Fabrication of an antimony doped tin oxide–graphene nanocomposite for highly effective capacitive deionization of saline water

In this study, antimony doped tin oxide loaded reduced graphene oxide (ATO–RGO) nanocomposites were synthesized via a facile hydrothermal approach. As a typical N-type semiconductor, the ATO in the composite can enhance the conductivity between graphene sheets, thus improving the specific capacitance and electrosorption performance. Under the optimal conditions, the largest surface area was 445.2 m² g⁻¹ when the mass content of ATO in the nanocomposite was 20 wt%. The synthesized optimal ATO–RGO electrode displayed excellent specific capacity (158.2 F g⁻¹) and outstanding electrosorptive capacity (8.63 mg g⁻¹) in sodium chloride solution, which were much higher than the corresponding results of pristine graphene (74.3 F g⁻¹ and 3.98 mg g⁻¹). At the same applied voltage, electrosorption capacity and charge efficiency of the ATO–RGO (20 wt%) material were better than those of reported carbon materials in recent years.

Antimony doped tin oxide–graphene nanocomposites synthesized via a facile hydrothermal approach displayed good specific capacity and electrosorptive capacity.     

Reduced graphene oxide decorated with octahedral NiS2/NiS nanocrystals: facile synthesis and tunable high frequency attenuation

Reduced graphene oxide (RGO) decorated with octahedral NiS₂/NiS nanocrystals were fabricated via a facile synthetic strategy. By appropriate adjustment of the weight ratio of GO and NiS₂/NiS nanocrystals, RGO–NiS₂/NiS nanocomposites with an excellent microwave absorption performance were achieved. As expected, RGO–NiS₂/NiS nanocomposites in a polyvinylidene fluoride (PVDF) matrix with different mass fractions (5, 10, 15, 20 wt%) possess effective absorption in the high frequency range with a thin thickness (1.5 mm) compared with those of octahedral NiS₂/NiS nanocrystals. It was revealed that RGO–NiS₂/NiS nanocomposites with a GO : NiS₂/NiS weight ratio of 1 : 4 exhibited the most prominent microwave absorption property. The optimal effective frequency bandwidth of this sample covers 4.32 GHz at a thin coating layer of 1.5 mm (15 wt%). The corresponding reflection loss value can reach −32.2 dB at 14.32 GHz. Moreover, the fundamental attenuation mechanisms are also discussed in detail.

Reduced graphene oxide (RGO) decorated with octahedral NiS₂/NiS nanocrystals were fabricated and they possessed an excellent microwave absorption performance in the high frequency range.     

Microstructure and electrochemical properties of high performance graphene/manganese oxide hybrid electrodes

Hybrids consisting of 2D ultra-large reduced graphene oxide (RGO) sheets (∼30 μm long) and 1D α-phase manganese oxide (MnO₂) nanowires were fabricated through a versatile synthesis technique that results in electrostatic binding of the nanowires and sheets. Two different hybrid (RGO/MnO₂) compositions had remarkable features and performance: 3 : 1 MnO₂/RGO (75/25 wt%) denoted as 3H and 10 : 1 MnO₂/RGO (90/10 wt%) denoted as 10H. Characterization using spectroscopy, microscopy, and thermal analysis provided insights into the microstructure and behavior of the individual components and hybrids. Both hybrids exhibited higher specific capacitance than their individual components. 3H demonstrated excellent overall electrochemical performance with specific capacitance of 225 F g⁻¹, pseudocapacitive and electrochemical double-layer capacitance (EDLC) contributions, charge-transfer resistance <1 Ω, and 97.8% capacitive retention after 1000 cycles. These properties were better than those of 10H; this was attributed 3H''s more uniform distribution of nanowires enabling more effective electronic transport. Thermal annealing was used to produce reduced graphene oxide (RGO) that exhibited significant removal of oxygen functionality with a resulting interlayer spacing of 0.391 nm, higher D/G ratio, higher specific capacitance, and electrochemical properties representing more ideal capacitive behavior than GO. Integrating ultra-large RGO with very high surface area and MnO₂ nanowires enables chemical interactions that may improve processability into complex architectures and electrochemical performance of electrodes for applications in electronics, sensors, catalysis, and deionization.

Tuning the microstructure of ultra-large reduced graphene oxide (RGO) 2D sheets and manganese oxide (MnO₂) 1D nanowires to produce a hybrid material enabled achieving excellent electrochemical capacitive behavior for energy storage.     

A pH-stable positively charged composite nanofiltration membrane with excellent rejection performance

A novel kind of pH-stable positively charged composite nanofiltration (NF) membrane with excellent rejection performance was developed via interfacial polymerization on the surface of a polysulfone (PSF) ultrafiltration (UF) membrane, using a mixture of polyethyleneimine (PEI) and piperazine (PIP) as the monomers of the aqueous phase, and cyanuric chloride (CC) as the monomer of the organic phase. The strong electron withdrawing and steric hindrance effects of the chloride group in the molecules of CC could protect the amido bond from the attack of hydrogen ions (H⁺) or hydroxyl ions (OH⁻) under acidic or alkaline conditions, thus the resultant polyamide composite membranes could be stable in acidic or alkali aqueous solution. A more compact PA active layer could be developed via mixing PIP into the PEI aqueous solution, where the PIP molecules could fill the pores of the polymer networks. There was no obvious change in the surface morphologies, the chemical structures, and the rejection performances after immersing the resultant polyamine composite NF membranes in the strong acidic solution (pH 1) and the strong alkaline solution (pH 13) for 30 days, respectively. The rejection performances of this kind of polyamine composite NF membranes could be adjusted through adjusting the mass ratio of PEI to PIP in the aqueous phase.

A pH-stable positively charged composite nanofiltration (NF) membrane was developed via the interfacial polymerization (IP) between polyethyleneimine (PEI), piperazine (PIP), and cyanuric chloride (CC).     

Effect of nickel ion doping in MnO2/reduced graphene oxide nanocomposites for lithium adsorption and recovery from aqueous media

Novel and effective reduced graphene oxide–nickel (Ni) doped manganese oxide (RGO/Ni-MnO₂) adsorbents were fabricated via a hydrothermal approach. The reduction of graphite to graphene oxide (GO), formation of α-MnO₂, and decoration of Ni-MnO₂ onto the surface of reduced graphene oxide (RGO) were independently carried out by a hydrothermal technique. The physical and morphological properties of the as-synthesized adsorbents were analyzed. Batch adsorption experiments were performed to identify the lithium uptake capacities of adsorbents. The optimized parameters for Li⁺ adsorption investigated were pH = 12, dose loading = 0.1 g, Li⁺ initial concentration = 50 mg L⁻¹, in 10 h at 25 °C. It is noticeable that the highest adsorption of Li⁺ at optimized parameters are in the following order: RGO/Ni3-MnO₂ (63 mg g⁻¹) > RGO/Ni2-MnO₂ (56 mg g⁻¹) > RGO/Ni1-MnO₂ (52 mg g⁻¹). A Kinetic study revealed that the experimental data were best designated pseudo-second order for each adsorbent. Li⁺ desorption experiments were performed using HCl as an extracting agent. Furthermore, all adsorbents exhibit efficient regeneration ability and to some extent satisfying selectivity for Li⁺ recovery. Briefly, it can be concluded that among the fabricated adsorbents, the RGO/Ni3-MnO₂ exhibited the greatest potential for Li⁺ uptake from aqueous solutions as compared to others.

Novel and effective reduced graphene oxide–nickel (Ni) doped manganese oxide (RGO/Ni-MnO₂) adsorbents were fabricated via a hydrothermal approach for lithium adsorption and recovery from aqueous media.     

Reduced graphene oxide as a water,carbon dioxide and oxygen barrier in plasticized poly(vinyl chloride) films

Herein, we report the incorporation of a 10 μm thick reduced graphene oxide (RGO) barrier layer in a plasticized poly(vinyl chloride) (PVC) film as the main constituent in ion-selective membranes used in potentiometric solid-contact ion-selective electrodes (SCISE). Fourier transform infrared attenuated total reflection (FTIR-ATR) and oxygen transmission rate (OTR) measurements showed that the embedded RGO barrier efficiently impedes the diffusion of liquid water, carbon dioxide and oxygen (O₂) through the 400 μm thick PVC film, which causes potential instability and irreproducibility of the SCISEs. The measurements revealed that the RGO layer completely blocks the carbon dioxide diffusion, while it fully blocks the water diffusion for 16 h and reduced the OTR by 85% on average. The μm-thick RGO films used in this study were easier to handle and incorporate into host polymers, and form more efficient and robust barriers compared to the mono-, few- and multilayer graphene commonly applied as barrier layers for liquids and gases. We also demonstrated that the FTIR-ATR technique employed in the permeability measurements is a versatile and very sensitive technique for studying the diffusion of small amounts of water and carbon dioxide through graphene-based thin films.

A 10 μm-thick reduced graphene oxide barrier layer efficiently blocks water, carbon dioxide and oxygen diffusion through plasticized PVC.     

The synergistic influence of polyethyleneimine-grafted graphene oxide and iodide for the protection of steel in acidizing conditions

Herein, graphene oxide (GO) was chemically functionalized with polyethyleneimine (PEI) in a single step to obtain PEI-GO, which was characterized via FTIR spectroscopy, SEM, and TEM. Additionally, for the first time, PEI-GO was employed for the corrosion mitigation of carbon steel in a solution of 15% HCl. The corrosion performance of the inhibitor was evaluated by utilizing weight loss tests, electrochemical measurements with impedance analysis, electrochemical frequency modulation, and potentiodynamic polarization studies. Thorough surface analysis was performed using 3D profilometry and static water contact angle measurements. PEI-GO was adsorbed on the steel surface and showed mixed-type corrosion inhibition behavior with the prevalence of cathodic characteristics. Additionally, potassium iodide was incorporated in the acid solution as a synergistic agent to enhance the corrosion inhibition behavior of PEI-GO. The obtained results showed that PEI-GO alone provided a high corrosion inhibition efficiency of 88.24% at a temperature of 65 °C and in the presence of KI, it showed an I.E. of 95.77% due to their synergistic effect. These interesting results demonstrate that PEI-GO can act as a potential corrosion inhibitor in acidizing conditions. The DFT-based computational studies showed that the inhibitor functioned in both its neutral and protonated forms.

Herein, graphene oxide (GO) was chemically functionalized with polyethyleneimine (PEI) in a single step to obtain PEI-GO, which was characterized via FTIR spectroscopy, SEM, and TEM.     

Monometallic and bimetallic Cu–Ag MOF/MCM-41 composites: structural characterization and catalytic activity

Monometallic and bimetallic MOF/MCM-41 composites (Cu, Ag and Cu–Ag) were synthesized via a solvothermal method. The synthesized composites were characterized by XRD, FTIR, SEM, EDX and BET surface area measurements. The acidity was determined through two techniques; potentiometric titration with n-butyl amine for determining the strength and the total number of acid sites and FTIR spectra of chemisorbed pyridine on the surface of MOFs for determining the type of acid sites (Brønsted and/or Lewis). All the prepared MOFs showed Lewis-acid sites and the higher acidity was observed for the bimetallic Cu–Ag MOF/MCM-41 composite. The catalytic activity was examined on the synthesis of 1-amidoalkyl-2-naphthol via the reaction of benzaldehyde, 2-naphthol and benzamide. The best yield (92.86%) was obtained in the least time (10 min) with a molar ratio 1.2 : 1.2 : 1.7 of benzaldehyde : β-naphthol : benzamide and 0.1 g bimetallic Cu–Ag MOF/MCM-41 composite under solvent-free conditions at 130 °C. Reuse of the catalysts showed that they could be used at least four times without any reduction in the catalytic activity.

Monometallic and bimetallic MOF/MCM-41 composites (Cu, Ag and Cu–Ag) were synthesized via a solvothermal method.     

Synthesis of multifunctional CuFe2O4–reduced graphene oxide nanocomposite: an efficient magnetically separable catalyst as well as high performance supercapacitor and first-principles calculations of its electronic structures

Here, we report an ‘in situ’ co-precipitation reduction based synthetic methodology to prepare CuFe₂O₄ nanoparticle–reduced graphene oxide (CuFe₂O₄–RGO) nanocomposites. First principles calculations based on Density Functional Theory (DFT) were performed to obtain the electronic structures and properties of CuFe₂O₄, graphene and CuFe₂O₄–graphene composites, and to understand the interfacial interaction between CuFe₂O₄ and graphene in the composite. The synergistic effect, which resulted from the combination of the unique properties of RGO and CuFe₂O₄ nanoparticles, was exploited to design a magnetically separable catalyst and high performance supercapacitor. It has been demonstrated that the incorporation of RGO in the composite enhanced its catalytic properties as well as supercapacitance performance compared with pure CuFe₂O₄. The nanocomposite with 96 wt% CuFe₂O₄ and 4 wt% RGO (96CuFe₂O₄–4RGO) exhibited high catalytic efficiency towards (i) reduction of 4-nitrophenol to 4-aminophenol, and (ii) epoxidation of styrene to styrene oxide. For both of these reactions, the catalytic efficiency of 96CuFe₂O₄–4RGO was significantly higher than that of pure CuFe₂O₄. The easy magnetic separation of 96CuFe₂O₄–4RGO from the reaction mixture and good reusability of the recovered catalyst also showed here. 96CuFe₂O₄–4RGO also demonstrated better supercapacitance performance than pure CuFe₂O₄. 96CuFe₂O₄–4RGO showed specific capacitance of 797 F g⁻¹ at a current density of 2 A g⁻¹, along with ∼92% retention for up to 2000 cycles. To the best of our knowledge, this is the first investigation on the catalytic properties of CuFe₂O₄–RGO towards the reduction of 4-nitrophenol and the epoxidation reaction, and DFT calculations on the CuFe₂O₄–graphene composite have been reported.

Here, we report an ‘in situ’ co-precipitation reduction based synthetic methodology to prepare CuFe₂O₄ nanoparticle–reduced graphene oxide (CuFe₂O₄–RGO) nanocomposites.     

Hyperbranched polyamide modified graphene oxide-reinforced polyurethane nanocomposites with enhanced mechanical properties

As is well known, it is difficult to simultaneously improve both the strength and elongation at break of polymers filled with nanomaterials. This work obtained high-performance composites with enhanced strength and elongation at break via cross-linking hydroxyl-terminated polybutadiene (HTPB) chains with hyperbranched-polyamide-modified graphene oxide (HGO), and the preparation, characterization, and mechanical properties of the composites serving as a composite solid-propellant binder have been described in detail. Compared with pure HTPB polyurethane (P-HTPB), the tensile strength and elastic modulus of the composite containing 0.1 wt% HGO (H-0.1/HTPB) increase by 57.8% and 65.3%, respectively. Notably, the elongation at break of the H-0.1/HTPB composite can reach up to 1292.6%, which is even higher than that of P-HTPB. Moreover, the capabilities of the composites to resist deformation have also been enhanced significantly. The glass transition temperatures of the composites are still extremely low (∼−73 °C), which is beneficial for their applications. It can be expected that this study can provide an effective fabrication approach and strategy for preparing high-performance polyurethane composites.

We successfully modified graphene oxide with amino-terminated hyperbranched polyamide (HGO), and obtained a high-performance composite with enhanced strength and elongation at break via cross-linking hydroxyl-terminated polybutadiene chains with HGO.     

Reduced graphene oxide-mediated synthesis of Mn3O4 nanomaterials for an asymmetric supercapacitor cell

Herein, Mn₃O₄/reduced graphene oxide composites are prepared via a facile solution-phase method for supercapacitor application. Transmission electron microscopy results reveal the uniform distribution of Mn₃O₄ nanoparticles on graphene layers. The morphology of the Mn₃O₄ nanomaterial is changed by introducing the reduced graphene oxide during the preparation process. An asymmetric supercapacitor cell based on the Mn₃O₄/reduced graphene oxide composite with the weight ratio of 1 : 1 exhibits relatively superior charge storage properties with higher specific capacitance and larger energy density compared with those of pure reduced graphene oxide or Mn₃O₄. More importantly, the long-term stability of the composite with more than 90.3% capacitance retention after 10 000 cycles can ensure that the product is widely applied in energy storage devices.

The existence presence of rGO can affect the morphology of an Mn₃O₄/rGO composite, and the asymmetric supercapacitor cell created with this composite exhibits good capacitive performance.     

A novel positively charged composite nanofiltration membrane based on polyethyleneimine with a tunable active layer structure developed via interfacial polymerization

A novel positively charged composite nanofiltration (NF) membrane with tunable active layer structure was successfully developed via interfacial polymerization on a polysulfone (PSF) ultrafiltration (UF) membrane surface, using polyethyleneimine (PEI) as the monomer of the aqueous phase, and a mixture of isophthaloyl dichloride (IPC) and tri-mesoyl chloride (TMC) as the monomer of the organic phase. Interestingly, a synergetic effect of the mass ratio of IPC and TMC was observed on the pore size and the structure of the active layer of the resultant polyamide (PA)/polysulfone (PSF) composite NF membrane. The rejection (R) to the inorganic electrolytes increased with the mass ratio of IPC to TMC, while the permeate flux (F) escalated up to a 1 : 1 mixing ratio of IPC to TMC and dropped at higher mixing ratios. The rejection to different inorganic electrolytes decreased in the order of ZnCl₂, MgCl₂, CaCl₂, CuCl₂, MgSO₄, NaCl, and Na₂SO₄. At ambient temperature and 0.4 MPa, the optimized membrane demonstrated R and F to 1 g L⁻¹ MgCl₂ aqueous solution as 98.1% and 27.6 L m⁻² h⁻¹, respectively. Its rejection to various dyes reduced significantly in the order of cationic red X-GTL (100%), rhodamine B (94.2%), cationic gold yellow X-GL (93.5%), and brilliant blue KN-R (43.9%), in agreement with the decrease in the molecular weight (M_w) and the overall charges of the dye.

The tunable active layer structure was developed via interfacial polymerization, using polyethyleneimine as the monomer of the aqueous phase, and a mixture of isophthaloyl dichloride and tri-mesoyl chloride as the monomer of the organic phase.     

Fabrication of CS/GA/RGO/Pd composite hydrogels for highly efficient catalytic reduction of organic pollutants

In this study, natural polymer material chitosan (CS) and graphene oxide (GO) with large specific surface area were used to prepare a new CS/RGO-based composite hydrogel by using glutaraldehyde (GA) as cross-linking agent. In addition, a CS/GA/RGO/Pd composite hydrogel was prepared by loading palladium nanoparticles (Pd NPs). The morphologies and microstructures of the prepared hydrogels were characterized by SEM, TEM, XRD, TG, and BET. The catalytic performance of the CS/GA/RGO/Pd composite hydrogel was analyzed, and the experimental results showed that the CS/GA/RGO/Pd composite hydrogel had good catalytic performance for degradation of p-nitrophenol (4-NP) and o-nitroaniline (2-NA). Therefore, this study has potential application prospect in wastewater treatment and provides new information for composite hydrogel design.

New functional CS/GA/RGO/Pd composite hydrogels are prepared via a self-assembly process, demonstrating potential applications in catalysis as well as composite materials.     

Fabrication of a magnetic ternary ZnFe2O4/TiO2/RGO Z-scheme system with efficient photocatalytic activity and easy recyclability

A magnetic composite based on TiO₂ nanosheets, ZnFe₂O₄ and reduced graphene oxide (RGO) was synthesized by a one-step hydrothermal synthesis method, which possessed the band structure of a Z-scheme photocatalytic system. The properties and structures of the samples were characterized by XRD, UV-Vis DRS, Raman spectroscopy, SEM, EDS, XPS and PL spectroscopy. Compared with TiO₂ nanosheets and the TiO₂/RGO composite, the obtained ternary composite with 3 wt% RGO exhibited a significant enhancement in photocatalytic activities, attributed to the efficient charge separation induced by the fabricated Z-scheme system. About 99.7% of p-nitrophenol (p-NP) degraded within 60 min under simulated solar irradiation. Trapping experiments showed that superoxide anions (˙O₂⁻) and hydroxyl radicals (˙OH) were the main active species in the p-NP photocatalytic degradation. Finally, a possible photocatalytic mechanism of Z-scheme ZnFe₂O₄/TiO₂/RGO was proposed based on the results of trapping experiments and the energy bands of TiO₂ and ZnFe₂O₄.

A magnetic separable Z-scheme composite based on ZnFe₂O₄, TiO₂ nanosheets and RGO exhibits efficient photocatalytic degradation of p-NP.     

Influence of composition on the external quantum efficiency of reduced graphene oxide/carbon nanoparticle based photodetector used for human body IR detection

Here, we developed an efficient infrared (IR) detector comprising reduced graphene oxide (RGO) and carbon nanoparticles (CNPs) for detecting human body IR radiation under ambient conditions. The RGO/CNP nanocomposite thin-film based photodetectors were assembled via a simple solution-phase cost-effective route with different concentrations of RGO solution while keeping CNP concentration constant. Three RGO/CNP nanocomposite photodetector devices were fabricated with three different concentrations of RGO (keeping CNP concentration constant) and their photoresponse properties have been studied. The devices showed a sharp response to IR radiation emitted by the human body at room temperature having a wavelength of nearly 780 nm. I–V characteristics, radiation current responsivity, and time response curves as well as their external quantum efficiencies have been studied and explained. We measured two important parameters, namely, IR responsivity (R_λ) and external quantum efficiency (EQE) of RGO/CNP based IR detector devices. Our annotations show that R_λ and EQE increase with increasing concentration of GO in RGO/CNP nanocomposites as expected. This simple and inexpensive approach based on the integration of RGO and CNP could also be useful for the design of other potential optoelectronic devices such as photosensors for use in auto-doors to permit the entrance of human bodies only and in spaceships or robots to identify the existence of humans on Mars and the Moon.

We report an efficient infrared (IR) detector comprising reduced graphene oxide (RGO) and carbon nanoparticles (CNPs) for detecting human body IR radiation under ambient conditions.     

Optimization and characterization of magnetite–reduced graphene oxide nanocomposites for demulsification of crude oil in water emulsion

Oily wastewater from the oil and gas industry negatively affects the environment. Oily wastewater typically exists in the form of an oil-in-water emulsion. Conventional methods to treat oily wastewater have low separation efficiency and long separation time and use large equipment. Therefore, a simple but effective method must be developed to separate oil-in-water emulsions with high separation efficiency and short separation times. Magnetite–reduced graphene oxide (M–RGO) nanocomposites were used as a demulsifier in this work. Magnetite nanoparticles (Fe₃O₄) were coated on reduced graphene oxide (rGO) nanosheets via an in situ chemical synthesis method. The synthesized M–RGO nanocomposites are environmentally friendly and can be recovered after demulsification by an external magnetic field. M–RGO characterization was performed using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning microscopy, Raman spectroscopy, and vibrating sample magnetometry. Demulsification performance was evaluated in terms of M–RGO dosage, effects of pH, and brine concentration. The demulsification capability of M–RGO was determined based on the residual oil content of the emulsion, which was measured with a UV-vis spectrometer. The response surface method was used to determine the optimum conditions of the input variables. The optimum demulsification efficiency achieved at pH 4 and M–RGO dosage of 29 g L⁻¹ was approximately 96%. This finding demonstrates that M–RGO nanocomposites are potential magnetic demulsifiers for oily wastewater that contains oil-in-water emulsions. Also, the recyclability of this nanocomposite has been tested and the results shown that it is a good recyclable demulsifier.

Magnetite reduced graphene oxide were synthesized for separation of crude oil in water emulsion.     

A study on graphene composites for peripheral nerve injury repair under electrical stimulation

Electrical stimulation (ES) provides an effective alternative to peripheral nerve repair via conductive scaffolds. The aim of the present study is to investigate a graphene (GR)/thermoplastic polyurethane (TPU) composite for the repair of peripheral nerve injury under ES. To this end, conductive composite membranes were fabricated by blending GR (2, 4 and 6 wt%) with TPU. GR maintains its own structure in the composite and enhances the mechanical and electrical properties of the composite. The composites with excellent biocompatibility had a hemolysis rate of less than 5%. As a result, the 4GR–TPU (4 wt% GR) sample with enhanced mechanical properties possessed the highest conductivity value of 33.45 ± 0.78 S m⁻¹. Compared with the non-conductive sample, 4GR–TPU was favorable for the viability of Schwann cells (SCs) under ES. When different voltages of ES were applied, a direct current of 10 mV was more suitable for the growth and proliferation of SCs. This study provides beneficial information for peripheral nerve repair via ES.

Electrical stimulation (ES) provides an effective alternative to peripheral nerve repair via conductive scaffolds.     

One-pot mechanochemical exfoliation of graphite and in situ polymerization of aniline for the production of graphene/polyaniline composites for high-performance supercapacitors

Graphene/polyaniline composites have attracted considerable attention as high-performance supercapacitor electrode materials; however, there are still numerous challenges for their practical applications, such as the complex preparation process, high cost, and disequilibrium between energy density and power density. Herein, we report an efficient method to produce graphene/polyaniline composites via a one-pot ball-milling process, in which aniline molecules act as both the intercalator for the exfoliation of graphite and the monomer for mechanochemical polymerization into polyaniline clusters on the in situ exfoliated graphene sheets. The graphene/polyaniline composite electrode delivered a large specific capacitance of 886 F g⁻¹ at 5 mV s⁻¹ with a high retention of 73.4% at 100 mV s⁻¹. The high capacitance and rate capability of the graphene/polyaniline composite can contribute to the fast electron/ion transfer and dominantly capacitive contribution because of the synergistic effects between the conductive graphene and pseudocapacitive polyaniline. In addition, a high energy density of 40.9 W h kg⁻¹ was achieved by the graphene/polyaniline-based symmetric supercapacitor at a power density of 0.25 kW kg⁻¹, and the supercapacitor also maintained 89.1% of the initial capacitance over 10 000 cycles.

Efficient ball-milling production of graphene/polyaniline composites as supercapacitor electrodes with enhanced capacitive contribution, rate capability, and specific capacitance.     

Fabrication and characterization of a novel corn straw/modified ammonium lignosulfonate bio-composite strengthened by polyethylenimine pretreatment

This study focuses on the development of novel bio-composites via the pretreatment of corn straw particles (PCSP) and modified ammonium lignosulfonate (MAL) as a binder. The corn stalk particles (CSP) were pretreated with polyethylenimine (PEI) to enhance compatibility. The effects of PEI dosage on the mechanical properties and dimensional stability were examined, where PEI pretreatment improved the interfacial properties of MAL and CSP considerably. The optimum values of the PCSP/MAL composites complied with the Chinese national standard for load-bearing particleboard. Furthermore, the results confirmed that PEI pretreatment resulted in good surface activity and exhibited a favorable effect on the crystallinity of the PCSP/MAL composites. The storage moduli E′ and tan δ peak of the PCSP/MAL composites were considerably greater than those of the CSP/MAL composites. The fractured morphology of the composites clearly showed that PEI pretreatment improves the interfacial adhesion of MAL and CSP.

This study focuses on the development of novel bio-composites via the pretreatment of corn straw particles (PCSP) and modified ammonium lignosulfonate (MAL) as a binder.     

Investigation on the role of different conductive polymers in supercapacitors based on a zinc sulfide/reduced graphene oxide/conductive polymer ternary composite electrode

Conductive polymers, such as polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh) and poly 3,4-ethylenedioxythiophene (PEDOT), play an important role in the application of pseudocapacitors. It is necessary to explore the effects of different conductive polymers in electrode composites. Herein, we prepare zinc sulfide/reduced graphene oxide (ZnS/RGO) by the hydrothermal method, and conductive polymers (PANI, PPy, PTh and PEDOT) doped with the same mass ratio (polymer to 70 wt%) via in situ polymerization on the surface of ZnS/RGO composite. For the supercapacitor application, the ZnS/RGO/PANI ternary electrode composite possesses the best capacitance performance and cycle stability out of all of the polymer-coated ZnS/RGO composites. In the three-electrode system, the discharge specific capacitance and cycle stability of ZnS/RGO/PANI are 1045.3 F g⁻¹ and 160% at 1 A g⁻¹ after 1000 loops. In a two-electrode symmetric system, the discharge specific capacitance and cycle stability of ZnS/RGO/PANI are 722.0 F g⁻¹ and 76.1% at 1 A g⁻¹ after 1000 loops, and the greatest energy and power density of the ZnS/RGO/PANI electrode are 349.7 W h kg⁻¹ and 18.0 kW kg⁻¹. In addition, conductive polymers can effectively improve the voltage range of the electrode composites in 6 M KOH electrolyte for the two-electrode system. The discharge voltage ∼1.6 V makes them promising electrode materials for supercapacitors.

Conductive polymers, such as polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh) and poly 3,4-ethylenedioxythiophene (PEDOT), play an important role in the application of pseudocapacitors.