Zinc Oxide-reduced Graphene Oxide Research Articles

Enhanced catalytic degradation of amoxicillin by phyto-mediated synthesised ZnO NPs and ZnO-rGO hybrid nanocomposite: Assessment of antioxidant activity, adsorption, and thermodynamic analysis

Abstract Antibiotics are resistant compounds that become emerging contaminants that cause hazards to human health and the ecological environment due to their wide production and consumption. The present research reveals the remediation of amoxicillin (AMX) antibiotic by catalytic degradation using fabricated zinc oxide (ZnO) and zinc oxide-reduced graphene oxide (ZnO-rGO) catalysts. The characterization of the catalyst was carried out via UV–Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and scanning electron microscopy to evaluate the morphology and composition of synthesised catalyst. The catalytic ability of ZnO-rGO and ZnO was investigated by analysing the degradation of AMX. The ZnO-rGO nanocomposites (NCs) showed improved catalytic performance towards AMX degradation (96%) than pure ZnO nanoparticles (85%), which may be attributed to the incorporation of rGO, which enhanced the adsorption rate and changed the electron–hole recombination rate. The antioxidant potential of synthesised nanomaterials was also analysed by three different methods. The adsorption behaviour was explained through the Langmuir and Freundlich models, and the results revealed that AMX adsorption followed the Freundlich model more closely for both catalysts. The adsorption of AMX was also studied thermodynamically at different temperatures. The negative Gibbs energy change, positive enthalpy change, and entropy change showed the reaction’s spontaneity and endothermic nature. Finally, it can be assumed that the ZnO-rGO NCs could be an effective semiconductor for the degradation of AMX from wastewater.

Strategic decolorization of rose bengal in an aqueous environment using a zinc oxide-loaded reduced graphene oxide photocatalyst

The environmental and health hazards posed by synthetic organic dyes, such as Rose Bengal, have spurred significant concern in recent years. Herein, a novel zinc oxide/reduced graphene oxide (ZnO/rGO)-based photocatalyst is developed and used for the efficient decolorization of RB dye in aqueous solutions. The as-synthesized nanostructured material is characterized using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) mapping to elucidate its crystalline structure, morphology, and elemental composition. The XRD pattern confirmed the wurtzite crystalline phase structure with an average size of 67.8 nm, while SEM imaging verified the successful incorporation of ZnO nanoparticles into the rGO matrix. Further, the as-prepared material was used as a photocatalyst, which demonstrated remarkable performance in RB dye decolorization, achieving ≥96.1 % degradation within just 5 min at a minimal catalyst dosage of 8.0 mg. Moreover, kinetic studies revealed that the decolorization process followed a pseudo-second-order reaction mechanism, further enhancing the understanding of the catalytic behavior. It is more interesting that the catalyst exhibited exceptional reusability for up to seven cycles with only a decrease in catalyst efficiency from 96.1 % to 77.5 %, underscoring its practical viability and sustainability. The significance of this work lies in its contribution to addressing the environmental challenges associated with synthetic dyes, particularly rose bengal, by offering an efficient and reliable photocatalytic solution. The demonstrated efficacy of the ZnO/rGO photocatalyst not only showcases its potential for large-scale rose bengal dye degradation but also suggests broader applicability for the treatment of other synthetic dye pollutants.

PVDF composite fibers for wireless fall-alert detection

As the demand for healthcare devices continues to rise, novel technologies centered on personalized motion monitoring systems are being developed, wherein wearable sensors play a pivotal role. In the present investigation, an innovative wireless apparatus for detecting falls is introduced, which encompasses a specifically engineered pressure sensor composed of polyvinylidene fluoride (PVDF) composite fibers. Our design consists of high β-phase content of electrospun composites including 0.1 wt% of zinc oxide/reduced graphene oxide (ZnO/rGO) hybrid (mass ratio 90/10) which shows enhanced electrical voltage of 11.36 ± 0.72 V compared to pristine PVDF fiber. This piezoelectric pressure sensor is integrated with a wireless embedded system capable of transmitting an “SOS” message to a mobile phone upon the user’s fall experience. Such wearable fall alert detection systems with improved characteristics could benefit the elderly and patients requiring continuous monitoring for possible falls.

ZnO-rGO-based electrochemical biosensor for the detection of organophosphorus pesticides

The accurate determination of organophosphorus pesticide residues is of great importance for human disease monitoring and environmental safety. Numerous detection methods exist, among which sensitive monitoring of organophosphorus compounds using electrochemical sensors has gradually become a research hotspot. This paper used acetylcholinesterase (AChE) as an indicator anchored on a zinc oxide-reduced graphene oxide (ZnO-rGO) composite rich in active sites, in which green non-toxic zinc oxide (ZnO) nanomaterials were uniformly distributed on the reduced graphene for rapid detection of organophosphorus. The effects of different ratios of ZnO to reduced graphene on the performance of ZnO-rGO nanocomposites were investigated. The AChE/ZnO-rGO biosensor detects organophosphorus by electrochemical inhibition of acetylcholinesterase in the presence of organophosphorus. The developed electrochemical biosensor has high selectivity and good linearity, and the ZnO-rGO nanocomposite as a matrix for immobilization of acetylcholinesterase and detection of organophosphorus has the potential for highly sensitive pesticide detection.

Enhanced photocatalytic degradation of Rhodamine B employing transition metal (Fe, Cu, Co) doped ZnO/rGO nanostructures synthesized by electrospinning-hydrothermal technique

In the present work, the use of transition metal-doped zinc Oxide/reduced graphene oxide (ZnO/rGO) nanostructures for photocatalytic applications was investigated. The paper presents a novel and cost-effective electrospinning-assisted hydrothermal method of synthesizing these nanostructures onto fluorine-doped tin oxide (FTO) substrates. The research focuses on the effects of the rGO sheets attached to the ZnO nanostructure and of Fe, Cu, and Co ions as dopant transition metals. The doped ZnO/rGO photocatalysts obtained were characterized using various techniques, including Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD), Raman spectroscopy, and Photoluminescence (PL). The results showed that the doped ZnO/rGO samples exhibited pure composition, hexagonal wurtzite structure with high crystallinity, and nanorod-like morphologies with reduced mean diameters due to doping and the rGO anchoring. Additionally, the PL experiments demonstrated that charge carrier recombination was effectively inhibited for the doped ZnO/rGO samples. The photocatalytic performances of the undoped and doped ZnO/rGO nanostructures were tested through the degradation of Rhodamine B (RhB) dye under simulated sunlight irradiation. An improvement in photocatalytic activity compared to pristine ZnO was achieved mainly due to dopants and the presence of rGO, both of which intensified the separation of photogenerated electron-hole pairs and thus hindered their recombination. The study also acknowledges some scientific challenges in controlling the doping process to achieve consistent and uniform properties. However, despite these issues, the potential applications and advantages of transition metal-doped ZnO/rGO nanostructures make them promising materials for future efficient and sustainable photocatalytic applications.

Engineering of ZnO/rGO towards NO2 Gas Detection: Ratio Modulated Sensing Type and Heterojunction Determined Response

Nanoscale heterostructured zinc oxide/reduced graphene oxide (ZnO/rGO) materials with p-n heterojunctions exhibit excellent low temperature NO2 gas sensing performance, but their doping ratio modulated sensing properties remain poorly understood. Herein, ZnO nanoparticles were loaded with 0.1~4% rGO by a facile hydrothermal method and evaluated as NO2 gas chemiresistor. We have the following key findings. First, ZnO/rGO manifests doping ratio-dependent sensing type switching. Increasing the rGO concentration changes the type of ZnO/rGO conductivity from n-type (<0.6% rGO) to mixed n/p -type (0.6~1.4% rGO) and finally to p-type (>1.4% rGO). Second, interestingly, different sensing regions exhibit different sensing characteristics. In the n-type NO2 gas sensing region, all the sensors exhibit the maximum gas response at the optimum working temperature. Among them, the sensor that shows the maximum gas response exhibits a minimum optimum working temperature. In the mixed n/p-type region, the material displays abnormal reversal from n- to p-type sensing transitions as a function of the doping ratio, NO2 concentration and working temperature. In the p-type gas sensing region, the response decreases with increasing rGO ratio and working temperature. Third, we derive a conduction path model that shows how the sensing type switches in ZnO/rGO. We also find that p-n heterojunction ratio (np-n/nrGO) plays a key role in the optimal response condition. The model is supported by UV-vis experimental data. The approach presented in this work can be extended to other p-n heterostructures and the insights will benefit the design of more efficient chemiresistive gas sensors.

Broad spectrum antibacterial zinc oxide-reduced graphene oxide nanocomposite for water depollution

Antimicrobial-resistance (AMR) is a global health challenge arising from the evolution of bacteria, viruses, fungi, and parasites, such that pathogenic microorganisms no longer respond to classical therapies. AMR and the rise of so-called ‘superbugs’ requires innovative nanomaterials and biostatic strategies. Here we report a broad spectrum, antimicrobial nanomaterial integrating light-responsive ZnO nanoparticles (NP) and reduced graphene oxide (rGO) into a heterojunction semiconductor nanocomposite for water depollution. Simultaneous chemical reduction of Zn sulphate and GO sheets yields a low concentration (0.5 mol%) of 10 nm ZnO nanoparticles decorating fragmented rGO nanosheets, with a total surface area of 12 m2/g and optical band gap of 1.6 eV. Antimicrobial performance of the ZnO-rGO nanocomposite was evaluated against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli 0157:H7 and Salmonella typhimurium bacteria, which are prevalent in contaminated aquatic systems; antimicrobial efficacy against these organisms was 96%, 97%, and 73%, respectively, for a loading of 2 mg/mL, evidencing a strong synergy compared with pure ZnO or rGO components. ZnO-rGO was also an effective photocatalyst for the aqueous degradation of Malachite Green dye, suggesting that its mode of antibacterial action reflects the production of reactive oxygen species under ambient illumination.

High surface area ZnO/rGO aerogel for sensitive and selective NO2 detection at room temperature

Accurate and convenient detection of nitrogen dioxide (NO2) in the air, which is harmful to human health, is vital. However, it is difficult for many NO2 detection devices to achieve high sensitivity at room temperature. In this work, we synthesized zeolite-imidazolate-frameworks-8 (ZIF-8) nanoparticles and zinc oxide/reduced graphene oxide (ZnO/rGO) aerogel by low-temperature synthesis and sol-gel method. The aerogel composite materials were investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM), Brunaue-Emmette-Teller (BET), and Raman spectroscopy. The gas-sensitive element prepared by the material with the mass ratio ZIF-8 to rGO is 5:1 possesses excellent selectivity and higher sensitivity (3.21) to 100 ppm NO2 at room temperature. Reduced graphene oxide (rGO) provides more gas transmission and diffusion channels for improving sensitivity because of a three-dimensional porous structure. When NO2 is exposed, electrons transfer into p-n heterostructure formed by rGO and ZnO composite to achieve the purpose of sense. In this study, the material preparation method is relatively simple and efficient, which is of profound significance to accurately detect the variation of NO2 concentration in air at room temperature.

One-Pot Sol-Gel Synthesis of a Zinc Oxide-Reduced Graphene Oxide Composite: Photocatalysis and Kinetics Studies using a Fuzzy Inference System

One-Pot Sol-Gel Synthesis of a Zinc Oxide-Reduced Graphene Oxide Composite: Photocatalysis and Kinetics Studies using a Fuzzy Inference System

One-Pot Sol-Gel Synthesis of a Zinc Oxide-Reduced Graphene Oxide Composite: Photocatalysis and Kinetics Studies using a Fuzzy Inference System

One-Pot Sol-Gel Synthesis of a Zinc Oxide-Reduced Graphene Oxide Composite: Photocatalysis and Kinetics Studies using a Fuzzy Inference System

Graphene-substrate fabricated oxides and zinc oxide catalysts for the degradation of the methylene blue in the industrial wastewater

Abstract The release of unsafe color dyes into various industrial effluents can harm the environment and human health and therefore needs remediation. The current research assesses the environmental friendly photo-less catalytic performance of zinc oxide/reduced graphene oxide (ZnO/RGO) nanocomposites, prepared via green synthetic route, for the degradation, and decontamination of methylene blue (MB) dye from industrial aqueous effluents and compared with that of zinc oxide (ZnO), hydrogen peroxide (H2O2), and reduced graphene oxide (RGO). The materials were characterized for surface morphology, functional groups, and crystallinity by using Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analysis, respectively, showing that ZnO nanoparticles (NPs) were well-formed on the RGO surface and were having uniform pore sizes and large surface area. The degradation pattern of MB from its 40, 60, 80, and 100 ppm solutions by employing the degradation materials were examined using UV–Visible spectral analysis. The pH before and after the degradation of the MB in all the sample solutions was noted and found to change slightly after the degradation of MB. The results demonstrate that the ZnO/RGO nanocomposites display a better catalytic degradation efficiency (99.57%) as compared to the other degradation materials with the order of efficiency as ZnO/RGO &gt; RGO &gt; H2O2 &gt; ZnO which shows that the degradation efficiency of ZnO (∼14%) can be significantly improved while fabricating its nanocomposite with RGO (99.57%). These findings can be utilized on a large-scale decontamination of dyes from industrial wastes without the involvement of light i.e., photo-less degradation.

Porous ZnO/rGO Nanosheet‐Based NO2 Gas Sensor with High Sensitivity and ppb‐Level Detection Limit at Room Temperature

AbstractHigh‐performance gas sensors are highly desirable for environmental monitoring, clinical medicine, and industrial production. Herein, a gas sensor with excellent sensing response at room temperature is presented based on zinc oxide/reduced graphene oxide (ZnO/rGO) composites. The ZnO/rGO composites with various contents of rGO and the pure ZnO are successfully fabricated by a facile hydrothermal method. Particularly, the ZnO/rGO sensor with 1.5 mL of the rGO exhibits highest sensing response in a wide range from 5 ppb to 10 ppm NO2 concentration and its response arrives at 13.46 when exposed to 2 ppm NO2 at room temperature. Furthermore, ZnO/rGO sensors show short response time (2 ppm, 26 s) and recovery time (2 ppm, 164 s) at room temperature. The proposed ZnO/rGO sensors present high sensitivity, excellent reproducibility, and stability. In addition, the density functional theory (DFT) calculations show that the increased electrical conductivity under exposure of NO2 gas are attributed to the numerous reactive sites and carrier mobility of rGO. These results demonstrate that ZnO/rGO gas sensor has huge potential for applications in industrial and environmental monitoring.

Unravelling the Role of Synthesis Conditions on the Structure of Zinc Oxide-Reduced Graphene Oxide Nanofillers.

The diversity of zinc oxide (ZnO) particles and derived composites applications is highly dependent on their structure, size, morphology, defect amounts, and/or presence of dopant molecules. In this work, ZnO nanostructures are grown in situ on graphene oxide (GO) sheets by an easily implementable solvothermal method with simultaneous reduction of GO. The effect of two zinc precursors (zinc acetate (ZA) and zinc acetate dihydrate (ZAD)), NaOH concentration (0.5, 1 or 2 M), and concentration (1 and 12.5 mg/mL) and pH (pH = 1, 4, 8, and 12) of GO suspension were evaluated. While the ZnO particle morphology shows to be precursor dependent, the average particle size length decreases with lower NaOH concentration, as well as with the addition of a higher basicity and concentration of GO suspension. A lowered band gap and a higher specific surface area are obtained from the ZnO composites with higher amounts of GO suspension. Otherwise, the low concentration and the higher pH of GO suspension induce more lattice defects on the ZnO crystal structure. The role of the different condition parameters on the ZnO nanostructures and their interaction with graphene sheets was observed to tune the ZnO–rGO nanofiller properties for photocatalytic and antimicrobial activities.

The effects of nano zinc oxide (ZnO) and nano reduced graphene oxide (RGO) on moisture susceptibility property of stone mastic asphalt (SMA)

Moisture damage is one of the most common and main distresses in asphalt pavements. Using Nanomaterials due to their unique and outstanding properties in the asphalt pavement industry has received much attention in recent years. This paper investigated the effects of Nano Zinc Oxide (ZnO) and Nano Reduced Graphene Oxide (RGO) on moisture susceptibility resistance of Stone Mastic Asphalt (SMA) mixtures. SMA mixtures are a type of hot mix asphalt (HMA) containing two main parts of coarse aggregates and bitumen-filled mortar (bitumen, stabilizing additives, and filler aggregates). There is a wide range of test methods for evaluating the moisture resistance of asphalt mixtures; this study used the immersion Marshall test, indirect tensile strength test, boiling water test, static creep test, pull-off adhesion, and Semi-circular bending (SCB) fracture test for this aim. The pure bitumen was modified with three content of Nano ZnO and Nano RGO (0.2 %, 0.4 %, and 0.6 % by weight of asphalt binder). The experimental results obtained in this research indicated that the addition of Nano RGO in pure binder increases the softening point and viscosity and decreases the penetration and ductility properties of pure bitumen. Also, the addition of Nano ZnO in bitumen can increase the ductility, softening point, and viscosity, and decrease the penetration properties of pure bitumen. The mechanical test results showed that an increase in the percentage of Nano ZnO and RGO lead to a rise in Marshall Stability, indirect tensile strength, accumulated strain, pull-off adhesion strength, and fracture energy and improve the bitumen coating on aggregates in SMA mixtures. According to calculated moisture susceptibility indices of the mentioned tests above, the Nano ZnO and Nano RGO can significantly improve the resistance of stone mastic asphalt mixtures against moisture susceptibility. Examination of the test results showed that the ITS, pull-off, and Semi-circular bending (SCB) fracture test can give a good estimation of the moisture susceptibility of asphalt mixture. In addition, the results of the ANOVA test depicted that in ITS, Pull-off, and SCB fracture tests, Nano ZnO has a more significant effect on improving moisture susceptibility than Nano RGO.

Development of photo-anodes based on strontium doped zinc oxide-reduced graphene oxide nanocomposites for improving performance of dye-sensitized solar cells

The goal of this study was to create highly efficient dye-sensitized solar cells (DSSCs) using strontium doped zinc oxide-reduced graphene oxide (Sr-doped ZnO/rGO) nanocomposites. As photo-anodes of DSSCs, ZnO, ZnO/rGO (with weight percent rGO in composites: 0, 0.01, 0.1, 0.5, and 1 wt%) and Sr-doped ZnO/rGO (with Zn1-xSrxO nanoparticle stoichiometry: x = 0, 0.02, 0.04, 0.06 and 0.08) nanocomposites were designed and characterized. AFM, FESEM, XRD, EDS, XPS, PL, and FTIR analyses were used to investigate the morphology and structure properties of prepared nanocomposites. UV–vis spectroscopy and photo-electrochemical measurements were used to investigate the efficiency of prepared photo-anodes. The efficiency (η) and short-circuit photocurrent density (JSC) of DSSCs based on Zn0.92Sr0.08O/rGO nanocomposite were 7.98 % and 18.4 mA cm−2, respectively. The results showed that doping Sr on ZnO/rGO nanocomposites resulted in a wide bandgap energy and increased the values of η, JSC, IPCE, and photo-anode electron transportability. These findings suggest that Sr-doped ZnO/rGO nanocomposites can provide a novel approach for increasing photo-electrochemical activity in ZnO-based DSSCs.

Direct coating of multifunctional zinc oxide-reduced graphene oxide interlayer on cathode for lithium-sulfur batteries

In this work, a multifunctional interlayer composed of ZnO nanoparticles (NPs)-reduced graphene oxide (rGO) composite nanosheets was directly coated on the top of sulfur-rGO composite (S-rGO) cathode for the improvement of the electrochemical performances of lithium-sulfur batteries. With this configuration, the rGO network well connecting the interlayer and cathode provides an appropriate electrically conductive pathway for the discharge and charge processes. The soluble lithium polysulfides formed during the discharge process are efficiently absorbed on ZnO NPs to suppress the shuttle effect. In addition, the ZnO NP plays the role of an electrochemical catalyst to accelerate the redox kinetics. With the ZnO-rGO interlayer, the cathode also exhibits the considerably enhanced Li ion transfer/transport properties. The reversible conversion of sulfur to Li2S2/Li2S therefore occurs in the ZnO-rGO interlayer to efficiently reutilize the retained active materials. Moreover, the ZnO-rGO interlayer, which accounts for ~8.5 wt% of the whole cathode, can buffer the volume expansion in the cathode to prevent irreversible structural destruction. Accordingly, a capacity degradation of 0.04% per cycle at 1C after 500 cycles with a capacity retention of 838 mAhg−1 is delivered by S-rGO cathode with the ZnO-rGO interlayer.

Fabrication of ZnO/rGO and ZnO/MWCNT nanohybrids to reinforce the anticorrosion performance of polyurethane coating

Polyurethane (PU) has been widely utilized in different applications due to its unique properties. Substantial attempts have been made to enhance the corrosion resistance and mechanical properties of PU coating through the addition of nanomaterials. In this study, zinc oxide/reduced graphene oxide (ZnO/rGO) and zinc oxide/multiwalled carbon nanotube (ZnO/MWCNT) nanohybrids were synthesized and incorporated into the PU matrix to enhance the anti-corrosion property of the PU coating. The synthesized nanofillers were thoroughly characterized through Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray spectroscopy (EDX). The rGO/ZnO-PU and MWCNT/ZnO-PU nanocomposites, and also neat PU were coated on the mild steel (MS) substrate, and the surfaces of the coated samples were probed by Contact angle technique, Atomic Force Microscopy (AFM), and SEM analysis. Electrochemical impedance spectroscopy and potentiodynamic polarization tests were carried out to examine the effects of rGO/ZnO and CNT/ZnO nanofillers in improving the protection and barrier properties of pure PU coating. Electrochemical corrosion data revealed the superior anticorrosion efficiency for rGO/ZnO decorated PU coating (99.09%) compared to that of MWCNT/ZnO dispersed PU coating (95.24%). The high surface area and aspect ratio of rGO make it an effective nanofiller in reinforcing the PU matrix for anticorrosion application.

Zinc Oxide/Reduced Graphene Oxide Nanocomposites for Rapid Detection of Toluene Gas at Room Temperature

In this study, a nanostructured zinc oxide/reduced graphene oxide (ZnO/rGO) composite was deposited on a quartz crystal microbalance (QCM) as a toluene gas sensor at room temperature. A series of ZnO, rGO and ZnO/rGO sensing materials was fabricated and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Raman spectroscopy. There was significant efficiency of the ZnO/rGO composite on the sensing performance for toluene. For specific gas fluxes, the nanostructured ZnO/rGO offered sufficient paths and region for vapor diffusion and adsorption. The sensing test results illustrated that the nanostructured ZnO/rGO composite showed significant enhancement in the frequency shifts (△f) for toluene comparing to pure ZnO and rGO. Also, the ZnO/rGO-coated QCM sensor displayed a fast response (both the response and recovery times &lt; 30 s) and reproducibility for sensing toluene gas at room temperature. We believe that the novel insights on ambient temperature gas sensing on nanostructured ZnO/rGO composite could provide a new strategy for preparing a highly efficient sensing materials.

High‐performance HTL‐free perovskite solar cell: An efficient composition of ZnO NRs, RGO, and CuInS2 QDs, as electron‐transporting layer matrix

AbstractA hole‐transporting layer (HTL)‐free perovskite solar cell (PSC) with fluorine‐doped tin oxide (FTO)/nanocomposite electron‐transporting layer (ETL)/perovskite/Au structure is presented that takes advantage of a novel ternary nanocomposite constructed of zinc oxide (ZnO) nanorods, reduced graphene oxide (RGO), and copper indium sulfide quantum dots (CuInS2 QDs), as ETL. Concisely, the photoelectric and photovoltaic properties of all the individual, binary, and ternary composites were monitored by using of the photoluminescence (PL) spectroscopy, UV‐visible (vis) spectroscopy, J‐V curves, and incident photon‐to‐current conversion efficiency (IPCE) spectra studies. The comparative values exhibited a noticeable benefit for the ZnO‐RGO5%‐CuInS220% ternary nanocomposite as an appropriate ETL for PCS. Also, the comparative structural studies on the individual nanoscale components, binary, and ternary nanocomposite (with different percentages of CuInS2 QDs) were precisely performed by Fourier transform infrared (FT‐IR), energy‐dispersive X‐ray (EDX), X‐ray diffraction (XRD), Raman spectroscopy, and field emission scanning electron microscopy (FESEM), as well. Overall, after careful optimization of the ETL, a15.74% efficiency was resulted through applying the prepared ZnO‐RGO5%‐CuInS220% composite in a HTL‐free PCS with 0.33 cm2 active area.

The Spinning Voltage Influence on the Growth of ZnO-rGO Nanorods for Photocatalytic Degradation of Methyl Orange Dye

In this work, well-designed zinc oxide-reduced graphene oxide (ZnO-rGO) nanorods (NRs) were synthesized by a hydrothermal method using electrospun ZnO-rGO seed layers. The ZnO-rGO seed layers were fabricated on fluorine-doped tin oxide (FTO) glass substrates through calcined of electrospun nanofibers at 400 °C in the air for 1 h. The nanofibers were prepared by electrospinning different spinning voltages and a spinning solution containing zinc acetate, polyvinyl pyrrolidone, and 0.2 wt% rGO. From a detailed characterization using various analytical techniques, for instance, X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS), the dependence of the structure, morphology, and optical properties of the ZnO-rGO NRs was demonstrated. The photocatalytic activities of ZnO-rGO nanorods were evaluated through the degradation of dye methyl orange (MO). The results show that the change of spinning voltages and the coupling of rGO with ZnO improved photodecomposition efficiency as compared to pure ZnO. The highest photocatalytic efficiency was obtained for the ZnO-rGO NRs prepared with a spinning voltage of 40 kV.