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The performance development of rGO-FET biosensors by analyzing the influence of GO flake size on biosensing efficacy. GO flakes of varying sizes, from 1 µm to 20 µm, were prepared under controlled conditions, followed by characterization through SEM and XPS to evaluate their size, surface area, and C/O ratio. The biosensing performance was systematically assessed by rGO-FET biosensors, examining the effects of GO flake size, C/O ratio, and film thickness. PACAP38 was employed as a biomarker for receptor-mediated detection, while chlorine ions served as model analytes for receptor-free small molecule detection. The results indicate that decreasing the GO flake size enhanced the performance for both target biomolecules. These findings highlight the crucial importance of selecting GO flake sizes specific to target analytes and detection strategies, thereby optimizing biosensor efficiency. [ABSTRACT FROM AUTHOR]

A nanocomposite consisting of gold nanoparticles (AuNPs), poly(diallyldimethylammonium chloride) (PDDA), and reduced graphene oxide (rGO) was fabricated by a two-step chemical reduction method. Firstly, a PDDA-rGO composite was prepared by using hydrazine hydrate as a reducing agent. Subsequently, the AuNP-PDDA-rGO composite was prepared in ethylene glycol with PDDA-rGO and HAuCl4 as raw materials using sodium citrate as a reduction agent. The resulting composite was characterized using X-ray powder diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), and electrochemical methods. This composite was then modified on a glassy carbon electrode (GCE) by the dropping method. The electrochemical behavior of bromate on this modified electrode was investigated. The results showed that PDDA-rGO can be used as a good carrier to obtain AuNPs with small particle sizes and good dispersion. The AuNPs and PDDA-rGO in composite enhanced the electrochemical activity of the electrode. Under the synergistic action of each component, the resulting electrode exhibited high activity for the electrochemical reduction of bromate. Based on this, an amperometric bromate sensor was fabricated in N2-saturated 0.10 mol/L HCl with attractive features including a wide linear range of 1.0 × 10−7–1.7 × 10−3 mol/L, a low detection limit (3sb) of 3.2 × 10−8 mol/L, and a high sensitivity of 2317 µA/mM/cm2. The sensor was successively used for the determination of bromate in drinking water. [ABSTRACT FROM AUTHOR]

The optical properties that define the characteristics of optical thin films are highly relevant since they determine the applicability of the thin films in optical and photoelectric products. The prospect of being able to design optical properties is one of the most challenging objectives in the generation of optical materials. In recent years, Metal-Organic Framework (MOF)-based optical thin films have attracted much attention because of their characteristic optical characteristics and the fact that they are built with modules to control related properties. This work aims to understand the effect of reduced graphene oxide (rGO) on the structural and optical characteristics of Zinc-based metal-organic framework (ZiF-8) thin films. The incorporation of rGO into ZiF-8 thin films was done, and the thin films were characterized using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and UV-Vis spectroscopy. The transmittance decreased with increasing the rGO concentrations. The energy gap of the pure ZiF-8 thin films has been negatively impacted by the addition of rGO. The photon energy was 3.45 eV for 7.5% rGO, which is the lowest value, and 3.72 eV for ZiF-8 thin films pure film, which is the highest value. The results of this study suggest that the inclusion of rGO in ZiF-8 thin coatings can be a promising approach for tuning the structural and optical properties of ZiF-8 thin coatings, which can have potential applications in various fields such as photocatalysis, sensing, and optoelectronics. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries are gaining attention as a viable alternative to lithium-ion batteries, primarily due to the widespread availability and affordability of sodium. However, the challenge of developing efficient cathode materials remains significant. In this study, we present an economical synthesis method to stabilize Na3V2(PO4)2F3@C (NVPF@C) nanoparticles, which are encapsulated within a conductive reduced graphene oxide network (NVPF@C/rGO), serving as an advanced cathode material for sodium-ion batteries. The resulting structure features 50 nm nanoparticles encased in a carbon layer and intertwined with reduced graphene sheets, leading to improved electronic conductivity and better accommodation of volume changes during cycling. When used as a cathode in sodium-ion half-cells, the NVPF@C/rGO nanocomposite demonstrated an impressive reversible capacity of 130 mAh.g−1 at a 0.5 C rate, along with exceptional cycling stability, maintaining 99% of its capacity after 500 cycles, and retaining a capacity of 115 mAh.g−1 even at a high rate of 10 C. Detailed characterizations indicated that the graphene encapsulation not only supports efficient electron transport but also ensures reversible sodium storage by maintaining structural integrity. Moreover, the outstanding energy storage performance of the Na3V2(PO4)2F3@C/rGO cathode material in full sodium-ion cell tests underscores its potential for practical applications. [ABSTRACT FROM AUTHOR]

The present work reports the development of a disposable nanocomposite-based amperometric sensor for reduced nicotinamide adenine dinucleotide (NADH). To fabricate disposable electrodes, conductive carbon and silver ink were screen-printed on a polyethylene terephthalate (PET) film substrate. The surface of the working electrode was modified with gold nanoparticles (AuNPs) decorated reduced graphene oxide (rGO) and subsequently electro-polymerized with methylene blue for the determination of NADH. The nanocomposite modified electrode decreases the potential for NADH oxidation with a significant increase in the current due to the synergy between AuNP and rGO. The developed electrochemical sensor determined NADH at 0 V versus pseudo-Ag/AgCl with linear relationships from 25 µmol L−1 to 1.0 mmol L−1 and 1.0 mmol L−1 to 10 mmol L−1. The sensor exhibits a good sensitivity of 35.49 µA/mmol L−1/cm2 and a detection limit of 6.61 µmol L−1 based upon a signal-to-noise ratio of 3. Furthermore, interferences from electroactive substances such as ascorbic acid and uric acid are eliminated at an oxidation potential of 0 V. Thus, the modified electrode provides a simple, selective, disposable, and low-cost approach for the amperometric determination of NADH. [ABSTRACT FROM AUTHOR]

Graphene is a promising electromagnetic wave absorption (EMWA) material because of its structural designability, controllable electromagnetic properties, and excellent stability. However, the impedance mismatch caused by high conductivity and dielectric properties has seriously hindered the application of graphene in the EMWA field. In this work, based on the dielectric dispersion behavior of ideal broadband absorption as a guide, a Fe microsheet/reduced graphene oxide (Fe/RGO) composite was prepared by simple hydrothermal and thermal reduction methods. The permittivity of RGO is optimized by adjusting the content of anisotropic Fe microsheets, and a balance between attenuation ability and impedance matching is achieved. Theoretical calculations and off-axis electron holography results reveal that the abundant polar sites and heterogeneous interfaces of Fe and RGO enhance the dipole and interface polarizations. The three-dimensional (3D) conductive network structure contributes to multiple reflections of incident electromagnetic waves and conduction loss. The natural and exchange resonances and eddy current loss caused by anisotropic Fe microsheets further increase magnetic loss. Based on the dielectric-magnetic loss mechanism and good impedance matching, Fe/RGO achieves a minimum reflection loss (RLmin) of −67.95 dB at 8.48 GHz and a maximum effective absorption bandwidth (EABmax) of 6.91 GHz (11.09–18 GHz) with a low filling content of 10 wt%. In addition, Fe/RGO has excellent radar stealth performance, with a radar cross section (RCS) of −31.21 dBm2 at 0°. Therefore, the proposed strategy and theoretical analysis provide a reference for the microstructure design, composition, and mechanism analysis of EMWA materials.

The over-dependence on fossil fuels for energy generation, especially in developing countries like Nigeria, is a major setback to the economy. There is a hike in its price, hence the need to commercialize a renewable form of energy such as solar energy. Solar energy's intermittent nature is a barrier, requiring an efficient, affordable, clean energy storage mechanism such as a supercapacitor. Electrodes are a supercapacitor's basic components, and optimizing an electrode material leads to wide electrochemical applications. In this study, Ni-doped thin films were synthesized by electrochemical deposition, and the optical, morphological, and electrochemical properties were investigated through different characterization techniques. The optical properties were analyzed using a UV-Vis spectrophotometer, a decrease in absorbance (25%), absorption coefficient , extinction coefficient , real dielectric constant and energy band gap (1.8 eV) of the film with the highest concentration of Ni was observed. The SEM result shows the films densely adhered to the substrate but unevenly distributed with imperfections (cracks and voids) as the concentration of Ni increases. The specific capacitance of the film was measured to be 410.8 F/g, 235.7 F/g, and 184.2 F/g in the presence of 6M KOH electrolyte at a scan rate of 10 mV/s, 20 mV/s, 50 mV/s, respectively at the same current density of 0.3 A/g with the highest electrical conductivity of .These results indicate the promising features of Ni-doped thin films are used as electrode material for supercapacitor applications.

Scientists are researching new catalysts that can be used in the photocatalytic degradation of water pollution caused by organic dyes. The challenges of photocatalysis are the high recombination rate and low conductivity of photogenerated electrons (e−) and photogenerated holes (h+). To address these issues, the synthesis of hetero-structured composites can provide a solution. Reduced graphene oxide (rGO) can enhance the photocatalytic properties of hetero-structured composite when used together in a composite material. The combination of these materials can lead to improved performance in the degradation of organic dyes, such as methyl blue (MB), in wastewater treatment. In this study, the preparation of copper cobaltite (CuCo2O4) and copper cobaltite-reduced graphene oxide (CuCo2O4-rGO) composites was carried out using an economical chemical method, resulting in a high-performing photocatalyst. The structural, morphological and functional properties of the composites were characterised using X-ray Diffractometry (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), and Fourier Transform Infrared Spectroscopy (FTIR). Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-vis DRS) revealed the optical band gap 1.52 eV and 1.44 eV for CuCo2O4 and CuCo2O4-rGO composites respectively. Photoluminescence Spectroscopy (PL) of CuCo2O4-rGO showed peak with decreased intensity as compared to CuCo2O4, which is indicative of low recombination rate. Brunauer-Emmett-Teller (BET) analysis showed that CuCo2O4-rGO has high surface area 125.479 m2/g and large pore volume 0.03850 cc/g. Narrow arc radius of Nyquist plot of CuCo2O4-rGO obtained by Electrochemical Impedance Spectroscopy (EIS) demonstrated better charge separation than CuCo2O4. The findings of this study demonstrated that both synthesised photocatalysts exhibit exceptional photocatalytic activity for the degradation of dye under solar irradiation but rGO incorporated CuCo2O4 showed more improved photocatalytic behaviour as compared to CuCo2O4. This improvement is credited to large surface area and high electrical conductivity of rGO, which facilitated the transfer of photogenerated electrons from CuCo2O4 to rGO, reduced the chance of recombination and increased the overall efficiency. [ABSTRACT FROM AUTHOR]

The demand for non-invasive, real-time health monitoring has driven advancements in wearable sensors for tracking biomarkers in sweat. Ammonium ions (NH4+) in sweat serve as indicators of metabolic function, muscle fatigue, and kidney health. Although current ion-selective all-solid-state printed sensors based on nanocomposites typically exhibit good sensitivity (~50 mV/log [NH4+]), low detection limits (LOD ranging from 10−6 to 10−7 M), and wide linearity ranges (from 10−5 to 10−1 M), few have reported the stability test results necessary for their integration into commercial products for future practical applications. This study presents a highly stable, wearable electrochemical sensor based on a composite of metal–organic frameworks (MOFs) and reduced graphene oxide (rGO) for monitoring NH4+ in sweat. The synergistic properties of Ni-based MOFs and rGO enhance the sensor's electrochemical performance by improving charge transfer rates and expanding the electroactive surface area. The MOF/rGO sensor demonstrates high sensitivity, with a Nernstian response of 59.2 ± 1.5 mV/log [NH4+], an LOD of 10−6.37 M, and a linearity range of 10−6 to 10−1 M. Additionally, the hydrophobic nature of the MOF/rGO composite prevents water layer formation at the sensing interface, thereby enhancing long-term stability, while its high double-layer capacitance minimizes potential drift (7.2 µV/s (i = ±1 nA)) in short-term measurements. Extensive testing verified the sensor's exceptional stability, maintaining consistent performance and stable responses across varying NH4+ concentrations over 7 days under ambient conditions. On-body tests further confirmed the sensor's suitability for the continuous monitoring of NH4+ levels during physical activities. Further investigations are required to fully elucidate the impact of interference from other sweat components (such as K+, Na+, Ca2+, etc.) and the influence of environmental factors (including the subject's physical activity, posture, etc.). With a clearer understanding of these factors, the sensor has the potential to emerge as a promising tool for wearable health monitoring applications. [ABSTRACT FROM AUTHOR]

As windows for the transmission of photons and electrons, applications of front contact transparent conducting electrodes (TCE) have played significant roles in efficient organometallic halide perovskite solar cells (PSCs). The widely exploited indium-doped SnO2 (ITO) electrodes have indeed been searched for replacements because of their increasing cost and inherent fragility. So far, ultrathin metal film adhesion to surfaces has indeed been characterized by a rough, discontinuous morphology and poor opto-physical properties. The suggested possible steadier and better work functions of TCEs are the most economically advantageous methods for boosting the effectiveness of the optimized PSC through the drift–diffusion approach. Reduced graphene oxide (rGO) stands out as one of the appropriate special TCE applications among the many perspectives with high conductivity and transparency, because of its abundance in nature, exceptional optoelectronic properties, and potential for large-scale production. For excellent performance in the optimal PSC, the design has an extensive range of fascinated on rGO as TCEs and with the extreme thickness of methyl ammonium lead iodide-bromide (MAPbI2Br1), offered a maximum PCE of 25.01% under the AM1.5 spectrum. It also explored the contribution of ultrathin TCE film thickness to short-circuit density (JSC), which is a possibility to accurately control the uniformity surface. In addition, the lower optimal trap densities of perovskite and the function of normalized temperature might both help the superior products to achieve a cost-effective PSC device structure for reasonable fabrication. [ABSTRACT FROM AUTHOR]

Engine oils are the lifeblood of any internal combustion engine, playing a crucial role in lubricating, cooling, and protecting its moving parts. They come in various formulations and viscosities, tailored to meet the specific needs of different engines. From enhancing performance to ensuring longevity, understanding engine oil types, properties, and functions is essential for maintaining a healthy and efficient engine. Given the high-strength properties of graphene-based nanoparticles, this study compares and analyzes the thermophysical performance of the commonly used SAE20W40 oil in automobile engines with Reduced Graphene Oxide (RGO) and Carboxyl Graphene (CG) mono and hybrid nanoparticles of 0.001% and 0.005%, respectively. This study aims to enhance the thermophysical properties of the SAE 20W40 oil and improve engine performance and the oil's life span. [ABSTRACT FROM AUTHOR]

Ethyl acetate was used to extract bioactive compounds from the fruits of the Iraqi sumac plant Rhus coriaria. This sumac fruit extract was then utilized as a natural reducing agent to convert graphene oxide into reduced graphene oxide (rGO) nanosheets through a green synthesis method. Gas chromatography-mass spectrometry (GC-MS) analysis of the ethyl acetate sumac fruit extract identified phytochemicals that likely facilitated the biosynthesis of the rGO nanosheets. The biosynthesized EERCF-rGO was characterized by using UV-Vis 234 nm. FTIR spectrum was used to know functional groups of EERCF-rGO, XRD spectra of EERCF-rGO displayed sized at 26.91 nm, Raman spectra of EERCF-rGO showed D peak at (1335 cm-1) and a G peak at (1592 cm-1). The morphology of EERCF-rGO was determined using FESEM, which offers plates shape. Also, the TEM of EERCF-rGO showed a size at 12 nm. The biosynthesized of EERCF-rGO appeared to have anticancer activity in vitro cytotoxicity by MTT assay, IC50 is (189.67 μg/mL) against human breast cancer (MCF-7) cell line. The use of biological extracts as reducing agents to produce reduced graphene oxide is an inexpensive, nontoxic, and environmentally friendly approach. The reduced graphene oxide biosynthesized using extracts from the fruits of the Iraqi Rhus coriaria plant demonstrated anticancer properties. This method of green synthesis and the resulting anticancer biomaterial show potential for further development. [ABSTRACT FROM AUTHOR]

Advanced aqueous zinc-ion batteries have been greatly limited application caused by uncontrollable dendrite formation, hydrogen evolution and zinc metal corrosion, which can lead to quick failure of the battery and low Coulombic efficiency. Three-dimensional (3D) porous host strategy is available to limit zinc dendrite growth and electrode interfacial side reactions. Herein, an ingenious local levelling and macro stereo strategy is rationally designed as a Zn plating/stripping scaffold. The flexible 3D carbon cloth as the structural and conductive framework is coated by Ag-Cu-reduced graphene oxide (Ag-Cu-rGO) and Ketjen black. Benefiting from the uniformly dispersed zincophilic Ag on the surface of Cu nanoboxes, the anode suppresses hydrogen evolution side reactions and reduces local current density via more nucleation sites. In addition, rGO homogenizes both the ion flux and electric field at the electrode surface, resulting from high conductivity and large specific surface area of rGO. As a result, the fabricated Zn//Ag-Cu-rGO asymmetric cells exhibit stable voltage profiles for plating and striping 250 cycles, maintain nearly 100% Coulombic efficiency at 2 mA·cm−2 and 1 mAh·cm−2 as well as behave an extremely small nucleation overpotential of 34 mV and Ag-Cu-rGO@Zn symmetric cell presents highly uniform electric field with a superior lifespan over 2500 h at 1 mA·cm−2 and 1 mAh·cm−2, respectively. Meanwhile, this efficient Ag-Cu-rGO@Zn anode also enables a substantially stable Ag-Cu-rGO@Zn//V2O3 full cell over 2000 cycles. The work opens a new avenue of 3D host for durable and dendrite-free flexible aqueous zinc-ion batteries anode. [ABSTRACT FROM AUTHOR]

The fabrication process of reduced graphene oxide depends on many factors (e.g., graphite precursor, methods of oxidation, reduction, and exfoliation) which have a significant influence on the properties of this material. Therefore, their selection is not easy due to the large number of possible combinations of these factors. To overcome this problem, we proposed to use a multivariate analysis of variance method of finding associations between the qualitative type of independent variables and the quantitative type of dependent variable. Using ANOVA, we showed that the combination (interaction) of these variables is more important than the individual influence of the variables on the fabricated rGO. Knowing how the particular variables and their combinations affect the properties of rGO, it is easier to plan the fabrication process of this material. In this paper, we analyzed the number of oxide layers and designated the most promising oxides in terms of sensor gas application. Independently, we fabricated chemiresistor sensors and studied their response to NO2 in the analyzed atmosphere. We were able to combine the experimental results with statistical analysis indicating which oxidation methods and which graphite precursors will provide the best sensitivity. [ABSTRACT FROM AUTHOR]

This research aims to synthesize and characterize reduced graphene oxide (RGO), as well as analyse its electrochemical properties. The synthesis of RGO material from corn cobs went through several stage: carbonization, oxidation and reduction. The synthesis of RGO used a modified Hummer method, and was reduced using the reducing agent ascorbic acid. The synthesized RGO was then characterized using Fourier Transform Independent Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). Electrochemical analysis using the cyclic voltammetry method, the specific capacitance value obtained showed that RGO had a higher capacitance value than GO. The research results showed that carbon from corn cobs, which has not been utilized optimally, can be synthesized as a basic material for making RGO as a quite promising material.

Organic–inorganic hybrid nanocomposites (OIHN), with tailored surface chemistry, offer ultra-sensitive architecture capable of detecting ultra-low concentrations of target analytes with precision. In the present work, a novel nano-biosensor was fabricated, acquainting dynamic synergy of reduced graphene oxide (rGO) decorated hexagonal boron nitride nanosheets (hBNNS) for detection of carcinoembryonic antigen (CEA). Extensive spectroscopic and microscopic analyses confirmed the successful hydrothermal synthesis of cross-linked rGO-hBNNS nanocomposite. Uniform micro-electrodes of rGO-hBNNS onto pre-hydrolyzed ITO were obtained via electrophoretic deposition (EPD) technique at low DC potential (15 V). Optimization of antibody incubation time, pH of supporting electrolyte, and immunoelectrode preparation was thoroughly investigated to enhance nano-biosensing efficacy. rGO-modified hBNNS demonstrated 29% boost in electrochemical performance over bare hBNNS, signifying remarkable electro-catalytic activity of nano-biosensor. The presence of multifunctional groups on the interface facilitated stable crosslinking chemistry, increased immobilization density, and enabled site-specific anchoring of Anti-CEA, resulting in improved binding affinity. The nano-biosensor demonstrated a remarkably low limit of detection of 5.47 pg/mL (R2 = 0.99963), indicating exceptional sensitivity and accuracy in detecting CEA concentrations from 0 to 50 ng/mL. The clinical evaluation confirmed its exceptional shelf life, minimal cross-reactivity, and robust recovery rates in human serum samples, thereby unraveling the potential for early, highly sensitive, and reliable CEA detection. [ABSTRACT FROM AUTHOR]

Extraction of graphene and graphene derivatives from non‐toxic, biocompatible, eco‐friendly, and biodegradable resources with a one‐step production process is a challenge. This work is the first attempt at the one‐step graphenization of Shellac, a biopolymer derived from natural resources, achieved using direct laser patterning. Interestingly, the process highlights substrate independence by producing reduced graphene oxide (rGO) from multiple substrates, such as glass slides, Copper (Cu) adhesive tape, and overhead projector (OHP) plastic films. The produced rGO is fully characterized, and it is found that the sheet resistance is as low as 5.4., 24.65, and 8.4 Ω Sq−1. on the glass slide, OHP plastic sheet, and Cu adhesive, respectively. Moreover, developing various logos on resin‐coated ceramic tiles demonstrated the possibility of patterning desired conductive rGO patterns. Furthermore, a recyclable flexible rGO/Shellac heater is fabricated to validate its electrothermal performance (117.3 °C at 9.5 V) with foldable stability. The proposed one‐step substrate independent two‐material fabrication will revolutionize the process, potentially replacing conventional toxic routes of graphene production. [ABSTRACT FROM AUTHOR]

The present work illustrates the synthesis and electrochemical performance of rGO-TiO2 composite electrodes for their potential application in energy storage devices. The rGO-TiO2 composite was prepared via ultrasonication method, and rGO-TiO2 electrodes were prepared by drop-cast technique. The rGO-TiO2 composite electrodes were electrochemically analyzed using galvanostatic charge–discharge (GCD) and cyclic voltammetry (CV) methods. These tests were performed with three distinct electrolytes (H2SO4, Na2SO4, and KOH), each with a 1 molar concentration. The rGO-TiO2 composite electrodes' specific capacitance (Csp) in 1 M H2SO4 electrolyte was estimated to be 4.89 F/g; it was estimated to be 3.35 F/g in case of 1 M Na2SO4 and 1.42 F/g for the 1 M KOH liquid electrolyte at a scan rate of 0.05 V/s. Using GCD, it was found that in the case of 1 M H2SO4, energy density and power density values were 1.78 Wh/kg and 4000 Wh/kg at a current density of 10 A/g, respectively; in 1 M Na2SO4, the energy density was found to be 2.58 Wh/kg, and conversely, in 1 M KOH, the energy density was measured as 2.39 Wh/kg at 1.25 A/g. AC impedance studies were conducted, and the prepared rGO-TiO2 electrodes exhibited specific capacitance values of 14.21 F/g, 12.68 F/g, and 15.02 F/g in H2SO4, Na2SO4, and KOH electrolytes, respectively. Hence, the research work demonstrated a simple and affordable method of synthesis of rGO-TiO2 electrodes that holds promise for supercapacitor applications, particularly when optimized for specific electrolyte conditions. [ABSTRACT FROM AUTHOR]

Annealing at high temperatures holds the possibility of concentrating defects in the graphene. Moreover, a significant increase in annealing temperature destroys the surface properties. In this work, the reduced graphene oxide (RGO) was prepared by an electrochemical technique with a high voltage (V = ∼ 2 4 V, I = ∼ 3. 2 5 A). Then, the potential effects of impact on thermal treatment in a temperature range of 800–1000∘C in nitrogen-rich environment on the microstructure and surface morphology, thermal stability, phase and crystallinity, structural disorder, absorption properties, and optical properties of RGO for optoelectronic applications were investigated. In addition, a link was established between the estimated crystallite sizes determined by X-ray diffraction (XRD) and Raman data. The microstructural data indicate that the annealing temperature has a significant effect on the microstructure and carbon–oxygen (C/O) ratio. The C/O ratio increases as a function of annealing temperature. Atomic force microscope (AFM) analysis revealed that the root mean square (RMS) roughness of annealed RGO increases with increasing annealing temperature indicating an increase in crystallite size during annealing. Since most organic compounds were removed from the surface of the annealed RGO, oxygen functionalities appear to have minimal effect on the thermal stability of RGO. The size of graphene crystallites increases with annealing temperature, as shown by XRD observations. The crystalline structure was restored by annealing. The Raman results show that in the "low" defect density zone, the I D ∕ I G values increase because a larger defect density causes a stronger elastic scattering. UV–Vis spectroscopy shows that the absorption of RGO is not affected by annealing temperatures between 800∘C and 900∘C. The optical bandgap of annealed RGOs decreases from 4.08 to 3.72 eV upon annealing in the temperature range of 800–1000∘C. [ABSTRACT FROM AUTHOR]

Na3V2(PO4)2F3 has garnered attention as a promising cathode material, primarily due to its substantial theoretical capacity, high operating voltage, and high structural stability. Nonetheless, this material suffers from the low intrinsic electronic conductivity, resulting in a considerable impact on the material properties. To address this challenge, we employ a straightforward hydro-solvothermal reduction process to fabricate Na3V2(PO4)2F3/reduced graphene oxide composites featuring a three-dimensional conductive structure. Through an integrated approach involving material synthesis, structural characterization, and electrochemical analysis, we elucidate the synergistic effects between Na3V2(PO4)2F3 and reduced graphene oxide in facilitating sodium ion storage and transport. The Na3V2(PO4)2F3/reduced graphene oxide cathode in a Na ion cell exhibits reversible capacities of 127 mAh.g−1 at 0.1C and 74 mAh.g−1 at 10C with a 99% retention after 100 cycles at 25 °C. Excellent capacity, reversibility, structure stability, and improved ionic diffusivity make novel composite material an advanced cathode material for sodium-ion batteries, contributing to the development of cost-effective and high-performance energy storage solutions for a sustainable future. [ABSTRACT FROM AUTHOR]

Copper indium gallium selenide solar cells (CIGS-SCs) have gained attention due to their cost-effectiveness and environmentally friendly characteristics, making them a promising option for future electricity generation. The efficiency of CIGS-SCs can be enhanced by adding a back surface field layer (BSFL) under the absorber layer to reduce recombination losses. In this study, the electrical parameters, such as the series resistance, shunt resistance, and ideality factor, are calculated for CIGS-SCs with an advanced design, using the SC capacitance simulator (SCAPS) software. The detailed model used in the simulations considers the material properties and fabrication process of BSFL. By utilizing a reduced graphene oxide (rGO) BSFL, a conversion efficiency of 24% and a significant increase in the fill factor are predicted. This increase is primarily attributed to the ability of the rGO layer to mitigate the recombination of charge carriers and establish a quasi-ohmic contact at the metal-semiconductor interface. At higher temperatures, BSFL can become less effective due to an increased recombination and, in turn, a decreased carrier lifetime. Overall, this study provides valuable insights into the underlying physics of CIGS-SCs with BSFL and highlights the potential for improving their efficiency through advanced design and fabrication techniques. [ABSTRACT FROM AUTHOR]

Cellulose and reduced graphene oxide (rGO) composites have garnered significant attention for their potential in transistor applications, combining environmental sustainability with advanced electrical functionalities. This comprehensive review delves into the recent advancements in the synthesis, characterization, and application of cellulose/rGO composites, particularly in the realm of transistors. We explore various synthesis methodologies such as in-situ reduction, chemical grafting, and physical mixing, examining their effects on the composites' structural, chemical, and morphological properties. The review highlights the deployment of these composites in diverse transistor types including field-effect transistors (FETs), organic field-effect transistors (OFETs), and biosensors, emphasizing their design, functionality, and performance enhancements. Furthermore, we discuss strategies for material optimization such as tuning composite ratios, functionalization, and the integration of additional materials to boost electrical conductivity, charge carrier mobility, and sensitivity. The review also addresses the challenges of scalability, reproducibility, and long-term stability of cellulose/rGO composites, proposing future research directions for novel composite formulations, device architectures, and broader applications in flexible and wearable electronics. This analysis not only underscores the unique properties of cellulose/rGO composites but also their transformative potential in developing sustainable, high-performance electronic devices. [ABSTRACT FROM AUTHOR]

Nanomaterials for suitable particle sizes, shapes, surface properties, biocompatibility, magnetic properties, and chemical stability are candidates for biomedical applications. Among these nanomaterials, iron-based ones are highly interested in their morphological and magnetic properties for potential utilizations in biomedicine. However, iron-based nanoparticles lose their chemical stability in body fluids because of their oxide formations and transformations. Their use in biomedical applications, especially in imaging, may be less effective if they are oxidized and have lower magnetization values. Thus, the idea of coating them with a protective layer has recently emerged to prevent magnetic nanoparticles from degrading in human fluids and losing their magnetic properties. However, the biological effects of these coated nanoparticles on human cells are poorly understood. In this paper, the synthesis of multilayer graphene (MLG) encapsulated iron-based nanoparticles was investigated by solvothermal and chemical vapor deposition (CVD) methods followed by purification. Subsequently, their surface modification was conducted with pyrene end-functional POEGMA obtained by atom transfer radical polymerization (ATRP). Cytotoxicities of synthesized nanoparticles were evaluated in MCF7 cell lines, which is a commonly used model for breast cancer research. We also compare the results with those obtained from bare iron oxide nanoparticles (IONPs) and iron oxides that were embedded in reduced graphene oxide (rGO) or partially coated with it. We aim to evaluate the safety and efficiency of these nanoparticles and increase their chemical stability as a multifunctional nano platform for cancer diagnosis and treatment. Characterization techniques such as XRD, XPS, SEM, TEM, DTA/TG, DLS, zeta potential, BET, NMR, FTIR, and VSM were performed on the nanoparticles. Cytotoxicity assessments on MCF-7 cell lines indicated the potential of these graphene-based magnetic nanoparticles for biomedical applications, particularly drug delivery, due to their small size, soft ferromagnetic properties, high chemical stability, and cytocompatibility at concentrations below 500 μg/mL over short incubation times.

The performance development of rGO-FET biosensors by analyzing the influence of GO flake size on biosensing efficacy. GO flakes of varying sizes, from 1 µm to 20 µm, were prepared under controlled conditions, followed by characterization through SEM and XPS to evaluate their size, surface area, and C/O ratio. The biosensing performance was systematically assessed by rGO-FET biosensors, examining the effects of GO flake size, C/O ratio, and film thickness. PACAP38 was employed as a biomarker for receptor-mediated detection, while chlorine ions served as model analytes for receptor-free small molecule detection. The results indicate that decreasing the GO flake size enhanced the performance for both target biomolecules. These findings highlight the crucial importance of selecting GO flake sizes specific to target analytes and detection strategies, thereby optimizing biosensor efficiency.

Graphene in the form of film, fiber, fabrics and composites is widely investigated research area because of its remarkable physical, chemical and thermal properties. The acceptance of plant-derived products to synthesize graphene or reduced graphene oxide (RGO) has the supremacy of environmentally friendly, mild reaction condition, sustainability, cost effective and simple reaction procedure compared with conventional chemical synthesis methods. To synthesize RGO from graphene oxide (GO) in traditional chemical reduction method, highly toxic and hazardous reducing agents, capping agents, solvents are generally employed which severely affect and threaten ecological equilibrium and human well-being. In this paper, different highly facile and eco-friendly, low-cost green synthesis of RGO using aqueous plant extracts have been surveyed. The phytochemical present in plant extract, methods of preparation of the extract, detection of phytochemical present in extract, preparation of GO, methods of reduction of GO, mechanism of reduction of GO by greener way are discussed. Graphene has been widely recognized as one of the most significant new 2D nanomaterials and graphene oxide (GO) plays as a building block to synthesize graphene. Though there are several ways to produce reduced graphene oxide, the greener approach is superior due to its environmentally friendly, mild reaction condition, sustainable, cost-effective procedure. The discussed topic includes the phytochemicals found in plant extracts, extract preparation methods, detection of phytochemicals present and how to reduce GO in a more environmentally friendly way. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (rGO) and a proteasome inhibitor (MG-132) are some of the most commonly used compounds in various biomedical applications. However, the mechanisms of rGO- and MG-132-induced cytotoxicity remain unclear. The aim of this study was to investigate the anticancer effect of rGO and MG-132 against ZR-75-1 and MDA-MB-231 breast cancer cell lines. The results demonstrated that rGO, MG-132 or a mix (rGO + MG-132) induced time- and dose-dependent cytotoxicity in ZR-75-1 and MDA-MB-231 cells. Apart from that, we found that treatment with rGO and MG-132 or the mix increased apoptosis, necrosis and induction of caspase-8 and caspase-9 activity in both breast cancer cell lines. Apoptosis and caspase activation were accompanied by changes in the ultrastructure of mitochondria in ZR-75-1 and MDA-MB-231 cells incubated with rGO. Additionally, in the analyzed cells, we observed the induction of oxidative stress, accompanied by increased apoptosis and cell necrosis. In conclusion, oxidative stress induces apoptosis in the tested cells. At the same time, both mitochondrial and receptor apoptosis pathways are activated. These studies provided new information on the molecular mechanisms of apoptosis in the ZR-75-1 and MDA-MB-231 breast cancer cell lines. [ABSTRACT FROM AUTHOR]

This study tackles the critical demand for sustainable synthesis methods of reduced graphene oxide (rGO), highlighting the environmental drawbacks of conventional chemical processes. We introduce a novel, green synthesis technique involving the irradiation of a 500 eV argon ion beam, which not only facilitates the creation of micro-patterned rGO on a graphene oxide (GO) film but also enables simultaneous material characterization and patterning. By adjusting the irradiation exposure time between 0 and 80 s, we achieve meticulous control over the attributes and the reduction process of the material. The use of X-ray photoelectron spectroscopy (XPS) allows for real-time monitoring of the reduction from GO to rGO, evidenced by a notable reduction in the intensities of C-O, C=O, and O-C=O bonds, and an increase in C-C bond intensities, indicating a significant reduction level. Our research demonstrates the efficient production of eco-friendly rGO using precise, controlled argon ion beam irradiation, proving its advantages over traditional methods. These results contribute to the development of sustainable material science technologies, with potential applications in electronics, energy storage, and more. [ABSTRACT FROM AUTHOR]

Designing efficient and cost‐effective electrocatalysts in simple ways is very important for energy efficiency. In this sense, nano‐sized materials have been extensively utilized for the development of efficient electrodes for electrochemical CO2 reduction. In the present study, we have developed a Sn/chitosan‐reduced graphene oxide (chi‐rGO)/SnO2 composite electrode via only electrochemical techniques and tested it for electrochemical reduction of CO2 to formate. A bare Sn plate was modified with a reduced graphene oxide layer in the presence of chitosan to get a stable Sn/chi‐rGO composite structure and to get more active sites, thus an efficient reduction process was performed. The surface of the Sn/chi‐rGO composite was further modified by SnO2 nanoparticles via the potentiostatic electrodeposition method at a fixed applied potential of −0.6 V for varying periods. The calculated double‐layer capacitance (Cdl) of the Sn/chi‐rGO/SnO2 electrode was about 80 times larger than the bare Sn plate implying that the coexistence of SnO2 nanoparticles on the (chi‐rGO) structure enhanced the electrochemically active sites. The maximum Faradaic efficiency was recorded as 88 % towards the production of formate at an average current density of −7.36 mAcm−2 at −1.8 V. Electrochemical measurements and the stability test revealed that the resultant Sn/chi‐rGO/SnO2 composite structure behaves as a potential electrode material for efficient CO2 conversion to formate.The study presents a simple and low‐cost electrode preparation procedure including only electrochemical techniques which can be conducted within a very short time and without using extra energy and chemicals/additives. [ABSTRACT FROM AUTHOR]

Acetaminophen (AP) is one of the most commonly used antipyretics. Accurate and efficient determination of its concentration is of great significance to human health. In this work, FeNi alloy nanoparticles and reduced graphene oxide (rGO) were compounded by an ultrasonic method to obtain FeNi/rGO nanocomposites. The nanocomposites were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and cyclic voltammetry (CV). Due to the catalytic activity of FeNi alloy nanoparticles and the synergy between the high specific surface area and conductivity of reduced graphene oxice (rGO), a FeNi/rGO nanocomposite showed excellent electrocatalysis for acetaminophen determination. With differential pulse voltammetry (DPV) as the analytical method, the linear range for acetaminophen is from 1 to 100 and 100 to 3,000 μM with a limit of detection (LOD) equal to 0.3 μM. Moreover, the sensor also has good reproducibility and selectivity with high recoveries in practical analysis. [ABSTRACT FROM AUTHOR]

MiR-451a is a biomolecule tightly related to resistance development during treatment with selective estrogen-receptor modulators for breast cancer. Accurately and sensitively monitoring its level in cells is of great significance for the drug selection and the evaluation of this cancer. However, the commonly obtainable ssDNA probe cannot efficiently enter the cell to sensitively emit reliable signals by avoiding nuclease digestion. Herein, a sensing system is reported to monitor miR-451a in living cells with high specificity and sensitivity. The system consisted of reduced graphene oxide (rGO), duplex-specific nuclease (DSN), and a fluorescence-labeled ssDNA nanoprobe. The fluorescence probe on the rGO surface provided an ultra-low background and resistance to endonuclease digestion. Duplex-specific nuclease sequentially triggered the hybridization cycle and the cleavage of ssDNA nanoprobe. The signal amplification provided a detection limit of 1 fM miR-451a using the optimal conditions with a linear range from 1 fM to 100 nM. Finally, the developed method was used to determine miR-451a in breast cancer tissue. This strategy provides a promising tool for clinical diagnosis and evaluation of miR-451a related cancer. [ABSTRACT FROM AUTHOR]

Increasing graphite demand for energy storage applications creates the need to make graphite using precursors and processes that are affordable and friendly to the environment. Non-graphitizing precursors such as biomass or polymers are known for their low cost and sustainability; therefore, graphitizing them will be an accomplishment. In this work, a process of converting a non-graphitizing precursor, phenolic resin novolac (N), into a graphitic carbon is presented. This was achieved by the addition of five additives categorized as graphene oxide (GO) and its derivatives with varied oxygen concentrations. The hypothesis is that the additives act as templates that promote matrix aromatic alignment to their basal planes during carbonization (physical templating) in addition to forming radical sites that bond to the decomposing matrix (chemical templating). Results showed that the addition of reduced graphene oxide (RGO) additives of approximately 15.4 at.(%) oxygen content to the novolac matrix (RGO-N) show the best graphitic quality. In contrast, the addition of GO additive of twice or more oxygen content ≥ 30.8 at.(%) to the novolac matrix (GO-N) led to poor graphitic quality. This suggests that there is an optimum amount of oxygen content in GO additives needed to induce graphitization of the novolac matrix.

Abstract Extraction of graphene and graphene derivatives from non‐toxic, biocompatible, eco‐friendly, and biodegradable resources with a one‐step production process is a challenge. This work is the first attempt at the one‐step graphenization of Shellac, a biopolymer derived from natural resources, achieved using direct laser patterning. Interestingly, the process highlights substrate independence by producing reduced graphene oxide (rGO) from multiple substrates, such as glass slides, Copper (Cu) adhesive tape, and overhead projector (OHP) plastic films. The produced rGO is fully characterized, and it is found that the sheet resistance is as low as 5.4., 24.65, and 8.4 Ω Sq−1. on the glass slide, OHP plastic sheet, and Cu adhesive, respectively. Moreover, developing various logos on resin‐coated ceramic tiles demonstrated the possibility of patterning desired conductive rGO patterns. Furthermore, a recyclable flexible rGO/Shellac heater is fabricated to validate its electrothermal performance (117.3 °C at 9.5 V) with foldable stability. The proposed one‐step substrate independent two‐material fabrication will revolutionize the process, potentially replacing conventional toxic routes of graphene production.

The demand for non-invasive, real-time health monitoring has driven advancements in wearable sensors for tracking biomarkers in sweat. Ammonium ions (NH4+) in sweat serve as indicators of metabolic function, muscle fatigue, and kidney health. Although current ion-selective all-solid-state printed sensors based on nanocomposites typically exhibit good sensitivity (~50 mV/log [NH4+]), low detection limits (LOD ranging from 10−6 to 10−7 M), and wide linearity ranges (from 10−5 to 10−1 M), few have reported the stability test results necessary for their integration into commercial products for future practical applications. This study presents a highly stable, wearable electrochemical sensor based on a composite of metal–organic frameworks (MOFs) and reduced graphene oxide (rGO) for monitoring NH4+ in sweat. The synergistic properties of Ni-based MOFs and rGO enhance the sensor’s electrochemical performance by improving charge transfer rates and expanding the electroactive surface area. The MOF/rGO sensor demonstrates high sensitivity, with a Nernstian response of 59.2 ± 1.5 mV/log [NH4+], an LOD of 10−6.37 M, and a linearity range of 10−6 to 10−1 M. Additionally, the hydrophobic nature of the MOF/rGO composite prevents water layer formation at the sensing interface, thereby enhancing long-term stability, while its high double-layer capacitance minimizes potential drift (7.2 µV/s (i = ±1 nA)) in short-term measurements. Extensive testing verified the sensor’s exceptional stability, maintaining consistent performance and stable responses across varying NH4+ concentrations over 7 days under ambient conditions. On-body tests further confirmed the sensor’s suitability for the continuous monitoring of NH4+ levels during physical activities. Further investigations are required to fully elucidate the impact of interference from other sweat components (such as K+, Na+, Ca2+, etc.) and the influence of environmental factors (including the subject’s physical activity, posture, etc.). With a clearer understanding of these factors, the sensor has the potential to emerge as a promising tool for wearable health monitoring applications.