Reduced Graphene Oxide Composites Research Articles

Application of N/P-rGO composite electrode materials and novel electrolytes in high-performance supercapacitors

Traditional graphene-based electrode materials often can not have excellent gravimetric and volumetric electrochemical properties at the same time. Furthermore, the gel electrolyte widely used at present has the disadvantages of poor water retention, easy solidification, low ionic conductivity, and narrow working temperature range during the working process. In this paper, nanocellulose/N, P co-doped reduced graphene oxide composites (NC-NPrGOs) were synthesized via a simple approach using graphene oxide (GO), ammonium dihydrogen phosphate, and nanocellulose (NC) as raw materials. Meanwhile, a new type of gel electrolyte (SNG) with renewable, wide working temperature range and ultra-high water retention properties was prepared using sodium alginate (SA), NC, GO, and potassium hydroxide as precursors. Benefiting from the unique physical and chemical properties of NC-NPrGOs, the assembled aqueous symmetric supercapacitors assembled by NC-NPrGOs present high gravimetric (303.9 F/g) and volumetric specific capacitance (416.5 F cm−3), large gravimetric (10.5 Wh kg−1) and volumetric energy density (14.6 Wh/L). Due to the multiple interactions of several components in SNG, the flexible solid-state supercapacitors (ASSC) assembled by NC-NPrGO55 and SNG deliver high specific capacitance (240.0 F/g), ultra-long cycling life, excellent bending resistance, a wide range of operating temperatures, and good regenerative performance. In summary, NC-NPrGOs and SNGs are ideal for the investigation of new energy storage devices.

Synthesis of Niobium Pentoxide and Its Reduced Graphene Oxide Nanocomposite for Enhanced Supercapacitor Applications

Synthesis of Niobium Pentoxide and Its Reduced Graphene Oxide Nanocomposite for Enhanced Supercapacitor Applications

Perovskite-type samarium iron oxide adorned on reduced graphene oxide composite: A high-performance electrocatalyst for OER

The oxygen evolution process (OER), an essential and necessary reaction in water splitting to produce clean hydrogen fuel were investigated using a number of electrocatalysts. Non-noble metal catalysts are increasingly being used in place of noble metal catalysts because of their unique qualities, which include affordability, environmental friendliness and electrocatalytic activity. In this work, SmFeO3/rGO composite is prepared for an anion exchange reaction, which is used as catalyst on nickel foam in 1.00 M KOH electrolyte for OER. The fabricated electrocatalysts were confirmed by X-ray powder diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray (EDX) spectroscopy and scanning electron microscopy (SEM). The BET determined surface area of SmFeO3/rGO composite is 51 cm2/g which is better for OER activity. The distinct structure of the nanocomposite displays increased surface area, increasing active sites with plentiful potential for charge transfer and prolonging the material's life. The electrochemical results represented that composite had lower overpotential (180 mV) with Tafel slope (34 mV/dec), displaying higher charge transfer during OER showing efficient electrocatalytic activity and high reliability of 55h. The reasons for lower overpotential and lower Tafel slope values were increased surface area and enhanced number of active spots in composite and also due to presence of non-kinetic effects that alter the Tafel slope values. The electrocatalyst may be able to facilitate the oxidation reaction based on all of these qualities. As a consequence, created composite reacts with outstanding efficacy for the OER process and energy conversion applications.

Exploring a novel approach for the synthesis of MIL-53(Fe)/reduced graphene oxide composites with preserved structural integrity for high performance for electromagnetic wave shielding

Efficient electromagnetic waves absorbing materials while preserving structural integrity based on MIL-53(Fe)/reduced graphene oxide composites remains a challenging task. Most reported preparation techniques compromise structural integrity which limits its practical applications. This study reports innovative method by carefully controlling pyrolysis in a tubular furnace to produce Pyrolyzed MIL-53(Fe)/reduced graphene oxide (P-MIL-53(Fe)/RGO) composites to safeguard structural integrity while preserving RGO’s structure and achieving high EMI shielding efficiency. Various mass ratios of reduced graphene oxide were investigated (15%, 20%, and 30%) to indicate the impact of calcination in changing the degree of graphitization and its effect on the shielding performance. P-MIL-53(Fe)/RGO30 stands out, achieving notable total shielding effectiveness (SET) of 46.5 dB and absorption shielding efficiency (SEA) of 40.3 dB with 2 g of reduced graphene oxide (5 mm thick). The study offers a simple strategy to produce the desired composite with preserved reduced graphene oxide’s structural integrity which has a potential EMI shielding performance. These insights hold promise for diverse applications demanding robust, high-performance electromagnetic wave shielding materials.

Constructing a novel electrochemical sensor for the detection of fenitrothion using rare-earth orthophosphate incorporated reduced graphene oxide composite

Fenitrothion (FNT), an organophosphorus insecticide widely used in agriculture, forestry, and public health initiatives, poses substantial risks to human health, the environment, and non-target organisms. Therefore, monitoring FNT's presence in the environment is critical. Recently, rare earth phosphate compounds have gained recognition in materials science, optics, and electronics, with diverse applications. In line with this trend, our research focuses on developing a novel material by incorporating gadolinium phosphate (GdPO4) into reduced graphene oxide (RGO) for FNT detection. We successfully synthesized GdPO4/RGO using a straightforward hydrothermal method, confirmed through various spectroscopic techniques. Introducing RGO significantly enhanced GdPO4's electrical conductivity; this has been confirmed through experimental techniques such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Electrochemical examinations confirmed the GdPO4/RGO/GCE sensor's exceptional sensitivity and selectivity for FNT. Furthermore, the sensor exhibited remarkable sensitivity (0.8802 μA μM−1 cm−2), a low detection limit (LOD) of 0.007 µM, and a linear detection range of 0.01–342 µM for FNT under optimized conditions. The effective use of our proposed sensor in detecting FNT in different water samples was evidenced by achieving a substantial recovery rate ranging from 98.3% to 98.8%.

Photocatalytic degradation of methylene blue by efficient TiO2‐partially reduced graphene oxide composites

The effect of graphene oxide with different reduction degrees on the photocatalytic efficiency of titanium dioxide‐graphene (TiO2‐G) composites has not been systematically studied. In this paper, titanium dioxide‐partially reduced graphene oxide (TiO2‐PRGO) nanocomposites were prepared by a modified one‐step solvent‐thermal method and further reduced with ascorbic acid to obtain TiO2‐PRGO(xh) with a higher degree of reduction (ascorbic acid 80° reduced TiO2‐PRGO x h, x = 1, 2, 3, 4). The composites were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (DRS). The transient photocurrent response and electrochemical impedance results show that TiO2‐PRGO has the most outstanding photoelectrochemical properties. Compared with pure TiO2 and other samples, the TiO2‐PRGO nanocomposites exhibited excellent photocatalytic properties, and their photocatalytic efficiencies for the degradation of methylene blue (MB) were up to seven times higher than those of the pure TiO2 nanomaterials, and twice that of TiO2‐PRGO(4h). The photodegradation of methylene blue by the composites decreased as the degree of PRGO reduction increased. The efficient photocatalytic performance of TiO2‐PRGO can be attributed to the high TiO2 loading and good electrical conductivity. Notably, TiO2‐PRGO photocatalysis for 90 min resulted in 100% degradation of MB. Meanwhile, TiO2‐PRGO has good reusability, and the degradation rate of TiO2‐PRGO remained at 95% after four times of degradation in MB solution.

Preparation of molecularly imprinted electrochemical sensors for selective detection of hydroxyl radicals based on reduced graphene oxide nanosilver (rGO/AgNPs) composites

An electrochemical sensor for selective detection of hydroxyl radicals (OH) has been developed, which is based on silver nanoparticles and reduced graphene oxide composites (rGO/AgNPs) synthesized in situ by the green reduction method, combined with the electrochemical polymerization method for preparation of molecularly imprinted polymers (MIPs) to modify the screen-printed electrodes. During the assay, the concentration of hydroxyl radicals was obtained by capturing the product 2,5-dihydroxybenzoic acid (2,5-DHBA). Under the optimal experimental conditions, the oxidation peak currents of the target 2,5-DHBA by differential pulse voltammetry (DPV) and its concentration showed a good linear relationship in the concentration ranges of 0.1 ∼ 0.5 μM and 1 ∼ 100 μM, with the limit of detection (LOD) of 0.021 μM. Interference experiments and other studies were also carried out, and the results showed that the sensor has good reproducibility, stability, and selectivity, and the comparison of the detection results with the conventional detection method, high-performance liquid chromatography, indicated the accuracy of the sensor detection, which is a convenient, sensitive, and efficient method for the detection of hydroxyl radicals.

A Magnetic Reduced Graphene Oxide Nanocomposite: Synthesis, Characterization, and Application for High-Efficiency Detoxification of Aflatoxin B1.

(1) Background: Safety problems associated with aflatoxin B1 (AFB1) contamination have always been a major threat to human health. Removing AFB1 through adsorption is considered an attractive remediation technique. (2) Methods: To produce an adsorbent with a high AFB1 adsorption efficiency, a magnetic reduced graphene oxide composite (Fe3O4@rGO) was synthesized using one-step hydrothermal fabrication. Then, the adsorbent was characterized using a series of techniques, such as SEM, TEM, XRD, FT-IR, VSM, and nitrogen adsorption-desorption analysis. Finally, the effects of this nanocomposite on the nutritional components of treated foods, such as vegetable oil and peanut milk, were also examined. (3) Results: The optimal synthesis conditions for Fe3O4@rGO were determined to be 200 °C for 6 h. The synthesis temperature significantly affected the adsorption properties of the prepared material due to its effect on the layered structure of graphene and the loading of Fe3O4 nanoparticles. The results of various characterizations illustrated that the surface of Fe3O4@rGO had a two-dimensional layered nanostructure with many folds and that Fe3O4 nanoparticles were distributed uniformly on the surface of the composite material. Moreover, the results of isotherm, kinetic, and thermodynamic analyses indicated that the adsorption of AFB1 by Fe3O4@rGO conformed to the Langmuir model, with a maximum adsorption capacity of 82.64 mg·g-1; the rapid and efficient adsorption of AFB1 occurred mainly through chemical adsorption via a spontaneous endothermic process. When applied to treat vegetable oil and peanut milk, the prepared material minimized the loss of nutrients and thus preserved food quality. (4) Conclusions: The above findings reveal a promising adsorbent, Fe3O4@rGO, with favorable properties for AFB1 adsorption and potential for food safety applications.

Palladium phosphoselenide (PdPSe) – Reduced graphene oxide composite: A tri-functional electrocatalyst and a cathode catalyst for alkaline fuel cells

Developing a new and efficient electrocatalyst is highly desirable for fundamental electrochemical energy applications such as fuel cells. In this work, we have introduced palladium phosphoselenide (PdPSe), a layer-type ternary material, as a tri-functional electrocatalyst in the three most fundamental electrochemical reactions, such as oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER). To enhance the electrocatalytic activity and stability of the electrode material, reduced graphene oxide (rGO) is incorporated into the system by making a composite (rGO-PdPSe), which effectively reduces the overpotentials and increases the current densities for HER and OER. Moreover, in ORR, it turns into a four-electron pathway with comparable kinetics. Further, the composite material is applied in anion exchange membrane fuel cell application as a cathode catalyst. This composite's facile kinetics and robust performance suggests that ternary phosphoselenides based trifunctional electrocatalysts would be a promising material for large-scale application of clean energy conversion devices.

Effective monitoring of environmental hazardous drug moxifloxacin hydrochloride using silver selenide on octadecyl amine modified reduced graphene oxide composite

The precise detection of antibiotics is very critical. Here, silver selenide (Ag2Se) nanorods are hydrothermally synthesized and ultrasonically treated with rGO surface modified with octadecylamine (rGO-ODA). The optical, structural, morphological, and functional analysis were performed which revealed the orthorhombic pattern of the P2221 E space group, the crystalline purity of Ag2Se, and the substantial composite formation. The morphological studies revealed nanorod like structure of the Ag2Se material and wrinkled sheets of rGO-ODA. A sensor that detects moxifloxacin hydrochloride (MOXH) antibiotic using the cyclic voltammetry (CV), differential pulse voltammetry (DPV) and UV-Vis absorbance was developed. For DPV analysis, a quite low value for detection limit 12.46 nM was exhibited with 0.199 μM – 425.16 μM linear range, and a sensitivity of 5.0439 μA M−1cm−2. For UV-Vis, the sensor demonstrated a very low limit of detection 17.42 nM over 0.12 μM – 7.7 μM working range. The use of this sensor was validated in real-time analysis with industrial waste water, fish, human blood, and urine samples. The results suggested an excellent rate of analyte recovery and enhanced efficiency for MOXH detection with a potential for commercialization in the future.

Cubic cobalt ferrite anchored on graphene sheets for non-enzymatic electrochemical detection of 17α-ethinyl estradiol in environmental and biological samples

Recently, the endocrine interference of endocrine disruptors on the environment and aquatic organisms has been a hot topic. Ethinyl estradiol (EE2) is an estrogen endocrine disruptor and one of the most widely used ingredients in oral contraceptives, resulting in high emissions and environmental pollution. Therefore, it is urgent to construct a non-enzymic, simple and low-cost sensor to detect EE2 in environmental and biological samples. We successfully prepared cobalt ferric oxide with anti-spinel structure and reduced graphene oxide composite (CoFe2O4/RGO) using hydrothermal synthesis, which decorated on the glass carbon electrode (GCE) to detect EE2. The morphological structure of CoFe2O4/RGO composites was studied by FESEM, HRTEM, EDX, FT-IR, XRD, and XPS techniques. Additionally, the experimental conditions were optimized and the oxidation mechanism of EE2 was explained theoretically and EE2 was detected by CV, EIS, and SWV, which displayed a fantastic current response of EE2. The electrochemical results illustrated that the prepared sensor has good selectivity, high sensitivity, a wide linear range of 0.05–100 μM, and a lower detection limit of 42 nM. Finally, the practicability of the sensor to detect EE2 in real samples was also studied and obtained a satisfactory recovery.

B2O3‐Nanoparticles‐Decorated N‐Rich Reduced Graphene Oxide Composites for the Enhanced Visible‐Light‐Assisted Photocatalytic Degradation of Ciprofloxacin

B₂O₃‐Nanoparticles‐Decorated N‐Rich Reduced Graphene Oxide Composites for the Enhanced Visible‐Light‐Assisted Photocatalytic Degradation of Ciprofloxacin

Sunlight-driven photocatalytic degradation of Norfloxacin antibiotic in wastewater by ZnSe microsphere functionalized RGO composite

The release of hazardous pollutants into the water, such as dyes, phenolic compounds, pesticides, different heavy metals, and antibiotics is the primary cause of environmental pollution. The solar energy-based photocatalysis technique has the potential to eliminate pollutants from the aquatic environment. ZnSe is a significant and commendable II-VI group photocatalyst having 2.82 eV direct band gap energy. Its performance towards degrading antibiotics in the presence of light was improved by anchoring it on the Reduced graphene oxide (RGO) matrix. Solution-processable RGO-ZnSe composites were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Several spectroscopic studies like Raman spectroscopy, ultraviolet-visible spectroscopy, and photoluminescence spectroscopy were employed to illustrate the optical properties of the composites. The findings demonstrate that the ZnSe microsphere was supported effectively onto the two-dimensional RGO matrix. The performance of as-synthesized RGO-ZnSe composites was assessed based on the photocatalytic degradation of the antibiotic Norfloxacin in the presence of simulated solar light. An optimized RGO-ZnSe composite degrades approximately 83.5% of Norfloxacin in 40 min, while controlled-ZnSe photocatalysis only yields 33% in an identical experimental condition. The optimized RGO-ZnSe achieves the highest degradation reaction rate constant (k) of Norfloxacin (k = 0.057 min−1), and the k value is 4.38 times greater compared to the controlled-ZnSe microsphere. The light-dependent catalytic degradation mechanism was examined by employing scavenger experiments which gave away the responsible reactive radicals. Our results establish that the photo-generated hole has the leading role in the degradation of Norfloxacin in our system. In addition to that, the oxide radical and hydroxyl radical has also an important role in the degradation of Norfloxacin under our experimental condition. The finding suggests that the addition of RGO has enhanced photocatalytic performance and cyclic stability by preventing photo-generated electron-hole pair recombination. The photocatalytic oxidative deactivation mechanism of the Norfloxacin antibiotic was proposed. Our study offers new perceptiveness for the design of efficient solution-processable solar light-responsible photocatalysts for environmental pollution remediation.

Europium oxide modified reduced graphene oxide composite for trace detection of hydrogen phosphate ions in soil samples

The phosphate (PO43−) ion is a constituent of the environment, soil, plants, and animals. There should be a real-time and portable phosphate detection sensor. Herein we propose a colorimetry based sensitive method for hydrogen phosphate (HPO42−) ions detection using europium oxide modified reduced graphene oxide composite (Eu2O3-RGO) and gold nanoparticles (Au NPs). We detect the HPO42− by observing the anti-aggregation of gold nanoparticles. In the presence of a Eu2O3-RGO composite, the Au NPs underwent an aggregation process, causing a colour change of Au NPs from wine red to wine blue. Once Eu-modified RGO was pre-mixed with HPO42− ions and introduced into Au NPs, the Eu nanoparticles in the Eu-modified RGO were attracted to the HPO42− ions. Because of this, the aggregated Au NPs started to anti-aggregate, and the colour of Au NPs changed from wine blue to wine red. The calibration curve of the sensor goes from 0 nM to 500 nM concentration of HPO42− ions. Our sensor has a detection limit of 0.08 nM, which is lower than the reported values. This improved lower detection limit is probably due to the use of RGO, which according to the literature review, can adsorb phosphate ions onto its surface. We optimized the incubation time and europium oxide (Eu2O3) nanoparticle concentration to improve the sensor's sensitivity. Lastly, we tested an agricultural sample using our developed method.

B2O3‐Nanoparticles‐Decorated N‐Rich Reduced Graphene Oxide Composites for the Enhanced Visible‐Light‐Assisted Photocatalytic Degradation of Ciprofloxacin

The occurrence of pharmaceutical pollutants in the environment is a mounting concern due to their detrimental effects on living organisms, including humans. Ciprofloxacin (CIP) is a regularly used antibiotic detected in wastewater and surface water. Therefore, developing effective, sustainable strategies for its elimination is paramount. Photocatalysis is an efficient approach that has been widely recommended for the removal of CIP from water. However, improved photocatalyst performance, stability, and activation in abundant visible light are essential for better photocatalyst systems. In this study, a novel boron‐oxide‐decorated nitrogen‐rich reduced graphene oxide (B2O3/N‐rGO) nanocomposite is prepared and characterized for its photocatalytic performance toward CIP degradation. The B2O3/N‐rGO nanocomposites are in situ synthesized via wet chemical route, and the morphology and structural properties of nanocomposites are extensively characterized. In the results, it is shown that the B2O3/N‐rGO nanocomposite demonstrated significantly enhanced photocatalytic performance (98%, 3 h) compared to N‐rGO and pure B2O3 toward the degradation of CIP under visible‐light irradiation. The enhanced photocatalytic activity is attributed to the synergistic benefit of B2O3 and N‐rGO, which improves light absorption, charge separation efficiency, adsorption sites, and delayed electron–hole recombination. In summary, the synthesized B2O3/N‐rGO nanocomposite photocatalyst can potentially be applied for various environmental remediation and energy‐related applications.

The comparing on the adsorption/desorption of Pd(II) and Pt(IV) ions by using 4-chlorophenyl sulfoxide modified the reduced graphene oxide composite

The comparing on the adsorption/desorption of Pd(II) and Pt(IV) ions by using 4-chlorophenyl sulfoxide modified the reduced graphene oxide composite

2D hydroxylated MXene (OH-MXene)/RGO composites modification toward superior electrocatalytic degradation of paracetamol

The MXene precursor was adjusted with a combination of –OH grafting and reduced graphene oxide (RGO) via alkalization and hydrothermal method to improve the electrocatalytic performance. The as-prepared hydroxylated MXene (OH-MXene)/RGO composites possess maximum 100 % paracetamol (APAP) degradation efficiency under an applied current of 15 mA, temperature of 25 °C, and electrolyte of 1 g/L NaCl. All characterization and experiment results showed that the grafting of –OH groups into MXene could access the active site of Ti-OH, strengthen the linking of OH-MXene and RGO layers (as C-Ti-Ox), accelerate the free electrons transfer from OH-MXene to RGO; thus, enhancing the catalytic activity of OH-MXene/RGO composites. Then, •OH, 1O2, O2•−, and active chlorine were determined as secondary active species in the solution, which dominated the APAP degradation. Three degradation pathways of APAP were further proven by gas chromatography-mass spectrum (GC–MS) with cleavage of N-branched chain and benzene rings. In addition, the superior and stable performance of OH-MG-15h under various operation conditions confirmed the application perspective of self-prepared material. The research not only provides feasible methods for MXene adjustment and electrocatalytic activity improvement but also proves its possibility for environmental application.

Detection of nitrofurazone with metal–organic frameworks and reduced graphene oxide composites: insights from molecular dynamics simulations

Two-dimensional metal-organic framework (MOF) composites were produced by incorporating Fe-MOFs into reduced graphene oxide (rGO) nanosheets to form Fe-MOF/rGO composites by hydrothermal synthesis. SEM, TEM, XRD, XPS, and measurements of contact angles were used to characterize the composites. TEM studies revealed that the rod-like-shaped Fe-MOFs were extensively dispersed on the rGO sheets. Incorporating Fe-MOF into rGO significantly improves performance due to the large surface area, chemical stability, and high electrical conductivity. The response signals for the electrochemical sensing performance of Fe-MOF/rGO-modified electrodes to nitrofurazone (NFZ) were significantly enhanced. Differential pulse voltammetry was used to detect the NFZ, and the MOF/rGO sensor possesses a lower detection limit (0.77μM) with two dynamic ranges from 0.6-60 to 128-499.3 μM and high sensitivity (1.909 μA·mM-1·cm-2). Moreover, the anti-interference properties of the sensor were quite reproducible and stable. To understand the mechanism responsible for the enhanced sensing performance of the composite, grand canonical Monte Carlo calculations were performed for Fe-MOF/rGO composites with five unit cells of Fe-MOF and four layers of rGO. We attributed the improvement to the fact that the interface between the Fe-MOF and rGO absorbed increased NFZ molecules. The findings reported herein confirm that such Fe-MOF/rGO composites have significantly improved electrochemical performance and practical applicability of sensing nitrofurazone.

Porous potassium tantalate-reduced graphene oxide nano cube architecture for high performance hybrid supercapacitors

Energy storage has always been a major concern in the present-day situation. Advanced energy storage devices are batteries, supercapacitor and solar cells. However, advancements have been noteworthy in the field of high-performance hybrid supercapacitors. On this note, we have fabricated a hybrid supercapacitor electrode material Potassium tantalate nano cube (KT NCs) and its reduced graphene oxide composite (KT-rGO NCs) and tested its electrochemical performance. The materials showed high performances with specific capacitance of 565 F/g for KT NCs and 850 F/g for KT-rGO NCs respectively. Energy densities of both KT NCs & KT-rGO NCs are 28.24 Wh/Kg and 29.50 Wh/kg with good retention capacities. Further detailed study of both KT NCs and KT-rGO NCs are carried out with characterization techniques like XRD, FTIR, BET, Raman and HRTEM for structural analysis and electrochemical measurements to analyse various parameters pertaining to its charge storage capacity.

Synthesis of 3D nitrogen-doped graphene quantum dots and reduced graphene oxide composites by a hydrothermal method for supercapacitors anodes

Synthesis of 3D nitrogen-doped graphene quantum dots and reduced graphene oxide composites by a hydrothermal method for supercapacitors anodes