Graphene Oxide ZnO Research Articles

Preparation of polycrystalline ZnO nanoparticles loaded onto graphene oxide and their antibacterial properties

The GO–ZnO nanocomplexes that polycrystalline ZnO particles were loaded onto graphene oxide (GO) were prepared conveniently through the one-step reflux method and their antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were also investigated. The results showed, a complete polycrystalline ZnO particle in the complexes had a quasi-spherical structure with less than 200 nm in diameter, and it was formed from approximately 15 nm crystal hexagonal wurtzite with distinct lattice planes. These polycrystalline ZnO particles possessed greater specific surface areas and well dispersed on the surface of GO. Their antibacterial properties indicated when 0.28 and 0.42 mg mL−1 GO–ZnO nanocomplexes were added to E. coli and S. aureus physiological solutions, their bactericidal percentages were > 99.9 % and approximately 90 % in 0.5 h and 4 h, respectively, which exhibited favorable antibacterial activities against the two germs. The antibacterial performance of the nanocomplexes was achieved through the synergistic action between GO and polycrystalline ZnO particles.

Removal of Mn(II) from Acidic Wastewaters Using Graphene Oxide-ZnO Nanocomposites.

Pollution due to acidic and metal-enriched waters affects the quality of surface and groundwater resources, limiting their uses for various purposes. Particularly, manganese pollution has attracted attention due to its impact on human health and its negative effects on ecosystems. Applications of nanomaterials such as graphene oxide (GO) have emerged as potential candidates for removing complex contaminants. In this study, we present the preliminary results of the removal of Mn(II) ions from acidic waters by using GO functionalized with zinc oxide nanoparticles (ZnO). Batch adsorption experiments were performed under two different acidity conditions (pH1 = 5.0 and pH2 = 4.0), in order to evaluate the impact of acid pH on the adsorption capacity. We observed that the adsorption of Mn(II) was independent of the pHPZC value of the nanoadsorbents. The qmax with GO/ZnO nanocomposites was 5.6 mg/g (34.1% removal) at pH = 5.0, while with more acidic conditions (pH = 4.0) it reached 12.6 mg/g (61.2% removal). In turn, the results show that GO/ZnO nanocomposites were more efficient to remove Mn(II) compared with non-functionalized GO under the pH2 condition (pH2 = 4.0). Both Langmuir and Freundlich models fit well with the adsorption process, suggesting that both mechanisms are involved in the removal of Mn(II) with GO and GO/ZnO nanocomposites. Furthermore, adsorption isotherms were efficiently modeled with the pseudo-second-order kinetic model. These results indicate that the removal of Mn(II) by GO/ZnO is strongly influenced by the pH of the solution, and the decoration with ZnO significantly increases the adsorption capacity of Mn(II) ions. These findings can provide valuable information for optimizing the design and configuration of wastewater treatment technologies based on GO nanomaterials for the removal of Mn(II) from natural and industrial waters.

Utilization of metallurgical waste for the preparation of photocatalytically active composites based on ZnO–graphene oxide

Steel sludge was used as a source of technical zinc oxide (ZnOL) for the preparation of ZnO–graphene oxide (ZnOL–GO) composite with photocatalytic effects. The specific surface of the manufactured product was determined by SBET method, and structural analysis was performed by FTIR spectroscopy. The photocatalytic efficiency of the ZnOL–GO composite was studied using optical methods (UV–Vis spectroscopy, photoluminescence). The obtained results were confronted with a model composite prepared from pure components. It was found that the prepared ZnOL–GO composite showed excellent photodegradation activities against the azo dye Acid Orange 7 in comparison with the model composite. The presence of other metal oxides in ZnOL in conjunction with GO causes a significant increase in the photocatalytic efficiency of the prepared composite material, which can be explained by the modification of the electronic structure and more efficient separation of charge carriers. The obtained results show new possibilities in the field of processing and further use of metallurgical waste.

Reduced graphene oxide-ZnO hybrid composites as photocatalysts: The role of nature of the molecular target in catalytic performance

Spurred by controversial literature findings, we enwrapped reduced graphene oxide (rGO) in ZnO hierarchical microstructures (rGO loadings spanning from 0.01 to 2 wt%) using an in situ synthetic procedure. The obtained hybrid composites were carefully characterized, aiming at shining light on the possible role of rGO on the claimed increased performance as photocatalysts. Several characterization tools were exploited to unveil the effect exerted by rGO, including steady state and time resolved photoluminescence, electron microscopies and electrochemical techniques, in order to evaluate the physical, optical and electrical features involved in determining the catalytic degradation of rhodamine B and phenol in water.Several properties of native ZnO structures were found changed upon the rGO enwrapping (including optical absorbance, concentration of native defects in the ZnO matrix and double-layer capacitance), which are all involved in determining the photocatalytic performance of the hybrid composites. The findings discussed in the present work highlight the high complexity of the field of application of graphene-derivatives as supporters of semiconducting metal oxides functionality, which has to be analyzed through a multi-parametric approach.

Engineering of TiO2 or ZnO—Graphene Oxide Nanoheterojunctions for Hybrid Solar Cells Devices

It is currently of huge importance to find alternatives to fossil fuels to produce clean energy and to ensure the energy demands of modern society. In the present work, two types of hybrid solar cell devices were developed and characterized. The photoactive layers of the hybrid heterojunctions comprise poly (allylamine chloride) (PAH) and graphene oxide (GO) and TiO2 or ZnO films, which were deposited using the layer-by-layer technique and DC-reactive magnetron sputtering, respectively, onto fluorine-doped tin oxide (FTO)-coated glass substrates. Scanning electron microscopy evidenced a homogeneous inorganic layer, the surface morphology of which was dependent on the number of organic bilayers. The electrical characterization pointed out that FTO/(PAH/GO)50/TiO2/Al, FTO/(PAH/GO)30/ZnO/Al, and FTO/(PAH/GO)50/ZnO/Al architectures were the only ones to exhibit a diode behavior, and the last one experienced a decrease in current in a low-humidity environment. The (PAH/GO)20 impedance spectroscopy study further revealed the typical impedance of a parallel RC circuit for a dry environment, whereas in a humid environment, it approached the impedance of a series of three parallel RC circuits, indicating that water and oxygen contribute to other conduction processes. Finally, the achieved devices should be encapsulated to work successfully as solar cells.

Enhanced Photocatalytic Activity of ZnO-Graphene Oxide Nanocomposite by Electron Scavenging

Advances in nanotechnology have opened new doors to overcome the problems related to contaminated water by introducing photocatalytic nanomaterials. These materials can effectively degrade toxic contaminants, such as dyes and other organic pollutants, into harmless by-products such as carbon dioxide and water. Consequently, these photocatalytic nanomaterials have the potential to provide low-cost and environment-friendly alternatives to conventional water and wastewater treatment techniques. In this study, a nanocomposite of zinc oxide and graphene oxide was developed and evaluated for photocatalysis. This nanocomposite was characterized by XRD, FTIR, FESEM, Diffuse Reflectance Spectroscopy (DRS), TEM and UV-Vis spectrophotometer. The photocatalytic behavior of the nanocomposite was studied through the degradation of methyl orange under ultraviolet light. It is reported that the weight ratios of zinc oxide and graphene oxide do not considerably affect the photocatalytic performance, which gives this process more compositional flexibility. Moreover, hydrogen peroxide was used as an electron scavenger to increase the time-efficiency of the process. The photodegradation rate can be significantly improved (up to 24 times) with the addition of hydrogen peroxide, which increases the number of trapped electrons and generates more oxidizing species, consequently increasing the reaction rate.

Photocatalytic degradation of atenolol with graphene oxide/zinc oxide composite: Optimization of process parameters using statistical method

A four factor three level Box-Behnken design (BBD) was analysed to define the photocatalytic degradation of atenolol in an aqueous solution in slurry mode. The four different process variables under consideration in BBD model included synthesized Graphene Oxide-ZnO (GO/ZnO) catalyst dose, pH, Atenolol concentration and variation of light intensity. The model predicted the optimum value for maximum degradation rate with conditions set at 1.2 g/L catalyst concentration, pH of 4, 25 mg/l substrate concentration and 940 W light intensity. The first-order reaction rate at this optimum reaction condition is 0.845 min−1. The substrate concentration and light intensity showed highest positive effect on atenolol degradation while pH and catalyst concentration showed negative effect towards atenolol degradation. The data obtained from 29 experiments suggest that maximum rate of reaction (0.783 min−1) has been achieved within 1 h under solar irradiation at pH 6.5 using 25 ppm atenolol concentration and catalyst concentration of 1.25 g/L at light intensity of 1000 W. The model shows high correlation (R2 > 0.953) between experimental and predicted values. It was observed that the rate of degradation with GO/ZnO composite is faster when compared to Graphene/TiO2 composite.

Potent E. coli M-17 Growth Inhibition by Ultrasonically Complexed Acetylsalicylic Acid–ZnO–Graphene Oxide Nanoparticles

A single-step ultrasonic method (20 kHz) is demonstrated for the complexation of acetylsalicylic acid (ASA)–ZnO–graphene oxide (GO) nanoparticles with an average size of <70 nm in aqueous solution....

Cheap Nano-Adsorbents Based on Zno/Mineral Nanocomposites for Removal of Chloroform from Water Solution

Background: Chloroform, as a hazardous chemical, can contaminate water resources via the reaction of chlorine as an antiseptic chemical with humic acids resulted from agricultural activities. In humans, chloroform may cause dizziness, heart disorders, and disorders of the nervous system. Hence, its removal is of crucial importance. Objectives: The current study aimed to propose cheap and efficient adsorbents to remove chloroform from water. Methods: Four different nanomaterials (ZnO, ZnO/graphene oxide (ZnO/GO), ZnO/GO/Zeolite, and GO/Zeolite nanocomposites) were prepared and characterized with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) images. Textural properties of the nano- adsorbents were evaluated using Brunauer Emmet Teller (BET) and Barrett-Joyner-Halenda (BJH) techniques. Different isotherms and kinetic models were studied. The effect of pH on the removal efficiency of the nano-adsorbents was tested. Regenerability of the nano-adsorbents towards the removal of the chloroform was also evaluated. Results: XRD patterns and FESEM images of the nanocomposites confirmed lattice structures and nanoscale particle size of the prepared nanocomposites. According to the BET and BJH models, all samples had mesoporous structures. The BJH cumulative surface area of pores of ZnO, ZnO/GO, ZnO/GO/Zeolite, and GO/Zeolite nanocomposites were 8.5, 26.4, 17.2, and 20.8 m2/g, respectively. The best removal speed and efficiency were obtained according to the different isotherm and kinetic models for the removal of chloroform ZnO/GO nanocomposites. All adsorbents revealed characteristic adsorption in the pH range of 7 to 8. Conclusion: The ZnO/GO, a cheap and efficient nanocomposite, showed the best performance to remove chloroform from water samples due to its superior textural property. Hence, it can be used to remove chloroform from water for up to 5 cycles.

Facile design of graphene oxide-ZnO nanorod-based ternary nanocomposite as a superhydrophobic and corrosion-barrier coating

We reported a facile design of ternary nanocomposites of polydimethylsiloxane (PDMS)/graphene oxide nanosheets decorated with ZnO nanorods (GO-ZnO NRs) as an outstanding superhydrophobic and anticorrosion coating material for steel substrates. GO-ZnO hybrid nanofiller was synthesized using a one-step chemical bath deposition, and the ternary nanocomposite was fabricated by solution casting. Hierarchical ZnO NRs were single crystals with 40–50 nm average width, < 1 μm average length, wurtzite structure, and exposed site in the [0001] crystal orientation. These NRs were decorated on < 2 nm-thick sheets of GO with nanoscale sizes, morphologies, and geometries. The PDMS/GO-ZnO ternary nanocomposite was dried through hydrosilation curing. The effects of different concentrations of GO-ZnO hybrid nanofiller dispersed in the PDMS resin on the barrier and anticorrosion properties were investigated. Surface features, including free energy, superhydrophobicity, chemical heterogeneity, and micro-nano roughness of the nanocomposite coatings were also studied. Electrochemical experiments including determination of Tafel polarization, electrochemical impedance spectra, and open circuit potential were conducted over carbon steel as the relatively immersed surface in a solution of 3.5% NaCl. Salt spray test was performed on the coated specimens for 500 h to study their corrosion protection. Results indicated that the silicone composite with 1 wt.% of GO-ZnO hybrid nanofillers exhibited excellent coating performance. This composite showed enhanced superhydrophobicity and roughness with water contact angle of 151° and corrosion protection. Hence, the designed PDMS/GO-ZnO ternary nanocomposite possesses outstanding superhydrophobic and anticorrosion features and could be used to design next-generation anticorrosive coatings.

Electrolyte dependent performance of graphene–mixed metal oxide composites for enhanced supercapacitor applications

Graphene–metal frameworks have been extensively studied and developed as electrode materials for next generation energy storage materials. Their high surface area and easily transformable structure enhances its specific capacitance characteristics. In the present study, graphene oxide (GO) was synthesized using Hummers method. Zinc oxide and copper oxide nanoparticles were incorporated in to the GO matrix to form mixed metal oxides. GO, GO–CuO and GO–ZnO were characterized using UV–Visible, FTIR, FT Raman spectroscopy, SEM and XRD to confirm their effective formation. The surface of the glassy carbon electrode was modified by drop casting with the samples on its surface and its electrochemical properties were studied. Cyclic Voltammetry studies were conducted at various scan rates in different electrolytes (KCl, H2SO4 and Na2SO4) and the characteristic curves were observed to be asymmetric in nature. GO–CuO exhibits the highest specific capacitance of 790 F/g at 5 mV/s in KCl. The specific capacitance of the modified electrodes was also measured using the Chronopotentiometry technique. GO–CuO nanocomposites show a maximum specific capacitance of 800 F/g at 1 A/g. The nanocomposites showed enhanced electrochemical behaviour of the nanocomposites when compared to pure GO. The nanocomposites also showed good cycling stability. The superior performance of the GO–CuO and GO–ZnO nanocomposite electrode renders it as a promising material for supercapacitors applications.

Graphene Oxide-ZnO Nanocomposites for Removal of Aluminum and Copper Ions from Acid Mine Drainage Wastewater.

Adsorption technologies are a focus of interest for the removal of pollutants in water treatment systems. These removal methods offer several design, operation and efficiency advantages over other wastewater remediation technologies. Particularly, graphene oxide (GO) has attracted great attention due to its high surface area and its effectiveness in removing heavy metals. In this work, we study the functionalization of GO with zinc oxide nanoparticles (ZnO) to improve the removal capacity of aluminum (Al) and copper (Cu) in acidic waters. Experiments were performed at different pH conditions (with and without pH adjustment). In both cases, decorated GO (GO/ZnO) nanocomposites showed an improvement in the removal capacity compared with non-functionalized GO, even when the pH of zero charge (pHPZC) was higher for GO/ZnO (5.57) than for GO (3.98). In adsorption experiments without pH adjustment, the maximum removal capacities for Al and Cu were 29.1 mg/g and 45.5 mg/g, respectively. The maximum removal percentages of the studied cations (Al and Cu) were higher than 88%. Further, under more acidic conditions (pH 4), the maximum sorption capacities using GO/ZnO as adsorbent were 19.9 mg/g and 33.5 mg/g for Al and Cu, respectively. Moreover, the removal percentages reach 95.6% for Al and 92.9% for Cu. This shows that decoration with ZnO nanoparticles is a good option for improving the sorption capacity of GO for Cu removal and to a lesser extent for Al, even when the pH was not favorable in terms of electrostatic affinity for cations. These findings contribute to a better understanding of the potential and effectiveness of GO functionalization with ZnO nanoparticles to treat acidic waters contaminated with heavy metals and its applicability for wastewater remediation.

Non-volatile resistive switching memory device based on ZnO-graphene oxide embedded in a polymer matrix fabricated on a flexible PET substrate

This study demonstrates non-volatile resistive switching memory using ZnO nanoparticles (NPs) embedded in GO-PVA composites deposited on pattern Al coated flexible PET substrate. The fabricated Al/ZnO-GO-PVA composite/Al/flexible PET substrate device reveals bipolar non-volatile resistive switching characteristics. This memory device shows a significant reduction in both SET voltages (VSET) and RESET voltages (VRESET) as compared to that of control Al/GO-PVA composite/Al/flexible PET substrate device. This reduction of VSET and VRESET in the case of ZnO/GO-PVA nanocomposite is due to the presence of ZnO NPs, resulting in increasing the concentration of oxygen vacancies (holes) into the GO-PVA nanocomposite. It consequently forms the conductive path between Al top electrode (TE) and Al bottom electrode (BE) which is confirmed by using X-ray photoelectron spectroscopy (XPS). This Al/ZnO-GO-PVA composite/Al/flexible PET substrate memory device is measured and tested for the flexibility, stability, retention and endurance by constantly bending the device 50 times from an angle of 180 degree (without bending) to an angle of 90 degree. Surprisingly, the resistances of both high resistance state (HRS) and low resistance state (LRS) reveal no detectable change with different bending angles (500, 700, 900, 1200, 1500) and without bending (1800). There is also no noticeable change in the current-voltage resistive switching characteristics even after the memory device is bent from 1800 to 500 angles. This memory device demonstrates good marks in mechanical endurance and flexibility, and indicates the sample is good for bendable non-volatile memory applications.

Photocatalytic Degradation of Phenol and Methyl Orange with Titania-Based Photocatalysts Synthesized by Various Methods in Comparison with ZnO–Graphene Oxide Composite

Photocatalysis is one of the effective methods to treat wastewater and degrade pollutants. Titania (TiO2) is usually chosen based on its superior properties and its high performance as reported in many publications. However, the properties of TiO2 may be influenced by the synthesis method. In this work, several methods were applied to synthesize TiO2, and its modified form (composite with graphene oxide) to explore the influence of synthesis method on its photocatalytic activity for the methyl orange and phenol degradation under UV light illumination. The results showed that the synthesis method significantly influences on the morphology, particle sizes and surface area of the catalysts as examined by SEM and BET techniques but did not differentiate crystal structure and crystallite dimensions of catalysts as seen by XRD measurement. TiO2 catalyst synthesized by hydrothermal method using P123 template was almost anatase phase, possessed high surface area (110 m2/g) and exhibited highest activity for methyl orange and phenol degradation under UV light illumination. However, the addition of graphene oxide to the catalyst is not yet able to improve its activity under visible light. Compared with ZnO-graphene oxide photocatalyst (almost 100% phenol degraded after 275 min of the treatment), TiO2-graphene oxide catalyst exhibited much less activity for methyl orange and phenol degradation under visible light irradiation.

ZnO@graphene oxide core@shell nanoparticles prepared via one-pot approach based on laser ablation in water

Core-shell nanoparticles (NPs) have attracted tremendous attention due to their tunable properties and numerous potential applications. However, preparation of uniform and size-controlled core-shell nanomaterials of ZnO with graphene oxide (GO) is still considered as a challenging task even after years of research. In this work, we report on a facile one-pot organics-free method for preparation of GO-wrapped ZnO NPs. Laser ablation of zinc and carbon targets in water medium at ambient atmosphere resulted in formation of spherical ZnO core and GO shell, respectively. According to Raman active modes, the GO shell was layered and the ZnO core was polycrystalline. Both Raman spectra and X-ray diffraction patterns revealed that formation of layered GO increased stress inside the ZnO core. Surface layers reduced the density of defects and disorders in the ZnO crystal lattice and enhanced the phonon lifetime. Also, the minimal interfacial disorder between the layered GO and ZnO core resulted in continuous formation of a GO layer. Thus, laser ablation in liquid is demonstrated to provide stable and uniform core-shell GO@ZnO NPs with controlled GO layer that can find applications in biomedical and sensing fields.

Phytochemically fabricated reduced graphene Oxide-ZnO NCs by Sesbania bispinosa for photocatalytic performances

In this work, we demonstrated the fabrication of uniformly decorated zinc oxide (ZnO) on reduced graphene oxide (ZnO-rGO) nanocomposites using Sesbania bispinosa as photocatalyst for methylene blue dye-degradation. In the synthesis, rationally zinc-acetate and graphene oxide (GO) were added to autoclave and kept for 4 hrs with aforementioned leaves extract, later an optimized product ZnO-rGO was confirmed by using standard spectroscopy techniques. Under UV–visible light, photocatalytic performance of rGO-ZnO NCs achieved the highest dye degradation efficiency towards methylene blue from water. Thus, as an attractive paradigm rGO@ZnO for degradation of hazardous organic dyes from water to make soothing social life.

Room temperature SO2 and H2 gas sensing using hydrothermally grown GO–ZnO nanorod composite films

Graphene based 2D materials with a surfeit of active sites and advantageously high surface to volume ratio are effectively linked to well established nanostructured semiconducting metal oxides for development of nanocomposites with enhanced gas sensing properties. Graphene Oxide (GO), a sister material of graphene, is therefore a natural choice for development of room temperature operated gas sensors. In the current investigation hydrothermally grown GO and ZnO nanorods composite (GO–ZnO–NR) is utilised for room temperature gas sensing of H2 and SO2 gases. Room temperature detection of H2 and SO2 at sub-100 ppm levels with linear variation in response for different concentrations is demonstrated. Morphological and structural analyses are conducted using Scanning electron microscopy, Raman spectroscopy and X-ray diffraction. GO-ZnO-NR composite sensor is seen to exhibit robust sensing response of 5.82 and 5.45 for 100 ppm each of H2 and SO2 gases respectively at room temperature. Further, the delayed response and recovery times exhibited by the sensor for SO2 gas are recognized to be due to formation of strongly adhering SO3 species.

Improving performance of ZnO flexible dye sensitized solar cell by incorporation of graphene oxide

At today great interest has been paid to hydrogen production by water electrolysis due to their simplicity and low cost. Dye sensitized solar cell are promising devices as renewable electrical power source to achieve water electrolysis because they possess high theoretical efficiency compared with Si based solar cells. In this research, ZnO photo catalyst was modified with graphene oxide (GO) by means of high energy milling. The anode of the flexible dye-sensitized solar cell was fabricated by electrophoretic deposition of the photo catalyst onto flexible electrodes. The obtained materials were characterized by FTIR, XRD, XPS and SEM–EDS. The efficiency and fill factor of ZnO and ZnO–GO cells were estimated from the I–V curve, measured under simulated sunlight. The obtained results demonstrate that ZnO–GO cell have higher efficiency compared with the ZnO cell. The latter can be explained by the better dispersion of ZnO that enlace the dye adsorption onto the fabricated anode and by the presence of GO that improve the absorption of photons from the light.

Graphene oxide coated flower-shaped ZnO nanorods: Optoelectronic properties

Abstract In this paper, the influence of graphene oxide coating on optical and photoluminescence properties of zinc oxide nanorods (ZnO NRs) has been investigated. ZnO NRs were prepared using a hydrothermal route (from zinc nitrate hexahydrate and hexamethylenetetramine), graphene oxide (GO) was fabricated by Hummer’s method, while for synthesis of ZnO nanorods:graphene oxide nanocomposite (ZnO NRs:GO) on Si (100) substrate, a facile technique (drop coating) was proposed. The structural, morphological, optical and luminescence properties of the films were investigated using X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), together with Fourier transform infrared (FT-IR), Raman, ultraviolet–visible–near-infrared (UV/VIS/NIR) and photoluminescence (PL) spectroscopies. As revealed by XRD analysis, composites display a hexagonal wurtzite type structure with a (101) preferred grain orientation. The average crystallite sizes decrease from 45 to 40 nm after GO coating. The SEM study confirms successful coating of GO layers on flower-like ZnO nanostructures. The FTIR and Raman analyses validated the hybridization of nanocomposite and the strong interaction between ZnO NRs and GO. The band gap of the ZnO NRs:GO nanocomposite is lower (2.95eV) compared to that of ZnO NRs (3.11 eV), as determined from the analysis of UV absorbance spectra. The ZnO NRs:GO nanocomposite exhibits a broad PL band, from ∼450 nm to ∼750 nm, with a nearly white-light integrated emission and a chromaticity coordinate of (0.25, 0.34). Gaussian deconvoluted broad PL band exhibits three distinct sub-bands, associated with radiative recombinations in ZnO and GO.

Preparation and thermal conductivity investigation of reduced graphene oxide-ZnO nanocomposite-based nanofluid synthesised by ultrasound-assisted method

ABSTRACT Preparation of water-based nanofluid containing reduced graphene oxide-zinc oxide (rGO-ZnO) nanocomposite particles synthesised by ultrasonic-assisted method has been carried out in this work. Energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray pPhotoelectron sSpectroscopyand Raman spectroscopy were used to confirm the successful formation of the nanocomposite. The reduction of GO and attachment of the ZnO nanoparticles to it was evident from all the characterisation techniques. For 0.1 vol.% of rGO-ZnO nanocomposite-based nanofluid, the thermal conductivity was found to be 2.95 W/mK at 50°C. It further increased with increase in temperature and concentration of the nanofluid, for which a new correlation has been proposed, which can satisfactorily predict the behaviour. Also, comparison of thermal conductivity of rGO-ZnO nanocomposite-based nanofluid with nanofluids containing rGO, ZnO nanoparticles and other rGO-based nanocomposite particles has been done. This study suggests a possible application of the rGO-ZnO nanocomposite-based nanofluid for various heat transfer applications.