N-RGO Sheets Research Articles

Highly efficient nitrogen-doped reduced graphene oxide-Sr0.7Sm0.3Fe0.4Co0.6O2.65 nanocomposites utilized as a counter electrode in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) are known for their aesthetic properties, not limited to colour tuneability and transparency, but are also promising renewable energy technology that can efficiently harvest sunlight to generate electricity without releasing toxic gases. DSSCs are one of the potential candidates for fabricating colourful and see-through solar cells for energy-harvesting aesthetic windows. However, a trade-off between transparency and power conversion efficiency (PCE) has to be tackled amicably to realize solar cells with good PCE and transparency. Judicious selection of dyes to bypass light absorption in the high eye-sensitivity region (500 – 600 nm) is one of the plausible solutions. Most importantly, developing novel counter electrode materials using facile preparation techniques, low-cost materials, and environmentally friendly conditions helps overcome the limitations of commonly used but expensive and corroding metals, thereby improving the PCE of DSSCs. Herein, we report the synthesis of a novel hybrid nitrogen-doped reduced graphene oxide-Sr0.7Sm0.3Fe0.4Co0.6O2.65 (N-RGO-SSFC) nanocomposite using the thermal treatment method. The N-RGO-SSFC nanocomposites were characterized using microscopic and spectroscopic techniques and applied as counter electrodes in DSSCs. Scanning electron microscopy images revealed the presence of N-RGO sheets decorated by SSFC nanoparticles. The introduction of SSFC nanoparticles onto N-RGO sheets led to the formation of nanocomposites with a tetragonal structure, a surface area of 178.0 m2 g-1, an electrical conductivity of 13.02 S cm-1, and a charge transfer resistance of 10.6 Ω. The N-RGO-SSFC nanocomposite counter electrodes resulted in DSSCs with an enhanced PCE of 6.64% due to the formation of excellent electron transfer pathways. This outperformed DSSCs based on the Pt reference electrode with a PCE of 5.52%. Hence, N-RGO-SSFC nanocomposites can be applied as a potential counter-electrode material in DSSCs.

Synthesis of nitrogen-doped reduced graphene oxide/magnesium ferrite/polyaniline composite aerogel as a lightweight, broadband and efficient microwave absorber

The fabrication of graphene-based microwave absorbing materials with low density, small filling ratio, broad bandwidth and strong absorption remains a huge challenge. In this work, nitrogen-doped reduced graphene oxide/magnesium ferrite/polyaniline (NRGO/MgFe2O4/PANI) composite aerogel was synthesized by a three-step method of solvothermal reaction, in situ chemical oxidation polymerization and hydrothermal self-assembly. The results showed that the obtained aerogels had a unique three-dimensional (3D) porous network structure and low bulk density (11.1–13.0 mg cm−3). It was worth noting that in the NRGO/MgFe2O4/PANI ternary composite aerogel, MgFe2O4 coated with a thin PANI layer was anchored on the surface of NRGO sheets. Furthermore, the NRGO/MgFe2O4/PANI ternary composite aerogel showed much better microwave absorbing capacity compared with pure NRGO aerogel and NRGO/MgFe2O4 binary composite aerogel. When the filling ratio was as low as 11.5 wt.%, the obtained ternary composite aerogel exhibited the maximum effective absorption bandwidth of 7.0 GHz at a matching thickness of 2.1 mm, and the minimum reflection loss of -42.9 dB at a thickness of 3.57 mm. Additionally, the probable microwave dissipation mechanism was also elucidated. It was believed that this study would pave the way for the construction of 3D graphene-based composites as lightweight, broadband and efficient microwave absorbents.

Facile Hydrothermal Fabrication of an α-Ni(OH)2/N-Doped Reduced Graphene Oxide Nanohybrid as a High-Performance Anode Material for Lithium-Ion Batteries

Metal hydroxides are a kind of promising anode materials for lithium-ion batteries (LIBs) because of their large theoretical capacity, easy preparation, and low cost. However, their application has been restricted by cycling instability and slow kinetics arising from large volume variation and poor conductivity. Herein, a nanostructured α-Ni(OH)2/N-doped reduced graphene oxide (NrGO) hybrid is fabricated through a hydrothermal approach. This Ni(OH)2/NrGO hybrid exhibits high reversible capacity (1220 mA h g–1 at 0.2 A g–1), superior cyclability, and superb rate ability (559 mA h g–1 at 10 A g–1). The excellent electrochemical performance benefits from the hybrid nanostructure, which inhibits the agglomeration of active nanoparticles, exposes more electroactive sites, inhibits the restacking of NrGO sheets, and retains mechanical integrity during cycling. Besides, the highly conductive NrGO sheets provide efficient transport pathways for electrons and further enhance the electrochemical kinetics. When paired with the LiCoO2 cathode, this Ni(OH)2/NrGO hybrid displays a stable capacity in a full cell, demonstrating its promising practicability in LIBs.

Facile Synthesis Sandwich-Structured Ge/NrGO Nanocomposite as Anodes for High-Performance Lithium-Ion Batteries

This work aimed to design a facile preparation of sandwich-liked Ge nanoparticles/nitrogen-doped reduced graphene oxide (Ge/NrGO) nanocomposites used as anode in lithium-ion batteries through the chemical solution route. The advanced electron microscopy, STEM-HAADF and STEM-EDS mapping, evidenced that the individual Ge particles with sizes ranging from 5 to 20 nm were distributed and wrapped as sandwiches within the multi-layered NrGO sheets, which were mainly composed of the pyridinic-N form (4.8%wt.). The battery performances of the 20Ge/NrGO nanocomposite anode exhibit a high reversible capacity (700 mAh g−1) and retained its outstanding stability during long-term cycling. The internal resistance (28.0 Ω) was also decreased after cycling, according to EIS measurement. The sandwiched structure of Ge-based nanocomposite with the interconnected NrGO layers discussed in this article possessed the high-performance LIBs with great potential application in energy storage technologies.

One-pot hydrothermal synthesis of N-rGO supported Fe2O3 nanoparticles as a superior anode material for lithium-ion batteries

Fe2O3 nanoparticles with a diameter of 60–70 nm are uniformly grown on the surface of N-rGO sheets via a facile hydrothermal method to form two-dimensional hybrid nanostructures. When evaluated as an anode material for lithium-ion batteries, this Fe2O3/N-rGO composite exhibits outstanding lithium storage performance, with a high reversible capacity of 1398 mAh g−1 at 0.5 A g−1 after 200 cycles and 652 mAh g−1 at 15 A g−1. The excellent performance of the Fe2O3/N-rGO hybrid can be attributed to the N-rGO sheets that benefit the fast transport of both lithium ions and electrons during electrochemical reactions; besides, the well-dispersed Fe2O3 nanoparticles and the flexible N-rGO substrate could effectively release the volume effect of the Fe2O3 during discharge/charge processes. Due to the unique two-dimensional hybrid nanostructure, Fe2O3/N-rGO composite shows significant pseudocapacitive behavior during discharge/charge processes, which partially accounts for the excellent lithium ion storage performance.

Synthesis of ultralight three-dimensional nitrogen-doped reduced graphene oxide/multi-walled carbon nanotubes/zinc ferrite composite aerogel for highly efficient electromagnetic wave absorption

Developing light-weight, thin thickness and high-efficiency electromagnetic wave (EMW) absorbers was regarded as an effective strategy for dealing with the increasingly serious problem of electromagnetic radiation pollution. Herein, nitrogen-doped reduced graphene oxide/multi-walled carbon nanotubes/zinc ferrite (NRGO/MWCNTs/ZnFe2O4) composite aerogel was synthesized via solvothermal followed by hydrothermal and lyophilization processes. Morphological characterization results manifested that the attained ternary composite aerogel displayed unique three-dimensional porous netlike structure, which was composed of partial stack of adjacent NRGO sheets entangled by MWCNTs and decorated with ZnFe2O4 microspheres. Moreover, the influences of complexing with conductive MWCNTs and magnetic ZnFe2O4, and filler contents on the EMW attenuation performance of ternary composite aerogel were examined. Significantly, the ternary composite aerogel exhibited notably strengthened EMW absorption capacity in comparison with NRGO/MWCNTs composite aerogel, NRGO aerogel and ZnFe2O4 microspheres. The minimum reflection loss (RLmin) was up to −52.6 dB at a thin matching thickness of 1.7 mm and effective absorption bandwidth (EAB) was 5.1 GHz (12.7–17.8 GHz) under an ultrathin thickness of 1.65 mm with a low filler content of 10 wt%. Remarkably, the |SRLmin| (|specific RLmin value per thickness|) could achieve 30.9 dB/mm, which overwhelmed almost all the reported RGO-based composite aerogels. Besides, the possible EMW absorption mechanisms of as-synthesized ternary composite aerogel were proposed. It was believed that our results provided a valuable guidance for fabricating graphene-based composites with three-dimensional netlike structure as light-weight, thin thickness and high-performance EMW absorbers.

Synthesizing pyridinic-N dominate-doped graphene/BiVO4 nanocomposite as a superior photocatalyst for degradation under visible-irradiation

Abstract The disadvantage of bismuth vanadate (BiVO4), a metal oxide semiconductor photocatalytic material, can be overcome by constructing nitrogen-doped graphene-based nanocomposites. Here we state to synthesis pyridinic-N doped graphene/BiVO4 nanocomposite (N-rGO/BiVO4). Because of many defects were existed pyridinic N-rGO, more tiny particle size and interaction from abundant interfacial, between BiVO4 and N-rGO sheets, can produce synergistic effects and enhance photocatalytic performance. N-rGO/BiVO4 composite has a large light absorption range and high photocatalytic activity compared with BiVO4 and rGO/BiVO4. XPS, PXRD, HRTEM, FESEM, UV–vis, PL. etc analytical methods are used to characterize samples and the change of bandgap of samples is verified through theoretical analysis and simulation. After photocatalytic testing, the decomposition of methylene blue dye just required only 80 min under visible light and photocatalytic degradation efficiency of 99.3%. N-rGO/BiVO4 has great potential for the removal of refractory pollutants from wastewater.

Synthesis of nitrogen-doped reduced graphene oxide/cobalt-zinc ferrite composite aerogels with superior compression recovery and electromagnetic wave absorption performance.

Graphene aerogels possessing a three-dimensional (3D) porous netlike structure, good electrical conductivity and ultralow density have been widely regarded as a promising candidate for high-efficiency electromagnetic wave (EMW) absorption. Herein, nitrogen-doped reduced graphene oxide/cobalt-zinc ferrite (NRGO/Co0.5Zn0.5Fe2O4) composite aerogels were synthesized through a solvothermal and subsequent hydrothermal self-assembly two-step method. The results of micromorphology analysis showed that the 3D networks were well constructed through the partial stacking of adjacent NRGO sheets, which were decorated with numerous Co0.5Zn0.5Fe2O4 microspheres. The as-synthesized NRGO/Co0.5Zn0.5Fe2O4 composite aerogels have a very low density (12.1-14.6 mg cm-3) and good compression recovery. Moreover, excellent EMW absorption performance could be achieved through facilely regulating the additive volume of ethylenediamine (i.e. nitrogen doping contents) and filler contents. Impressively, the composite aerogel with a doped nitrogen content of 2.5 wt% displayed the optimal minimum reflection loss (RLmin) of -66.8 dB in the X-band at a thickness of 2.6 mm and the broadest effective absorption bandwidth of 5.0 GHz under an ultrathin thickness of merely 1.6 mm. Meanwhile, the RLmin of NRGO/Co0.5Zn0.5Fe2O4 composite aerogels below -20 dB could be reached in almost the whole tested thickness range (1.4-5.0 mm). Additionally, the potential EMW absorption mechanisms were revealed, which was mainly due to the unique 3D porous netlike structure, synergistic effects among conduction loss, magnetic resonance loss and polarization loss, as well as the balanced attenuation capacity and impedance matching. It was believed that this work provided an alternative way for fabricating strong mechanical graphene-based 3D magnetic/dielectric composites as light-weight and high-efficiency EMW absorbers.

Photodetector Based on Spontaneously Grown Strongly Coupled MAPbBr3/N-rGO Hybrids Showing Enhanced Performance.

Recently, metal-halide perovskites have emerged as a candidate for optoelectronic applications such as photodetectors. However, the poor device performance and instability have limited their future commercialization. Herein, we report the spontaneous growth of perovskite/N-rGO hybrid structures using a facile solution method and their applications for photodetectors. In the hybrid structures, perovskites were homogeneously wrapped by N-rGO sheets through strong hydrogen bonding. The strongly coupled N-rGOs facilitate the charge carrier transportation across the perovskite crystals but also distort the surface lattice of the perovskite creating a potential barrier for charge transfer. We optimize the addition of N-rGO in the hybrid structures to balance interfacial structural distortion and the intercrystal conductivity. High-performance photodetection up to 3 × 104 A/W, external quantum efficiency exceeding 105%, and detectivity up to 1012 Jones were achieved in the optimal device with the weight ratio between perovskites and N-rGO to be 8:1.5. The underlying mechanism behind the optimal N-rGO addition ratio in the hybrids has also been rationalized via time-resolved spectroscopic studies as a reference for future applications.

Cobalt nitride embedded holey N-doped graphene as advanced bifunctional electrocatalysts for Zn-Air batteries and overall water splitting

Exploration of cost-effective and highly durable carbon-based multifunctional electrocatalysts for energy conversion and storage devices (e.g., metal-air batteries) is of critical significance. Herein, we present a unique worm-like structure of hierarchically porous nitrogen-doped graphene (N-rGO) embedded with cobalt nitride (Co5.47N) nanoparticles (named as Co5.47N@N-rGO) by tannic acid assisted nitridation method for Zn-air batteries and overall water splitting. Benefiting from the unique worm-like structure to expose more active sites and the synergy advantages of a close contact between Co5.47N nanoparticles and the N-rGO sheets, the Co5.47N@N-rGO exhibits efficient bifunctional catalytic activities toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Notably, Zn-air batteries assembled with Co5.47N@N-rGO-750 show a power density of 120.7 mWcm−2 and excellent cycling stabilities for 330 h in an aqueous electrolyte. More interestingly, when assembled into a flexible solid-state rechargeable Zn-air battery, the Co5.47N@N-rGO-750 displays a specific capacity of 610 mAh gzn−1 and good cycling stability over 40 h. Moreover, the integrated device for water splitting powered by Zn-air batteries is also fabricated by using the Co5.47N@N-rGO-750 electrocatalyst, exhibiting a good gas generation rate. This work offers a new strategy to design and synthesize efficient multifunctional carbon-based electrocatalysts applied in electrochemical devices.

Facile synthesis of Pd/N-doped reduced graphene oxide via a moderate wet-chemical route for non-enzymatic electrochemical detection of estradiol

In this work, Pd-decorated N-doped reduced graphene oxide (Pd/N-RGO) was successfully synthesized by a simple wet-chemical method without using any capping agent and stabilizer. The synthesized Pd/N-RGO composite has been carefully characterized by various techniques. The X-ray photoelectron spectra provide the evidence of successful incorporation of N into the N-RGO sheets, while the presence of Pd nanoparticles with the sizes of 5–20 nm on the N-RGO sheets was confirmed by the transmission electron microscopy. By integrating the advantages of the large surface area of N-RGO sheets and good electron transfer efficiency of Pd nanoparticles, the Pd/N-RGO-based sensor shows an improved electrocatalytic activity toward the estradiol oxidation. Therefore, the Pd/N-RGO composite can be used as an effective sensing platform for the non-enzymatic detection of estradiol. It also demonstrates that the fabricated sensor has two linear concentration ranges (0.1–2 and 2–400 μM) and a low detection limit (1.8 nM) for the estradiol detection. Finally, the resulting sensor was successfully used to detect estradiol in some real samples and the satisfactory recoveries of 96.0–103.9% were obtained. The prepared Pd/N-RGO composite with more distinct merits including simple manufacture, preferable reproducibility and long-term stability can be a promising candidate for the advanced electrode material in sensing applications.

Facile synthesis of Ag@Cu2O heterogeneous nanocrystals decorated N-doped reduced graphene oxide with enhanced electrocatalytic activity for ultrasensitive detection of H2O2

A nanohybrid composed of Ag@Cu2O heterogeneous nanocrystals supported on N-doped reduced graphene oxide (Ag@Cu2O/N-RGO) has been synthesized by a simple wet-chemical method. The resultant composite consists of N-RGO sheets fully and homogeneously coated with a dense layer of Ag@Cu2O nanocrystals. Both Ag and N-RGO are in direct contact with Cu2O, and Ag nanoparticles with sizes of 2–5 nm are mainly deposited on the surface of Cu2O cubes (edge length of 500 nm). The electrochemical studies reveal that the ternary Ag@Cu2O/N-RGO composite exhibit significantly enhanced electrocatalytic activity for H2O2 sensing compared with either the single component (N-RGO) or two component systems (Cu2O/N-RGO and Ag/N-RGO), which is mainly due to the synergetic catalysis of the ternary system. The nonenzymatic sensor based on Ag@Cu2O/N-RGO composite shows overwhelmingly superior comprehensive performance for the H2O2 detection over the documented Ag-based sensors. More specifically, it displays a rapid response (10 s) to H2O2 over a wide linear range of 54–700 nM with a high sensitivity of 1298.3 μA mM−1 cm−2 and a low detection limit of 10 nM. Moreover, the sensor also exhibits the preferable selectivity in the presence of biologically coactive compounds accompanied with long-term stability and good reproducibility.

Enhanced shielding effectiveness in nanohybrids of graphene derivatives with Fe3O4 and ε-Fe3N in the X-band microwave region.

Novel nanocomposites of reduced graphene oxide (rGO)-Fe3O4, denoted as 'rGO:IO, and nitrogen doped rGO-ε-Fe3N, denoted as 'NrGO:IN', were prepared by a modified polyol method, wherein both the reduction of graphene oxide and oxidation of Fe2+/Fe3+ ions occurred simultaneously, followed by ammonia nitridation. The electron microscopy analysis of the rGO:IO and NrGO:IN nanocomposites revealed unique morphologies. In rGO:IO, the Fe3O4 nanoparticles having a mean diameter of 38 nm were found to be uniformly anchored to the rGO sheet surface, whereas in NrGO:IN, the ε-Fe3N nanoparticles (∼150 nm) were shielded by the NrGO sheets. Superparamagnetic and weak ferromagnetic characteristics with saturation magnetization values of 39.5 and 46 emu g-1 were observed in the rGO:IO and NrGO:IN nanocomposites respectively, which can be attributed to the nature of the constituent magnetic nanoparticles, Fe3O4 and ε-Fe3N. In addition, the graphene derivatives such as rGO and NrGO contributed to the enhanced electrical properties of the nanocomposite. The electrochemical impedance spectroscopy analysis showed that, compared to pure Fe3O4 and ε-Fe3N nanoparticles, the total electrical resistance of rGO:IO and NrGO:IN was reduced by 33 344.8 and 1569.87 Ω cm-2, respectively, when combined with the rGO and NrGO sheets. Further, the electromagnetic shielding performance of the NrGO:IN nanocomposite was investigated for the first time and was compared with the other samples. Of the two prepared nanocomposites, NrGO:IN exhibited electromagnetic shielding effectiveness of 35.33 dB at 11.4 GHz, which is considerably larger than that of rGO:IO (14.4 dB at 8 GHz). This enhanced shielding effectiveness is not only due to the high inherent magnetic and electrical properties of ε-Fe3N nanoparticles, but also due to the 'particle shielded by sheet' morphology of the NrGO:IN, which enhances the charge accumulation at the heterogeneous interfaces of NrGO sheets/ε-Fe3N nanoparticles.

Facile synthesis of Pd−Cu@Cu2O/N-RGO hybrid and its application for electrochemical detection of tryptophan

In this work, the N doping together with Pd−Cu@Cu2O hybridization for graphene oxide was achieved by a combined process of hydrothermal treatment and chemical reduction, based on which a novel Pd−Cu@Cu2O cubes decorated N-doped reduced graphene oxide (Pd−Cu@Cu2O/N-RGO) hybrid was obtained. The synthesized Pd−Cu@Cu2O/N-RGO was detailedly characterized by various technologies. The results show that the low Pd loading Cu@Cu2O cubes with the sizes of 300–500 nm are well dispersed on N-RGO sheets, thereby avoiding the serious aggregation and maintaining a large electroactive surface area of the attained hybrid. Benefiting from the synergistic effect of the properties of Pd−Cu@Cu2O particles and N-RGO sheets, the Pd−Cu@Cu2O/N-RGO modified electrode exhibits remarkable electrocatalytic performance on the oxidation of tryptophan with the enhanced oxidation response and the lowered oxidation overpotential. Under the optimal conditions for the electrochemical detection of tryptophan, the constructed sensor displays a wide linear range (0.01–40.0 μM) and a low detection limit (1.9 nM), outperforming most of the reported hybrid-based sensors. The proposed sensor also features good selectivity, stability and reproducibility, which has been successfully applied for the detection of tryptophan in the urine and milk samples with satisfactory recoveries. All these results suggest that the Pd−Cu@Cu2O/N-RGO hybrid could be a promising and convenient material for the fabrication of high-performance electrochemical sensors.

Synthesis of a nanocomposite consisting of Cu2O and N-doped reduced graphene oxide with enhanced electrocatalytic activity for amperometric determination of diethylstilbestrol

The authors report on a low temperature method for large-scale fabrication of cuprous oxide nanocubes deposited on nitrogen-doped reduced graphene oxide (Cu2O/N-RGO). The material was deposited in a glassy carbon electrode (GCE) where it is found to display enhanced electrocatalytic activity for oxidation of diethylstilbestrol (DES). The morphology and composition of Cu2O/N-RGO were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and energy-dispersive spectroscopy. The results demonstrate that the RGO is doped with 3.5% of nitrogen (atomic ratio), and that nanostructured Cu2O particles with controlled cubical morphology and an average size of about 450 nm have been homogeneously deposited on the surface of N-RGO sheets. The oxidation peak of DES was recorded at 0.315 V (vs. saturated calomel electrode) using differential pulse voltammetry. Under the optimal conditions, the modified GCE displays a linear response in the 0.3 to 150 μM DES concentration range, and the limit of detection is 10 nM. The method was applied to the determination of DES in spiked milk, meat and urine samples and gave excellent selectivity, stability and reproducibility.

A novel high-performance supercapacitor based on high-quality CeO2/nitrogen-doped reduced graphene oxide nanocomposite

In this work, we have developed a novel nanocomposite via deposition of ceria (CeO2) on nitrogen-doped reduced graphene (CeO2/NRGO). NRGO was synthesized through a facile, safe, and scalable method to achieve simultaneous thermal reduction along with nitrogen doping of graphene oxide (GO) in air at much lower reaction temperature. CeO2/NRGO was prepared via a sonochemical method in which ceria nanoparticles were uniformly distributed on NRGO sheets. The structure and morphology of CeO2/NRGO nanocomposites were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), and Raman spectroscopy. Electrochemical properties of the proposed nanocomposite electrodes were investigated by cyclic voltammetry (CV), galvanostatic charge/discharge, continuous cyclic voltammetry (CCV), and electrochemical impedance spectroscopy (EIS) measurements. CeO2–NRGO nanocomposite electrodes showed excellent supercapacitive behavior, including much higher specific capacitance (230 F g−1 at 2 mV s−1) and higher rate capability compared to pure N-graphene. The cycling stability of the electrodes was measured by continues cyclic voltammetry (CCV) technique. The CCV showed that the specific capacitance of the CeO2/NRGO and NRGO nanocomposite maintained at 94.1 and 93.2% after 4000 cycles. The results suggest its promising potential as efficient electrode material for supercapacitors.

Synthesis of anatase TiO2 with exposed (001) facets grown on N-doped reduced graphene oxide for enhanced hydrogen storage

Homogeneously distributed TiO2 nanoparticles with (001) reactive facets were grown over nitrogen-doped reduced graphene oxide sheets (N-rGO) under solvothermal conditions. Hydrogen storage capacity of the system was significantly improved to 0.91 wt% at room temperature and pressure of 0.8 MPa that is the highest hydrogen storage ever reported for graphene-based nanocomposites at room temperature and low pressures. Importantly, this nanocomposite exhibits ∼91% capacity retention through 5 cycles with more than 88% release of the stored hydrogen at ambient conditions. Enhanced hydrogen uptake and capacity retention were attributed to the synergistic effect of i) reactive facets of TiO2, ii) high dispersion of nanoparticles with the average size of 6 nm, and iii) strong interaction between substrate and TiO2 nanoparticles through polarized C–N bonding of N-rGO sheets.

An extremely facile route to Co@CoO/N-RGO/AB with an enhanced electrocatalytic activity for ORR

A novel Co@CoO/N-reduced graphene oxide (RGO)/acetylene black (AB) hybrid was synthesized via an extremely facile route. The Co@CoO particles with sizes of 20–40nm and the shell thickness of 5–10nm together with AB particles are well anchored on the wrinkled N-RGO sheets, which exhibits a remarkably higher electrocatalytic activity for oxygen reduction reaction than RGO, N-RGO, Co@CoO/RGO and Co@CoO/RGO/AB, and overwhelmingly superior methanol tolerance and long-term durability relative to the commercial 20wt% Pt/C.

Synthesis of a novel magnetite/nitrogen-doped reduced graphene oxide nanocomposite as high performance supercapacitor

In this research, magnetite/nitrogen-doped reduced graphene oxide (Fe3O4/NRGO) nanocomposites were synthesized through sonochemical route. The morphology and structure of the synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, field emission scanning electron microscopy (FE-SEM), and Raman spectroscopy. The synthesized nanocomposites display amorphous morphologies, with micro-mesoporous Fe3O4 particles that are uniformly distributed on the NRGO sheets. The electrochemical performance of nanocomposite-based electrodes were evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS) and continues cyclic voltammetry (CCV). The prepared nanocomposite-based electrodes showed superior supercapacitive performance including good rate capability, high specific capacitance, and excellent cyclic performance. The Fe3O4/NRGO nanocomposite electrodes exhibited specific capacitance of 355Fg−1 at scan rate of 2mVs−1 in 0.5M Na2SO4 electrolyte, indicating considerable improvement in supercapacitive performance compared with pristine Fe3O4 and magnetite/reduced graphene oxide (Fe3O4/RGO) electrodes. Moreover, in CCV measurements, excellent capacitance retention (97.1%) was also observed for Fe3O4/NRGO nanocomposite during 4000 continuous potential cycling. Therefore, the prepared nanocomposite has great potential as an electrode materials for supercapacitors.

Molybdenum Disulfide Nanosheets Interconnected Nitrogen-Doped Reduced Graphene Oxide Hydrogel: A High-Performance Heterostructure for Lithium-Ion Batteries

We demonstrate an efficient and large-scale synthesis approach of a novel heterostructure comprised of molybdenum disulfide (MoS2) and nitrogen-doped reduced graphene oxide (n-RGO) hydrogel (MoS2/n-RGO) via two-step hydrothermal process. Due to the strong molybdenum⿿nitrogen (Mo⿿N) bond, the n-RGO sheets are well interconnected to the MoS2 sheets and restacking of the two components is minimized. The hybrid possesses an open-pore structure, large surface area, and high nitrogen content. As an anode for lithium-ion batteries, the MoS2/n-RGO manifests a high specific capacity of 1140mA h g⿿1at the current density of 100mAg⿿1, which is higher than that of the MoS2/non-doped RGO (MoS2/RGO) counterpart. A remarkable rate capability and excellent electrochemical stability (94% retention after 130 cycles) is also achieved. Furthermore, the MoS2/n-RGO hybrid delivers a maximum energy density of 890 Wh kg⿿1 with the power density of 130Wkg⿿1. The superior electrochemical performance can be attributed to the durability and improved charge kinetics of the MoS2/n-RGO heterostructure owing to the nitrogen-doping effect. This study sheds light on the importance of a nitrogen-doped architecture in the creation of novel functional materials that can act as advanced electrodes for lithium-ion batteries.