In the present study, we prepared reduced graphene oxide (rGO) decorated with Ag nanoparticles by a one pot, simultaneous reduction method. The effect of AgNO3 amount on the chemical, morphological and electrochemical properties of binary rGO-Ag nanocomposite for supercapacitor application was investigated. The chemical and morphological characterization of prepared rGO-Ag nanocomposites was realized with field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). For supercapacitor application, electrochemical performance of the nanocomposites was investigated with cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. As a result of their excellent conductivity and spacer role which prevent aggregation of rGO nanosheets and maintain the electroactive surface area, Ag nanoparticles significantly enhance the electrochemical performance of the nanocomposite. The rGO-Ag nanoparticle nanocomposite exhibited a maximum specific capacitance of 34.2?mF?cm?2 at 0.6?A?cm?2 current density. The nanocomposite electrode also has excellent rate capability and cycle life. The capacitance retention of rGO-Ag electrode is 98% after 1000 charge-discharge cycle. The results showed that rGO-Ag nanocomposite is a building block for ternary or other multicomponent nanocomposites. 相似文献
The coupling effect and synergistic effect between the two metal elements of the bimetallic oxide make it has unique electrical characteristics and gas-sensitive properties, but it has the limitation of low conductivity. In this paper, the bimetallic oxide Zn2SnO4 was decorated with reduced graphene oxide (rGO) to increase its electrical conductivity and promote charge transfer during gas adsorption, which enhances the response and shortens the response time of the bimetallic oxide gas sensor. The high-performance ammonia sensor based on Zn2SnO4/rGO nanocomposite material was prepared by environmentally friendly hydrothermal method and spin coating technology. The structure and properties of composite materials were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The ammonia sensing performance of Zn2SnO4/rGO nanocomposite sensor was tested at room temperature, including the dynamic response, response/recovery time, selectivity, repeatability, long-term stability. It showed a good sensing response to ammonia (22.94 for 100 ppm), and a fast response/recovery time (20 s/27 s). Finally, the response mechanism of Zn2SnO4/rGO nanocomposite sensor is explained. The enhanced ammonia sensing properties of Zn2SnO4/rGO nanocomposite sensor were ascribed to the synergistic effect and p–n heterojunction between Zn2SnO4 and rGO.
Transition metal chalcogenide with tailored nanosheet architectures with reduced graphene oxide (rGO) for high performance electrochemical sodium ion batteries (SIBs) are presented. Via one‐step oriented attachment growth, a facile synthesis of Co9Se8 nanosheets anchored on rGO matrix nanocomposites is demonstrated. As effective anode materials of SIBs, Co9Se8/rGO nanocomposites can deliver a highly reversible capacity of 406 mA h g?1 at a current density of 50 mA g?1 with long cycle stability. It can also deliver a high specific capacity of 295 mA h g?1 at a high current density of 5 A g?1 indicating its high rate capability. Furthermore, ex situ transmission electron microscopy observations provide insight into the reaction path of nontopotactic conversion in the hybrid anode, revealing the highly reversible conversion directly between the hybrid Co9Se8/rGO and Co nanoparticles/Na2Se matrix during the sodiation/desodiation process. In addition, it is experimentally demonstrated that rGO plays significant roles in both controllable growth and electrochemical conversion processes, which can not only modulate the morphology of the product but also tune the sodium storage performance. The investigation on hybrid Co9Se8/rGO nanosheets as SIBs anode may shed light on designing new metal chalcogenide materials for high energy storage system. 相似文献
In this work, CuFe2O4/CuO nanocomposites have been synthesized by galvanostatic cathodic electrodeposition. The obtained nanocomposites were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier Transform Infrared, and Brunauer–Emmett–Teller surface area analysis. The electrochemical properties of CuFe2O4/CuO nanocomposites were evaluated by cyclic voltammetry, galvanostatic charge–discharge cycling, and electrochemical impedance spectroscopy in 1.0 M KOH. The CuFe2O4/CuO nanocomposites have shown the high specific capacitance of 322.49 F g?1 at the scan rate of 1 mV s?1. After 5000 cycles, 92% of this specific capacitance was retained. Although the prepared nanocomposite has shown a mediocre specific capacitance compared to other metal oxide-based materials, the low cost of the starting materials and the ease of preparation make this nanocomposite a good candidate for supercapacitor applications. 相似文献
This paper reports a facile one-step hydrothermal treatment of graphene oxide (GO) and cobalt acetate (Co(Ac)2) for preparing reduced GO (rGO)/Co3O4 composites which were used as electrode materials for supercapacitors containing electrolytes of 2 M KOH aqueous solution. The morphologies and structures of rGO/Co3O4 composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectrum, and N2 adsorption–desorption isotherms. The electrochemical performances of two-electrode supercapacitors were evaluated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques. During the hydrothermal reaction, GO was reduced and 10–30 nm-sized Co3O4 nanoparticles were in situ grown onto the rGO sheets simultaneously. The effects of mass ratios of GO and Co(Ac)2 on the performances of supercapacitors were investigated. In comparison with pure Co3O4-based supercapacitor, supercapacitors based on rGO/Co3O4 composites show better performances because both the specific surface areas and the electrical conductivities of electrode materials were increased by the introduction of rGO. When the mass ratio of GO and Co(Ac)2 is 1:2, rGO/Co3O4 composite electrode exhibits the highest capacitance of 263.0 F/g at a constant current density of 0.2 A/g in a two-electrode supercapacitor. In addition, the supercapacitor shows high rate capability and long cyclic durability. 相似文献
Ultrathin Co3O4 nanosheets grown on the reduced graphene oxide (Co3O4/rGO) was synthesized by a simple hydrothermal method and was investigated as a cathode in a Li-O2 battery. Benefited from the synergistic effect between Co3O4 and rGO, the hybrid exhibits a high initial capacity of 10,528 mAh g?1 along with a high coulombic efficiency (84.4%) at 100 mA g?1. In addition, the batteries show an enhanced cycling stability and after 113 cycles, the cut-off discharge voltage remains above 2.5 V. The outstanding performance is intimately related to the high surface area of rGO, which not only provide carbon skeleton for the uniform distribution of Co3O4 nanosheets but also facilitate the reversible formation and decomposition of insoluble Li2O2. The results of electrochemical tests confirm that the Co3O4/rGO hybrid is a promising candidate for the Li-O2 batteries. 相似文献
3D graphene frameworks/Co3O4 composites are produced by the thermal explosion method, in which the generation of Co3O4 nanoparticles, reduction of graphene oxide, and creation of 3D frameworks are simultaneously completed. The process prevents the agglomeration of Co3O4 particles effectively, resulting in monodispersed Co3O4 nanoparticles scattered on the 3D graphene frameworks evenly. The prepared 3D graphene frameworks/Co3O4 composites used as electrodes for supercapacitor display a definite improvement on electrochemical performance with high specific capacitance (≈1765 F g?1 at a current density of 1 A g?1), good rate performance (≈1266 F g?1 at a current density of 20 A g?1), and excellent stability (≈93% maintenance of specific capacitance at a constant current density of 10 A g?1 after 5000 cycles). In addition, the composites are also employed as nonenzymatic sensors for the electrochemical detection of glucose, which exhibit high sensitivity (122.16 µA mM ?1 cm?2) and noteworthy lower detection limit (157 × 10?9 M , S/N = 3). Therefore, the authors expect that the 3D graphene frameworks/Co3O4 composites described here would possess potential applications as the electrode materials in supercapacitors and nonenzymatic detection of glucose. 相似文献
GO and Co(NO3)2 were respectively used as rGO and Co3O4 precursors for preparing magnetically separable Co3O4NPs attached Co3O4NPs@rGO nanocomposites by a straightforward sol–gel technique. To characterize the nanocomposite materials, FESEM, EDX, elemental mapping, XRD, FTIR, Raman spectroscopy, UV–vis, VSM and BET were employed. When exposed to UV rays, the nanocomposite showed extraordinary photocatalytic degradation of MO dye. According to the measurements of photocatalytic activity, the highly efficient photocatalytic efficiency of the nanocomposite could be attributed to preventing electron-hole recombination by highly effective electron transfer between rGO and semiconductor NPs. The nanocomposite succeeded in the efficient degradation of MO dye, even after five photocatalytic cycles. 相似文献
Ferrite, as a kind of common magnetic adsorbent, always tend to reuniting and lead to the poor performance for removing contaminant in aqueous. Meanwhile, reduced graphene oxide (rGO), a high-efficiency adsorbent used for water treatment, is hydrophobic and easy to stack because of the Van der Waals force, resulting in the low adsorption capacity. Herein, we prepare the magnetic CoFe2O4/rGO nanocomposites to solve the reuniting of CoFe2O4 and stacking of rGO simultaneously. The rGO nanosheets can improve the dispersion of CoFe2O4 nanoparticles. As sorbent, the adsorption behaviors of carbamazepine on the nanocomposites can be fitted well by the Langmuir and pseudo-second-order kinetic models. In addition, the CoFe2O4/rGO nanocomposites show enhanced adsorption performance than that of the pure CoFe2O4 nanoparticles, and the loading of rGO can affect their adsorption performance. The adsorption of carbamazepine on CoFe2O4/rGO is exothermic and mainly controlled by π–π interaction and hydrogen bond interaction. Furthermore, the CoFe2O4/rGO can be used to remove other organic pollutants simultaneously. Finally, the nanocomposites can be collected by external magnet, and the regenerated nanocomposites still showed a high adsorption capacity retention (90%) after five cycles. 相似文献
Poly(amidoamine) dendrimers-modified reduced graphene oxide nanosheets (PAMAM/rGO) composite was selected as a carrier of heterogeneous Ag0.3Co0.7 nanoparticles in order to obtain an excellent catalyst for ammonia borane (AB) hydrolysis. During the synthetic processes, GO could easily assembled with PAMAM by the electrostatic and hydrogen-bonding interactions. Structural characterization revealed that Ag0.3Co0.7 bimetallic nanoparticles with uniform size distribution of 5 nm are well dispersed on PAMAM/rGO composite architecture. Ag0.3Co0.7@PAMAM/rGO was found to be a highly active and reusable catalyst in hydrogen generation from the hydrolysis of AB with a turnover frequency value (TOF) of 19.79 molH2 min–1 molM–1 at 25.0 ± 0.1 °C and retained 75.4% of their initial activity with a complete release of hydrogen in five runs. The relatively high TOF value and low apparent activation energy (34.21 kJ mol–1) make these Ag0.3Co0.7@PAMAM/rGO NPs as a high-efficient catalyst for catalytic dehydrogenation of AB facilitating the development of practically applicable energy storage materials. 相似文献
A facile method is introduced for incorporating reduced graphene oxide (rGO) into poly(safranine T) (PST) films. First, ST-functionalized GO (ST/GO) was obtained via the absorption of ST on GO in pH 7.0 phosphate buffer solution. Then rGO/PST composite was synthesized by the electropolymerization of ST and the subsequent electrochemical reduction of GO. The as-prepared PST/rGO composite films are characterized using scanning electron microscope, X-ray diffraction, and Fourier transform–infrared spectroscopy. PST/rGO composites possess a microporous structure, which creates enormous amount of pores, and therefore provides larger interfaces for charge carrier. The properties of electrochemical capacitance for PST/rGO composites have also been investigated with cyclic voltammetry (CV) and galvanostatic charge–discharge measurements. The experimental results manifest that the PST/rGO composite showed high capacitance (293.2 F g?1) at 20-mV s?1 CV scan and an excellent cycling stability (8.3% drop after 1000 cycles) in 0.1 M Na2SO4 electrolyte. 相似文献
A new kind of Co2SnO4-based electrode materials for supercapacitor was synthesized by co-precipitation method. The microstructure and surface morphology of Co2SnO4 were characterized by X-ray diffraction and scanning electron microscopy, respectively. Cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy were employed for the determination of specific capacitance and the equivalent series resistance of Co2SnO4/activated carbon composite electrode in KCl solution. It was shown that the composite electrode with 25 wt% Co2SnO4 had excellent specific capacitance up to 285.3 F g−1 at the current density of 5 mA cm−2. In addition, the composite electrode exhibited excellent long-term stability and, after 1000 cycles, 70.6% of initial capacitance was retained. Regarding the low cost, easy preparation, steady performance and environment friendliness, Co2SnO4/activated carbon composite electrode could have potentially promising application for supercapacitor. 相似文献
A Co9S8/C nanocomposite has been prepared using a solid-state reaction followed by a facile mechanical ball-milling treatment with sucrose as the carbon source. The phases, morphology, and detailed structures of Co9S8/C nanocomposite are well characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. Our experimental results show that not only a process of particle size reduction, the ball-milling treatment also promotes the carbon and Co9S8 combining with each other more effectively to form an ultrafine nanocomposite. When used as an electrode material in supercapacitor, Co9S8/C nanocomposite exhibits a high initial specific capacitance of 756.2 F g?1 at 1 A g?1 and excellent cycling stability with 73.4% retention after 2000 cycles. Its outstanding electrochemical properties are mainly attributed to the nanosize of particles and amorphous carbon layer coating on its surface. 相似文献
Flexible power sources have shown great promise in next‐generation bendable, implantable, and wearable electronic systems. Here, flexible and binder‐free electrodes of Na3V2(PO4)3/reduced graphene oxide (NVP/rGO) and Sb/rGO nanocomposites for sodium‐ion batteries are reported. The Sb/rGO and NVP/rGO paper electrodes with high flexibility and tailorability can be easily fabricated. Sb and NVP nanoparticles are embedded homogenously in the interconnected framework of rGO nanosheets, which provides structurally stable hosts for Na‐ion intercalation and deintercalation. The NVP/rGO paper‐like cathode delivers a reversible capacity of 113 mAh g?1 at 100 mA g?1 and high capacity retention of ≈96.6% after 120 cycles. The Sb/rGO paper‐like anode gives a highly reversible capacity of 612 mAh g?1 at 100 mA g?1, an excellent rate capacity up to 30 C, and a good cycle performance. Moreover, the sodium‐ion full cell of NVP/rGO//Sb/rGO has been fabricated, delivering a highly reversible capacity of ≈400 mAh g?1 at a current density of 100 mA g?1 after 100 charge/discharge cycles. This work may provide promising electrode candidates for developing next‐generation energy‐storage devices with high capacity and long cycle life. 相似文献
The rGO–ZnO–Fe3O4 nanocomposites were synthesized by a simple, economical and environmentally benign solvothermal method. The morphology, structure and photocatalytic activity of rGO–ZnO–Fe3O4 nanocomposites were characterized, and the effects of the preparation conditions were analyzed. The 25 mg of rGO–ZnO–Fe3O4 nanocomposites performed efficient photocatalytic activity for the degradation of 25 mL of 4.79 mg/L Rhodamine B under both ultraviolet and visible light irradiation. The nanocomposites could be easily retrieved from the wastewater by extra magnetic field due to the presence of magnetic Fe3O4 nanoparticles. After the degradation experiment was carried out five times, the degradation ratio is still close to 90% after irradiation after 5 cyclic, indicating that the rGO–ZnO–Fe3O4 nanocomposites have high stability for reuse. Therefore, the prepared rGO–ZnO–Fe3O4 nanocomposites may be a promising potential material for wastewater treatment. 相似文献
The polyimide/CaMoO4 nanocomposites were successfully prepared by ex-situ polymerization. (3-Aminopropyl) triethoxysilane (KH550) was used as coupling agent to disperse the CaMoO4 nanoparticles in polyimide matrix homogeneously. To characterize the structure and properties of the obtained nanocomposites, Scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, dielectric properties and thermal stability were studied. It was observed that the CaMoO4 nanoparticles were dispersed homogeneously in the polyimide matrix without obvious aggregation. The results show that nano-sized CaMoO4 will improve dielectric constant and decrease dielectric loss of the nanocomposites in the relatively high-frequency region (>10 kHz). And the nanocomposite with excellent dielectric properties of ε?=?3.04, δ?=?8.0?×?10?3 was obtained after doping 2.5 wt% nano-sized CaMoO4 into polyimides. Dielectric loss of the nanocomposites is reduced in low frequency domain (<10 kHz) and enhanced in high frequency domain (>10 kHz). In addition, the thermal stability of the nanocomposites was enhanced from 544 to 651?°C compared to pure polyimide. 相似文献
Novel SnO2–x/g-C3N4 heterojunction nanocomposites composed of reduced SnO2–x nanoparticles and exfoliated g-C3N4 nanosheets were prepared by a convenient one-step pyrolysis method. The structural, morphological, and optical properties of the as-prepared nanocomposites were characterized in detail, indicating that the aggregation of g-C3N4 nanosheets was prevented by small, well-dispersed SnO2–x nanoparticles. The ultraviolet–visible spectroscopy absorption bands of the nanocomposites were shifted to a longer wavelength region than those exhibited by pure SnO2 or g-C3N4. The charge transfer and recombination processes occurring in the nanocomposites were investigated using linear scan voltammetry and electrochemical impedance spectroscopy. Under 30-W visible-light-emitting diode irradiation, the heterojunction containing 27.4 wt.% SnO2–x exhibited the highest photocurrent density of 0.0468 mA·cm–2, which is 33.43 and 5.64 times larger than that of pure SnO2 and g-C3N4, respectively. The photocatalytic activity of the heterojunction material was investigated by degrading rhodamine B under irradiation from the same light source. Kinetic study revealed a promising degradation rate constant of 0.0226 min?1 for the heterojunction containing 27.4 wt.% SnO2–x, which is 32.28 and 5.79 times higher than that of pure SnO2 and g-C3N4, respectively. The enhanced photoelectrochemical and photocatalytic performances of the nanocomposite may be due to its appropriate SnO2–x content and the compact structure of the junction between the SnO2–x nanoparticles and the g-C3N4 nanosheets, which inhibits the recombination of photogenerated electrons and holes.
Herein, a facile sol–gel strategy for building the ordered interpenetrating network of Ni(OH)2 and reduced graphene oxide (rGO) was proposed. In this strategy, rGO nanosheets were homogeneously fixed inside composite utilizing the pores of Ni(OH)2 gel as template, forming rGO-interpenetrated gel network. It was found that the rGO nanosheets could effectively reduce the internal resistant of composites and provide mechanical support for the gel network of Ni(OH)2. Therefore, the composite presented high electrochemical performance, especially high-rate performance, due to the interpenetrating of rGO nanosheets plus the supplementary role of acetylene black. It had high specific capacitance of 2163 F g?1 at low current density of 2.9 A g?1 and 733 F g?1 at high current density of 86.8 A g?1. 相似文献
In this work, we report the preparation of Co2(OH)3Cl nanoparticles with average size of ~20 nm and well-defined cubic shape at room temperature by an epoxide precipitation route. It was found that the as-prepared Co2(OH)3Cl nanoparticles could be used as a promising new electrode material for application in redox supercapacitors due to its high electrochemical performance. It presented superior specific capacitance of 783 F g?1 at low current density of 2.8 A g?1, while it had a high value of 604 F g?1 at high current density of 56.6 A g?1, proving its excellent high rate performance. Its 75% capacitance retention after 10,000 cycles of charge–discharge demonstrated its long-life span. According to characterization results, the possible mechanism for the electrochemical process that Co2(OH)3Cl nanoparticles underwent was proposed as a process of Co2(OH)3Cl → β-Co(OH)2 → CoOOH ? Co3O4. 相似文献