rGO Surface Research Articles

In Situ Synthesis of CoMoO4 Microsphere@rGO as a Matrix for High-Performance Li-S Batteries at Room and Low Temperatures.

Lithium-sulfur batteries (Li-S batteries) have attracted wide attention due to their high theoretical energy density and the low cost of sulfur cathode material. However, the poor conductivity of the sulfur cathode, the polysulfide shuttle effect, and the slow redox kinetics severely affect their cycling performance and Coulombic efficiencies, especially under low-temperature conditions, where these effects are more exacerbated. To address these issues, this study designs and synthesizes a microspherical cobalt molybdate@reduced graphene oxide (CoMoO4@rGO) composite material as the cathode material for Li-S batteries. By growing CoMoO4 nanoparticles on the rGO surface, the composite material not only provides a good conductive network but also significantly enhances the adsorption capacity to polysulfides, effectively suppressing the shuttle effect. After 100 cycles at room temperature with a current density of 1 C, the reversible specific capacity of the battery stabilizes at 805 mAh g-1. Notably, at -20 °C, the S/CoMoO4@rGO composite achieves a reversible specific capacity of 840 mAh g-1. This study demonstrates that the CoMoO4@rGO composite has significant advantages in suppressing polysulfide diffusion and expanding the working temperature range of Li-S batteries, showing great potential for applications in next-generation high-performance Li-S batteries.

Facile One-Pot Synthesis of Fe3O4 Nanoparticles Composited with Reduced Graphene Oxide as Fast-Chargeable Anode Material for Lithium-Ion Batteries.

To address the rapidly growing demand for high performance of lithium-ion batteries (LIBs), the development of high-capacity anode materials should focus on the practical perspective of a facile synthetic process. In this work, iron oxide nanoparticles (Fe3O4 NPs) in situ grown on the surface of reduced graphene oxide (rGO), denoted as Fe3O4 NPs@rGO, were prepared through a facile one-pot synthesis under the wet-colloidal conditions. The synthesized Fe3O4 NPs showed that uniform Fe3O4 NPs, with a size of around 9 nm, were distributed on the rGO surfaces. When applied as an anode material for LIBs, the Fe3O4 NPs@rGO anode revealed a high reversible capacity of 1191 mAh g-1 at 1.0 A g-1 after 200 cycles. It also exhibited excellent rate performance, achieving 608 mAh g-1 at a current density of 5.0 A g-1 over 500 cycles, with improved electronic and ionic conductivities due to the rGO template. This suggested that practically available anode materials can be developed through our one-pot synthesis by in situ growing the Fe3O4 NPs.

Efficient photocatalytic degradation of chloramphenicol from contaminated water over rGO@MoS2 nanocomposites

Antibiotics-based effluents pose a severe threat to the natural ecosystem by acting as reservoirs for the growth of drug-resistant bacteria if untreated. Herein, a facile and scalable approach was developed to engineer photocatalysts associating reduced graphene oxide (rGO) and molybdenum disulfide (rGO@MoS2) that were used for the degradation of chloramphenicol (CAP) from contaminated water under UV-light. The hydrothermally produced rGO@MoS2 catalysts contain CO, COH, and COC functional groups that contribute to the binding of CAP onto their surface. The rGO surface modification with MoS2 layers offers a high surface area for light absorption. Results show that the rGO@MoS2 catalyst (1:1 w/w) exhibits the highest degradation efficiency (DE) of 86 % within 180 min of light exposure at neutral pH. Further, the kinetic modelling studies for CAP degradation by rGO@MoS2 1:1 showed high linearity with pseudo-first order kinetics (R2 ∼ 0.9). The isotherm modelling studies correspond to Langmuir isotherm (R2 ∼ 0.99), suggesting monolayer-type interaction of CAP with the photocatalyst surface during photodegradation. Furthermore, the mechanism of degradation elucidated using scavenging experiments showed the involvement of both holes (h+) and electrons (e−) that contribute to the degradation of CAP by generating reactive oxygen species (ROS) like OH● and O2●− radicals. The applicability of the rGO@MoS2 photocatalyst towards the degradation of CAP was tested in Ganga water, wherein a similar ∼86 % CAP removal was observed. Furthermore, the photocatalyst was found to be stable and could be reused five times. Overall, these findings demonstrate the usefulness of the rGO@MoS2 1:1 composite as an efficient photocatalyst that can be used for the degradation of harmful organic pollutants from water bodies to provide a safer and cleaner environment.

Quantification of the Contribution of Heterogeneous Surface Processes to Pollutant Abatement during Heterogeneous Catalytic Ozonation.

Heterogeneous surface processes such as adsorption and oxidation with surface-adsorbed reactive oxygen species (ROSad, e.g., adsorbed oxygen atom (*Oad) and hydroxyl radicals (•OHad)) have been suggested to play an important role in pollutant abatement during heterogeneous catalytic ozonation (HCO). However, to date, there is no reliable method to quantitatively evaluate the contribution of heterogeneous surface processes to pollutant abatement (fS) during HCO. In this study, we developed a method by combining probe compound-based experiments with kinetic modeling to distinguish heterogeneous surface processes from homogeneous bulk reactions with aqueous O3 and ROS (•OH and superoxide radicals (O2•-) in the abatement of various pollutants (e.g., atrazine, ibuprofen, tetrachloroethylene, and perfluorooctanoic acid) during HCO with reduced graphene oxide. The results show that the pollutants that have a low affinity for the rGO surface (e.g., ibuprofen and tetrachloroethylene) were essentially abated by homogeneous bulk reactions, while the contribution of heterogeneous surface processes was negligible (fS < 5%). In contrast, heterogeneous surface processes played an important or even dominant role in the abatement of pollutants that have a high surface affinity (e.g., fS = 32-82% for atrazine and perfluorooctanoic acid). This study is a critical first step in quantitatively evaluating the role of heterogeneous surface processes for pollutant abatement during HCO, which is crucial to understanding the mechanism of HCO and designing catalysts for effective pollutant abatement.

Collective effect of reduced graphene oxide and Zn2U hexaferrite filler based epoxy composites on microwave absorption with improved mechanical properties

Herein, we have synthesized Ba4Zn2Fe36O60 (Zn2U) and have produced reduced graphene oxide (rGO) wrapped filler material for the preparation of epoxy composites of different weight percentages (40, 50 and 60 wt %). These rGO wrapped Zn2U hexaferrite filler was analyzed by XRD and SEM to examine the crystal structure and distribution of Zn2U hexaferrite in between/on the surface of rGO respectively. The magnetic and mechanical properties of prepared rGO@Zn2U@epoxy composites were evaluated by employing vibrating sample magnetometer and universal testing machine respectively. The investigation involved analyzing the complex permittivity and permeability, and based on this information, an assessment of the reflection loss was conducted. The results obtained indicate that epoxy composites with a filler content of 60 % rGO@Zn2U have significant promise as an advantageous choice for EMI shielding and microwave absorption applications.

Polyaniline/graphitic carbon nitride/reduced graphene oxide ternary nanocomposite film for flexible thermoelectric application

The present study outlines the preparation of a ternary nanocomposite film comprising of polyaniline doped with camphor sulfonic acid (PANI), reduced graphene oxide (rGO), and graphitic carbon nitride (g-C3N4), and delves into its thermoelectric performance. PANI is known to possess high electrical conductivity (σ) and poor thermal conductivity (κ). However, its potential for thermoelectric applications is constrained by the low value of the Seebeck coefficient (S). The incorporation of g-C3N4in PANI has been demonstrated to result in an improvement of the Seebeck coefficient. Furthermore, the addition of rGO to the PANI/g-C3N4sample counteracts the decrease in electrical conductivity. The PANI/g-C3N4/rGO ternary nanocomposite film exhibits an enhanced Seebeck coefficient of ∼2.2 times when compared to the PANI sample. The Seebeck coefficient of the PANI/g-C3N4/rGO nanocomposite is enhanced by the energy filtering effect that occurs at the interfaces between g-C3N4/PANI and PANI/rGO. Theπ-πinteraction between the PANI chains and rGO is responsible for the increased electrical conductivity resulting from the well-ordered polymer chain arrangement on the g-C3N4and rGO surfaces. The ternary nanocomposite sample demonstrated a synergistic improvement in both electrical conductivity and Seebeck coefficient, resulting in a remarkable ∼4.6-fold increment in power factor and an ∼4.3-fold enhancement in the figure of merit (zT), as compared to the pristine PANI film.

A fresh perspective to synthesizing and designing carbon/sulfur composite cathodes using supercritical CO2 technology for advanced Li-S battery cathodes

The morphology and surface chemistry of the sulfur host within lithium-sulfur (Li-S) batteries significantly influence the overall battery performance. To investigate this relationship, we employed a non-toxic heat treatment to produce reduced graphene oxide (rGO) with varying degrees of reduction, resulting in distinct surface chemistries. The physicochemical characteristics and electrochemical properties of four differently reduced GO samples and rGO/sulfur composite cathodes developed with supercritical CO2 technology were examined. Our study established a clear correlation between the specific surface area and porosity of rGO and the electrochemical performance of the corresponding rGO/sulfur composite cathodes. Notably, rGO samples reduced at 350°C (rGO350) exhibited superior discharge capacity and long-term cycling stability compared to those reduced at higher temperatures. This performance enhancement can be attributed to the combination of high surface area, porosity, and an open morphology in rGO350. These findings underscore the importance of optimizing carbon chemistry, microstructure, and cathode synthesis strategies in Li-S batteries. By effectively controlling sulfur loading and distribution within the rGO network, we can enhance active material utilization, boost electronic conductivity, and ensure the long-term stability of rGO/sulfur composite cathodes. Our research suggests that SC-CO2-assisted synthesis offers a promising approach for designing high-performance carbon/sulfur composite cathodes for Li-S batteries. This method provides a versatile platform for tailoring the rGO morphology and surface chemistry, optimizing battery performance. By carefully considering the interplay between these factors, we can unlock the full potential of Li-S batteries for various applications.

Influence of reduced graphene oxide layer on sensing characteristics of Co3O4/rGO nanocomposite towards Liquefied Petroleum Gas (LPG)

Liquefied petroleum gas (LPG), a mixture of different hydrocarbons, is a highly inflammable and explosive gas that is harmful to the environment and human health. Thus, it is imperative to fabricate LPG sensors with higher sensitivity, selectivity, stability, and minimal power consumption, functioning at low temperatures. The current study reports on the monitoring and detection of LPG at low functional temperatures using Co3O4-loaded on rGO (rGO-Co) prepared using the hydrothermal method. The microstructural properties of the materials were investigated in detail. The rGO-Co (80 wt%) sensor showed outstanding sensitivity (0.00364 ppm−1) and selectivity toward LPG, as well as a limit of detection of 1 ppm at a temperature of 125 °C. The sensing mechanism showed that an even distribution of Co3O4 throughout the rGO layers, serving as efficient sites for the adsorption and desorption of LPG molecules, was associated with enhanced gas-sensing capabilities. Furthermore, the response to LPG detection was significantly influenced by the combination of the finite spherical nanoparticles with increased pore sizes between them and reduced energy band gaps. Thus, the novel improvement of the sensor towards LPG detection was linked to the ohmic connection formed between rGO and Co3O4 forming a p-p heterojunction at the interface. Additionally, the coupling of Co-O-C bonds validated by high-temperature X-ray diffraction and X-ray photoelectron spectroscopy provided extra active sites from Co3+ for effective LPG adsorption. The sensing mechanism induced by the loading of Co3O4 on the rGO surface was also deliberated.

Application of Reduced Graphene Oxide-Zinc Oxide Nanocomposite in the Removal of Pb(II) and Cd(II) Contaminated Wastewater

Toxic metal wastewater is a challenge for exposed terrestrial and aquatic environments, as well as the recyclability of the water, prompting inputs for the development of promising treatment methods. Consequently, the rGO/ZnONP nanocomposite was synthesized at room temperature for four hours and was tested for the adsorption of cadmium and lead in wastewater. The optimized nanocomposite had the lowest band gap energy (2.69 eV), and functional group interactions were at 516, 1220, 1732, 3009, and 3460 cm−1. The nanocomposite showed good ZnO nanoparticle size distribution and separation on rGO surfaces. The nanocomposite’s D and G band intensities were almost the same, constituting the ZnO presence on rGO from the Raman spectrum. The adsorption equilibrium time for cadmium and lead was reached within 10 and 90 min with efficiencies of ~100%. Sips and Freundlich best fitted the cadmium and lead adsorption data (R2 ~ 1); therefore, the adsorption was a multilayer coverage for lead and a mixture of heterogenous and homogenous coverage for cadmium adsorption. Both adsorptions were best fitted by the pseudo-first-order model, suggesting the multilayer coverage dominance. The adsorbent was reused for three and seven times for cadmium and lead. The nanocomposite showed selectivity towards lead (95%) and cadmium (100%) in the interfering wastewater matrix. Conclusively, the nanocomposite may be embedded within upcoming lab-scale treatment plants, which could lead to further upscaling and it serving as an industrial wastewater treatment material.

Low temperature coupled oxidative/adsorptive desulfurization catalyzed by FeOOH/rGO nanocomposite

Abstract Desulfurization of fossil fuel products has grabbed increased attention, where many research themes focus on the synthesis of novel materials with enhanced desulfurization potentialities, at a reasonable cost, and within a shorter working time. So, in this work, we synthesized ultrathin FeOOH nanorods and then anchored them over reduced graphene oxide (FeOOH/rGO nanocomposite) to act as catalyst/adsorbent system during in situ oxidative/adsorptive desulfurization of diesel fuel model. The XRD, FTIR and Raman analyses demonstrated the successful combination of the FeOOH with the rGO surface. The BET surface area of the FeOOH/rGO was enhanced by 2.2 folds compared to the parent FeOOH, with pore volume ~0.268 cc/g. TEM investigation proved the FeOOH-rGO conjugation. The catalytic processes were carried out in association with H2O2 as an oxidizing element in different conditions. FeOOH showed a high adsorption capacity of ~960 mg/g, and obeyed pseudo-second order kinetic confirming chemisorption nature, while the process Ea recorded about ~85.4 kJ/mol. On the other hand, FeOOH/rGO system achieved ultra-high adsorption capacity of ~989 mg/g with high removal efficiency (98.9%), which assumed FeOOH/rGO as a highly potential catalyst/adsorbent system for ultra desulfurization process.

Effects of Heteroatom Doping on the Electrochemical Hydrogen Uptake and Release of Pd-Decorated Reduced Graphene Oxide.

Heteroatom doping has been widely recognized as a key strategy for improving the electrochemical properties of graphene-based materials for hydrogen storage. However, a precise understanding of how heteroatom doping influences catalytic performance, specifically regarding the intricate effects of doping-induced electron redistribution, has been lacking. Here, we report on a comprehensive exploration of the electrochemical performance enhancement in Pd-decorated reduced graphene oxide (rGO) nanocomposites through fluorine (F) or nitrogen (N) doping. Various analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) were employed to thoroughly characterize the synthesized nanocomposites. The findings revealed that either F or N doping effectively addressed clustering issues of Pd nanoparticles formed on the rGO surface, resulting in improved homogeneity of Pd distribution. Electrochemical studies provided crucial insights into hydrogen adsorption-desorption behaviors. The heteroatom doped nanocomposites, Pd/N-rGO and Pd/F-rGO, exhibited superior electrochemical performance, which can be attributed to the increase of the active sites due to the N-/F-doping, respectively. The hydrogen discharge capacities of Pd/N-rGO (80.9 mAh g-1) and Pd/F-rGO (25.0 mAh g-1) nanocomposites were determined to be over 4.0 and 1.2 times higher than that of the Pd/rGO (20.1 mAh g-1), respectively. The distinctive electrochemical performances observed between the two types of heteroatom-containing nanocomposites highlight the subtle structural modifications of Pd nanoparticles as the key factor influencing performance. This research contributes essential knowledge to the evolving field of hydrogen storage materials, emphasizing the promising potential of heteroatom-doped Pd-decorated rGO nanocomposites for advancing clean and sustainable energy solutions.

Utilization of copper chromite-reduced graphene oxide nanocomposite for the wastewater remediation and effective supercapacitive performance

This article has detailed the growth of virgin copper chromite nanoparticles (CuCr2O4 NPs) and reduced graphene oxide sheet (rGO)-based CuCr2O4 nanocomposite through the process of reflux condensation method and calcination process. When exposed to visible light, these two synthesized nanomaterials exhibit enhanced photocatalytic activity which helps in the degradation of organic dyes such as methylene blue. Numerous characterization methods, including FTIR, UV–visible analysis, and XRD, verify the creation of these nanomaterials. The CuCr2O4-rGO nanocomposite's semiconductor nature is confirmed by the band gap analysis using Tauc's formula. The CuCr2O4 NPs grown on the rGO surface have a dimension of 6 nm, according to the TEM study and particle distribution graph. To find the reason for the enhanced photo-activity, we have proposed a photocatalytic mechanism which is supported by photoluminescence result. Recyclability in five more cycles is used to measure the stability of the nanocomposite, and it is found that photocatalytic efficiency does not significantly decline up to five cycles. When exploring the CuCr2O4-rGO nanocomposite as a material for supercapacitor electrodes, it showcased a remarkable specific capacity of 681.43 F/g at 0.5 A g−1. Moreover, the CuCr2O4-rGO nanocomposite electrode displayed a long-term life cycle, retaining 93.8 % of its initial capacity after 1200 cycles, paired with a commendable Coulombic efficiency of 95.31 % and outstanding power and energy density of 1504 W/kg and 23.66 Wh/kg respectively.

Highly sensitive disposable test strips for sweat chloride detection using silver nanoparticles decorated reduced graphene oxide

The quantification of chloride ions in sweat by a point-of-care test system is a useful strategy in the early screening of cystic fibrosis. In this context, silver nanoparticles decorated reduced graphene oxide were synthesized by one-pot reduction method in this work. This reaction in situ produces silver nanoparticles spread across thin sheets of rGO with high surface area. This helps in the electrochemical detection of chloride ions by conversion of silver to silver chloride and formation of a thin layer of silver chloride on the surface of nanocomposite. The validity of this strategy has been demonstrated by voltammetric analysis of chloride ions using the screen-printed Ag-rGO nanocomposite. For electrodes tested in buffer, the sensitivity was 37.66 ± 0.99 mA (log mM)−1 cm−2 with a high selectivity and detection range from 30 to 400 mM chloride concentration. The lower detection limit is 1.02 mM (S/N = 3), and the relative standard deviation (RSD) of sensor response is 4.77 %. Disposable sensor test strips fabricated with screen printing of the catalyst followed by layer by layer array of electrolyte and hydrophilic membrane shows a sensitivity of 165.2 ± 4.3 µA mM−1 cm−2, a linear detection range upto 210 mM, and a LOD of 2.46 ± 0.06 µM. The quantification of the developed sensor strips were confirmed by comparing the values from clinical laboratories. This finding confirms the potentiality of the developed method and its possible application in the rapid and easy-to-use point-of-care devices. Notable advantages of the Ag-rGO nanocomposite is its reversibility due to the regeneration of fresh silver nanoparticles on the rGO surface and increased electrochemical response. This feature realizes a high stability even at multiple trials with a RSD of 2.63 % and long-time storage tested upto 3 months. Using this superior performance, the developed sensor test strip demonstrates a disposable, non-invasive, reproducible, reversible, highly selective, and sensitive monitoring of chloride ions.

Theoretical Analysis of Superior Photodegradation of Methylene Blue by Cerium Oxide/Reduced Graphene Oxide vs. Graphene.

Density functional theory and a semi-empirical quantum chemical approach were used to evaluate the photocatalytic efficiency of ceria (CeO2) combined with reduced graphene oxide (rGO) and graphene (GP) for degrading methylene blue (MB). Two main aspects were examined: the adsorption ability of rGO and GP for MB, and the separation of photogenerated electrons and holes in CeO2/rGO and CeO2/GP. Our results, based on calculations of the adsorption energy, population analysis, bond strength index, and reduced density gradient, show favorable energetics for MB adsorption on both rGO and GP surfaces. The process is driven by weak, non-covalent interactions, with rGO showing better MB adsorption. A detailed analysis involving parameters like fractional occupation density, the centroid distance between molecular orbitals, and the Lewis acid index of the catalysts highlights the effective charge separation in CeO2/rGO compared to CeO2/GP. These findings are crucial for understanding photocatalytic degradation mechanisms of organic dyes and developing efficient photocatalysts.

Production and characterizations of silver-doped copper ferrite anchored in RGO surface

The rapid advancements in nanotechnology have spurred the search for more efficient materials across various advanced applications. To this end, this study aimed to synthesize and investigate the structural properties of copper ferrite and mixed copper-silver ferrite anchored onto reduced graphene oxide (rGO) sheets. Samples were synthesized via the hydrothermal method at four different temperature ranges for 6 h at pH 11. The systems were analyzed using Raman spectroscopy, X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). XRD analysis revealed changes in the structural parameters of the ferrite, the presence of Fe2O3 and Ag, and confirmed the anchorage of submicron particles onto rGO, along with diversified morphologies. Both Raman spectroscopy and XRD confirmed the reduction of graphene oxide (GO) to rGO.

Hybrid of sub-1 nm single-dispersed polyoxometalate and reduced graphene oxide as advanced anodes for durable sodium-ion batteries

Polyoxometalates (POMs) are widely thought as promising choices for sodium-ion batteries (SIBs) because of their refined molecular structures and excellent reversible multielectron charge-discharge behaviors. Nevertheless, the POMs anion clusters could dissolve in the electrolyte when attacked by solvent molecules, thus reducing active sites and affecting the actual performance of these POMs-based electrodes. Herein, we report the development of a new type of electrode system that produces single-dispersed POMs molecular cluster/polydopamine/reduced graphene oxide composites ({PMo12}/PDA@rGO) through a self-assembly method. PDA acts as the role of “killing two birds with one stone”. It not only works as the linker to promote the formation of stable and uniform monodisperse {PMo12} clusters on the rGO surface, but also prevents the POMs from desorbing and dissolving upon deep cycling test. As a consequence, when used as the anode material for SIBs, the obtained {PMo12}/PDA@rGO exhibits an admirable long-term cycling performance, for instance, it holds a high Na-storage capacity of 277.5 mAh g−1 with an average Coulomb efficiency up to 99.89 % over 2000 cycles at 1 A g−1. This work offers versatile possibilities for designing POMs-based composites and provides new insight into developing single dispersed POMs for advanced SIBs.

One-step solvothermal synthesis of Zn2SnO4/rGO composite material and highly gas sensing performance to acetone

In this study, one-step solvothermal method was employed to synthesize Zn2SnO4 and Zn2SnO4/rGO composites. Zn2SnO4 was bonded to the rGO surface or in the spaces between the lamellar layers to create a semiconductor composite material that is physically supported by heterojunction. Compared to Zn2SnO4 sensor, the Zn2SnO4/rGO sensing material exhibits superior gas-sensing properties to acetone. The optimal temperature of Zn2SnO4/rGO sensor was just 200 °C, while its sensitivity to 100 ppm acetone gas was up to 11.2. Its response and recovery times were only 8 s and 11 s, respectively. The large specific surface area and distinctive heterojunction of the composite material are responsible for the enhanced gas-sensing performance of Zn2SnO4/rGO sensing material. Zn2SnO4/rGO is an ideal sensing material due to high sensitivity, fast response/recovery properties, great selectivity, and stability.

Synergistic effect of Al2O3-decorated reduced graphene oxide on microstructure and mechanical properties of 6061 aluminium alloy

In this study, Al6061 alloy matrix composites reinforced Al2O3-decorated reduced graphene oxide (Al2O3/RGO) with 0.1, 0.3 and 0.5 weight present (wt%) were successfully fabricated using high energy ball milling and hot extrusion techniques. The microstructures of these Al2O3/RGO/Al6061 aluminum matrix composites (Al MMCs) were characterized. The results showed that Al2O3/RGO were uniformly distributed within the Al6061 matrix and tightly bonded to the matrix. Al2O3 encapsulation on RGO surface would prevent the formation of Al4C3 brittle phase in matrix, ensuring that there was no reaction between the reinforcement and the matrix Al6061. Tensile strength and Vickers hardness tests demonstrated that the mechanical properties of Al MMCs significantly increased with addition of Al2O3/RGOs. Remarkably, Al MMCs with 0.1 wt% reinforcement showed tensile yield and tensile strengths of 270 MPa and 286 MPa, respectively, which were 49% and 43% higher than those of pure Al6061 prepared using the same process. Furthermore, the 0.1 wt% Al2O3/RGO composite also showed the best plastic deformation capability in considering of the strength.

Highly sensitive electrochemical sensor for glutathione detection using zinc oxide quantum dots anchored on reduced graphene oxide

This work presents a highly sensitive and selective electrochemical sensor for glutathione (GSH) detection using a glassy carbon (GC) electrode modified with zinc oxide quantum dots-reduced graphene oxide nanocomposites (ZnO QDs-rGO NCs). The ZnO QDs (diameters about ∼2 to 8 nm) were synthesized and successfully anchored onto the surface of reduced graphene oxide (rGO). The resulting nanocomposites were then characterized using various spectroscopic and microscopic techniques. The wurtzite crystal structure of ZnO and anchored onto the rGO surface were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The synergistic interaction between ZnO QDs with rGO provides a large surface area, high conductivity, and efficient transfer of electrons, resulting in improved electrocatalytic activity for GSH oxidation. The ZnO QDs-rGO/GC electrode exhibits exceptional performance with a wide linear range (0.01–10 μM), high sensitivity (3.66 μAμM−1), and excellent selectivity for GSH. The sensor demonstrates good analytical stability, characterized by high reproducibility (%RSD = 2.90%) and repeatability (%RSD = 1.49%), and maintains its performance in the presence of common biological interferences. The applicability of the sensor was validated through successful GSH detection in complex matrices like human blood and pharmaceutical capsules, achieving recovery rates of 98.1-102.0% with excellent reliability.

Enhancing radical scavenging using reduced graphene oxide based metal organic frameworks: A comparative study

This work reports the facile fabrication of reduced graphene oxide (rGO) based metallic (R) (copper (Cu), silver (Ag), gold (Au) and trimetallic (Tm)) nanocomposites or metal organic frameworks (MOFs) using glucose as a reducing and stabilizing agent in an eco-friendly and low-cost method. The morphology, physicochemical properties and size of different nanocomposites were determined by Scanning Electron Microscopy (SEM), UV–Visible spectroscopy, Transmission electron Microscopy (TEM), Cyclic voltametry and Raman spectra, respectively. In comparative experimental investigations, antioxidant behavior of rGO, RNPs (metallic nanoparticles: AuNPs, CuNPs, AgNPs, TmNPs (trimetallic NPs), rGO-RNPs (rGOCuNPs, rGO-AgNPs, rGO-AuNPs, and rGO-TmNPs or Au@Ag@Cu decorated rGO) was explored for the first time. The antioxidant behavior was estimated by radical scavenging assays viz. total antioxidant, ferric power reducing and hydrogen peroxide assay. Interestingly, antioxidant properties of rGO-RNPs nanocomposite (R-Cu/Au/Ag/Tm)) were found to be arranged in the descending order of AA (ascorbic acid)>rGO-TmNPs > TmNPs >rGOCuNPs > rGO-AgNPs > rGO-AuNPs >AgNPs > CuNPs > AuNPs for total antioxidant assay. In similar way order or arrangmet was rGO-TmNPs > rGO-AgNPs > rGO-AuNPs > AuNPs > TmNPs > rGOCuNPs > AA >AgNPs > CuNPs for hydrogen peroxide scavenging method. And order of arrangment was found to be rGO-TmNPs-GO > rGOCuNPs > rGO-AgNPs > rGO-AuNPs > CuNPs > AgNPs > AuNPs> TmNPs > AA using ferric reducing power assay. These findings indicated that TmNPs decorated rGO showed the best antioxidant capabilities among rGO, RNPs and rGO-RNPs nanocomposites. Furthermore, electrochemical assessment of kinetic parameters (such as peak separation potential, peak current, diffusion coefficient, k°, Ψ, concentration of ionic species etc.) estimated using cyclic voltammetry provided insight towards favourable drift obsereved in all these parameters, that appear to be contributing towards improved conducting behavior. This behavior could also have emerged from improving the disorder in sp2/sp3 carbon of rGO and metal nanoparticles, thereby improving the stability and favorable ease in transfer of electrons between metal NPs and rGO surface. Since these metallic RNPs were found to be uniformly distributed onto rGO surface, this synergistic amalgamation of rGO and multi-metallic nanoparticles possess great potential for low cost, eco-friendly opportunities to tap various environmental and industrial applications. Further investigations to assess catalytic applications, clinical diagnostics and antimicrobial activity estimations are under way.