Addition Of rGO Research Articles

Hydrothermal synthesis of zinc-cobalt binary hydroxide / reduced graphene oxide composite nanosheets as electrode materials with surface redox pseudocapacitive behaviour

Binary metal hydroxides have grabbed the attention of researchers in energy storage field owing to their better electrochemical properties compared to that of monometallic counterparts and metal oxides. Being an eco-friendly, abundant, and cost effective metal, Zinc has been chosen to form binary hydroxide with cobalt which can show multiple valence states during electrochemical reactions. Zinc-Cobalt binary hydroxide (ZCH) nanosheets and its nanocomposite with reduced Graphene Oxide (ZCH-rGO) were synthesized through a simple hydrothermal method. Electrochemical properties of the prepared samples were analyzed by means of cyclic voltammograms, chronopotentiograms, and Nyquist plots. ZCH-rGO nanocomposite exhibited a high specific capacitance of ⁓756.8 F/g whilst ZCH nanosheets showed relatively less specific capacitance of ⁓594.6 F/g at 1 A/g. The electrochemical performance of ZCH-rGO nanocomposite was assessed using a two-electrode system from which the energy density was found to be 10.6 Wh/kg. This electrochemical setup of ZCH-rGO nanosheets displayed a capacitance retention of 126.6 % after 2000 charge-discharge cycles. Addition of rGO changed the primary electrochemical behaviour of ZCH from battery-type to capacitive-type thereby producing an electrode material with surface redox pseudocapacitive properties.

An investigation of structural, optical, and electrical properties of poly(3‐hexylthiophene)/reduced graphene oxide nanocomposites for electronic and optoelectronic applications

AbstractPoly(3‐hexylthiophene)/reduced graphene oxide nanocomposites (P3HT/rGO) were successfully prepared starting with 3‐hexylthiophene (3HT) monomer. 1H NMR was utilized to determine the regioregularity of the polymer and the degree of polymerization. The interaction of rGO was identified by employing Fourier transform infrared spectroscopy and X‐ray diffraction (XRD). Besides, the XRD results revealed the crystallinity was enhanced with the increment of rGO. Upon filling with rGO, High‐resolution transmission electron high‐resolution transmission electron microscopy images manifested a fluffy morphology, while field emission scanning electron microscope demonstrated a high level of compactness and uniformity. Optical spectrophotometry (UV–Vis–NIR) was implied to determine the impact of rGO on the optical properties. It was found that the bandgap was reduced upon the addition of rGO. The temperature and frequency‐dependent electrical properties including complex permittivity, tangent loss, complex electrical modulus, impedance, and conductivity for revealing both the dipolar relaxation and charge transportation were investigated. It is revealed that P3HT/rGO has significantly higher conductivity values compared to P3HT. Further, the temperature dependence of the Dc—conductivity for pure P3HT was governed by the Vogel–Fulcher–Tamman (VFT) approach, whereas it was altered to Arrhenius upon the inclusion of rGO. The fact that the P3HT/rGO nanocomposite has a higher ε' value, lower tangent loss, and higher conductivity than the pristine P3HT, suggested these nanocomposites are more favorable than pure P3HT in optoelectronic and thermoelectric applications.

In situ Raman analysis of reduced-graphene oxide-based electroactive nanofluids

This study investigates the effect of an applied stationary voltage on the vibrational properties of 1 M H2SO4 and H2SO4-based reduced-graphene oxide (rGO) nanofluids, commonly used as electrolytes in electrochemical cells. Our findings indicate that the energy of the symmetric stretching vibrations of H2SO4 remains unaffected by the electric field. However, a slight deviation toward lower energy and an enhancement of Raman intensity are observed in the asymmetric stretching vibration of H2SO4 due to the applied voltage. Furthermore, the addition of rGO to the base fluid produces a significant redshift in the symmetric stretching bands, indicating that the presence of rGO produces important changes at the macroscopic level in the base fluid. Synchronous and asynchronous maps further uncover the positive correlations between the D and G bands as well as between rGO and the base fluid bands. Specifically, the asynchronous map revealed complex dynamics between the rGO and H2SO4 bands and only positive correlations between H2SO4 bands. These results demonstrate the potential of Raman spectroscopy as a non-invasive technique to systematically study the influence of electric fields on the vibrational properties of fluids and nanofluids, which can ultimately lead to the development of significantly more efficient electrochemical cells.

Synergistic Remediation of Organic Dye by Titanium Dioxide/Reduced Graphene Oxide Nanocomposite.

In this work, nanocomposites based on titanium dioxide and reduced graphene oxide (TiO2@rGO) with different weight percentages of rGO (4, 8, and 16 wt%) were prepared by the hydrothermal/solvothermal synthesis method and thermally treated at 300 °C. The prepared nanocomposites were explored for the removal of methylene blue dye (MB) in the presence of simulated solar illumination as well as natural sunlight. The structural, morphological, chemical, and optical properties of the as-synthesized TiO2@rGO nanocomposites were characterized. The obtained results of the graphene-based nanocomposite materials indicated the existence of interactions between TiO2 and rGO, i.e., the Ti-O-C bond, which confirmed the successful integration of both components to form the TiO2@rGO nanocomposites. The addition of rGO increased the specific surface area, decreased the band gap energy, and increased the photocatalytic degradation efficiency of MB from water compared to TiO2 nanoparticles. The results of photocatalytic activity indicated that the amount of rGO in the prepared TiO2@rGO nanocomposites played a significant role in the application of different photocatalytic parameters, including the initial dye concentration, catalyst concentration, water environment, and illumination source. Our studies show that the reinforcement of the nanocomposite with 8 wt% of rGO allowed us to obtain the maximum photocatalytic decomposition performance of MB (10 mg·L-1) with a removal percentage of 99.20 after 2 h. Additionally, the obtained results show that the prepared TiO2@rGO_8 wt% nanocomposite can be used in three consecutive cycles while maintaining photocatalytic activity over 90%.

Synthesis, structural and electrochemical investigations of reduced graphene oxide loaded zinc vanadate nanoparticles for high performance supercapacitors

In this study, supercapacitor performances of reduced graphene oxide-loaded zinc vanadate (Zn3(VO4)2 - ZV) nanoparticles (NPs) were reported. Reduced graphene oxide (rGO) loaded zinc vanadate (Zn3(VO4)2@rGO - ZVR) nanocomposites (NCs) were synthesized through a simple reflux method and their structural, functional group, and morphological properties were analyzed by X-ray diffraction, FT-IR, and electron microscopic analyses. Working electrodes of ZV NPs and ZVR NCs were fabricated using doctor blade technique and their supercapacitor performances were tested with an aqueous KOH electrolyte. Incorporation of rGO greatly enhanced the specific capacitance value of ZV NPs from 104 F g−1 to 1910 F g−1 at 5 mVs−1 (CV studies). At the same, the highest specific capacitance value from the GCD analysis was found to be 1315 F g−1 for ZVR NCs, which was very much greater than pure ZV NPs (53.7 F g−1). The fabricated asymmetrical supercapacitors using ZVR NCs-based working electrode exhibited the higher power and energy densities of 2050 W kg−1 and 13.13 Wh kg−1, respectively. Furthermore, the fabricated supercapacitors demonstrated an excellent cyclic stability of 95.1 % after 2000 GCD cycles, when compared to ZV NPs (90 %). The electrochemical results proved that the supercapacitor performances of ZV NPs were greatly enhanced by the addition of rGO.

Hydrothermally synthesized MoS2 composites with rGO and PEDOT:PSS for Li-Ion batteries: enhanced capacity reclamation with rGO addition

Hydrothermally synthesized MoS2 composites with rGO and PEDOT:PSS for Li-Ion batteries: enhanced capacity reclamation with rGO addition

Hot deformation behavior of 0.5Y2O3/Al2O3-Cu/30Mo3SiC composites doped with reduced graphene oxide

The 0.5Y2O3/Al2O3-Cu/30Mo3SiC and 0.3GO-0.5Y2O3/Al2O3-Cu/30Mo3SiC composites were fabricated by fast hot press sintering. Hot compression tests of the composites were carried out using the Gleeble-1500 simulator at 0.001–10 s−1 strain rates and 650–950 °C deformation temperatures. The effects of doped reduced graphene oxide (rGO) on the hot deformation behavior and microstructure of 0.5Y2O3/Al2O3-Cu/30Mo3SiC composites were investigated. Trace of molybdenum carbide (MoC) layers/nanoparticles formed in-situ at the rGO-Cu/Mo interface, which is beneficial to the interfacial bonding of the composite. The enhanced flow stress and activation energy of hot deformation is attributed to the addition of the rGO. The activation energy of the composites was improved by 11% with the addition of rGO. The dislocation density and texture orientation ratio decrease at higher deformation temperatures.

ZrO2 nanoparticles anchored on RGO sheets: Eco-friendly synthesis from Acacia nilotica (L.) fruit extract, characterization, and enhanced anticancer activity in different human cancer cells

Surface defects and the ability to tune the physicochemical properties of zirconium oxide nanoparticles (ZrO2 NPs) have made them a hot topic in biological research. We investigated the anticancer properties of Acacia nilotica (L.) fruit extract–green produced ZrO2/RGO nanocomposites (NCs). Fruit extract's polyphenolic and flavonoid compounds served as reducing and capping agents for the creation of ZrO2 adorned RGO sheets. Our goal was to maximize the anticancer potential of ZrO2/RGO NCs while simultaneously reducing their toxicity to normal tissues and reducing their impact on the environment. The XPS, XRD, TEM, SEM, EDS, and PL were used to characterize the pure ZrO2 NPs and ZrO2/RGO NCs that were green produced. XRD analysis revealed that ZrO2 crystallized in two different phases, monoclinic and tetragonal. TEM and SEM images demonstrated that ZrO2 particles were uniformly attached on RGO sheets. XPS and EDX analysis of the produced NCs verified the presence of ZrO2 and RGO. ZrO2 NPs had their particle size and PL intensity decreased after RGO addition. Anticancer data shown that ZrO2/RGO NCs was two-times more effective than pure ZrO2 NPs in inhibiting the growth of different human cancer cells (A549, HepG2, and MCF7). Mechanistic evidence revealed that intracellular reactive oxygen species production and glutathione reduction constituted oxidative stress that caused the anticancer response of ZrO2/RGO NCs. Apoptosis is also suggested by the decrease of mitochondrial membrane potential in cancer cells after they have been exposed to as produced NCs. In addition, when compared to pure ZrO2 NPs, ZrO2/RGO NCs showed greater cytocompatibility in normal cell lines (IMR90 and MCF10A). This innovative method highlights the significance of plant-based synthesis of nanocomposites for biomedical research as being both environmentally benign and low-cost.

Exploring the repairing mechanisms of reduced graphene oxide (rGo) on the dysregulation of Xenopus Laevis larva hypothalamus-pituitary-thyroid (HPT) axis caused by chiral triazole fungicide metconazole

Replacing chair fungicide racemate marketed product by its enantiomer with high activity and low environmental risk for application is a more environmentally friendly methods to control crop diseases. Moreover, carbon-based nanomaterials, with the desirable chemical and mechanical properties, exhibits latent reduce fungicide toxicity capability, while the mechanism is still poorly understood. Therefore, the present study characterized the toxicity of rac-metconazole (Mez; (1RS,5RS;1RS,5SR)-5-(4-chlorobenzyl)-2,2-dimethyl-1-(1H)) and its two cis-enantiomers as well as the repairing effect of reduced graphene oxide (rGo) on Xenopus Laevis larva by examining growth appearance indexes, Mez bioaccumulation, and hypothalamus-pituitary-thyroid (HPT) axis related hormone contents and gene expression after 14 and 28 days exposure. Compared with two cis-Mez, rac-Mez was preferentially bioaccumulated in tadpoles, and rac-Mez treatment showed a higher toxicity effect on tadpole including growth stage and body weight inhibition by dysregulating tadpole thyroid stimulating hormone (TSH) and thyroid hormone (TH) contents and related gene expression. Enantioselectivity was observed in two cis-Mez treatments. Compared with R,S-Mez, S,R-Mez treatment showed more severe damage on tadpole HPT axis related physiological and biochemical processes. rGo could effectively decrease the toxicity of Mez, especially shown the capacity of repairing the hormone dysregulation caused by R,S-Mez treatment. Moreover, the addition of rGo can decrease the bioaccumulation of Mez in tadpoles. Therefore, R,S-Mez is less toxic to Xenopus Laevis larva growth, and its toxicity could be effectively repaired by the addition of rGO.

Bi2O3-Doped WO3 Nanoparticles Decorated on rGO Sheets: Simple Synthesis, Characterization, Photocatalytic Performance, and Selective Cytotoxicity toward Human Cancer Cells.

Graphene derivatives and metal oxide-based nanocomposites (NCs) are being studied for their diverse applications including gas sensing, environmental remediation, and biomedicine. The aim of the present work was to evaluate the effect of rGO and Bi2O3 integration on photocatalytic and anticancer efficacy. A novel Bi2O3-WO3/rGO NCs was successfully prepared via the precipitation method. X-ray crystallography (XRD) data confirmed the crystallographic structure and the phase composition of the prepared samples. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis confirmed the loading of Bi2O3-doped WO3 NPs on rGO sheets. Energy-dispersive X-ray (EDX) results confirmed that all elements of carbon (C), oxygen (O), tungsten (W), and bismuth (Bi) were present in Bi2O3-WO3/rGO NCs. The oxidation state and presence of elemental compositions in Bi2O3-WO3/rGO NCs were verified by the X-ray photoelectron spectroscopy (XPS) study. Raman spectra indicate a reduction in carbon-oxygen functional groups and an increase in the graphitic carbon percentage of the Bi2O3-WO3/rGO NCs. The functional group present in the prepared samples was examined by Fourier transform infrared (FTIR) spectroscopy. UV analysis showed that the band gap energy of the synthesized samples was slightly decreased with Bi2O3 and rGO doping. Photoluminescence (PL) spectra showed that the recombination rate of the electron-hole pair decreased with the dopants. Degradation of RhB dye under UV light was employed to evaluate photocatalytic performance. The results showed that the Bi2O3-WO3/rGO NCs have high photocatalytic activity with a degradation rate of up to 91%. Cytotoxicity studies showed that Bi2O3 and rGO addition enhance the anticancer activity of WO3 against human lung cancer cells (A549) and colorectal cancer cells (HCT116). Moreover, Bi2O3-WO3/rGO NCs showed improved biocompatibility in human umbilical vein endothelial cells (HUVECs) than pure WO3 NPs. The results of this work showed that Bi2O3-doped WO3 particles decorated on rGO sheets display improved photocatalytic and anticancer activity. The preliminary data warrants further research on such NCs for their applications in the environment and medicine.

Multifunctional performance of core–shell rGO@Fe3O4 on the mechanical, electrical/thermal, EMI, and microstructure properties of cement-based composites

This research study focuses on the development of a multifunctional cement nanocomposite using reduced graphene oxide (rGO) nanosheets. To address the challenges of rGO dispersion, a core–shell structure of rGO@Fe3O4 (rGO@F) was investigated in cement paste. The rGO@F nanohybrid was thoroughly characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The main objectives of this study were to improve the mechanical properties, electrical conductivity, thermal conductivity, and chemical properties of the cement composite through the incorporation of rGO@F. The performance of the cement paste containing rGO0.1@Fe3O4 (0.1 wt% rGO and 1 wt% Fe3O4) was evaluated, and it was found that its toughness and compressive strength were significantly enhanced compared to the reference sample. Furthermore, the addition of rGO@F led to a remarkable increase in the electrical and thermal conductivity of the modified cement composite, attributed to the formation of conductive pathways facilitated by the rGO nanosheets. Comprehensive analyses including XRD, TGA, differential scanning calorimetry (DSC), thermally assisted microscopy (TAM), FTIR, and X-ray photoelectron spectroscopy (XPS) confirmed that the rGO@F nanohybrid had a significant impact on the chemical properties and hydration process of the hardened cement paste. SEM images revealed a more compact microstructure of the cement paste in the presence of rGO@F, demonstrating its role in crack inhibition. Additionally, an increase in the formation of improved hydration crystals such as tobermorite and jennite was observed. The core–shell structure of rGO@F exhibited exceptional electromagnetic wave absorption properties due to its layered configuration, effectively trapping the electromagnetic waves. Overall, this research study highlights the successful fabrication of a multifunctional cement nanocomposite through the incorporation of rGO@F. The findings demonstrate significant improvements in mechanical strength, electrical conductivity, thermal conductivity, chemical properties, crack inhibition, and electromagnetic wave absorption. This research contributes to the advancement of cement-based materials with enhanced performance and opens up avenues for various applications in fields such as construction, infrastructure, and telecommunications.

Facile Hydrothermal Synthesis of Visible‐Light‐Driven MnS/rGO Nanocomposite for Photocatalytic Degradation of Methylene Blue Dye

Currently, the global problem of poisonous and nondegradable organic water pollutants cannot be ignored. Heterogeneous photocatalysis is an advanced oxidation process (AOP) that uses semiconducting materials as a catalyst to clean water. Nanosize semiconductor photocatalysts are well recognized for their practical and cost‐effective way of cleaning up environmental pollution when exposed to visible light. Herein, a simple hydrothermal approach is used to create an MnS/rGO nanocomposite for the degradation of aromatic dyes under visible light. Powder X‐ray diffraction, scanning electron microscopy, and UV–visible spectroscopy are utilized to analyze the synthesized photocatalyst. Methylene blue is investigated for photocatalytic degradation using the MnS/rGO heterostructure nanocomposite. Under visible light, the composite shows photocatalytic degradation efficiency of 91.8% owing to the addition of rGO, its synergistic effects, high specific surface area, and a decrease in photoinduced electron–hole pair recombination. The fabricated nanocomposite MnS/rGO with significantly better photoresponse activity is successfully protected from charge recombination by reduced graphene oxide, which functions as a superb electron‐carrying material.

Enriched electrochemical performance of copper vanadate loaded reduced graphene oxide for supercapacitor applications

In this work, the electrochemical performance of copper vanadate (Cu3V2O8) nanoparticles (NPs) and Cu3V2O8 NPs loaded reduced graphene oxide (Cu3V2O8@rGO) nanocomposites (NCs) were reported. Cu3V2O8 NPs and Cu3V2O8@rGO (0.02 M Cu3V2O8 and 0.01 g of rGO) NCs were prepared by a simple reflux technique, and the prepared NCs were analytically investigated. The monoclinic crystalline structure of the prepared Cu3V2O8 NPs was revealed by the XRD analysis. Presence of plate-like structured Cu3V2O8 NPs and layer-structured rGO in the prepared NCs were observed through HR-TEM images. The electrochemical performance of the prepared NCs was investigated through the fabrication of Cu3V2O8 NPs, and Cu3V2O8@rGO NCs modified working electrode and supercapacitor under 1 M aqueous KOH electrolyte. The cyclic voltammetry result suggested that the pure Cu3V2O8 NPs modified working electrode possessed the specific capacitance value of 538 Fg-1 (at 5 mVs-1), and this value was further enhanced to 1341 Fg-1 by the addition of rGO. The maximum specific capacitance values calculated from GCD analysis were found to be 13.2 Fg-1 (at 0.1 Ag-1) for Cu3V2O8 NPs and 1305 Fg-1 (at 1.5 Ag-1) for Cu3V2O8@rGO NCs, based electrodes. The energy and power density values of the fabricated device using Cu3V2O8 NPs were found to be 2.067 W h kg1 and 403.8 W kg-1, respectively. Whereas, Cu3V2O8@rGO NCs-based device possessed 7.642 W h kg-1 and 90 W kg-1 of superior energy and power densities, respectively. The cyclic test result confirmed that the Cu3V2O8@rGO NCs-based device possessed the superior specific capacitance retention of 74% at the end of 2000 cycles, whereas, Cu3V2O8 NPs-based device exhibited only 69.5% of cyclic retention. The electrochemical results suggested that the inclusion of rGO in prepared copper vanadate nanoparticles induced the battery-like behavior. The proposed NCs can be utilized as the supercapacitor and/or battery electrodes.

Improving corrosion resistance and electrical conductivity of sunflower oil based polyurethane coatings by graphene oxide/reduced graphene oxide

In this study, polyurethane (PU) and graphene oxide (GO)/reduced graphene oxide (rGO) composites (GO-PU/rGO-PU) (0.5% GO-PU, 1.0% GO-PU, 0.5% rGO-PU and 1.0% rGO-PU) were prepared by adding different ratios of GO/rGO to Sunflower based PU. FTIR, XRD and SEM analyzes were performed for the characterization of the composites. In addition, the film properties of the composite materials developed in this study were investigated. Analysis results show that PU's adhesion and corrosion resistance can be enhanced with the addition of filler materials, namely GO and rGO, and electrical conductivity can be increased by the addition of rGO. These results indicate that rGO doped coatings may be an alternative coating as electrical conductive and corrosion resistant coatings in heavy environments.

Three-Dimensional Network Microstructure Design of the Li4Ti5O12/rGO Nanocomposite as an Anode Material for High-Performance Lithium-Ion Batteries

At present, the wide commercial application of Li4Ti5O12 (LTO) is limited as an anode for lithium-ion batteries because of its poor conductivity and lower rate performance. In this paper, LTO nanoparticles were embedded in a reduced graphene oxide (rGO) conductive network by an in situ electrostatic self-assembly effect using a simple hydrothermal reduction method. The microstructure and electrochemical performance of the LTO/rGO composite were investigated. The highlighted results showed that LTO nanoparticles were combined with rGO nanosheets by a Ti–O–C covalent bond, which was more stable than other bonding methods. At the same time, the addition of rGO not only enriches the structure and increases the specific surface area but also effectively prevents the agglomeration of LTO. The higher conductivity of LTO nanoparticles was bestowed by the rGO three-dimensional (3D) network, causing structural stability and high electrochemical performance. The LTO/rGO composite has high first discharge capacity (643.9 mAh/g at 0.5C), remarkable rate performance (290 mAh/g at 10C), and excellent cycle stability (271.7 mAh/g after the 1000th cycle at 10C) when tested in a half battery. Furthermore, it has higher discharge capacity (181.8 mAh/g at 1C, the first Coulombic efficiency was 90.1%) and excellent cycle stability (142.8 mAh/g after 500 cycles at 20C) when assembled into a full battery as the anode with commercial LiFePO4 (LFP) as the cathode. The lithium storage mechanism of the LTO/graphene composite was further discussed by first-principles calculations. With the addition of graphene to LTO, the electron transport ability was improved and the diffusion energy barrier was reduced. This made the composite expected to become a promising anode material for lithium-ion batteries.

Reduced Graphene Oxide on Activated Carbon-Manganese Dioxide Composite Materials for High-Performance Supercapacitor Electrodes

This study presents the addition of reduced graphene oxide (rGO) on the surface of activated carbon-manganese dioxide (ACMnO2) composite material via high-temperature variations of 350 to 450 °C to increase the specific capacitance of the ACMnO2/rGO composite electrode. The composite material is synthesized by coating the slurry mixture on the aluminum sheet using a 2-step doctor blade method with polyvinylidene difluoride (PVDF) material and dimethylformamide (DMF) solution as a binder. Then symmetric supercapacitor is fabricated using filter paper as a separator and 3M potassium hydroxide (KOH) solution as an electrolyte. The composite material analysis is characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) as well as cyclic voltammetry (CV) for the electrochemical properties. The ACMnO2/rGO composite electrode at a temperature variation of 350 °C showed the highest specific capacitance of 459.79 F g-1 at a scan rate of 9 mV s-1 with an energy density of 63.859 Wh kg-1. The addition of rGO on the surface of the ACMnO2 composite material increased the specific capacitance by about 58% compared to without rGO, showing promises for high-performance supercapacitor electrodes.

Hydrothermally synthesized rGO-BiVO4 nanocomposites for photocatalytic degradation of RhB

BiVO4 nanoparticles (NPs) synthesized by hydrothermal approach were hybridized with reduced graphene oxide (rGO) in various weight ratios (1:1, 1:3 & 3:1) and their effect of the composition on improving the photocatalytic degradation performance of the RhB dye was evaluated. The size and morphological variation of BiVO4 due to the hybridization of rGO have been analyzed with scanning electron microscopy and X-Ray diffraction studies, which confirms the formation of the composition. The intimate contact between 2D graphene oxide and BiVO4 is expected to lend higher separation of charge carriers due to the built-in electric field at the interface. A reduction in the bandgap of BiVO4 from 2.4 to 2.1 eV was demonstrated by UV-DRS and can be associated with the correct addition of rGO in BiVO4 NPs. In addition, Raman spectroscopy confirms the chemical reduction of GO in the hybrid nanocomposites. The photocatalytic analysis shows that 3:1-rGO-BiVO4 (3:1-RGB) nanocomposites have an almost 3.6 times higher performance in the complete degradation of RhB dyes as compared to bare BiVO4 NPs.

Highly Dispersed Pt‐Au/rGO Catalysts Prepared by Hyperbranched Polyglycerols for Efficient Electrooxidation of Methanol

AbstractRecently, fuel cells especially direct methanol fuel cells (DMFCs), have attracted great interest because of their high energy density, their pollution‐free operation mode and thus their prospect for use in convenient transportation. Although platinum (Pt) catalyst is an efficient catalysts for DMFCs, it has some problems such as high price, poor stability and durability. Therefore, the research of high performance Pt catalysts becomes the focus. Firstly, the hyperbranched polyglycerols (HPG) were synthesized by the one‐step anionic ring‐opening polymerization. The Pt‐Au bimetallic catalysts supported on reduced graphene oxide (Pt‐Au‐HPG/rGO) were synthesized via a hydrothermal method, using HPG as the template and stabilizer. The electrocatalytic performances for the electrooxidation of methanol were investigated by electrochemical methods. Compared with commercial Pt/C (10 wt %) catalysts, Pt‐Au‐HPG/rGO has the larger electrochemically active surface area (ECSA, 108.8 m2 g−1), higher catalytic performance (0.498 A mgmetal−1) and better stability. This excellent performance is attributed to the good dispersion and conductivity of Pt‐Au‐HPG/rGO for the addition of HPG, rGO and Au. Meanwhile, the bifunctional and electronic effects between Au and Pt improved the electrochemical performance of the samples.

Interface Engineering of Nickel Selenide and Graphene Nanocomposite for Hybrid Supercapacitor

Nickel selenide is an emerging electrode material for high‐performance hybrid supercapacitors; however, poor electrical conductivity and sluggish ion kinetics limit its application. Herein, a unique architecture by decorating NiSe nanoparticles on reduced graphene oxides (rGO) is developed. The synergistic effect of NiSe and rGO facilitated by the optimized addition of rGO results in significant improvement in the electrochemical performance. The physicochemical characterizations suggest that the enhancement can be attributed to increased interfacial interaction and access to the electrochemically active sites. The NiSe/rGO hybrid delivers a specific capacity of 351 mAh g−1 at 1 A g−1, which is significantly higher than that for bare NiSe. Later, the hybrid supercapacitor based on NiSe/rGO hybrid as positive and activated carbon as negative electrode delivers a maximum energy density of 49.6 Wh kg−1 at a power density of 748.37 W kg−1. In addition, the device shows good cyclic stability of 83.3% over 5000 cycles. Thus, an innovative approach to the development of high‐performance hybrid supercapacitors is offered.

Enhancing sodium-ion batteries performance enabled by three-dimensional nanoflower Sb2S3@rGO anode material

Sodium-ion batteries (SIBs) gradually become ideal substitutes to lithium-ion batteries (LIBs) as a result of higher applicability in new-generation energy storage system. However, the controlled preparation of superior electrode materials for obtaining high-performance SIBs remains a challenge. In this study, a composite structure comprising three-dimensional nanoflower Sb2S3 and reduced graphene oxide (rGO) was successfully manufactured by applying a hydrothermal method as an emerging anode material for SIBs. Nanoflower Sb2S3@rGO exhibited excellent electrochemical performance, yielding 544.8 mAh/g at a rate of 100 mA/g, and sustained stability in the later 200 cycles, which was 75.4% of the initial value for the specific capacity. Even the current density is 2000 mA/g, a specific energy capacity of 433.4 mAh/g was obtained. The sodium storage mechanism was explored using cyclic voltammetry at different sweep speeds to clearly point out the electrochemical process of forming nanoflower Sb2S3@rGO. The results indicate that the high performance is ascribed to the particular flower-like three-dimensional structure, which provides cache space for Sb2S3 volume expansion during charge/discharge, while the addition of rGO effectively improves the overall electrical conductivity of the electrode. This work furnishes a new insight into the construction of specially structured anode materials to promote the development of SIBs.