Two-dimensional (2D) nanomaterials are categorized as a new class of microwave absorption (MA) materials owing to their high specific surface area and peculiar electronic properties. In this study, ...2D WS
-reduced graphene oxide (WS
-rGO) heterostructure nanosheets were synthesized via a facile hydrothermal process; moreover, their dielectric and MA properties were reported for the first time. Remarkably, the maximum reflection loss (RL) of the sample-wax composites containing 40 wt% WS
-rGO was - 41.5 dB at a thickness of 2.7 mm; furthermore, the bandwidth where RL < - 10 dB can reach up to 13.62 GHz (4.38-18 GHz). Synergistic mechanisms derived from the interfacial dielectric coupling and multiple-interface scattering after hybridization of WS
with rGO were discussed to explain the drastically enhanced microwave absorption performance. The results indicate these lightweight WS
-rGO nanosheets to be potential materials for practical electromagnetic wave-absorbing applications.
NiO nanostructure was synthesized using a simple co-precipitation method and was embedded on reduced graphene oxide surface via ultrasonication. Structural investigations were made through X-ray ...diffraction (XRD) and functional groups were confirmed by Fourier transform infrared spectroscopy (FTIR). XRD analysis revealed the grain size reduction with doping. Fourier transform infrared spectroscopy confirmed the presence of metal-oxygen bond in pristine and doped NiO nanostructure as well as the presence of carbon containing groups. Scanning electron microscopy (SEM) indicated that the particle size decreased when NiO nanostructure was doped with copper. BET surface area was found to increase almost up to 43 m2/g for Cu doped NiO nanostructure/rGO composite. Current-voltage measurements were performed using two probe method. UV–Visible spectroscopic profiles showed the blue and red shift for Cu doped NiO nanostructure and Cu doped NiO Nanostructure/rGO composite respectively. Rate constant for Cu doped NiO nanostructure/rGO composite found to increase 4.4 times than pristine NiO nanostructure.
•A simple one-step method was proposed to synthesize S, N dual doped reduced graphene oxide.•Doping generates abundant active sites for oxygen reduction reaction (ORR).•This catalyst promotes both ...the 2- and 4-electron ORR processes.•The catalyst shows good activity, stability, and anti-tolerance toward methanol.
The commercial application of oxygen reduction reaction (ORR) technology challenges the development of new electrocatalysts with excellent performance, high stability and low cost. Non-metallic materials, especially graphene-based catalysts, have become potential electrocatalysts for ORR due to their source richness and good stability. Here, we report a simple one-step hydrothermal method to synthesize S, N dual-element doped reduced graphene oxide (S, N-rGO) for ORR using graphene oxide as carbon source, thiourea as both sulfur-nitrogen source and reducing agent. The ORR performance is effectively enhanced by heteroatoms doping that increases the active sites of edge defects, introduces new S and N active sites, and adjusts the electronic structure of rGO. The 0.05-S, N-rGO catalyst shows the optimal ORR activity under alkaline conditions with the onset potential of 0.793 V vs RHE, good stability and anti-tolerance toward methanol. The calculated electron transfer number of about 3.1 ± 0.1 suggests that both the two-electron and four-electron processes occur on the catalyst.
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•A nanofibrous membrane was prepared for contaminated water purification.•The membrane is based on reduced graphene and aromatic polymer.•The membrane can maintain the properties ...under multi-kinds external stimulations.•The membrane is suitable for recycled test without compromising the performance.•This material has great potential to be used at industrial level.
This work proposes an anti-corrosive nanofibrous membrane by combining one-pot solvothermal reduction method and electrospinning technology as a solution to the ever-increasing water pollution issues. Such membrane is made of aromatic polymer-polyimide and further modified by reduced graphene oxide, which maintained the original performance under different external environment and multi-cycled test, and achieved high separation efficiency (99.19%) and flux (2040.04 L m-2h−1) at the same time. The purification process is suitable for various contaminants and different combinations. Additionally, the inherent purification mechanism was fully explored in this study. The practicability of the membrane can be tested for the contaminated water purification, the recycle of poisonous and harmful substances, pre-process of precision extraction and so on.
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•Dopamine is used as a joint agent to closely combine MXene and RGO to improve the stability of the layered complex.•RGO/PDA/MXene composite membrane has a significant rejection rate ...of pollutants.•The film can remove dyes with different properties.•The membrane still maintains good stability under extreme pH conditions.•The membrane has excellent cycle performance.
Titanium carbide (MXene) sheet membranes have become attractive candidates in terms of solvent nanofiltration performance. Whereas, the low contaminant removal ability limited the practical application of MXene membranes in efficient separation. Here, the reduced graphene oxide (RGO)/polydopamine (PDA)/titanium carbide (MXene) composites were prepared by dopamine modification method. Then, the RGO/PDA/MXene composites were suction filtrated on a nylon membrane to construct the two-dimensional-two-dimensional (2D-2D) laminated composite membrane. The effects of MXene content on the surface hydrophilicity, dye retention and oil-water separation properties of the modified membrane were systematically studied. Among them, the RPM-8 membrane exhibited ultra-high separation effect (>96%) and excellent throughput (>200 L/m2·h) for Methylene Blue (MB), Methyl Orange (MO), Methyl Red (MR), Congo Red (CO) and Evans Blue (EB). At the same time, the modified membrane shows very high oil-water separation effect on the emulsion (>97%). In addition, long-term cycle experiments have also revealed the stability of RGO/PDA/MXene composite membranes. The above results further illustrated the importance of the regular straight rigid channels of the composite membrane in separation performance. Therefore, RGO/PDA/MXene composite membrane has tremendous potential in practical applications.
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•β-CD/rGO was synthesized using a one-step hydrothermal reduction.•The mechanism used for synthesis of the β-CD/rGO is described in detail.•β-CD/rGO adsorbed naproxen well and could ...be regenerated in aquatic solutions.•Adsorption occurred via chemisorption and was endothermic.•Mechanisms of adsorption included host-guest interactions, hydrogen bonding, and π-π interactions.
In this study, a one-step hydrothermal method synthesized β-cyclodextrin-immobilized reduced graphene oxide composite (β-CD/rGO) was employed to remove naproxen from aquatic environments. The β-CD/rGO had a porous structure with abundant hydroxyl groups, and acetalization between the β-CD and rGO provided a more stable three-dimensional structure. The maximum equilibrium adsorption capacity of naproxen on β-CD/rGO at 313 K was 361.85 mg g−1. The adsorption of naproxen onto the β-CD/rGO fit well with the pseudo-second-order kinetics and the Langmuir adsorption model. The ΔH was higher than 40 kJ mol−1, which indicated that this adsorption was chemisorptive and endothermic. Host-guest interaction, hydrogen bonding, and π-π interactions were uncovered as three main mechanisms involved in binding between naproxen and the β-CD/rGO. Moreover, used β-CD/rGO could be regenerated with ethanol, making this an attractive method for naproxen adsorption in aquatic environments.
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•2D-RGO was anchored on the surface of SnO2 to extend the absorption to visible region.•The enhanced photocatalytic activity of RGO-SnO2 can be attributed to the vectorial electron ...transfer process.•Synergistic interaction between RGO and SnO2 provides channels for the movement of electrons.•The photoresponse of RGO-SnO2 is found to be excellent under both UV and visible light irradiation.
2 dimensional-reduced graphene oxide (RGO) was anchored on the surface of tin oxide (SnO2) to extend the absorption to visible region. Rutile structure is confirmed for SnO2 and RGO-SnO2. Partial reduction of graphene oxide to RGO is confirmed by infrared and Raman spectroscopic techniques. RGO-SnO2 shows 30% reduced recombination of charge carriers. The enhanced photocatalytic activity of RGO-SnO2 can be attributed to vectorial electron transfer process in the continuous network of RGO with large specific surface area, synergistic interaction between RGO and SnO2, unique double layer characteristics and photosensitization process. Major photocatalytic degradation reaction intermediates were identified by GC-MS technique.
In this study, tin dioxide with vacancies (SnOx) was compounded with three-dimensional reduced graphene oxide (3D RGO) to obtain SnOx/3D RGO. The morphology, optical properties and structural ...composition of SnOx/3D RGO were analyzed by a series of techniques, and the photoconductive properties of the SnOx/3D RGO composites with different mass fractions of RGO were investigated. The photocurrent density of SnOx/3D RGO at 3D RGO mass fraction of 1.5 % reached a maximum value of 2.77 × 10−4 A/cm2, which was about twice and 1.2 times as large as that of SnOx and SnOx/2D RGO (two-dimensional reduced graphene oxide), respectively. In the linear scanning voltammetry and Mott-Schottky analysis results, SnOx/3D RGO exhibited the highest photocurrent (6.34 × 10−3 A/cm2) intensity at 1.0 V bias and the largest carrier density (2.61 × 1021cm−3). This was due to the fact that RGO played a charge transfer role in the composite material in both 2D and 3D structures. In contrast, the porous 3D RGO could connect separate lamellae, which prevented the aggregation of layers and enhanced the electron transfer, thus exhibiting superior performance than 2D graphene.
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