystallite phases were detected in the XRD pattern of the nano-composite. In addition, the average crystallite sizes of 22.15, 11.11, and 17.85 nm, as well as 46, 35, and 61 nm were estimated for the as-prepared ZnO, Cu2O, and Cu2O–ZnO samples by the Scherrer and the Williamson-Hall equations, respectively. Further, the bandgap energy (Eg) values of 3.12, 2.23, and 2.29 eV were obtained for the above-mentioned samples corresponding to their absorption-edge wavelengths of 398, 555, and 541 nm, respectively. Based on the findings, FTIR confirmed the synthesis of cubic Cu2O crystals during the synthesis procedure. Furthermore, direct photolysis and surface adsorption processes removed 1.7 and 2% of MB while the photodegradation process by ZnO, Cu2O, and Cu2O–ZnO simultaneously removed 35.1, 50.1, and 78.0% of MB molecules, respectively. The coupled system with the Cu2O:ZnO mole ratio of 1:2 showed the highest activity. Finally, the rate constant values of 0.0198 and 0.0192 min-1 corresponding to the t1/2 values of 35 and 36.1 min were obtained for MB photodegradation and photomineralization, respectively.

Catalytic Electrochemical Water Splitting Using Boron Doped Diamond (BDD) Electrodes as a Promising Energy Resource and Storage Solution

The present study developed a new system of electrochemical water splitting using a boron doped diamond (BDD) electrode in the electrochemical reactor. The new method assessed the electrical current, acidity (pH), electrical conductivity, absorbance, dissipation, and splitting energies in addition to the water splitting efficiency of the overall process. Employing CuO NPs and ZnO NPs as catalysts induced a significant impact in reducing the dissipated energy and in increasing the efficiency of splitting water. Specifically, CuO NPs showed a significant enhancement in reducing the dissipated energy and in keeping the electrical current of the reaction stable. Meanwhile, the system catalyzed with ZnO NPs induced a similar impact as that for CuO NPs at a lower rate only. The energy dissipation rates in the system were found to be 48% and 65% by using CuO and ZnO NPs, respectively. However, the dissipation rate for the normalized system without catalysis (water buffer at pH = 6.5) is known to be 100%. The energy efficiency of the system was found to be 25% without catalysis, while it was found to be 82% for the system catalyzed with ZnO NPs compared to that for CuO NPs (normalized to 100%). The energy dissipated in the case of the non-catalyzed system was found to be the highest. Overall, water splitting catalyzed with CuO NPs exhibits the best performance under the applied experimental conditions by using the BDD/Niobium (Nb) electrodes.

Addition of nanoparticles increases the abundance of mobile genetic elements and changes microbial community in the sludge anaerobic digestion system

This study explored the fate of mobile genetic elements (MGEs) in anaerobic digestion (AD) system with four nanoparticles (NPs) added, including carbon NPs, Al2O3 NPs, ZnO NPs, and CuO NPs. 16S rRNA amplicon sequencing and quantitative PCR to investigate the microbial community, MGEs abundance and the potential host in the AD process. The results of high-throughput sequencing showed that ZnO NPs and CuO NPs significantly reduced the microbial diversity and significantly changed the microbial community structure. Simultaneously, the absolute abundance of MGEs increased by 145.01%, 159.67%, 354.70%, and 132.80% on the carbon NPs, Al2O3 NPs, ZnO NPs, and CuO NPs. The enrichment rate of tnpA-03 in ZnO NPs group was the highest, which could reach up to 2854.80%. Co-occurrence analysis revealed that Proteobacteria harbored the vast majority of MGEs followed by Firmicutes. Redundancy analysis and variation partitioning analysis showed that metabolites were the main factors that shifted the succession of bacterial communities. Moreover, there were significant positive correlations between metabolites and part MGEs (such as tnpA-01, tnpA-02, tnpA-03, tnpA-04, tnpA-05, tnpA-07 and ISCR1). This study provides a new perspective that NPs increase the risk of antibiotic resistance through MGEs during AD process.

Weight-of-evidence process for assessing human health risk of mixture of metal oxide nanoparticles and corresponding ions in aquatic matrices

This study proposed a framework to estimate health risks due to exposure of mixture of nanoparticles (NPs) from surface water, for the first time, as per authors’ best knowledge. The framework consisted of hazard identification, exposure assessment, dose-response assessment, risk characterization and risk management steps. Concentrations of mixture of NPs and associated ions were compiled and range of values were used for exposure estimation. The resulting concentrations of nanoparticle and metal ions in simulated digestive fluid were calculated and used to estimate exposure dose to digestive system organs during a hypothetical exposure of water during recreational activity. Exposure doses of different possible combinations of ZnO NP, CuO NP, Zn2+ and Cu2+ ions were considered. The ECHA weight-of- evidence framework was used for formulating hypotheses and collecting evidence for determining reference dose (RfD) and interaction parameter for estimating hazard interaction value (an index for risk) as per the USEPA modified weight-of-evidence method for estimating risks of binary NPs and ions. RfD values of CuO (0.0262 mg/kg/d) and ZnO NP (0.0315 mg/kg/d) were derived using information from rat-based oral toxicity studies and assumed values of uncertainty factors. The results showed that mixture of NPs under environmentally-relevant conditions do not pose any health risk. The uncertainty analysis indicated that ZnO + CuO + Zn + Cu ion suspension posed the highest risk. The switchover analysis indicated that NP concentration >0.207 mg/L resulted in risk estimate greater than 1 and pose risk. Although risk estimate was found to be smaller than 1 under the studied natural water condition, efforts should be made to continue monitoring mixture of NPs as a precautionary approach. More efforts are required to obtain data on (i)toxicity of mixture of NPs, (ii)their interaction effects, (iii)fractions of NPs reaching target organ in order to accurately predict risk. Potential benefit of this framework is in its usage for development of structure for estimating exposure risks due to mixture of NPs and ions from surface water. This can also be used to adopt methodology for gathering information on evidence required in different steps of risk assessment process, like obtaining RfD/uncertainty factor -related parameters in dose-response assessment step, deriving interaction and mixture toxicity-related parameters in risk estimation step.

Effect of vegetable waste extract on microstructure, morphology, and photocatalytic efficiency of ZnO–CuO nanocomposites

Environment friendly and cost-effective structure-directing agents (SDAs) are highly desirable for the development of purposely designed functional nanomaterials. To comply, we aimed to explore vegetable waste extracts as potential SDAs for the synthesis of ZnO–CuO nanocomposites. Extracts of wastes of three different vegetables (cauliflowers, potatoes, and peas) were used, and their impact upon crystal structure, morphology, optical-band-gap (Eg ), and photocatalytic efficiency of ZnO–CuO was explored. XRD and SEM revealed that the crystallite size and morphology varied with the vegetable waste extract. Similarly, the wide Eg of n-type ZnO narrowed upon coupling with p-type CuO, and also varied significantly with the vegetable waste extract. The resulting ZnO–CuO nanocomposites were used as photocatalysts for the degradation of model environmental pollutant (an organic dye) under visible light, and it was found that 95.6%, 93%, and 91.3% of the dye decomposes in 120 min under ZnO–CuO photocatalysts synthesized using cauliflower, peas, and potatoes waste extracts, respectively.

Carbonylation of Methanol Over Nickel-Copper Based Supported Catalysts

The results are reported concerning the production of methyl acetate in the halide-free vapor-phase methanol carbonylation (MC) over NiCl2–CuCl2 based catalysts on activated carbons and honeycomb cordierite supports. The formation of the MeOAc with the yield of 18% over nickel-copper chlorides on the BAC-A grade carbon support is shown to be facilitated by the optimal combination of the characteristics of the porous structure (mesopores with an average diameter of ~ 7 nm) and the surface acidity of the catalyst. 15% of MeOAc yield over NiCl2–CuCl2/cordierite, commensurate with the YMeOAc for NiCl2–CuCl2/AC, is achieved due to advantages of structured systems in comparison with the highly porous granular ones, including more efficient mass transfer and heat removal as well as the increased outputs per active components loadings. Using CuO–ZnO–NiO/Al2O3/cordierite (to generate CO as a carbonylation agent by MeOH decomposition) and NiCl2–CuCl2/AC(or cordierite) catalysts placed in series-connected flow-type reactors or in a single reactor with two different temperature zones provides producing methyl acetate in a carbon monoxide free gas feedstock with the MeOAc yields of 13–16.5% in “self-carbonylation” tandem process.

Comparative Study of Impact of Zinc Oxide and Copper (II) Oxide Nanoparticles on Viscosity of Water Based Drilling Fluid

Drilling fluids play very important roles in the oil and gas industry hence the need to get method of improving their rheological properties cannot be over emphasized. In this study how drilling fluid rheological property can be improved using zinc oxide and copper (II) oxide nanoparticles were investigated. To achieve these objectives, water based drilling fluids (WBDF) were prepared using the standard laboratory barrel (350 ml) method from bentonite, xanthan gum and water. The Zinc oxide and Copper (II) nanoparticles were introduced into the formulation in different proportions. Brookfield rotational viscometer was used to determine the rheological properties of the samples while Fourier Transformation Infra-red (FTIR) spectroscopy was used to determine the structural analysis of the interaction between the nanoparticles and the Xanthan gum. The results showed that Zinc oxide and CuO nanoparticle improved the rheological properties of the water based drilling fluid. The zinc oxide at equal proportion with xanthan gum at 60 rpm shear rate increased the viscosity from 834.7 to 1597.3 mPa.s while the copper (II) oxide nanoparticles at equal proportion with xanthan gum at 60 rpm shear rate increased from 834.7 to 1452.3 mPa.s at low temperature of 31.5oC. The FTIR analysis of the nanoparticles and xanthan gum revealed that the interactions of the bonds between the nanoparticles and xanthan gum contributed to the improvement in the rheological properties of the drilling fluids. It is concluded that introduction of ZnO nanoparticles and CuO nanoparticles improved the rheological performance of water based drilling fluids with xanthan gum. The ZnO nanoparticles, however, exhibited better improvement than the CuO.

Comparative Study of Impact of Zinc Oxide and Copper (II) Oxide Nanoparticles on Viscosity of Water Based Drilling Fluid

Drilling fluids play very important roles in the oil and gas industry hence the need to get method of improving their rheological properties cannot be over emphasized. In this study how drilling fluid rheological property can be improved using zinc oxide and copper (II) oxide nanoparticles were investigated. To achieve these objectives, water based drilling fluids (WBDF) were prepared using the standard laboratory barrel (350 ml) method from bentonite, xanthan gum and water. The Zinc oxide and Copper (II) nanoparticles were introduced into the formulation in different proportions. Brookfield rotational viscometer was used to determine the rheological properties of the samples while Fourier Transformation Infra-red (FTIR) spectroscopy was used to determine the structural analysis of the interaction between the nanoparticles and the Xanthan gum. The results showed that Zinc oxide and CuO nanoparticle improved the rheological properties of the water based drilling fluid. The zinc oxide at equal proportion with xanthan gum at 60 rpm shear rate increased the viscosity from 834.7 to 1597.3 mPa.s while the copper (II) oxide nanoparticles at equal proportion with xanthan gum at 60 rpm shear rate increased from 834.7 to 1452.3 mPa.s at low temperature of 31.5oC. The FTIR analysis of the nanoparticles and xanthan gum revealed that the interactions of the bonds between the nanoparticles and xanthan gum contributed to the improvement in the rheological properties of the drilling fluids. It is concluded that introduction of ZnO nanoparticles and CuO nanoparticles improved the rheological performance of water based drilling fluids with xanthan gum. The ZnO nanoparticles, however, exhibited better improvement than the CuO.

Construction of carboxyl position-controlled Z-scheme n-ZnO/p-Cu2O heterojunctions with enhanced photocatalytic property for different pollutants

High reaction activity, strong redox capability, stable Z-scheme transfer and good photostability may benefit the enhancement of photocatalytic performance of n-p heterojunction. Herein, novel 1,2-, 1,3- and 1,4-benzene dicarboxylic acids (1,2-BDCA, 1,3-BDCA and 1,4-BDCA) were used to tune carboxyl positions during the hydrothermal formation process of ZnO nanostructures, and then Z-scheme n-p heterojunctions were constructed via anchoring Cu2O nanoparticles on ZnO surface. When 1,2-BDCA molecule is added into reaction solution, the synergistic capping effect of its two −COOH groups on ZnO surface becomes strong, and leads to the formation of many ZnO nanosheets and well-contacted interface between ZnO and Cu2O. When four pollutants are photodegraded, ZnO-Cu2O (S1-Cu2O) heterojunction prepared by 1,2-BDCA possesses higher charge separation efficiency, stronger redox potentials, and stabler Z-scheme charge transfer. Due to these advantages, S1-Cu2O heterojunction exhibits higher reaction activity and better photocatalytic performance than those of ZnO, Cu2O, TiO2-P25 and/or commercial ZnO (CZnO) under irradiation of ultraviolet and visible light. In addition, the ZnO-Cu2O heterojunction exhibits excellent photostability and recyclability for photodegradation of pollutants. Therefore, this study reports a novel strategy to control the Z-scheme charge transfer, and the as-prepared ZnO-Cu2O photocatalysts provide a perspective for the application in environmental purification and remediation.

Comparative evaluation of copper oxide nano-photocatalyst characteristics by formation of composite with TiO2 and ZnO

In this paper, the effect of composite formation of CuO–Cu2O with TiO2 and ZnO on photocatalytic degradation of methylene blue (MB) dye was studied under visible light irradiation. The X-ray diffraction (XRD) and Raman results revealed that both Cu2O and CuO phases were obtained. Field emission scanning electron microscopy (FESEM) results showed the uniform coverage of copper oxides with TiO2 and ZnO nanoparticles which will be beneficial for charge carriers transform between different phases and copper oxides. The highly decreased photoluminescence (PL) intensity of CuO–Cu2O–ZnO photocatalyst indicated better charge separation compared to those of other samples. However, diffuse reflectance spectroscopy (DRS) results showed the increased band gap energy from 1.6 to about 2.6 and 2.7 eV by the addition of ZnO and TiO2 over CuO–Cu2O, respectively. Relatively complete degradation of 5 mg L−1 of MB solution was obtained by CuO–Cu2O–ZnO photocatalyst after 180 min visible light irradiation. A study on the kinetics and mechanism of the photodegradation process showed the rate-determining step was the formation of hydroxyl radicals. The activation energy for photodegradation of MB by CuO–Cu2O was 17.7 kJ mol−1, which can be reduced to 8.8 kJ mol−1 by adding ZnO. Study on the thermodynamics of photocatalysis in the temperature range of 288–318 K using the activated complex theory revealed the endothermic and nonspontaneous features of the photocatalytic process.

Solar light assisted degradation of dyes and adsorption of heavy metal ions from water by CuO–ZnO tetrapodal hybrid nanocomposite

We report a facile and economic hydrothermal process for multifunctionally engineered copper oxide/zinc oxide-tetrapods (CuO/ZnO-T) nanocomposite for wastewater treatment. The resultant CuO/ZnO-T nanocomposite possesses high porosity, large surface area, and low band gap. All these properties are advantageous for photocatalyst and adsorbent for dyes and heavy metal ions removal. The morphology of synthesized nanocomposite was characterized using X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller, Fourier-transform infrared spectroscopy, and UV–Visible absorption spectroscopy. The results confirmed the attachment of CuO on the ZnO-T surface, forming a hybrid nanocomposite. The concentration of heavy metal ions was monitored using the atomic absorption spectroscopy technique. The synthesized CuO/ZnO-T nanocomposite was investigated for the decontamination of anionic and cationic dyes, Reactive yellow-145 (RY-145) and Basic violet-3 (BV-3) and heavy metal ions (Chromium (VI) and Lead (II)). The CuO/ZnO-T nanocomposite exhibited superior photocatalytic efficiency (80% RY-145 dye removal and 86% BV-3 dye removal) and adsorption capacity (99% Chromium (VI) removal and 97% Lead (II) removal) as compared to pristine ZnO-T. The mechanism for the reduction of dyes and heavy metal ions was discussed by different kinetics and isotherm models. The current study inferred that CuO/ZnO-T nanocomposite is a potential candidate as a proficient photocatalyst/adsorbent for the removal of various wastewater contaminants.

ZnO-CuO Core-Hollow Cube Nanostructures for Highly Sensitive Acetone Gas Sensors at the ppb Level.

This paper presents a ZnO-CuO p-n heterojunction chemiresistive sensor that comprises CuO hollow nanocubes attached to ZnO spherical cores as active materials. These ZnO-CuO core-hollow cube nanostructures exhibit a remarkable response of 11.14 at 1 ppm acetone and 200 °C, which is a superior result to those reported by other metal-oxide-based sensors. The response can be measured up to 40 ppb, and the limit of detection is estimated as 9 ppb. ZnO-CuO core-hollow cube nanostructures also present high selectivity toward acetone against other volatile organic compounds and demonstrate excellent stability for up to 40 days. The outstanding gas-sensing performance of the developed nanocubes is attributed to their uniform and unique morphology. Their core-shell-like structures allow the main charge transfer pathways to pass the interparticle p-p junctions, and the p-n junctions in each particle increase the sensitivity of the reactions to gas molecules. The small grain size and high surface area of each domain also enhance the surface gas adsorption.

Synthesis and characterization of nanocrystalline CuO/ZnO composite powders with enhanced photodegradation performance under sunlight irradiation

In the present work, the sol–gel auto-combustion method has been used to synthesize nanocrystalline copper-zinc oxide composite powders with different weight ratios using diethanolamine (DEA) as fuel. The structural, morphological, optical, and magnetic properties including the local atomic structure of each calcined sample were systematically characterized by means of XRD, SEM, UV-DRS, VSM, and synchrotron XANES measurements. The XRD results revealed the complete formation of CuO/ZnO nanocomposites, composed of monoclinic CuO and hexagonal wurtzite ZnO structures without any impurity phases. The observation of XANES spectra confirms that both Zn and Cu ions in all samples exhibit only fourfold coordination with oxygen atoms. UV-DRS analysis demonstrated that CuO-rich composites exhibited strong absorption in visible light with moderate infrared reflection efficiency as compared to the pure ZnO sample, but ZnO-rich composites show distinctive absorption in infrared region. According to magnetic measurements, both paramagnetism and ferromagnetism can simultaneously arise as the CuO content increases within the CuO/ZnO composites. The photocatalytic activity of CuO/ZnO composites was evaluated by the decomposition of four types of pollutants: phenol rhodamine B (RhB), heteropolyaromatic methylene blue (MB), azoic methyl orange (MO), and methyl red (MR) under sunlight irradiation. In comparison with pure ZnO, those CuO/ZnO samples for which the ratio has been optimized exhibit enhanced photocatalytic degradation in all organic dyes, reaching 90–96% within a period of 150 min. From these results, it can be argued that CuO/ZnO composites show considerable potential for the harvesting of solar energy as well as environmental remediation.

Enhanced photocatalytic properties of CuO–ZnO nanocomposites by decoration with Ag nanoparticles

Rational design of multi-component heterostructure photocatalyst is capable of combining the advantages of the different components. Here, a ternary CuO–ZnO–Ag nano-composite was fabricated by a facile sol-gel method for the photodegradation of organic dye pollutants in wastewater. Decorating Ag NPs on the surfaces of CuO–ZnO nanocomposites improves their photocatalytic activities, which can be further enhanced by tuning the Ag loading level. At 2 mol%, the photocatalytic degradation efficiencies of CuO–ZnO nanocomposites for methylene blue (MB), methyl orange (MO), rhodamine b (RhB) under simulated sunlight irradiation, and for MB under visible light irradiation are increased by 42%, 42%, 63% and 78%, respectively. The enhanced efficiencies can be attributed to the strengthened visible light absorption and the lower recombination rate of photogenerated electron-hole pairs. This work will trigger an inspiration for lowering the dosage of noble metal in photocatalyst by building the simple multiheterostructure consisting of the low-cost metal elements.

A Greener Approach to Extract Copper from Fertilizer Industry Spent Catalyst

Large quantities of catalysts after their useful life are discarded as waste material from fertilizer industry. Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste due to its heavy metals concentration. This investigation applied a novel approach to extract copper from spent low-temperature shift catalyst (CuO–ZnO–Al2O3) using chelation process. Ethylenediaminetetraacetic acid (EDTA) was used as the chelating agent. Optimum parameters to extract 95% copper were found as: EDTA concentration 0.5 M, reaction temperature 100 °C, solid-to-liquid ratio 1:25 (g/ml), particle size 120 µm and reaction time 4 h. A kinetic analysis of the experimental data was done by shrinking core model which revealed the rate-controlling step of the leaching process as product layer diffusion. The activation energy calculated was 10.58 kJ/mol which supports leaching process to be the product layer diffusion controlled. The process adopted is eco-friendly as the EDTA was recovered after the extraction of copper from the spent catalyst and reused again. The recycled EDTA obtained after the extraction was characterized by NMR and SEM. The activity of the recycled EDTA was found to be consistent with the fresh EDTA.

Toxicity assessment and comparison of the land snail's Cornu aspersum responses against CuO nanoparticles and ZnO nanoparticles

The goal of the present study was to examine the effects of ZnO NPs and CuO NPs on Cornu aspersum land snail, enlightening their cytotoxic profile. ZnO NPs and CuO NPs were synthesized and thoroughly characterized. Α series of concentrations of either ZnO NPs or CuO NPs were administered in the feed of snails for 20 days. Thereafter, neutral red retention assay was conducted, in order to estimate NRRT50 values. Subsequently, snails were fed with NPs concentrations slightly lower than the concentrations that were corresponding to the NRRT50 values, i.e. 3 mg·L−1 ZnO NPs and 6 mg·L−1 CuO NPs, for 1, 5, 10 and 20 days. Both NPs agglomerates were detected in hemocytes by Transmission Electron Microscopy. Moreover, both effectors resulted to toxicity in the snails' hemocytes. The latter was shown by changes in the NRRT50 values, increased reactive oxygen species (ROS) production, lipid peroxidation, DNA integrity loss, protein carbonyl content, ubiquitin conjugates and cleaved caspases conjugates levels compared to the untreated animals. Although ZnO NPs exhibited higher toxicity, as indicated by the NRRT50 values, both NPs affected similarly a wide range of the cellular parameters mentioned above. The latter parameters could constitute sensitive biomarkers in biomonitoring studies of terrestrial environment against nanoparticles.

Modelling and numerical analysis of ZnO/CuO/Cu2O heterojunction solar cell using SCAPS

In this work, the SCAPS-1D program was utilized to perform simulations of ZnO/CuO/Cu2O thin-film solar cells. Based on the cell structure and device fabrication process, solar cell structure parameters such as the thickness of the CuO layer, ZnO layer, donor density in the ZnO layer were evaluated in detail. The results indicated that an optimal structure of ZnO/CuO/Cu2O thin-film solar cell could be obtained when the thickness of the ZnO layer, CuO layer, and donor density in the ZnO layer is 100 nm, 500 nm, 1 × 1017 cm−3, respectively. The optimized solar cell structure of ZnO/CuO/Cu2O shows a potential efficiency of about 12% under the 1 sun air mass 1.5 G spectrum illumination. Besides that, the performance of the cell under individual solar concentrations and operating temperatures was also investigated.

Enhanced performance of the tangerines-like CuO-based gas sensor using ZnO nanowire arrays

In this work, sensors based on the ZnO nanowire arrays/CuO nanospheres heterostructure were prepared by using the simple low temperature hydrothermal method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (HRTEM) and energy dispersive spectrometry (EDX) were used to characterize the crystal phase, structure and surface morphology of the as-prepared samples, respectively. The sensing characteristics of the as prepared samples were systematically measured. Obviously, the sensors based on the ZnO/CuO heterostructure exhibited excellent sensor parameters than pure CuO nanospheres. The response value of the ZnO/CuO heterostructure sensor with the growth time of 5 h (ZC-2) to 100 ppm of ethanol gas is up to 55.4 at 122 °C, which is about 8.8 fold and 3.4 fold more than that of pure CuO nanospheres (R = 6.3) and ZnO nanowire arrays (R = 16.4), respectively. In addition, the ZC-2 sensor exhibits the excellent selectivity for ethanol compared to other test gases. Significant improvement of the gas sensing characteristics was related to the formation of n-p heterojunction. The prepared ZC-2 gas sensor exhibits broad application prospects in the detection of ethanol.

Metal oxide nanoparticles facilitate the accumulation of bifenthrin in earthworms by causing damage to body cavity

In this study, we explored the influence of two metal oxide nanoparticles, nano CuO and nano ZnO (10, 50, 250 mg/kg), on accumulation of bifenthrin (100 μg/kg) in earthworms (Eisenia fetida) and its mechanism. The concentrations of bifenthrin in earthworms from binary exposure groups (bifenthrin + CuO and bifenthrin + ZnO) reached up to 23.2 and 28.9 μg/g, which were 2.65 and 3.32 times of that in bifenthrin exposure group without nanoparticles, respectively, indicating that nanoparticles facilitated the uptake of bifenthrin in earthworms. The contents of biomarkers (ROS, SOD, and MDA) in earthworms indicated that nanoparticles and bifenthrin caused damage to earthworms. Ex vivo test was utilized to investigate the toxic effects of the pollutants to cell membrane of earthworm coelomocytes and mechanism of increased bifenthrin accumulation. In ex vivo test, cell viability in binary exposure groups declined up to 30% and 21% compared to the control group after 24 h incubation, suggesting that coelomocyte membrane was injured by the pollutants. We conclude that nanoparticles damage the body cavity of earthworms, and thus lead to more accumulation of bifenthrin in earthworms. Our findings provide insights into the interactive accumulation and toxicity of nanoparticles and pesticides to soil organisms.

Facile Solution Synthesis of Quasi‐0D/2D ZnO/CuO and ZnO/CuO/NiO Composites for Improved Photocatalytic Performance

Heterostructure ZnO/CuO (ZC) and ZnO/CuO/NiO (ZCN) composites are synthesized using a simple solution method. X‐ray diffraction and field‐emission scanning electron microscopy show that quasispherical (0D) monoclinic CuO and/or cubic NiO nanoparticles are found on the surface of the 2D hexagonal ZnO sheets. The photocatalytic properties of the composites in organic pollutant degradation and water splitting can be regulated by adjusting the proportions of Cu/Zn and Ni/Zn added during sample preparation. When ZnO is integrated with high levels of CuO, the binary ZC composites exhibit outstanding photocatalytic performance in degrading methylene blue. Photocatalytic water splitting for H2 production is improved after considerably reducing CuO levels. When ZnO is codoped with low CuO and NiO levels, the photocatalytic performance of ternary ZCN in H2 production is significantly enhanced. Herein, a method for designing ZnO‐based sheet/nanoparticle heterostructures is provided, which are widely used as efficient photocatalysts.