Reduced Graphene Oxide Nanosheets Research Articles

Enhanced Photocatalytic CO2 Reduction to CH4 Using Novel Ternary Photocatalyst RGO/Au-TNTAs

Photocatalytic CO2 reduction into hydrocarbon fuels is one of the most efficient processes since it serves as a renewable energy source while also lowering atmospheric CO2 levels. The development of appropriate materials and technology to attain greater yield in CO2 photoreduction is one of the key issues facing the 21st century. This study successfully fabricated novel ternary reduced graphene oxide (RGO)/Au-TiO2 nanotube arrays (TNTAs) photocatalysts to promote CO2 photoreduction to CH4. Visible light-responsive RGO/Au-TNTAs composite was synthesized by facile electrochemical deposition of Au nanoparticles (NPs) and immersion of RGO nanosheets onto TNTAs. The synthesized composite has been thoroughly investigated by FESEM, HR-TEM, XRD, XPS, FT-IR, UV-Vis DRS, and PL analyzer to explain structural and functional performance. Under the source of visible light, the maximum yield of CH4 was attained at 35.13 ppm/cm2 for the RGO/Au-TNTAs composite photocatalyst after 4 h, which was considerably higher by a wide margin than that of pure TNTAs, Au-TNTAs and RGO-TNTAs. The CO2 photoreduction of the RGO/Au-TNTAs composite has been improved due to the combined effects of Au NPs and RGO. Due to its surface plasmonic resonance (SPR) mechanism, Au NPs play a crucial role in the absorption of visible light. Additionally, the middle RGO layers serve as effective electron transporters, facilitating better separation of electron-hole pairs. The newly constructed composite would be a promising photocatalyst for future photocatalytic applications in other fields.

A stable and highly-sensitive flexible gas sensor based on Ceria (CeO2) nano-cube decorated rGO nanosheets for selective detection of NO2 at room temperature

Sensing and monitoring nitrogen dioxide (NO2) gas is essential, due to its adverse effect on humans and the environment. However, conventional NO2 gas-sensing materials have limitations like elevated temperature operations, lower response, and low selectivity. Herewith, ceria nano-cube decorated reduced graphene oxide nanosheets (CeO2@rGO) were synthesized by a hydrothermal process, and as-synthesized products were characterized by various methods, viz. XRD, FE-SEM, FTIR, Raman spectrometer, BET, and IV characteristics. Afterwards, CeO2@rGO flexible gas sensor was fabricated by drop-cast technique, which is utilized for real-time monitoring of NO2 at room temperature (RT) (24ºC). Notably, the CeO2@rGO-based sensor upholds a significantly high response of 52.84 % towards 70 ppm of NO2, with an ultrafast response and recovery time of 7 s and 58 s respectively, with the LOD of 1 ppm. In addition, the CeO2@rGO flexible gas sensor exhibited long-term stability up to 30 days, solid repeatability, and stability in high relative humidity (RH) conditions. The marvelous sensing characteristics of the CeO2@rGO were attributed to the synergetic effect between CeO2 and rGO. The mechanism of sensing response was exhaustively interpreted by the “surface electron depletion layer mechanism”. Certainly, the scientific investigation conducted in the present study will undeniably advance the possible uses of detecting NO2 at RT.

Unlocking the Stability of Reduced Graphene Oxide Nanosheets in Biological Media via Use of Sodium Ascorbate

AbstractGraphene oxide and reduced graphene oxide (RGO) are carbon bidimensional nanomaterials largely exploited in biomedicine. Their unique interactions with eukaryotic and prokaryotic cells are used to obtain precise intracellular delivery, to create device coatings, and to design theranostic materials for both therapeutic and imaging applications, mainly in the cancer research field. It is known, however, that the hydrophobic behavior of RGO limits its stability in biological media. Here, the employment of sodium ascorbate (NaA) as a reducing agent for the preparation of RGO to provide a nanomaterial with remarkable suitability for applications in cell culture media is proposed. It is demonstrated via a combined experimental and theoretical approach that NaA is able to yield a peculiar RGO derivative, exerting a twofold effect, that is, C sp2 network restoration upon epoxide reduction and RGO edge functionalization via H‐bonding, lending RGO a so far unexampled dispersibility in aqueous‐based media. The kinetic stability of the bidimensional layers of RGO obtained from NaA is demonstrated together with its superior biocompatibility for drug delivery, unlocking outstanding potentialities for biological applications.

Durable and rechargeable antimicrobial cotton driven by enhanced UV stability and real-time detection of biocidal factors

In this study, graphene oxide/N-halamine nanocomposite was synthesized through Pickering miniemulsion polymerization, which was then coated on cotton surface. The modified cotton exhibited excellent superhydrophobicity, which could effectively prevent microbial infestation and reduce the probability of hydrolysis of active chlorine, with virtually no active chlorine released in water after 72 h. Deposition of reduced graphene oxide nanosheets endowed cotton with ultraviolet-blocking properties, attributing to enhanced UV adsorption and long UV paths. Moreover, encapsulation of polymeric N-halamine resulted in improved UV stability, thus extending the life of N-halamine-based agents. After 24 h of irradiation, 85 % of original biocidal component (active chlorine content) was retained, and approximately 97 % of initial chlorine could be regenerated. Modified cotton has been proven to be an effective oxidizing material against organic pollutants and a potential antimicrobial substance. Inoculated bacteria were completely killed after 1 and 10 min of contact time, respectively. An innovative and simple scheme for determination of active chlorine content was also devised, and real-time inspection of bactericidal activity could be achieved to assure antimicrobial sustainability. Moreover, this method could be utilized to evaluate hazard classification of microbial contamination in different locations, thus broadening the application scope of N-halamine-based cotton fabrics.

Thermal and tribo-mechanical properties of high-performance poly(etheretherketone)/reduced graphene oxide nanocomposite coatings prepared by electrophoretic deposition

The thermal stability and degradation, near-to-surface mechanical properties, and scratch resistance and damage mechanism of poly(etheretherketone) (PEEK)/reduced graphene oxide (RGO) nanocomposite coatings are analyzed and discussed in terms of their nanosheet content and microstructure. Although RGO modified the thermal stability and degradation of the polymeric matrix, for instance, by slightly reducing the onset degradation temperature, its addition was not a limiting factor in the PEEK processing. Respecting the microstructural features induced by the nanosheets, the nanocomposite coatings were found to exhibit (i) a partially exfoliated and large-scale co-continuous morphology related to RGO nanosheets whose basal planes were mainly aligned with the coating surface, (ii) a dendritic morphology of PEEK domains related to transcrystallinity, (iii) and irregular domains associated with the deposition of PEEK particles wrapped by the nanosheets. The changes provoked by RGO in the morphology and PEEK crystalline phase influenced the near-to-surface mechanical properties, scratch resistance, and scratch damage mechanism of the nanocomposite coatings. Within this context, the interlayer strength between the nanosheets in the large-scale co-continuous morphology and PEEK transcrystallinity had an important effect. Furthermore, the random-bumpy surface texture formed by the irregular PEEK domains together with the conformal cracking damage mechanism was decisive in the scratch response of the PEEK/RGO nanocomposite coatings. The comprehensive characterization carried out in this work concludes that PEEK/RGO electrophoretic coatings are suitable for a variety of applications requiring tribo-mechanical resistance.Graphical

Composites of Ag-Doped ZnIn2S4 Nanoplates with Graphitic Carbon Nitride and Reduced Graphene Oxide Nanosheets for Sunlight-Driven Hydrogen Production and Water Purification

Photocatalysis is considered a promising technology to alleviate the energy crisis and environmental pollution; however, developing photocatalysts with improved light absorption efficiency is still a challenge. In this work, an effective strategy was proposed to synthesize a highly functional ternary nanocomposite (g-C3N4/RGO/AZIS) by coupling broader light-absorbing Ag-doped ZnIn2S4 (AZIS) nanoplates with ultrathin g-C3N4 and reduced graphene oxide (RGO) nanosheets. The 2D-on-2D stacking nanostructure of the composite provides a compact heterojunction, enlarged interfaces, and enriched active sites, resulting in the accelerated separation and relocation kinetics of charge carriers. Benefiting from these advantages, the g-C3N4/RGO/AZIS nanocomposite with systematically optimized contents of RGO and AZIS can serve as an efficient bifunctional photocatalyst for both H2 production from water splitting and methyl orange (MO) photodegradation under the irradiation of visible light. The H2 production rate of the ternary nanocomposite is 658.5 μmol h–1 g–1, which is 38 times higher than that of plain g-C3N4. The operation mechanism is proposed based on the results of scavenger tests and photoelectrochemical analysis. The formation of a type-II heterostructure between AZIS nanoplates and g-C3N4 nanosheets along with RGO with lower potential can maximize the separation efficiency of photogenerated electron–hole pairs and decrease the charge recombination. This work provides a viable strategy to develop bifunctional photocatalysts with enhanced performance for both H2 production and degradation of organic dyes.

Chromium vanadate nanoparticles entrapped reduced graphene oxide nanosheets: A nanocomposite with high catalytic activity for the detection of hypertension-drug nifedipine in biological samples

Though having excellent characteristics, chromium vanadate (CrV) use in the electrochemical sensor field has rarely been reported. Herein, we report the chromium vanadate/reduced graphene oxide (CrV/rGO) nanocomposite-modified electrode for the sensitive detection of Nifedipine (NF) for the first time. NF is a highly prescribed hypertension drug and also emerging as a pollutant due to its high consumption. Simple and rapid quantification of NF in water and biological fluids is highly required for water quality and pollution control. Precipitation followed by annealing synthesis has been adopted to design the CrV/rGO nanocomposite. The CrV/rGO nanocomposite's crystal structure, functional groups, and surface morphologies were determined utilizing XRD, XPS, FT-IR, Raman, HR-TEM, and FE-SEM. The pebbles-like irregular cube-shaped CrV nanoparticles embedded inside the wrinkly nanosheets of reduced graphene nanocomposite caused structural flaws that led to a large surface area and a straightforward electron transport channel. Using the CrV/rGO nanocomposite modified glassy carbon electrode (CrV/rGO/GCE), an extremely low detection limit of 0.0048 µM and sensitivity of 1.185 µA µM−1 cm2 were obtained. In addition, it demonstrated a respectable degree of selectivity among the prevalent interfering molecules. Furthermore, the CrV/rGO/GCE sensor could detect NF in human urine, and tap water samples with greater than > 98% recovery, demonstrating its suitability for rapid NF detection. Hence, using CrV/rGO nanocomposite material in high-performance electrochemical applications has great potential for practicality.

Zinc oxide doped on reduced graphene oxide nanosheets activated by solar radiation for degradation of organic pollutants and bacterial inactivation

Metal ion-based nanocomposite materials were recognized to exhibit a wide range of photocatalytic and biological applications. This study aims to synthesize zinc oxide doped reduced graphene oxide (ZnO/RGO) nanocomposite in sufficient quantities through the sol-gel method. The physical characters of the synthesized ZnO/RGO nanocomposite were determined by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), Energy-dispersive X-ray (EDS) and Transmission electron microscopy (TEM) techniques. The TEM image results revealed rod-like morphology of the ZnO/RGO nanocomposite. The X-ray photoelectron spectral data revealed the formation of ZnO nanostructures representing the banding energy gap value of 1044.6 and 1021.5 eV positions. Moreover, ZnO/RGO nanocomposites displayed excellent photocatalytic degradation with a degradation efficiency of 98.6%. This research not only demonstrates the photocatalytic efficiency of zinc oxide-doped RGO nanosheets but also illustrates the antibacterial efficacy against two different bacterial pathogens including Gram-positive E. coli and Gram-negative S. aureus. Furthermore, this research highlights an eco-friendly and inexpensive preparation of nanocomposite material for a wide range of environmental applications.

A novel fluorescent strategy for Golgi protein 73 determination based on aptamer/nitrogen-doped graphene quantum dots/molybdenum disulfide @ reduced graphene oxide nanosheets.

The effective detection of biomarkers associated with hepatocellular carcinoma (HCC) is of great importance. Golgi protein 73 (GP73), a serum biomarker of HCC, has better diagnostic value than Alpha-fetoprotein (AFP) has been reported. In this paper, highly accurate fluorescence sensing platform for detecting GP73 was constructed based on fluorescence resonance energy transfer (FRET), in which nitrogen-doped graphene quantum dots (NGQDs) labelling with GP73 aptamer (GP73Apt) was used as fluorescence probe, and molybdenum disulfide @ reduced graphene oxide (MoS2@RGO) nanosheets was used as fluorescent receptors. MoS2@RGO nanosheets can quench the fluorescence of NGQDs-GP73Apt owing to FRET mechanisms. In the presence of GP73, the NGQDs-GP73Apt specifically bound with GP73 to from the deployable structures, making NGQDs-GP73Apt far away from MoS2@RGO nanosheets, blocking the FRET process, resulting in fluorescence recovery of NGQDs-GP73Apt. Under optimal conditions, the recovery intensity of fluorescence in the detection system is linearly related to the concentration of GP73 in the range of 5ng/mL - 100ng/mL and the limit of detection is 4.54ng/mL (S/N=3). Moreover, detection of GP73 was performed in human serum samples with good recovery (97.21-100.83%). This platform provides a feasible method for the early diagnosis of HCC, and can be easily extended to the detection of other biomarkers.

Gold nanoparticles modified reduced graphene oxide nanosheets based dual-quencher for highly sensitive detection of carcinoembryonic antigen

In the current scenario, the dominance of cancer is becoming a disastrous threat to mankind. Therefore, an advanced analytical approach is desired as the need of the hour for early diagnosis to curb the menace of cancer. In this context, the present work reports the development of nano surface energy transfer (NSET) based fluorescent immunosensor for carcinoembryonic antigen (CEA) detection utilizing protein functionalized graphene quantum dots (anti-CEA/amine-GQDs) and a nanocomposite of nanostructured gold and reduced graphene oxide (AuNPs@rGO) as energy donor-acceptor pair, respectively. The obtained AuNPs@rGO nanocomposite has been characterized by different advanced analytical techniques. The functionality of the biosensor depends on quenching the fluorescence of anti-CEA/amine-GQDs donor species by AuNPs@rGO acceptor species, followed by the gradual recovery of GQDs' fluorescence after CEA addition. The efficient energy transfer kinetics have been envisaged by utilizing the AuNPs@rGO nanocomposite as a dual-quencher nanoprobe that revealed improved energy transfer and quenching efficiency (∼62 %, 88 %) compared to AuNPs (∼43 %, 81 %) as a single quencher. Further, the developed biosensing platform successfully detected CEA biomarker with notable biosensing parameters, including a wider linear detection range (0.001–500 ng mL−1), fast response time (24 min), and a significantly low detection limit (0.35 pg mL−1).

Mn3O4 nanoparticles decorated porous reduced graphene oxide with excellent oxidase-like activity for fast colorimetric detection of ascorbic acid.

Mn3O4 nanoparticles composed of porous reduced graphene oxide nanosheets (Mn3O4@p-rGO) with enhanced oxidase-like activity were successfully fabricated through an in-situ approach for fast colorimetric detection of ascorbic acid (AA). The residual Mn2+ in the GO suspension of Hummers method was directly reused as the manganese source, improving the atom utilization efficiency. Benefiting from the uniform distribution of Mn3O4 nanoparticles on the surface of p-rGO nanosheets, the nanocomposite exhibited larger surface area, more active sites, and accelerated electron transfer efficiency, which enhanced the oxidase-like activity. Mn3O4@p-rGO nanocomposite efficiently activate dissolved O2 to generate singlet oxygen (1O2), leading to high oxidation capacity toward the substrate 3,3',5,5'-tetramethylbenzidine (TMB) without the extra addition of H2O2. Furthermore, the prominent absorption peak of the blue ox-TMB at 652nm gradually decreased in the presence of AA, and a facile and fast colorimetric sensor was constructed with agood linear relationship (0.5-80μM) and low LOD (0.278μM) toward AA. Owing to the simplicity and excellent stability of the sensing platform, its practical application for AA detection in juices has shown good feasibility and reliability compared with HPLC and the 2, 4-dinitrophenylhydrazine colorimetric method. The oxidase-like Mn3O4@p-rGO provides a versatile platform for applications in food testing and disease diagnosis.

Assembly of Co3S4-encapsulated reduced graphene oxide nanosheets on Ni foam for binder-free supercapacitor electrode with boosted cycling stability

Assembly of Co3S4-encapsulated reduced graphene oxide nanosheets on Ni foam for binder-free supercapacitor electrode with boosted cycling stability

Hydrothermal-assisted green synthesis of reduced graphene oxide nanosheets (rGO) using lemon (Citrus Limon) peel extract

An economical, sustainable and environmentally friendly approach was employed to synthesise reduce graphene oxide from lemon (Citrus limon) peel extract. In the present study, highly exfoliated graphene oxide sheets were obtained from graphite flakes using the Tour method. Phytochemical extracts of lemon peel were adopted for the reduction of graphene oxide. The prepared graphene oxide and reduced graphene oxide were characterized using various techniques such as the X-ray diffraction (XRD) technique, Fourier transforms infrared (FTIR) spectroscopy, and UV–Visible spectroscopy. The morphology of synthesized graphene oxide and reduced graphene oxide were investigated using the scanning electron microscopy technique. UV–Vis absorption spectra show that the energy band gap reduces after the reduction of graphene oxide. According to the findings, lemon peel extract can function as a reducing agent, and hydrothermal treatment can start the reduction process, which results in the synthesis of high-quality reduced graphene oxide nanosheets.

Facile synthesis of Fe3O4 nanoparticles/reduced graphene oxide sandwich composites for highly efficient microwave absorption

Component regulation and microstructure design are two effective strategies to adjust electromagnetic parameters and improve the microwave absorption performance of materials. In this study, a facile synthesis strategy consisting of ultrasonic dispersion, blast drying, and roasting is proposed to build a sandwich-like graphene-based absorbent, in which Fe3O4 nanoparticles with adjustable content are sandwiched uniformly between reduced graphene oxide nanosheets. The sandwich structure can form multiple interfaces, prevent the aggregation of nanoparticles, facilitate interface polarization, and endow the material with multiple electromagnetic loss mechanisms, which is very beneficial for impedance matching and microwave attenuation. Notably, the effective absorption bandwidth achieves 5.7 GHz, and the minimum reflection loss value is −49.9 dB. In addition, the synthesis process is simple and suitable for large-scale production and possible industrial applications. Thus, this facile route to fabricate sandwich-like graphene-based absorbents provides new ideas and approaches for designing new graphene-based nanocomposites.

Nanocomposites of ZnO Nanostructures and Reduced Graphene Oxide Nanosheets for NO2 Gas Sensing

A depletion region formed at the junction of two materials depends on the charge carrier concentration and the barrier height. The depletion width can be controlled by the overlayer thickness. Modification of the depletion width after gas exposure is mainly contributing to the sensor response. The maximum effect of gas molecules can be realized when the depletion width becomes comparable to the Debye length. Consequently, the selection of an appropriate overlayer thickness is very crucial. In the present work, chemiresistive gas sensing characteristics of ZnO nanowire (NW) films modified with different thicknesses of reduced graphene oxide (rGO) have been studied. The hybrid films showed selective outstanding NO2 response as compared to pure ZnO NW films. At an optimum rGO thickness of ∼15.3 nm, the response toward NO2 (with a minimum detection limit of 400 ppb) was found to be the highest that is nearly three times higher than that of pure ZnO nanowire films. A synergetic balance of the depletion width at the ZnO/rGO interface with the Debye length is attributed to the improved selective NO2 response of hybrid films.

Green modification of graphene oxide nanosheets under specific pH conditions

Green surface modification of graphene oxide (GO) using lysine (Lys) under different pH conditions was studied, aiming to activate the specific functional group of the amino acid structure: carboxylic acid (pH 2), the primary amine of α-carbon (pH 9.8) and, the primary amine of the lateral chain and α-carbon (pH 12), promoting three interaction mechanisms between Lys and the oxygenated groups of GO nanosheets. Chemical analyses suggest that at pH 2, ester bonds are formed on the GO’s surface from its interaction with Lys, while at pH 9.8, the formation of C-N bonds takes place. However, at pH 14, chemical reduction of GO nanosheets is induced. Density functional calculations predicted possible binding modes and reaction pathways for forming ester (at pH 2) and C−N bonds (at pH 9.8) on basal planes of GO nanosheets and gave deep insights into the electronic structure of reduced GO materials. The chemical changes generated at the surface of GO modified the crystalline structure and the thermal properties of GO nanosheets. Our results suggest that controlled chemical functionalization/reduction of GO nanosheets under environmental conditions can be performed under specific pH. However, the promotion of those functional groups benefits the potential used in biological applications.

Hierarchically Structured CoNiP/CoNi Nanoparticle/Graphene/Carbon Foams as Effective Bifunctional Electrocatalysts for HER and OER

The rational assembly of multiple active components has been regarded as a feasible approach to constructing effective electrocatalysts for overall water splitting. In this work, we have first developed effective bifunctional electrocatalysts, namely, hierarchically structured CoNiP/CoNi nanoparticle/graphene/carbon foams. Reduced graphene oxide nanosheets like papers encapsulate the backbones of carbonized melamine foams; meanwhile, numerous hybrid CoNiP/CoNi nanoparticles are dispersedly attached to the carbon matrix. These special structures endow electrocatalysts with excellent HER and OER performances. Their overpotentials of 224 mV and 341 mV can carry out the current density of 10 mA/cm2, and the corresponding Tafel slopes are 85 mV/dec and 58 mV/dec. Moreover, this electrocatalyst has good durability in the long term electrolysis of HER and OER. In the end, the role of each component in the HER and OER processes has been revealed. Well-dispersed nanoparticles function as the main roles owing to their rich active sites and desirable electronic structures. Graphene nanosheets not only provide good substrates for nanoparticles but also hinder the shrinkage of carbonized melamine foams. Besides, 3D carbon foams inserted with plentiful graphene nanosheets could construct interconnected conductive networks and hierarchical porous structures, promoting electron-transfer kinetics and enhancing mass-transfer efficiency. Therefore, partially doping P atoms can largely enhance the electrocatalytic performances of bimetal CoNi, and the conjugation of 2D graphene nanosheets and 3D carbon foams would be one promising candidate for electrocatalytic support. This work may deliver valuable guidance for exploiting high-performance electrocatalysts.

Silver doped MnCo2O4 spinel mixed oxides with rGO nanocomposites for the photocatalytic and antibacterial studies

Silver doped manganese cobalt spinel mixed oxides (Ag/MnCo2O4) were synthesized through solvent free wet chemical approach. As-synthesized Ag/MnCo2O4 nanoparticles were embedded with reduced graphene oxide nanosheets (rGO) to synthesize Ag/MnCo2O4/rGO nanocomposite. Different techniques (XRD, FTIR, SEM and UV/VIS) were carried out to study structural and morphological properties. XRD analysis determined cubic face centered structure of synthesized MnCo2O4, Ag/MnCo2O4 and Ag/MnCo2O4/rGO nanocomposite. Methylene blue was used as organic pollutant to investigate photocatalytic test. Degradation percentages for MnCo2O4, Ag/MnCo2O4 and Ag/MnCo2O4/rGO nanocomposite were determined 43.24%, 50% and 84.3% respectively. Ag/MnCo2O4/rGO nanocomposite showed highest degradation efficiency under sunlight.

Formation of tin oxide superstructures on reduced graphene oxide nanosheets for high-performance supercapacitor with excellent cyclic stability

Among a wide range of metal oxide semiconductors, tin dioxide (SnO2) has been considered a promising material for pseudocapacitive electrodes. However, the performance of SnO2 supercapacitor is severely limited owing to their low electrical conductivities. Herein, we proposed SnO2 nanospheres (SnO2-NS) and reduced graphene oxide (rGO)-SnO2 superstructures (SnO2-rGOSS) for high performance supercapacitor. Cyclic voltammetry (CV) confirmed the capacitive behavior of the SnO2-rGOSS and SnO2-NS electrodes, with a specific capacitance of 320 and 44 F/g respectively, at a sweep rate of 5 mV/s. Remarkably, after cycling for 10,000 times at a sweep rate of 2 A/g, the SnO2-rGOSS electrode retained 150% more capacity than its initial value, indicating its outstanding durability.

Sonochemical synthesis and electrochemical performance of reduced graphene oxide/cerium dioxide nanocomposites

Reduced graphene oxide/cerium dioxide (is synthesized by a simple sonochemical route. The morphology and chemical structure of the nanocomposites are characterized by scanning electron microscopy, energy disperse spectroscopy, insitu infrared spectroscopy, and X-ray diffraction. The electrochemical properties of a fabricat reduced graphene oxide/cerium dioxide2 nanocomposite electrode examined by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The results indicate that the reduced graphene oxide can prevent the aggregation of cerium dioxide nanoparticles; meanwhile, the reduced graphene oxide/cerium dioxide-3 nanocomposite electrode exhibits excellent electrochemical performance with a high specific capacitance of 185 F·g−1 at 0.5 A·g−1, a high rate capability, and good reversibility, which results from the synergism and coupling between reduced graphene oxide nanosheets and cerium dioxide nanoparticles.