rGO Sheets Research Articles

Structural elucidation and environmental remediation potential of Ficus carica mediated synthesis of novel Eu3O4/rGO nanocatalyst

A novel europium oxide/reduced graphene oxide (Eu3O4/rGO) nanocatalyst was synthesized via green one pot method and green deposition method using Ficus carica leaves extract. The prepared nanocatalyst was characterized by UV–vis., FTIR, TGA, SEM, HR-TEM, and XRD. Band gaps of Eu3O4/rGO nanocatalyst by green one pot method and green deposition method were found 3.27 and 5.5 eV, respectively. The particle size of Eu3O4/rGO nanocatalyst determined by HRTEM was found 16.9 and 32.1 nm when prepared by using green one pot method and green deposition method, respectively. Significant morphology was observed in the SEM images of Eu3O4/rGO nanocatalysts; where Eu3O4 nanoparticles were observed to be dispersed on chunks of sheets of rGO. The catalytic activity of prepared nanocatalyst was performed against Methylene blue, Rhodamine B, and Ciprofloxacin. The green one pot method demonstrated highest levels of degradation activity 88, 75 and 54 % against MB, CIP, and Rh B pollutants present in wastewater, respectively and helps to achieve SDGs 6 and 13.

SnO2-TiO2/reduced graphene oxide nanocomposites: Green synthesis and enhanced photocatalytic efficiency for dye removal

Titanium oxide nanoparticles (TiO2 NPs) have been interested in potential applications, including gas-sensing, energy storage, environmental remediation, and medical fields. In the present work, fabricated SnO2-TiO2/RGO nanocomposites (NCs) have been produced through a green precipitation approach. XRD, TEM, SEM, EDX, XPS, FTIR, UV, and PL analyses have been carefully applied to invistage the physicochemical properties of prepared NPs and NCs. The XRD data showed that the crystal structure of the TiO2 NPs was affected by the introduction of SnO2 NPs and RGO sheets. The spherical shape of the prepared samples and their morphologies were confirmed using TEM and SEM images. EDX and XPS analyses confirmed that tin (Sn), titanium (Ti), oxygen (O), and carbon (C) were further present in the SnO2-TiO2/RGO NCs. FT-IR spectra determines the functional groups with bands between the compositions of obtained NPs and NCs. Besides, the band gap energies of prepares samples were estimated from UV–vis spectra. It displayed that the absorption peak of the synthesized TiO2 NPs was improved after the addition of SnO2 NPs and an RGO sheet. PL analysis indicate that the PL intensity of the prepared TiO2 NPs was decreased with the addition of SnO2 NPs and RGO sheets due to a decrease in the recombination rate of electrons (e−)-holes (h+). As shown in photocatalytic results, the photodegradation of methylene blue (MB) dye of SnO2-TiO2/RGO NCs was reached 92.20% after 140 min of UV irradiation. These results suggest that the addition of RGO sheets occupied a role in enhanced the photocatalytic performance of the prepared NCs. This study highlighted that these samples could be applied in various applications such as photocatalytic and therapeutic areas.

Reduced graphene oxide – CeO2 nanocomposites for photocatalytic dye degradation

Over the past few decades, the widespread use of dyes has led to considerable environmental pollution, posing serious threats to human health and ecosystems. In this context, here focus on a tailored nanocomposite comprising reduced graphene oxide (rGO) and cerium oxide (CeO2) to eradicate methylene blue (MB) dye. The fabrication process involves a facile synthesis wherein CeO2 nanoparticles are anchored onto rGO sheets through co-precipitation treatment by mixing a precursor salt of cerium with graphene oxide (GO) in presence of reducing agent. The resulting nanocomposites were characterized using X-ray diffraction (XRD) analysis which confirms the crystallite size of CeO2 and rGO-CeO2 determined to be 21.61 nm and 10.74 nm respectively. Further FE-SEM analysis vividly illustrates the relatively spherical form of CeO2, which is dispersed on the rGO surface and energy dispersive X-ray spectroscopy (EDX) results provide clear evidence of the presence of carbon, cerium and oxygen in the composite. Additionally, Fourier-transform infrared spectroscopy (FTIR) confirms the composition of the rGO-CeO2 nanocomposites demonstrating the existence of various oxygen-containing groups, including O–H, C=O and Ce–O bonds. Thermogravimetric analysis (TGA) highlights that the rGO-CeO2 nanocomposites exhibits higher thermal stability with only 21.88 % weight loss up to 400 °C. Moreover, the photocatalytic activity of rGO-CeO2 nanocomposite exhibits a remarkable 94.92 % degradation of MB dye within 80 min under optimal conditions of UV light irradiation (λ = 254 nm), with a catalyst dosage of 7 mg in a 20 ppm of MB dye solution at pH 9. In contrast, pristine rGO and CeO2 achieved only 32.27 % and 38.48 % in 100 and 90 min respectively. The kinetics of photocatalysis process were meticulously studied and revealed that they followed pseudo-second order kinetic model suggesting chemisorption of MB dye onto nanocomposites prior to degradation. The stability of the nanocomposite was assessed under optimal conditions, demonstrating robust MB degradation (78 %) even up to the 4th cycle. Overall, the successful outcomes of this study show significant potential for degrading MB dye in wastewater by using the rGO-CeO2 nanocomposite.

NdCoO3 nanoparticles grown on reduced graphene oxide sheets as an efficient electrocatalyst for hydrogen evolution reaction

To meet the huge energy crisis due to the limitation of fossil fuel, hydrogen has been considered the most promising clean energy source due to its high efficiency, non-toxic, and clean emission products. Therefore, over the past few years, researchers have been trying to find an effective route for bulk production of hydrogen energy from water splitting. Many efforts have already been made to use suitable electrocatalysts such as transition metal-based oxides, hydroxide alloys, and carbides for hydrogen production from water splitting but these electrocatalysts are hindered due to instability over prolonged usages in alkaline solution. To overcome this issue, rare-earth perovskite oxide materials are being focussed as an efficient electrocatalyst for electrocatalytic hydrogen evolution reaction (HER) through water splitting in an alkaline medium. In the present work, we have explored to synthesize the rare-earth perovskite neodymium cobalt oxide (NdCoO3) nanoparticles grown on reduced graphene oxide (rGO) sheet, via a hydrothermal route for electrochemical hydrogen evolution in an alkaline medium. The NdCoO3/rGO nanocomposite shows a remarkably low overpotential of 84mV at the desired current density of 10 mA/cm2, compared to pristine NdCoO3 and rGO. The synergistic impact between NdCoO3 and the rGO backbone, resulting in enhanced efficiency in the HER. The nanocomposite also shows high stability and durability even more than 100 h of electrolysis under an inert atmosphere.

Improving the NO2 Gas Sensing Performances at Room Temperature Based on TiO2 NTs/rGO Heterojunction Nanocomposites.

The development of energy-efficient, sensitive, and reliable gas sensors for monitoring NO2 concentrations has garnered considerable attention in recent years. In this manuscript, TiO2 nanotube arrays/reduced graphene oxide nanocomposites with varying rGO contents (TiO2 NTs/rGO) were synthesized via a two-step method for room temperature NO2 gas detection. From SEM and TEM images, it is evident that the rGO sheets not only partially surround the TiO2 nanotubes but also establish interconnection bridges between adjacent nanotubes, which is anticipated to enhance electron-hole separation by facilitating electron transfer. The optimized TiO2 NTs/rGO sensor demonstrated a sensitive response of 19.1 to 1 ppm of NO2, a 5.26-fold improvement over the undoped TiO2 sensor. Additionally, rGO doping significantly enhanced the sensor's response/recovery times, reducing them from 24 s/42 s to 18 s/33 s with just 1 wt.% rGO. These enhancements are attributed to the increased specific surface area, higher concentration of chemisorbed oxygen species, and the formation of p-n heterojunctions between TiO2 and rGO within the nanocomposites. This study provides valuable insights for the development of TiO2/graphene-based gas sensors for detecting oxidizing gases at room temperature.

Photocatalytic degradation of Rhodamine B using a reusable and magnetically separable Fe3O4/rGO/ZnO nanocomposite synthesized through green approach utilizing plant leaf extracts

We propose the magnetically separable, green synthesis of Fe3O4/rGO/ZnO using a higher mass ratio of Fe3O4/rGO and varying ZnO concentration to degrade an aqueous solution of Rhodamin B under Fenton reaction and UV light irradiation. Fe3O4 had been synthesized under the coprecipitation method utilizing Moringa oleifera leaf, while rGO had been fabricated by sonicating GO utilizing Amaranthus viridis leaf. Afterward, Fe3O4/rGO was composited under a facile method with a mass ratio of 5:5. And the last, Fe3O4/rGO/ZnO was green-synthesized through precipitation method using Amaranthus viridis leaf with various molarity ratio of Fe3O4/rGO: ZnO equal to 1:1, 1:2, 1:3, 1:4, and 1:5. X-ray diffraction revealed the presence of Fe3O4 and ZnO phases, while Raman spectroscopy confirmed the successful reduction of GO to rGO. The morphological analysis demonstrated that the particles were nearly spherical, nonuniform, and slightly dispersed, with some agglomeration observed on the rGO sheets. Fourier-transform infrared spectroscopy identified metallic functional groups, including Fe–O and Zn–O, at 524–570 cm−1 and 447–462 cm−1, respectively. However, redshift absorption and band gap narrowing were observed as the ZnO concentration increased. Photoluminescence analysis revealed that increased ZnO concentration reduces recombination and improves charge separation efficiency. The vibrating sample magnetometer exhibited soft magnetic properties. The magnetization of Fe3O4/rGO saturated at 21.7 emu/g and diminished as incorporated ZnO. The photodegradation increased with the increase of ZnO concentration, reaching its optimum at 1:5, about 89.9%. Fe3O4/rGO/ZnO demonstrates a possible ecologically friendly photocatalyst for wastewater remediation. The photocatalyst can be reused for up to three cycles with no significant change in its performance. Scavenger evaluation indicates that electrons and holes are the predominant reactive species in the photocatalytic reaction involving Fe₃O₄/rGO/ZnO.

Hetero‐Dimensional Micro‐Nano Architectures Toward Electromagnetic Devices and Hybrid Energy Transport

AbstractHuman spaceflight, lunar exploration projects, and interstellar travel are the grand visions of human exploration of the universe. However, the energy sustainability of these projects is a concern. Electromagnetic functional materials and devices are expected to fulfill their potential in electronic communication and energy utilization. Herein, hetero‐dimensional micro‐nano architectures composed of Cu3Se2 microspheres and reduced graphene oxide (rGO) sheets are fabricated for the first time by the sacrificial template method, anion substitution engineering, electrostatic adsorption, and reduction‐oxidation reaction. Based on the excellent electromagnetic response of the composites, they exhibit strong and ultra‐wide microwave absorption ability with the effective absorption bandwidth (EAB) reaching 8.24 GHz at a thickness of 2.2 mm. In addition, an electromagnetic metamaterial with an EAB to ≈13.5 GHz is proposed, exhibiting significant properties. More significantly, the composites can be used to construct a range of electromagnetic devices: a spiral antenna with adjustable return loss and gain, with a maximum gain of up to 2.5 dBi; a microstrip power divider that can efficiently split the input signal into four equal parts and output it; a hybridized energy transport device can convert and store electromagnetic energy. This work provides new inspiration for electromagnetic protection, electronic communication, and energy development.

Preferential Stripping Analysis of Post-Transition Metals (In and Ga) at Bi/Hg Films Electroplated on Graphene-Functionalized Graphite Rods

In this study, we introduce a novel electrochemical sensor combining reduced graphene oxide (rGO) sheets with a bismuth–mercury (Bi/Hg) film, electroplated onto pencil graphite electrodes (PGEs) for the high-sensitivity detection of trace amounts of gallium (Ga3+) and indium (In3+) in water samples using square wave anodic stripping voltammetry (SWASV). The electrochemical modification of PGEs with rGO and bimetallic Bi/Hg films (ERGO-Bi/HgF-PGE) exhibited synergistic effects, enhancing the oxidation signals of Ga and In. Graphene oxide (GO) was accumulated onto PGEs and reduced through cyclic reduction. Key parameters influencing the electroanalytical performance, such as deposition potential, deposition time, and pH, were systematically optimized. The improved adsorption of Ga3+ and In3+ ions at the Bi/Hg films on the graphene-functionalized electrodes during the preconcentration step significantly enhanced sensitivity, achieving detection limits of 2.53 nmol L−1 for Ga3+ and 7.27 nmol L−1 for In3+. The preferential accumulation of each post-transition metal, used in transparent displays, to form fused alloys at Bi and Hg films, respectively, is highlighted. The sensor demonstrated effective quantification of Ga3+ and In3+ in tap water, with detection capabilities well below the USEPA guidelines. This study pioneers the use of bimetallic films to selectively and simultaneously detect the post-transition metals In3+ and Ga3+, highlighting the role of graphene functionalization in augmenting metal film accumulation on cost-effective graphite rods. Additionally, the combined synergistic effects of Bi/Hg and graphene functionalization have been explored for the first time, offering promising implications for environmental analysis and water quality monitoring.

Hydrothermally synthesized hierarchical Pom-Pom-like gadolinium modified tungsten oxide reinforced with rGO for annihilation of acetylsalicylic acid and crystal violet

Herein, novel hierarchical Gd@WO3 pom-pom-like microstructures have been prepared through the hydrothermal method and combined with RGO sheets (denoted as RGO/Gd@WO3). The synthesized materials, along with their analogs, were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), Mott-Schottky, current-voltage (I-V), electrochemical impedance spectroscopy (EIS), and optical analyses. The unique morphology of pom-pom-like microstructures allowed better interaction with pollutant molecules. Rare earth element (Gd3+) ions act as trapping species for photo-generated electrons and prolong the life span of reactive oxygen species (ROS). The high conductivity and flexible nature of RGO sheets provided fast transport of active species and provided stability to the photocatalytic material. To test the photocatalytic efficiency of RGO/Gd@WO3, crystal violet (CV) and acetylsalicylic acid (ASA) were used as model pollutants. Under a mimetic light source, RGO/Gd@WO3 exhibited maximum photodegradation of 98.8 % and 84 % for CV and ASA within 120 min of irradiation, respectively. Photocurrent, Mott-Schottky, and EIS experiments proved the production, effective separation, and transmission of photo-active species in the presence of RGO/Gd@WO3 as compared to Gd@WO3 and WO3. Given the electrochemical testing and optical analysis, the photocatalytic mechanism is anticipated for the high photocatalytic activity of RGO/Gd@WO3. The novel RGO/Gd@WO3 photocatalyst proved to be a superior photocatalytic material for the photodegradation of organic pollutants.

Toxic Effects of Synthesized Bismuth Oxide/Reduced Graphene Oxide (Bi2O3/RGO) Nanocomposites in Two Distinct Mammalian Cell Lines: Role Oxidative Stress and Apoptosis.

Researchers have shown substantial interest in bismuth oxide/reduced graphene oxide (Bi2O3/RGO) nanocomposites due to their superior features that are not achievable by each material alone. The growing applications and manufacturing of Bi2O3/RGO nanocomposites have raised concerns regarding their potential human health risks. This work was designed to explore the possible toxicity mechanisms of Bi2O3/RGO nanocomposites in two distinct mammalian cell lines, normal rat kidney cells (NRK52E) and human liver cancer cells (HepG2). Bi2O3/RGO nanocomposites were prepared by a simple hydrothermal technique. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS) were used to characterize the synthesized nanocomposites. The cytotoxicity of Bi2O3/RGO nanocomposites in NRK52E and HepG2 cells was examined by MTT cell viability assay. Reactive oxygen species (ROS) and glutathione (GSH) were measured as the biomarkers of oxidative stress. The apoptosis study was carried out by measuring several parameters, including cell cycle and caspase-3. High-quality Bi2O3/RGO nanocomposites of ≈33-38 nm size without impurities, where crystalline Bi2O3 particles are evenly attached to the RGO sheets. Bi2O3/RGO nanocomposites exhibit cytotoxic effects on NRK52E and HepG2 cells, which were dose- and time-dependent. Interestingly, NRK52E exhibited marginally higher vulnerability to Bi2O3/RGO nanocomposites compared to HepG2. Bi2O3/RGO nanocomposites also cause a dose-dependent increase in ROS production and a decrease in GSH levels. Exposing NRK52E and HepG2 cells to Bi2O3/RGO nanocomposites results in activation of the caspase-3 enzyme and chromosomal condensation. The apoptotic response of Bi2O3/RGO nanocomposites against both types of cells was further confirmed by AO-EB dual staining and altered cell cycle. This study demonstrated that the toxicity of Bi2O3/RGO nanocomposites in both NRK52E and HepG2 cells is attributed to their ability to produce ROS, leading to apoptosis and cell cycle arrest as a consequence of oxidative stress.

Tree-like 3D GNP-rPN composite structure for solar-thermal evaporation and photocatalytic degradation of antibiotic wastewater

To realize high-yield and long-term purification of wastewater containing antibiotic ciprofloxacin hydrochloride (CIP) and seawater, a tree-like 3D GNP-rPN solar-driven water evaporation and photocatalysis evaporator is developed by preparing and assembling GO/NPDI/PVA (GNP) hydrogel (canopy) and rGO/PU/NPDI (rPN) foam (trunk). The “tree-like” evaporation and photocatalysis evaporator design in this work has the following three characteristics: First of all, graphene oxide (GO) and reduced graphene oxide (rGO) sheets broaden the light absorption range of the photocatalyst perylene imide nanowires (NPDI), which facilitates absorption of more sunlight; secondly, GO and rGO adsorb pollutants in water and provide them to NPDI for catalytic degradation under sunlight irradiation because of their huge specific surface area; thirdly, the excellent photothermal conversion ability of GO and rGO converts solar energy into heat energy, thus facilitating the catalytic degradation of CIP by NPDI. Thanks to the reduced enthalpy of water evaporation by GNP hydrogel, the sufficient top-down water supply, the superior photocatalytic performance of NPDI nanowires, and the efficient solar light absorption and solar-thermal energy conversion of the GO sheets and NPDI nanowires, the resultant GNP-rPN evaporation and photocatalysis system achieves an average water evaporation rate of 2.84 kg m−2 h−1 and a CIP degradation efficiency of 74.04 % within 1 h under 1-sun irradiation. The GNP-rPN system exhibits an optimal degradation efficiency of 74.04 % for a CIP solution with an initial concentration of 10 mg/L within 1 h of irradiation, reaching a degradation efficiency of 96.37 % after 4 h, demonstrating its effectiveness in purifying antibiotic-laden wastewater.

A sustainable strategy to improve photocatalytic degradation properties of CuO and CuO-rGO nanocomposite using Eucalyptus leaf extract

In this study, Copper oxide (CuO) nanoparticles were synthesized using a sustainable approach. The process comprised Eucalyptus leaf extract as both a biological capping agent and a reducing agent. The synthesis process used a one-pot hydrothermal technique to efficiently combine CuO nanoparticles with reduced graphene oxide (rGO). Analytical methods were utilized to investigate the prepared nanocomposite's structural, crystalline, morphological, functional, optical, and thermal characteristics. The prepared sample was analyzed using X-ray diffraction, which revealed that CuO nanoparticles have a monoclinic crystal structure, and no impurity peaks were observed. Field emission scanning microscopes displayed the uniform dispersion of spherical CuO nanoparticles with layered and non-agglomerated, resembling a sponge-like structure of rGO. The microstructural analysis also confirmed the dispersion of copper inside reduced graphene oxide (rGO) sheets. The optical properties, including light absorption and bandgap width, were investigated using UV–visible spectroscopy using bandgap energies of 2.5 and 2.8 eV. In addition, the nanocomposite's ability to degrade cationic Rhodamine 6G and anionic Rose Bengal dyes by photocatalysis was evaluated. The degradation of RB and Rh6G dyes was characterized by nanocatalysis using UV–visible spectroscopy and a pseudo-first-order kinetics model. The pseudo-first-order degradation kinetic rate of Rhodamine 6G was determined to be 2.55 x 10−2 min−1, indicating that the nanocomposite effectively initiates this dye's degradation. The results showed that dye degradation was effective even at reduced catalyst concentrations.

Eco-friendly synthesis and applications of graphene-titanium dioxide nanocomposites for pollutant degradation and energy storage

An innovative, eco-friendly method has been developed to synthesize reduced graphene oxide (rGO) sheets using orange peel extract. Following this, TiO2 nanoparticles are anchored to the rGO sheets through a hydrothermal process, resulting in an rGO/TiO2 nanocomposite (GTO/NC). This study utilized standard characterization techniques to confirm the formation of GTO/NC-1 and GTO/NC-2. Comparative analysis demonstrated that orange peel extract exhibits reducing capabilities compared to other natural reducers. The resulting GTO/NC-1 and GTO/NC-2, specifically GTO/NC-2, enhanced catalytic performance in degrading methyl orange a prevalent organic pollutant in various industrial applications. This nanocomposite achieved a turnover frequency of 0.003 mg MO/mg catalyst/min and displayed remarkable durability, enduring 3.0 cycles with robust first-order rate constants of 0.0193 min−1. Additionally, the electrochemical properties of GTO/NC-1 and GTO/NC-2 as electrode materials were assessed, revealing a specific capacitance of 320.0 Fg−1 at a current density of 1.0 Ag−1 and maintaining about 86.8 % of its initial capacitance after various charge–discharge cycles. These properties highlight the potential of GTO/NC-1 and GTO/NC-2 as both efficient catalysts for environmental remediation and durable materials for energy storage applications, offering substantial benefits for sustainable technology solutions.

Impedimetric Biosensor of Silver Molybdate Anchored on rGO Sheet for Detection of Breast Cancer Mucin‐1 Biomarker

AbstractThis work aims to detect the Mucin‐1 (MUC1) breast cancer biomarker using a label‐free impedimetric biosensor of silver molybdate anchored on reduced graphene oxide (Ag2MoO4‐rGO). A hydrothermal method has been employed to synthesize the Ag2MoO4‐rGO nanocomposite. Subsequently, they have been studied through analytical characterization techniques to study the electrocatalytic activity, electroactive surface area, surface functionalities, and morphologies to determine the suitability of the material for biosensor fabrication. Results reveal that the Ag2MoO4‐rGO nanocomposite possesses excellent electroconductivity and surface properties that have significant characteristics for the biosensor's performance. A biosensor has been fabricated by the immobilization of Ag2MoO4‐rGO nanocomposite and anti‐MUC1 antibody on a glassy carbon electrode. The electroanalytical studies revealed that the biosensor has excellent sensitivity and detection performance having a wide linearity of 100 fg mL−1–5 ng mL−1 and a low limit of detection of 2.70 fg mL−1. Moreover, the remarkable selectivity, reproducibility, stability, and detection in serum samples determine the high performance of the biosensor. Therefore, the presented biosensor could be a promising diagnostic tool that shows the remarkable potential to efficiently detect the breast cancer MUC1 biomarker in patient's serum samples.

Enhancing Oxygen Evolution Reaction Performance with rGO/CoNi-Prussian Blue-Derived Oxyhydroxide Nanocomposite Electrocatalyst: A Strategic Synthetic Approach.

Electrochemical water splitting is a promising approach in the development of renewable energy technologies, providing an alternative to fossil fuels. It has attracted considerable attention in recent years. The benchmark materials used in water splitting are precious metals that are expensive and scarce. Therefore, this work proposes a strategic electrochemical synthesis of a reduced graphene oxide and cobalt-nickel hexacyanoferrate (rGO/CoNiHCF)-derived composite (rGO/CoNiPBd-OOH) to achieve optimized OER performance. The optimum rGO/CoNiHCF was fabricated with the Co:Ni precursors in a 3:1 ratio with a ferricyanide solution of pH = 1.0. Using an alkaline electrochemical treatment, the well-distributed globular particles of CoNiHCF over rGO sheets were converted into layered frameworks of metallic (oxy)hydroxide species, giving the final rGO/CoNiPBd-OOH nanocomposite. This nanocomposite presented favorable kinetic activity resulting in a Tafel slope of 33 mV dec-1, while rGO, CoNiPBd-OOH, and RuO2 exhibited slopes of 80, 47, and 51 mV dec-1, respectively. Although the benchmark RuO2 electrocatalyst showed a lower overpotential (240 mV dec-1) at a current density of 10 mA cm-2, the rGO/CoNiPBd-OOH performed well with an overpotential of 346 mV, combined with superior stability compared to CoNiPBd-OOH and RuO2, maintaining a current density of 10 mA cm-2 for 15 h with an overpotential loss of 6.92%. This work successfully presents an "all-electrochemical" synthesis of a rGO/CoNiHCF-derived material with remarkable electrocatalytic activity for OER assisted by a strategic preparation methodology, which helped to understand the influence of synthetic parameters and choose their conditions to achieve the optimum OER performance.

Harnessing potential of microwave-assisted ultrafast synthesis of reduced graphene oxide/Mn3O4 bioactive nanocomposite hydrogel for bone tissue engineering

The development of functional materials with the potential for bone tissue regeneration along with rapid synthesis and cost-effective approach has been challenging. In this regard, hydrogels have been explored as a potent candidate to behave as a 3D scaffold for bone repair. However, poor mechanical attributes impeded their clinical translation. Enthralling demonstration of the potential of carbon-based nanocomposites in bone tissue engineering has been constantly encouraging the fabrication of advanced nanocomposites. Here, we investigated the fabrication of reduced graphene/manganese (II, III) oxide (RGO/Mn3O4) nanocomposites by taking advantage of the microwave-assisted synthesis approach for cost effective, and ultrafast synthesis. Mn3O4 nanoparticles with uniform distribution in RGO sheets and ∼ 1.7 nm size was fabricated using the approach. Further, fine-tuning of the structural interaction and mechanical behavior of the GelMA-based hydrogels upon reinforcement with RGO/Mn3O4 nanocomposites was investigated as a function of different concentrations of the nanocomposites where upto 50 % increment in the compressive stress was observed compared to native GelMA hydrogel. The ability of these hydrogels was further investigated for their osteogenic behaviour on MC3T3-E1 preosteoblast cells where constant cell proliferation for up to 10 days was witnessed for the hybrid hydrogel with the highest concentration of the nanofillers.

Exploring MOF-Derived CuO/rGO Heterostructures for Highly Efficient Room Temperature CO2 Sensors.

In response to the urgent need for advanced climate change mitigation tools, this study introduces an innovative CO2 gas sensor based on p-p-type heterostructures designed for effective operation at room temperature. This sensor represents a significant step forward, utilizing the synergistic effects of p-p heterojunctions to enhance the effective interfacial area, thereby improving sensitivity. The incorporation of CuO nanoparticles and rGO sheets also optimizes gas transport channels, enhancing the sensor's performance. Our CuO/rGO heterostructures, with 5 wt % rGO, have shown a notable maximum response of 39.6-500 ppm of CO2 at 25 °C, and a low detection limit of 2 ppm, indicating their potential as high-performance, room-temperature CO2 sensors. The prepared sensor demonstrates long-term stability, maintaining 98% of its initial performance over a 30-day period when tested at 1-day intervals. Additionally, the sensor remains stable under conditions of over 40% relative humidity. Furthermore, a first-principles study provides insights into the interaction mechanisms with CO2 molecules, enhancing our understanding of the sensor's operation. This research contributes to the development of CO2 monitoring solutions, offering a practical and cost-effective approach to environmental monitoring in the context of global climate change efforts.

Free-Standing Poly(vinyl benzoquinone)/Reduced Graphene Oxide Composite Films as a Cathode for Lithium-Ion Batteries.

Quinones with a rapid reduction-oxidation rate are promising high-capacity cathodes for lithium-ion batteries. However, the high solubility of quinone molecules in polar organic electrolytes results in low cycle stability, while their low electric conductivity causes low utilization of electrode materials. In this article, a new p-benzoquinone derivative, poly(vinyl benzoquinone) (PVBQ), is designed and synthesized, and a solution-based method of preparing free-standing PVBQ/reduced graphene oxide (RGO) composite films is developed. PVBQ has a high theoretical specific capacity (400 mA h g-1) because of its low dead moiety mass. In the produced composite films, PVBQ nanoparticles are uniformly dispersed on RGO sheets, which endows the composite films with high electric conductivity and inhibits the dissolution of PVBQ through strong adsorption. As a result, the composite films show a high active material utilization, high practical specific capacity, and excellent cycling stability. PVBQ in the composite membrane containing 60.2 wt % RGO deliver 244 mA h g-1 capacity after 200 charge-discharge cycles at a current density of 300 mA g-1. At a current density of 1500 mA g-1, the reversible specific capacity is still 170 mA h g-1. This work provides a high-performance cathode material for lithium-ion batteries, and the molecular structure and electrode structure design ideas are also instructive for developing other organic electrode materials.

Design and fabrication of MnCo2O4@MnCo2S4 Core@Shell nanostructured arrays decorated over the rGO sheets for high-performance asymmetric supercapacitor

In order to create reliable and effective energy storage systems, it is crucial to choose electrode materials that exhibit high stability and energy density. In this work, MnCo2S4@MnCo2O4 core@shell nanoneedle-like nanostructures (MCS@MCO/rGO) are synthesised over a rGO sheet using an innovative and easy hydrothermal technique. Electrolyte transport and sulphur incorporation during charge-discharge reactions are both made easier by the core@shell nanostructured arrays' large active surface area. With an appropriate pore size distribution centred at 13.4 nm and a high surface area of 125.4 m2g-1, the ternary electrodes composed of MCS@MCO and rGO have a rich mesoporous structure. A specific capacitance of 1346 Fg-1 at 1 Ag-1 demonstrates the exceptional performance of the MCS@MCO/rGO ternary electrode. The MCS@MCO/rGO ternary electrodes show a remarkable cyclic stability of 88.9 % capacity retention over 10,000 cycles, according to the cycling stability studies. With an impressive power density of 1010 Wkg-1 and remarkable cycling stability (95.5 % retention of the original capacitance after 10,000 cycles), the manufactured MCS@MCO/rGO//AC ACS displays an impressive energy density of 57.5 Whkg-1. The mesoporous structure is excellent for increasing the characteristics of supercapacitor electrodes, as these astounding results can demonstrate.

Fabrication of NiO/TiO2/rGO nanocomposites as a quasi-solid-state asymmetric supercapacitor: Paving the way for PhotoSupercapacitor application

In this present communication, a novel ternary nanocomposite, NiO/TiO2/rGO (NTG), was synthesised via a simple hydrothermal technique for photosupercapacitor application. The XRD pattern confirmed the crystalline nature and phase structure of the as-synthesised material. FE-SEM and HR-TEM analyses demonstrated the embellishment of NiO/TiO2 nanoparticles on the rGO sheets, which facilitates more voids and shorter diffusion paths. The electrochemical investigation of the prepared samples was assessed using 1 M Na2SO4 and Na2CO3 aqueous electrolyte solutions. Among the synthesised samples, NTG-2 carried out under 1 M Na2SO4 electrolyte exhibited a maximum specific capacitance of 1285 Fg-1 at 1 Ag-1, maintaining a capacitance retention of 94 % after 5000 cycles. The NTG-2 electrode was additionally utilised in the construction of an asymmetric supercapacitor that has an impressive specific capacitance of 478 Fg-1 at 1 Ag-1. This displays an intriguing performance in terms of energy and power density of 42.2 Wh Kg−1 at 0.5 kW kg−1. In PSC, the as-fabricated TiO2/N719/I−/I3−/Pt@NTG-2//AC architecture possessed a specific capacitance of 567.5 Fg-1 at 1 Ag-1, with an energy density of 50.4 Wh Kg−1 and a power density of 0.4 kW kg−1. As a result, it has been concluded that the novel NTG-2 device opens new opportunities to develop new architectures for efficient energy storage applications.