Achieving Well-Oriented FAPbI3 Perovskite Photovoltaics by Cyclohexane Modification.

It is essential and challenging to develop green and cost-effective solar cells to meet the energy demands. Solar cells with a perovskite light-harvesting layer are the most promising technology to propel the world toward next-generation solar energy. Formamidinium lead tri-iodide (FAPbI3)-based perovskite solar cells (F-PSCs), with their considerable performance, offer cost-effective solar cells. One of the major issues that the PSC community is now experiencing is the stability of α-FAPbI3 at relatively low temperatures. In this study, we fabricated FAPbI3-PSCs using cyclohexane (CHX) material via a two-step deposition method. For this purpose, CHX is added to the formamidinium iodide:methylammonium chloride (FAI:MACl) solution as an additive and used to form a better FAPbI3 layer by controlling the reaction between FAI and lead iodide (PbI2). The CHX additive induces the reaction of undercoordinated Pb2+ with FAI material and produces an α-FAPbI3 layer with low charge traps and large domains. In addition, the CHX-containing FAPbI3 layers show higher carrier lifetimes and facilitate carrier transfer in F-PSCs. The CHX-modified F-PSCs yield a high champion efficiency of 22.84% with improved ambient and thermal stability behavior. This breakthrough provides valuable findings regarding the formation of a desirable FAPbI3 layer for photovoltaic applications and holds promise for the industrialization of F-PSCs.

Ti-Doped AgNbO3 as Novel Dense Diffusion Barriers of Limiting Current Oxygen Sensors.

The oxygen sensors with limiting current derived from a dense diffusion barrier have an excellent advantage of detecting oxygen partial pressure by controlling the ratio of air and fuel in combustion environments. Therefore, AgNb1-xTixO3-δ (wherein x varies from 0.1 to 0.3) was prepared as such a dense diffusion barrier layer for sensor application. Among the investigated compositions as a new condensed barrier for the diffusion of sensors, AgNb1-xTixO3-δ (x = 0.1, 0.2, 0.3) exhibits oxygen ionic conductivities from 1.37 × 10-4 to 5.78 × 10-3 S·cm-1 in the temperature range of 600-900 °C and outstanding stable electrochemical properties. Herein, we employ these novel materials as dense diffusion barriers and 8 mol % zirconia stabilized by yttria (8YSZ) as a solid-state electrolyte for the fabrication of the oxygen sensors with limiting current. We observed a direct connection between the limiting current and oxygen content within the interval of 0.5-5.0 mol % at 800 °C and a low working voltage. The increase of Ti-doping amount in AgNbO3 accelerates the sensing response to oxygen gas and promotes the service life of the sensor.

In-MIL-68 derived In2O3/Fe2O3 shuttle-like structures with n-n heterojunctions to improve ethanol sensing performance.

Metal-organic frameworks (MOFs) have a variety of structures and unique properties that make them suitable for use in gas sensors. Herein, In2O3/Fe2O3 was successfully synthesized using simple solvothermal and impregnation methods. The response to 100 ppm of ethanol gas reached 67.5 at an optimum working temperature of 200 °C, and the response/recovery time was 9 s/236 s. The composite also exhibited excellent selectivity, repeatability, and long-term stability. SEM, TEM, XRD, and XPS were used for the characterization of materials. The excellent sensing performance of the sensors is attributed to the construction of n-n heterojunctions, an increase in oxygen vacancies, and the unique structural characteristics of MOFs. The above experimental results indicate that In-MIL-68-derived In2O3/Fe2O3 is a promising ethanol sensing material.

Improved eco-friendly CsSn0.5Ge0.5I3 perovskite photovoltaic efficiency beyond 20% with SMe-TATPyr hole-transporting layer.

Perovskites composed of inorganic cesium (Cs) halide provide a route to thermally resistant solar cells. Nevertheless, the use of hole-transporting layers (HTLs) with hydrophobic additives is constrained by moisture-induced phase deterioration. Due to significant electrical loss, dopant-free HTLs are unable to produce practical solar cells. In this article, we designed a two-dimensional 1,3,6,8-tetrakis[5-(N,N-di(p-(methylthio)phenyl)amino-p-phenyl)-thiophen-2-yl]pyrene (termed SMe-TATPyr) molecule as a new HTL to regulate electrical loss in lead-free perovskite solar cells (PSCs). We optimized the power conversion efficiency (PCE) of PSCs based on mixed tin (Sn)/germanium (Ge) halide perovskite (CsSn0.5Ge0.5I3) by exploring different factors, such as the deep and shallow levels of defects, density of states at the valence band (NV), thickness of the perovskite film, p-type doping concentration (NA) of HTL, the series and shunt resistances, and so on. We carried out comparative research by employing the 1D-SCAPS (a solar cell capacitance simulator) analysis tool. Through optimization of the PSC, we obtained the highest parameters in the simulated solar cell structure of fluorine tin oxide (FTO)/titanium dioxide (TiO2)/CsSn0.5Ge0.5I3/SMe-TATPyr/gold (Au), and the PCE reached up to 20% with a fill factor (FF) of 81.89%.

Design and characterization of molecular, crystal and interfacial structures of PVDF-based dielectric nanocomposites for electric energy storage.

PVDF-based polymers with polar covalent bonds are next-generation dielectric materials for electric energy storage applications. Several types of PVDF-based polymers, such as homopolymers, copolymers, terpolymers and tetrapolymers, were synthesized by radical addition reactions, controlled radical polymerizations, chemical modifications or reduction with the monomers of vinylidene fluoride (VDF), tetrafluoroethylene (TFE), trifluoroethylene (TrFE), hexafluoropropylene (HFP) and chlorotrifluoroethylene (CTFE). Owing to rich molecular structures and complicated crystal structures, PVDF-based dielectric polymers can show versatile dielectric polarization properties, including normal ferroelectrics, relaxor ferroelectrics, anti-ferroelectrics and linear dielectrics, which are beneficial for designing polymer films with high capacity and high charge-discharge efficiency for capacitor applications. Furthermore, to satisfy the requirements of practical high-capacity capacitors, the polymer nanocomposite method is another promising strategy to achieve high-capacitance dielectric materials by the addition of high-dielectric ceramic nanoparticles, moderate-dielectric nanoparticles (MgO, and Al2O3), high-insulation nanosheets (BN), etc. It is concluded with the current problems and future perspectives of interfacial engineering, such as core-shell strategies and hierarchical interfaces in polymer-based composite dielectrics for high-energy-density capacitor applications. In addition, an in-depth understanding of the roles of interfaces on the dielectric properties of nanocomposites can be achieved by indirect analysis techniques (theoretical simulation) and direct analysis techniques (scanning probe microscopy). Our systematic discussions on molecular, crystal and interfacial structures provide guidance for designing fluoropolymer-based nanocomposites for high-performance capacitor applications.

Understanding Auger recombination in perovskite solar cells.

Enhanced radiative efficiency, long carrier lifetimes, and high carrier mobilities are hallmarks of perovskite solar cells. Considering this, complete cells experience large nonradiative recombination losses that restrict their VOC considerably below the Shockley-Queisser limit. Auger recombination, which involves two free photo-induced carriers and a trapped charge carrier, is one potential mechanism. Herein, the effects of Auger capture coefficients in mixed-cation perovskites are analyzed employing SCAPS-1D computations. It is demonstrated that VOC and FF are severely decreased with an increase in the acceptor concentration and Auger capture coefficients of perovskites, thus reducing the device performance. When the Auger capture coefficient is increased to 10-20 cm6 s-1 under the acceptor concentration of 1016 cm-3, the performance is drastically lowered from 21.5% (without taking Auger recombination into account) to 9.9%. The findings suggest that in order to increase the efficiency of perovskite solar cells and prevent the effects of Auger recombination, the Auger recombination coefficients should be less than 10-24 cm6 s-1.

The effect of individual factors, their binary and ternary interactions on photodegradation rate of organic contaminants using photocatalysts based on multi-walled carbon nanotubes (MWCNTs): statistical analysis based on ANOVA and RSM.

The influence of three main parameters including irradiation time, weight fraction of photocatalysts including multi-walled carbon nanotubes and different amount of TiO2 (MCT#1 and MCT#2) and pH is investigated for the degradation rate of methyl orange (MO). Analysis of variance (ANOVA) and response surface methodology (RSM) have been applied to study the binary and ternary interactions of the main parameters on the degradation rate. The ANOVA results confirm that all of three studied factors have a considerable efficacy on degradation rate of MO at 5% level of probability. Meanwhile, the results show that the degradation rate is enhanced with increasing the weight fraction in range of 0.1 to 0.3%wt and irradiation time in a period of 5 to 35min.The lowest and highest degradation are observed at pH=7 and pH=3, respectively. The normality of residue distribution can be confirmed using graphical analysis. The RSM results reveal that the degradation rate dependency on irradiation time is higher than the weight fraction of photocatalysts.

Experimental and Theoretical Studies on Optical Properties of Tetra(Imidazole) of Palladium (II) Phthalocyanine.

In this work, the optical properties of tetra(imidazole) of palladium phthalocyanine (PdPc(Im)4) in solution form and thin films on glass and fluorine-doped tin oxide (FTO) substrates were investigated via the thermal evaporation technique. The optical band gap was evaluated by ultraviolet-visible spectroscopy (UV-Vis). The energy band gap values were determined based on the Tauc graph. In addition, time-dependent density functional theory (TD-DFT) was used to simulate the UV-Vis absorption spectrum of the (PdPc(Im)4) molecule in the Dimethyl Sulfoxide (DMSO) solution phase. A good correlation was found between the DFT results and the experimental optical results. The band gap values between the experimental and DFT-simulated values are presented. The energy band gap of (PdPc(Im)4) obtained from the DFT calculations showed that it can be efficiently regulated. Frontier molecular orbitals and molecular electrostatic potentials were also proposed in this work. The surface study of the layers deposited on FTO was considered by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the results demonstrated good homogeneity covering the entire surface. The SEM image showed a homogeneous distribution of the grains with some spherical or rod-shaped structures and no agglomeration structures. This work rendered a strategy for regulating the energy band gap and compared the experimental observations obtained with theoretical studies, which provides a fundamental insight into the optical band for optoelectronic and thin-film solar cells.

Opposite Sensing Response of Heterojunction Gas Sensors Based on SnO2-Cr2O3 Nanocomposites to H2 against CO and Its Selectivity Mechanism.

Metal oxide semiconductor (MOS) gas sensors show poor selectivity when exposed to mixed gases. This is a challenge in gas sensors and limits their wide applications. There is no efficient way to detect a specific gas when two homogeneous gases are concurrently exposed to sensing materials. The p-n nanojunction of xSnO2-yCr2O3 nanocomposites (NCs) are prepared and used as sensing materials (x/y shows the Sn/Cr molar ratio in the SnO2-Cr2O3 composite and is marked as SnxCry for simplicity). The gas sensing properties, crystal structure, morphology, and chemical states are characterized by employing an electrochemical workstation, an X-ray diffractometer, a transmission electron microscope, and an X-ray photoelectron spectrometer, respectively. The gas sensing results indicate that SnxCry NCs with x/y greater than 0.07 demonstrate a p-type behavior to both CO and H2, whereas the SnxCry NCs with x/y < 0.07 illustrate an n-type behavior to the aforementioned reduced gases. Interestingly, the SnxCry NCs with x/y = 0.07 show an n-type behavior to H2 but a p-type to CO. The effect of the operating temperature on the opposite sensing response of the fabricated sensors has been investigated. Most importantly, the mechanism of selectivity opposite sensing response is proposed using the aforementioned characterization techniques. This paper proposes a promising strategy to overcome the drawback of low selectivity of this type of sensor.

Multi-atomic loaded C2N1 catalysts for CO2 reduction to CO or formic acid.

In recent years, the development of highly active and selective electrocatalysts for the electrochemical reduction of CO2 to produce CO and formic acid has aroused great interest, and can reduce environmental pollution and greenhouse gas emissions. Due to the high utilization of atoms, atom-dispersed catalysts are widely used in CO2 reduction reactions (CO2RRs). Compared with single-atom catalysts (SACs), multi-atom catalysts have more flexible active sites, unique electronic structures and synergistic interatomic interactions, which have great potential in improving the catalytic performance. In this study, we established a single-layer nitrogen-graphene-supported transition metal catalyst (TM-C2N1) based on density functional theory, facilitating the reduction of CO2 to CO or HCOOH with single-atom and multi-atomic catalysts. For the first time, the TM-C2N1 monolayer was systematically screened for its catalytic activity with ab initio molecular dynamics, density of states, and charge density, confirming the stability of the TM-C2N1 catalyst structure. Furthermore, the Gibbs free energy and electronic structure analysis of 3TM-C2N1 revealed excellent catalytic performance for CO and HCOOH in the CO2RR with a lower limiting potential. Importantly, this work highlights the moderate adsorption energy of the intermediate on 3TM-C2N1. It is particularly noteworthy that 3Mo-C2N1 exhibited the best catalytic performance for CO, with a limiting potential (UL) of -0.62 V, while 3Ti-C2N1 showed the best performance for HCOOH, with a corresponding UL of -0.18 V. Additionally, 3TM-C2N1 significantly inhibited competitive hydrogen evolution reactions. We emphasize the crucial role of the d-band center in determining products, as well as the activity and selectivity of triple-atom catalysts in the CO2RR. This theoretical research not only advances our understanding of multi-atomic catalysts, but also offers new avenues for promoting sustainable CO2 conversion.

Two-photon photodynamic therapy based on FRET using tumor-cell targeted riboflavin conjugated graphene quantum dot.

The photodynamic therapy (PDT) is considered as a noninvasive and photo-controlled treatment for various cancers. However, its potential is not fully developed as current clinically approved photosensitizers (PSs) mainly absorb the light in the UV-visible region (less than 700 nm), where the depth of penetration is inadequate for reaching tumor cells under deeper tissue layers. Furthermore, the lack of specific accumulation capability of the conventional PSs in the tumor cells may cause serious toxicity and low treatment efficiency. To address these problems, riboflavin (Rf) conjugated and amine-functionalized nitrogen-doped graphene quantum dots (am-N-GQD) are herein proposed. Rf functions as both photosensitizer and targeting ligand by indirect excitation through intra-particle fluorescence resonance energy transfer (FRET) via two-photon (TP) excited am-N-GQD, to enhance the treatment depth, and further am-N-GQD-Rf accumulation in cancer cells using Rf transporter family (RFVTs) and Rf carrier proteins (RCPs). The one-photon (OP) and two-photon(TP)-PDT effect and cellular internalization ability of the am-N-GQD-Rf were investigated in vitro in different cancel cell lines. Besides the excellent cellular uptake as well TP-PDT capability, the superior biocompatibility of am-N-GQD-Rf in vitro makes it promising candidate in PDT.

Gold Sputtering at the Interfaces: An Easily Operated Strategy for Enhancing the Energy Storage Capability of Laminated Polymer Dielectrics.

Polymers with excellent dielectric properties are strongly desired for pulsed power film capacitors. However, the adverse coupling between the dielectric constant and breakdown strength greatly limits the energy storage capability of polymers. In this work, we report an easily operated method to solve this problem via sputtering the interface of bilayer polymer films with ultralow content of gold nanoparticles. Interestingly, the gold nanoparticles can effectively block the movement of charge carriers because of the Coulomb blocking effect, yielding significantly enhanced breakdown strength. Meanwhile, the gold nanoparticles can act as electrodes to form numerous equivalent microcapacitors, resulting in an obviously enhanced dielectric constant. Impressively, the polymer film with merely 0.01 vol % gold nanoparticles exhibits an obvious dielectric constant and breakdown strength, which are 129 and 131% that of the pristine polymer film, respectively. Consequently, a high energy density which is 176% of that of the pristine polymer film is achieved, and a high efficiency of 79.2% is maintained. Moreover, this process can be well combined with the production process of commercial dielectric polymer films, which is beneficial for mass production. This work offers an easily operated way to improve the dielectric capacitive energy storage properties of polymers, which could also be applicable to other materials, such as ceramics and composites.

Insights into Selective Mechanism of NiO-TiO2 Heterojunction to H2 and CO.

The construction of p-n heterojunctions has become a widely adopted strategy for achieving the selective detection of reducing gases, including H2 and CO. Nevertheless, the elucidation of the gas selectivity mechanism at the nanoscale remains elusive. First-principle calculations provide an attractive avenue for comprehending the influence of coordination structures on gas-sensitive selectivity, thereby unveiling the structure-activity relationship of p-n heterojunction sites. In this study, we investigate the selective adsorption behavior of H2 and CO on a NiO-TiO2 heterojunction using density functional theory. The results of d-band center analysis confirm that the NiO-TiO2 heterojunction with adsorbed oxygen significantly enhances the adsorption stability of reducing gases. Intriguingly, our calculations reveal that H2 has a higher affinity for adsorbed oxygen on the heterojunction surface compared to that of CO, corresponding to a lower H2 adsorption energy. Density of states (DOS) results indicate that the NiO-TiO2 heterojunction, with preadsorbed oxygen, exhibits ultrahigh selectivity with an n-type gas-sensitive response to H2, effectively eliminating the cross-sensitivity observed with CO, as confirmed by gas-sensitive characterization research. The sensing mechanism of the NiO-TiO2 heterojunction's selective detection of H2 without interference from CO can be visually explained by electron transfer and potential barrier changes, paving the way for future developments in novel, selective gas-sensitive materials.

Achieving remarkable energy storage enhancement in polymer dielectrics via constructing an ultrathin Coulomb blockade layer of gold nanoparticles.

High-energy density polymer dielectrics play a crucial role in various pulsed energy storage and conversion systems. So far, many strategies have been demonstrated to be able to effectively improve the energy density of polymer dielectrics, but sophisticated fabrication processes are usually needed which result in high cost and poor repeatability. Herein, an easy-operated sputtering and hot-pressing process is developed to significantly enhance the energy density of polymer dielectrics. Surprisingly, for the poly(vinylidene fluoride-hexafluoropropylene) films sputtered with merely 0.0064 vol% gold nanoparticles, the energy density is remarkably improved by 84.3% because of the concurrent enhancements in breakdown strength (by 37.5%) and dielectric permittivity (by 25.5%), which is demonstrated to have originated from the unique Coulomb blockade and micro-capacitor effect of the gold nanoparticles. It is further confirmed that this design strategy is also applicable for commercial biaxially oriented polypropylene and poly(methyl methacrylate). This work offers a novel, easy-operated and universally applicable route to improve the energy density of polymeric dielectrics, which paves the way for their application in modern electronics and power modules.

Surface wettability of various phases of titania thin films: Atomic-scale simulation studies.

In the paper, the wettability of different phases of TiO2 thin films (anatase, brookite, and rutile) have been studied using molecular-dynamics simulation. The principle of micro-wetting is discussed. The simulation results show that the contact angle decreases upon increasing the interaction energy between the water and the titanium dioxide interface during the wetting process. The values of contact angles from large to small are: rutile, brookite and anatase. The calculated equilibrium contact angles are 73.9°, 59.2°, and 43.7°, respectively. The reason is that the structural connection and the arrangement of the surface microtopography directly affect the movement of water droplets on the surface of the material, thus affecting the wettability. In addition, the amount of the interaction energy and the radial distribution function between these three interfaces and the droplets are calculated, and the density change of the droplet is analyzed further which indicate the difference in wetting between the three crystal structures. At the same time, by simulating and comparing the wettability of the trench surface and the original surface of anatase, it is inferred that the rough interface increases the contact angle with the droplet and reduces the wettability.

Polyimide/crown ether composite film with low dielectric constant and low dielectric loss for high signal transmission.

Dielectric properties of polyimide (PI) are constrained by its inherent molecular structure and inter-chain packing capacities. The compromised dielectric properties of PI, however, could be rescued by introducing trifluoromethyl and forming a host-guest inclusion complex with the introduction of crown ethers (CEs). Herein, we report PI/crown ether composite films as a communication substrate that could be applied under high frequency circumstances. In this work, three kinds of bisphenol A-containing diamine (2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(2-methyl-4-aminophenoxy)phenyl]propane, and 2,2-bis[4-(2-trifluoro methyl-4-aminophenoxy)phenyl]propane) are synthesized and polymerized with 4,4'-(hexafluoroisopropylidene)diphthalic anhydride to prepare low-dielectric PI films by means of thermal imidization. Crown ethers are introduced into the PI with different mass fractions to obtain three series of PI films. Following the combination of trifluoromethyl into the molecular chain of PI, high frequency dielectric loss of modified PI films can be effectively reduced. The properties of these materials (especially the dielectric properties) are thoroughly explored by crown ether addition. The results show that the crown ether addition process can offer crown ethers with increased free volume of PI matrix, thus allowing them to generate a special necklace-like supramolecular structure, which makes the crown ether disperse more uniformly in the PI matrix, resulting in improved dielectric properties. Importantly, the dielectric constant and dielectric loss of the composite films at high frequencies are remarkably reduced to 2.33 and 0.00337, respectively. Therefore, these composite films are expected to find extensive use as a 5G communication substrate at high frequencies in the future.

Conductivity and aging behavior of Sr(Ti0.6Fe0.4)1-x O3-δ mixed conductor materials.

Perovskite materials play a significant role in oxygen sensors due to their fascinating electrical and ionic conductivities. The sol-gel technique was employed to prepare various compositions of B-site-deficient Fe-doped SrTiO3 (iron-doped strontium titanate) or Sr(Ti0.6Fe0.4)1-x O3-δ , where x = 0.01, 0.02, and 0.03. The XRD results revealed that the principle crystalline phase of the samples was the cubic perovskite structure. The B-site deficiency improved the ionic and total conductivities of Sr(Ti0.6Fe0.4)1-x O3-δ . A small polaron conduction behavior occurred in the total electrical conductivity. The XPS results showed that the oxygen vacancy value decreased with the rise in the amount of B-site deficiencies. A lower B-site deficiency amount could produce more oxygen vacancies in the lattice but resulted in the ordering of vacancies and then lower ionic conductivity. The aging behavior was caused by the ordering of oxygen vacancies and resulted in a degeneration of electrical features under a long service time. Conversely, augmentation of the B-site deficiency amount inhibited the tendency for the ordering of oxygen vacancies and then promoted the electrical performance under a long usage time. The conduction mechanism of oxygen ions through oxygen vacancies was thoroughly investigated and discussed. The current study presents a feasible approach to ameliorate the physical features of conductors through doping the B-site of the perovskite layer with Fe, which would be a fruitful approach for numerous applications, including oxygen sensors and fuel cells anodes.

Metal-Decorated InN Monolayer Senses N2 against CO2.

Poor selectivity is a common problem faced by gas sensors. In particular, the contribution of each gas cannot be reasonably distributed when a binary mixture gas is co-adsorbed. In this paper, taking CO2 and N2 as an example, density functional theory is used to reveal the mechanism of selective adsorption of a transition metal (Fe, Co, Ni, and Cu)-decorated InN monolayer. The results show that Ni decoration can improve the conductivity of the InN monolayer while at the same time demonstrating an unexpected affinity for binding N2 instead of CO2. Compared with the pristine InN monolayer, the adsorption energies of N2 and CO2 on the Ni-decorated InN are dramatically increased from -0.1 to -1.93 eV and from -0.2 to -0.66 eV, respectively. Interestingly, for the first time, the density of states demonstrates that the Ni-decorated InN monolayer achieves a single electrical response to N2, eliminating the interference of CO2. Furthermore, the d-band center theory explains the advantage of Ni decorated in gas adsorption over Fe, Co, and Cu atoms. We also highlight the necessity of thermodynamic calculations in evaluating practical applications. Our theoretical results provide new insights and opportunities for exploring N2-sensitive materials with high selectivity.

Hydrothermal synthesis of a bimetallic metal-organic framework (MOF)-derived Co3O4/SnO2 composite as an effective material for ethanol detection.

This study utilized a hydrothermal method and air calcination to prepare a bimetallic metal-organic framework (MOF) derived Co3O4/SnO2 nanocomposite material, which was employed as a sensing material for ethanol detection. The structure, elemental composition, and surface morphology of Co3O4/SnO2 nanocomposite materials were defined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Compared to SnO2 nanoparticles derived from metal-organic frameworks, the bimetallic metal-organic framework-derived Co3O4/SnO2 nanocomposite material exhibits significantly superior ethanol sensing performance. At 225 °C, the response value (R = Ra/Rg) to 100 ppm ethanol is 135, demonstrating excellent repeatability, selectivity and stability. Gas sensitivity assessment findings indicate that the 3 at% (Co/Sn) Co3O4/SnO2 nanocomposite is an excellent gas sensing material, providing strong technical support for ethanol detection and environmental monitoring.

Ternary Metal (Cu-Ni-Zn) Oxide Nanocomposite via an Environmentally Friendly Route.

In this work, we report the engineering of sub-30 nm nanocomposites of CuO/ZnO/NiO by using Dodonaea viscosa leaf extract. Zinc sulfate, nickel chloride, and copper sulfate were used as salt precursors, and isopropyl alcohol and water were used as solvents. The growth of nanocomposites was investigated by varying the concentrations of precursors and surfactants at pH 12. The as-prepared composites were characterized by XRD analysis and found to have CuO (monoclinic), ZnO (hexagonal primitive), and NiO (cubic) phases with an average size of 29 nm. FTIR analysis was performed to investigate the mode of fundamental bonding vibrations of the as-prepared nanocomposites. The vibrations of the prepared CuO/ZnO/NiO nanocomposite were detected at 760 and 628 cm-1, respectively. The optical bandgap energy of the CuO/NiO/ZnO nanocomposite was 3.08 eV. Ultraviolet-visible spectroscopy was performed to calculate the band gap by the Tauc approach. Antimicrobial and antioxidant activities of the synthesized CuO/NiO/ZnO nanocomposite were investigated. It was found that the antimicrobial activity of the synthesized nanocomposite increases with an increase in the concentration. The antioxidant activity of the synthesized nanocomposite was examined by using both ABTS and DPPH assays. The obtained results show an IC50 value of 0.110 for the synthesized nanocomposite compared to DPPH and ABTS (0.512), which is smaller than that of ascorbic acid (IC50 = 1.047). Such a low IC50 value ensures that the antioxidant potential of the nanocomposite is higher than that of ascorbic acid, which in turn shows their excellent antioxidant activity against both DPPH and ABTS.