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Abstract: Reduced graphene oxide (RGO)-carbon nanotubes (CNTs) composite films were successfully fabricated by electrophoretic deposition and used as electrode materials for electrochemical supercapacitors. RGO was obtained by microwave-assisted reduction of graphene oxide dispersion in acidic aqueous solution using a microwave synthesis system. The electrochemical performances of the films were analyzed through cyclic voltammetry and chronopotentiometry tests. The results showed that as compared with pure RGO and CNTs, RGO–CNTs composite with 40% CNTs exhibited an optimal electrochemical capacitance of 87F/g due to a synergistic effect of RGO and CNTs. [Copyright &y& Elsevier]

Abstract: Graphene–ZnO nanocomposite was successfully synthesized via microwave-assisted reduction of zinc ions in aqueous solution with graphite oxide dispersion using a microwave synthesis system. The electrochemical performance of the nanocomposite was analyzed through cyclic voltammetry and chronopotentiometry tests. The results showed that as compared with pure graphene, graphene–ZnO composite exhibited an improved electrochemical capacitance of 146F/g with good reversible charge/discharge behavior. [Copyright &y& Elsevier]

Abstract: Graphene, graphene–ZnO and graphene–SnO2 films were successfully synthesized and used as electrode materials for electrochemical supercapacitors, respectively. The screen-printing approach was employed to fabricate graphene film on graphite substrate while the ZnO and SnO2 were deposited on graphene films by ultrasonic spray pyrolysis. The electrochemical performances of these electrodes were comparatively analyzed through electrochemical impedance spectrometry, cyclic voltammetry and chronopotentiometry tests. The results showed that the incorporation of ZnO or SnO2 improved the capacitive performance of graphene electrode. Graphene–ZnO composite electrode exhibited higher capacitance value (61.7F/g) and maximum power density (4.8kW/kg) as compared with graphene–SnO2 and pure graphene electrodes. [Copyright &y& Elsevier]

The electrochemical water splitting process is always restrained for its sluggish kinetics and high reaction energy barrier. Therefore, developing outstanding bifunctional catalysts to enhance the reaction kinetics and electron transfer efficiency of water splitting is crucial. In this work, we reported a bifunctional nanohybrid electrocatalyst consisting of Fe-doped CoS 2 nanocage-decorated reduced graphene oxide (FCSRGO) with superior water splitting activity. The Fe doping adjusts the density of state (DOS) to increase the conductivity and decreases the adsorption free energy of intermediates, contributing to optimized catalytic activity. Furthermore, the incorporation of RGO reduces the agglomeration of CoS 2 and improves the conductivity, thereby amplifying the charge/species transfer efficiency. By optimizing the amount of RGO, FCSRGO shows exceptional electrocatalytic performance, achieving a benchmark current density of 10 mA·cm−2 at remarkably low overpotentials (ƞ 10) of 107 mV and 239 mV in 1 M KOH solution for HER and OER, respectively. Moreover, the nanohybrid exhibits remarkable stability with the current density retention of 89.8% for HER and 85.8% for OER after 36000 s test. This work highlights the creating of high-performance electrocatalysts for efficient and sustainable hydrogen and oxygen evolution through heteroatom doping and carbon incorporation. [Display omitted] • A bifunctional electrocatalyst consisting of Fe-doped CoS 2 nanocage-decorated reduced graphene oxide is constructed. • The nanohybrid displays large surface area, improved conductivity and decreased adsorption free energy of intermediates. • The nanohybrid exhibits excellent electrocatalytic performances for both hydrogen and oxygen evolution. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a comparative study on electrosorptive behavior of commercial single walled and double walled carbon nanotubes (CNTs) and as-prepared graphene as potential electrode materials for capacitive deionization (CDI). Their electrosorptive behaviors are evaluated under the same experimental conditions and described by various adsorption isotherms and kinetics models. It was found that the electrosorptive capacity of CNTs (single walled or double walled)-based CDI is higher than that of graphene-based CDI, which is related to their specific surface area, pore structure and hydrophilic functional groups. Electrosorptive kinetics analysis further confirms that CNTs are more suitable as electrode materials than graphene. [Copyright &y& Elsevier]

One of the most challenging issues in developing supercapacitor and capacitive deionization (CDI) technologies is the rational design and synthesis of active electrode materials, with favorable morphologies, reasonable porous structure and high surface area. Recently, three-dimensional (3D) graphene frameworks (3DGF)-based hybrids have been considered as one of the most promising candidates for supercapacitor and CDI applications. By incorporating functional nanomaterials into 3DGF, the obtained 3DGF-based hybrids exhibited enhanced properties or unique character compared to 3DGF. Here we report novel hierarchical hybrids with microporous carbon spheres (MCS) decorated 3DGF (3DGF-MCS), which not only possesses a hierarchical porous structure, but also maintains favorable features for supercapacitor and CDI applications, such as a large surface area and good electrical conductivity. The results indicate that 3DGF-MCS with 10 wt% MCS exhibits excellent electrochemical performances, including a superior specific capacitance of 288.77 F g −1 , and an ultrahigh electrosorption capacity of 19.8 mg g −1 . The 3DGF-MCS should be promising electrode materials for highly efficient supercapacitor and CDI applications. [ABSTRACT FROM AUTHOR]

Here a facile strategy was proposed to prepare graphene (GE) sheets with unique mesoporous morphology (denoted as mGE) via a simple carbothermal reaction by using KMnO 4 as the etching agent. The morphology, structure and electrochemical properties of mGE were investigated by scanning electron microscopy, transmission electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy. The electrosorption performance of mGE in NaCl solution was studied and compared with GE. The results show that mGE electrode exhibits a high electrosorption capacity of 6.38 mg g −1 when the initial NaCl concentration is ∼75 mg L −1 and applied voltage is 1.2 V, which is about 2.3 and 1.5 times of those of GE (2.76 mg g −1 ) and recently reported microporous GE (∼4 mg g −1 ), respectively, and also higher than those of other carbon materials in the literatures, due to short ion diffusion path, large accessible surface area and low charge transfer resistance offered by its novel mesoporous structure. Therefore, it is believed that mGE is a promising candidate for practical capacitive deionization applications. [ABSTRACT FROM AUTHOR]

Abstract: ZnO–reduced graphene oxide (RGO) composites are successfully synthesized via UV-assisted photocatalytic reduction of graphite oxide by ZnO nanoparticles in ethanol. Their morphology, structure and photocatalytic performance in reduction of Cr(VI) are characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction spectroscopy, UV–vis absorption spectrophotometer, respectively. The results show that in the composites the RGO nanosheets are decorated densely by ZnO nanoparticles, which displays a good combination between RGO and ZnO. ZnO–RGO composites exhibit an enhanced photocatalytic performance in reduction of Cr(VI) with a maximum removal rate of 96% under UV light irradiation as compared with pure ZnO (67%) due to the increased light absorption intensity and range as well as the reduction of electron–hole pair recombination in ZnO with the introduction of RGO. [Copyright &y& Elsevier]

Abstract: A quick and facile microwave-assisted reaction is used to synthesize ZnO-reduced graphene oxide (RGO) hybrid composites by reducing graphite oxide dispersion with zinc nitrate using a microwave synthesis system. Their photocatalytic performance in degradation of methylene blue is investigated and the results show that the RGO plays an important role in the enhancement of photocatalytic performance and the ZnO–RGO composite with 1.1wt. % RGO achieves a maximum degradation efficiency of 88% in a neutral solution under UV light irradiation for 260min as compared with pure ZnO (68%) due to the increased light absorption, the reduced charge recombination with the introduction of RGO. [Copyright &y& Elsevier]

Abstract: Graphene–ZnO composite film was synthesized for its potential application in supercapacitors. Graphene was prepared by a modified Hummers method and hydrazine reduction process, and ZnO was deposited on graphene by ultrasonic spray pyrolysis. The electrochemical characteristics of the film were investigated through electrochemical impedance spectrometry, cyclic voltammetry and chronopotentiometry tests. The results showed that graphene–ZnO composite film exhibited an enhanced capacitive behavior with better reversible charging/discharging ability and higher capacitance values, by comparison to pure graphene or ZnO electrode. [Copyright &y& Elsevier]