N-doped rGO Research Articles

Plasma-induced, N-doped, and reduced graphene oxide–incorporated NiCo–layered double hydroxide nanowires as a high-capacity redox mediator for sustainable decoupled water electrolysis

Although the recent emergence of decoupled water electrolysis prevents typical H2/O2 mixing, the further development of decoupled water electrolysis has been confined by the lack of reliable redox mediator (RM) electrodes to support sustainable H2 production. As energy storage electrodes, layered double hydroxides (LDHs) possess inherently poor conductivity/stability, which can be improved by growing LDHs on graphene substrates in situ. The proper modification of the graphene surface structure can improve the electron transport and energy storage capacity of composite electrodes, while current methods are usually cumbersome and require high temperatures/chemical reagents. Therefore, in this study, dip coating was adopted to grow graphene oxide (GO) on nickel foam (NF). Then, the GO was reduced using nonthermal plasma (NTP) to reduced GO (rGO) in situ while simultaneously implementing N doping to obtain plasma-assisted N-doped rGO on NF (PNrGO/NF). The uniform conductive substrate ensured the subsequent growth of less-aggregated NiCo-LDH nanowires, which improved the conductivity and energy storage capacity (5.93 C/cm2 at 5 mA/cm2) of the NiCo-LDH@PNrGO/NF. For the decoupled system, the composite RM electrode exhibited a high buffering capacity for 1300 s during the decoupled H2/O2 evolution, and in the conventional coupled system, the necessary input voltage of 1.67 V was separated into two lower ones, 1.42/0.33 V for H2/O2 evolutions, respectively. Simultaneously, the RM possessed outstanding redox reversibility and structural stability during long-term cycling. This work could offer a feasible strategy for using NTP to synthesize excellent RM electrodes for application to decoupled water electrolysis.

Ultrasmall Pt/Nanoceria Hybrids Supported on N-Doped rGO as Electrocatalyst for the Hydrogen Evolution Reaction

Ultrasmall Pt/Nanoceria Hybrids Supported on N-Doped rGO as Electrocatalyst for the Hydrogen Evolution Reaction

Three-dimensional N-doped graphene coated with B-doped iron phosphide electrocatalysts: Nonmetallic element co-modification for enhanced dual-pH hydrogen evolution reaction

The construction of cost-effective and highly active transition metal phosphide-based electrocatalysts instead of noble metals through a feasible strategy is crucial for addressing the energy crisis. Herein, a novel three-dimensional structure N-doped RGO coated with a ‘worm-like’ B-doped FeP electrocatalyst (B-FeP/N-RGO) was successfully developed using a multi-step reaction. The composite catalyst possesses a unique three-dimensional structure that facilitates rapid mass transfer, gas release and exposure of abundant active sites, and non-metallic element doping optimizes the electronic structure of the matrix, which together improve the hydrogen evolution reaction performance. Notably, the B-FeP/N-RGO catalysts can achieve a current density of 10 mA cm−2 in both acidic and alkaline electrolytes with overpotentials of only 125 and 176 mV, while maintaining long-term stability. This study offers a promising approach for designing and fabricating highly efficient three-dimensional electrocatalysts that do not rely on noble-metals and are suitable for a wide pH range.

Facile fabrication of mesoporous SnO2@N-rGO nanocomposites by electrostatic self-assembly as anode for high performance lithium-ion batteries

Tin dioxide (SnO2) have been considered to be a promising anode material for high performance lithium-ion batteries (LIBs) due to its high lithium storage capacity of as high as 1494 mAh g−1, which has been impeded greatly due to its large volumetric expansion and low conductivity. Thus, the simple but effective approach for the fabrication of SnO2-based material is ever-urgent. To this end, the mesoporous SnO2@N-rGO nanocomposites were designed and fabricated by a simple and scalable electrostatic self-assembly method and investigated electrochemically as anode for LIBs. The results show that the as-obtained mesoporous SnO2@N-rGO nanocomposites exhibit an excellent cycling stability and outstanding rate capability after an initial activation due to the formation of SEI layer on the surface, which are mainly ascribed to the synergistic effect of nano-SnO2, high conductive N-doped rGO matrix network and rich mesopores. Therefore, this work offers an ingenious strategy to design and fabricate the SnO2-based anode material for high performance lithium-ion batteries.

Electrochemical performance of ZnxCo3-xO4/N-doped rGO nanocomposites for energy storage application

In this study, nanocomposites consisting of zinc-doped cobalt oxides with a spinel structure and nitrogen-doped reduced graphene oxide (ZnxCo3-xO4 (x = 0 and 1))/N-doped rGO) were synthesized using a solvothermal method. The synthesized materials were investigated using XRD, TEM, EDS, BET, Raman, and XPS for their phase formation, morphology, elemental composition, surface area, and chemical states. XRD analysis revealed that the metal oxides (Co3O4 and ZnCo2O4) present in the composites exhibited a single-phase cubic spinel structure, with a nanocrystalline nature and crystallite size ranging from 8 nm to 20 nm. Raman and TEM analyses revealed the co-existence of metal oxide nanoparticles and N-doped rGO phases in the composites. Electrodes were fabricated using the synthesized nanocomposite materials and subjected to electrochemical testing, including CV, GCD and EIS. The specific capacitiance (Cs) of samples determined to be 181 F/g and 234 F/g for CO/NrGO (Co3O4/N-doped rGO) and ZCO/NrGO (ZnCo2O4/N-doped rGO) nanocomposites, respectively, at lower current density (0.5 A/g). At all current densities, the CS of ZCO/NrGO nanocomposite electrode is observed to be higher than the CO/NrGO nanocomposite, probably due to structural defects and uniform anchoring of ZnCo2O4 particles over the layers of NrGO. The ZCO/NrGO composite electrode exhibits ∽86 % capacitance retention after 3000 cycles.

Design of S-scheme Sm-ZnO/N-rGO heterosystem for efficient H2 evolution under visible light illumination

Increasing the separation and transfer of photo-triggered electron-hole pairs is critical for developing a photocatalyst with excellent efficiency for hydrogen evolution reaction. Herein, an efficient and stable S-scheme Sm-ZnO/N-rGO heterosystem is successfully synthesized via a hydrothermal process for increased photocatalytic H2 activity. The anchoring of Sm-doped ZnO nanoparticles onto N-doped rGO nanosheets effectively enhances the light absorption, surface area, and transport and separation of photo-triggered carriers with strong redox potentials owing to the combined impact of doping and heterosystem formation. Upon light illumination, the photocatalytic hydrogen evolution performance over Sm-ZnO/N-rGO reaches 2361.8 μmolh-1g-1, which was significantly higher than that of Sm-ZnO and ZnO/N-rGO catalysts by a factor 5.5 and 2.9, respectively. In addition, the optimized composite shows high stability after five repetitive cycles. This research provides a feasible route to use the synergistic effect of doping and heterojunction for designing outstanding photocatalysts and further verifies the potentiality of ZnO for photocatalysis.

Gold nanoparticles supported on alumina grafted N-doped RGO: A green catalyst for the catalytic degradation of organic dyes and deprotection of oximes

An environmentally benign synthetic protocol for the preparation of gold supported N-doped TRGO-modified γ-alumina has been reported. The research focused on the use of different strategies for reduction of GO using natural as well as chemical reducing agents. Fresh tulsi and neem leaf extract were used for bio-reduction of GO, while hydrazine hydrate and sodium borohydride were used for the chemical reduction of GO to obtain RGO. The preliminary analysis from FT-IR and BET surface area authenticated that tulsi leaf extract was the best reducing agent among others for the preparation of RGO. TRGO (tulsi leaf extract reduced graphene oxide) obtained from the reduction of GO via tulsi leaf extract was doped with nitrogen to get N-doped TRGO followed by grafting with γ-Al2O3 and immobilization of Au NPs to get the desired catalyst. The developed catalyst was later examined via different characterization techniques. Further, the synthesized catalyst shows great potential for application in degradation of various dyes and oxidative deprotection of oximes. Nitrogen doping as well as the higher specific surface area of the catalyst were two key parameters influencing the higher catalytic performance of Au@NTRGO-γ-Al2O3. The rational strategy exhibited in the present work provides new insights into the development of green, efficient and sustainable catalysts for different organic transformations.

1T–2H MoSe2/N-doped rGO composites as anodes for high performance lithium-ion batteries

1T-2H MoSe2/N-doped rGO nanocomposites are fabricated by a hydrothermal method. The MoSe2 nanosheets are anchored on nitrogen-doped graphene. The MoSe2/N-doped rGO delivers high reversible capacity and long cycling stability as a potential anode for lithium-ion batteries.

Rational design of Ce-doped CdS/N-rGO photocatalyst enhanced interfacial charges transfer for high effective degradation of tetracycline

The charge carrier separation efficiency and the adsorption capacity of the photocatalyst usually affect the degradation rate of antibiotics. Herein, Cerium-doped leaf-like CdS (Ce-CdS) modified with ultrathin N-doped rGO (N-rGO) composites were successfully constructed (Ce-CdS/N-rGO) to investigate the removal efficiency of tetracycline (TC). X-ray photoelectron spectroscopy (XPS) and photoelectrochemical results revealed that Ce ions doped in CdS acting as the electron capture sites facilitated the interfacial charge transfer. Theoretical calculation (DFT) results indicated that the interfacial effect between Ce-CdS and ultrathin N-rGO promoted the transfer of photogenerated electrons under the synergistic effect between the doping and interface modification strategy. The optimized Ce5-CdS/N-rGO20 composites had the maximum TC removal capability (94.5%) and maintained a stable cycling performance. In addition, the adsorption-driven photocatalytic degradation pathway of TC was studied through mass spectrometry (MS) and in-situ Fourier transform infrared spectroscopy (in-situ FTIR). This study will provide an effective strategy for the construction of efficient photocatalytic composites for wastewater treatment.

Nitrogen doped reduced graphene oxide: Investigations on electronic properties using X-ray and Ultra-violet photoelectron spectroscopy and field electron emission behaviour

The practice of heteroatom doping has been proven to significantly enhance the intrinsic properties of host materials. A facile, one-step process due to the thermal reduction of ammonium hydroxide-treated graphene oxide (GO) was employed to yield nitrogen (N) doped reduced graphene oxide (rGO). In-depth characterization has been performed to reveal the phase, structure, morphology, and electronic properties of as-synthesized products. It is observed that the processing temperature noticeably affects the concentration and type of doped N species. The N-doped rGO (N-rGO) prepared at 900 ℃ exhibited excellent field electron emission (FEE) performance with relatively lower values of turn-on and threshold fields ∼ 1.28 and 1.52 V/µm, defined at emission current densities of 10 and 100 µA/cm2, respectively. Furthermore, a high current density of 5.83 mA/cm2 was drawn at an applied field of 2.51 V/µm, and the emitter showed equitably current stability tested at 10 µA. The obtained results promote the N-rGO emitter, with tuned concentrations of doped N-species, as a promising candidate for practical applications in various vacuum microelectronic devices.

Modulating the electronic structure of MoS2/NiS2 by functionalizing it over the N-doped reduced GO to improvise the catalytic hydrogen evolution

Metal chalcogenides are an inexpensive and abundantly available candidate for catalytic applications. MoS2 is one among the promising material that has been widely accepted for efficiently facilitating hydrogen evolution reaction (HER) due to the existence of rich edge active sites. However, aggregation of nanoparticles limits their electrochemical activities. Thus, to enhance the catalytic behaviour, functionalization with NiS2 and rGO is established so that the number of active sites for H absorption will be increased. Further, the heteroatom doping on the pristine rGO alters the electronic structure and facilitate HER. Consequently, MoS2/NiS2 functionalized N-doped rGO as an electrocatalyst manifested superior activity in catalyzing hydrogen evolution. An overpotential of about 164 mV for a current density (10 mA cm−2) in an acidic medium has proven the potential of the novel candidate to be highly promising. The same catalyst also displayed good stability for a longer time period of HER activity with no degradation of the catalyst. These findings affirm that MoS2/NiS2@N- doped rGO electrocatalyst is a promising candidate for hydrogen production using water electrolyzer.

Heterogeneous interface engineering of high-density MOFs-derived Co nanoparticles anchored on N-doped RGO toward wide-frequency electromagnetic wave absorption

Facing increasing electromagnetic (EM) wave pollution and interference issues, developing synergy EM wave absorption materials with rich heterogeneous interfaces is s an effective way to solve the above problems. In this work, two-dimensional (2D) cobalt-based metal-organic frameworks (Co-MOFs) nanosheets arrays are firstly growth on the 2D graphene oxide (GO) sheets. After undergoing the pyrolytic treatment in the N2 atmosphere, high-density MOFs-derived 0D Co nanoparticles (NPs) uniformly anchored on the Nitrogen-doped reduced graphene oxide (N-RGO), constructing 0D/2D magnetic-dielectric Co@N-RGO composites. By tuning the size of magnetic Co NPs by controlling the content of Co-MOFs nanosheets, the EM parameters and impedance match of Co@N-RGO sheets can be regulated to tune the EM wave absorption ability. Benefited from the synergy loss and high-density heterogeneous interfaces, obtained Co@N-RGO sheets exhibit excellent EM wave absorption intensity and tuning absorption frequency. The effective absorption bandwidth of the Co@N-RGO sheets ups to 6.0 GHz at 1.9 mm thickness, covering the entire Ku band (12–18 GHz). It can be concluded that constructing magnetic-dielectric system and high-density heterogeneous interfaces provides a new guide to obtain wide-frequency EM wave absorption materials.

Visible-light-driven photocatalytic activity of NiFe2O4@Ti-doped ZnO magnetically separable nanoparticles anchored on N-doped rGO nanosheets

Visible-light-driven photocatalytic activity of NiFe2O4@Ti-doped ZnO magnetically separable nanoparticles anchored on N-doped rGO nanosheets

Three-dimensional nitrogen-doped rGO-siloxene nanocomposite anode for Li-ion storage

In this work, we synthesize a 3D nitrogen-doped rGO (NrGO)-siloxene aerogel nanocomposite using a simple and low-cost hydrothermal process and demonstrate its use as an anode material for lithium-ion storage. The meso-macroporous structure of the N-doped rGO (NrGO) aerogel enhances the electrical conductivity and accommodates the volume expansion of siloxene sheets during cycling. Thereby, the NrGO-siloxene (NGSil) composite shows improved kinetics and structural stability resulting in an excellent reversible discharge capacity of 472.07 mA h g−1 at 0.1 A g−1, which is higher than those of the hydrothermally treated siloxene (HT-Sil, 31.59 mA h g−1) and the undoped rGO-siloxene (GSil, 296.33 mA h g−1). Moreover, the NGSil composite exhibits a good rate performance (177 mA h g−1 at 6 A g−1), and excellent long-term cycling stability (243.12 mA h g−1 after 1000 cycles) with a steady coulombic efficiency of 99.5% at 1 A g−1.

Highly sensitive and extremely durable wearable e-textiles of graphene/carbon nanotube hybrid for cardiorespiratory monitoring

Electroconductive textile yarns are of particular interest for their use as flexible and wearable sensors without compromising the properties and comfort of usual textiles. However, the detection of fine actions of the human body is quite challenging since it requires both the relatively higher sensitivity and stability of the sensor. Herein, highly sensitive, ultra-stable, and extremely durable piezoresistive wearable sensors were prepared by loading N-doped rGO and polydopamine-coated carbon nanotubes into silicon rubber tube. The wearable sensors thus produced show an excellent ability to sense subtle movement or stimuli with good sensitivity and repeatability. Furthermore, by bending the straight conductive silicon rubber tube (CSRT) into three different patterns, its sensitivity was then dramatically increased. Finally, the CSRT was found capable of sensing cardiorespiratory signals, indicating that the sensor would be an important step toward realizing bio-signal sensing for next-generation personalized health care applications.

Scalable production of reduced graphene oxide via biowaste valorisation: an efficient oxygen reduction reaction towards metal-free electrocatalysis

The development of environment-friendly, scalable, and low-cost electrocatalysts for an efficient ORR is important for green energy harvesting. This article deals with the scalable production of N-doped rGO for demonstrating better ORR activity.

Binary Co9S8–NiCo2S4 anchored on N-doped rGO backbone as an efficient bifunctional and durable hetero-catalyst for overall water-splitting in alkaline medium

A schematic illustration depicting the electrochemical water splitting by Co9S8–NiCo2S4/N-rGO heterocatalyst.

Bio-inspired micro-reactor mimicking multi-ridged mitochondrial intimae for efficient oxygen reduction

Fe3C embedded N-doped hollow rGO carbon spheres (Fe/N-HRCS) with multi-layered porous multi-ridged structure have been constructed as micro-reactors mimicking mitochondrial intimae. It is the first report on the application of a multi-layered porous hollow multi-ridged structure in oxygen reduction reaction (ORR) catalysis. Notably, the content of sacrificial template, silica nanoparticles, plays a decisive role on the microscopic morphology of micro-reactors. The optimal electrocatalyst, Fe/N-HRCS-1, exhibits a remarkable catalytic performance toward ORR with the onset potential of 1.03 V and half-wave potential of 0.88 V, which are comparable to that of commercial Pt/C. Such an extraordinary activity can be attributed to the synergistic effect between Fe3C nanoparticles embedded N-doped rGO layers and the distinctive bio-inspired structure. Moreover, the Fe/N-HRCS-1 catalyst also possesses superior methanol tolerance and durability, and thus holds a good promise for practical application. This work demonstrates a good example to design nature-inspired structures for high-efficiency non-noble metal electrocatalysts.

Energy Storage Performance of Nitrogen Doped Reduced Graphene Oxide/Co-Doped Polyaniline Nanocomposites

The design and exploration of carbon-based electrode materials have become highly significant for developing supercapacitor technology, which has attracted considerable attention in energy storage systems. Here, nitrogen-doped reduced graphene oxide (N-rGO) – Polyaniline (PANI) nanocomposites were synthesized by a facile two-step method in which in situ polymerization of aniline monomer was performed on hydrothermally synthesized N-rGO nanosheets in DBSA and H2SO4 medium for co-doping of PANI chains. The effects of various acid concentrations (DBSA:H2SO4 0.5 − 0.25:1 n/n) and N-rGO:aniline ratios (N-rGO:aniline 1:4–10 m/m) used in the preparation of the electrode material on the capacitive properties were investigated. It is found that the co-doped N-rGO-PANI nanocomposites exhibit a high specific capacitance of 346.3 F g− 1 at 1 A g− 1, remarkable rate capacity (99.9%, 1–10 A g− 1) and excellent cycle stability at 5 A g− 1 (81.3%, 5000 cycles) in a two-electrode system. As a result, constructing co-doped PANI chains and N-doped rGO provided a viable and simple way to improve the capacitive performances of supercapacitors.

Hollow spherical NiFe-MOF derivative and N-doped rGO composites towards the tunable wideband electromagnetic wave absorption: Experimental and theoretical study

N-doped rGO (N-rGO) based nano materials are considered to be competent candidates for absorbing electromagnetic waves (EMWs), owing to the low filler loading and abundant relaxation polarization losses. With a unique multistage porous structure, NiFe@N–C/rGO, derived from the composite of NiFe-MOF anchoring on GO nanosheeets, was successfully constructed by a facile solvothermal method and high-temperature annealing technique. Adjusting the ratio of GO is an effective strategy to optimize the EMWs absorption performance to a large extent. At a filler loading of 20 wt%, when the content of graphene is 30 mg, the corresponding product NiFe@N–C/rGO-30 is found to have a minimum reflection loss (RLmin) of −72.28 dB at 10.82 GHz, and an effective absorption bandwidth (EAB, RL ≤ −10 dB) is 5.25 GHz (12.43–17.68 GHz) under the matching thickness of 2.46 mm, its EAB dramatically reached 7.14 GHz (9.74–16.88 GHz) when the graphene content was increased to 90 mg at 2.04 mm matching thickness, which covers most of the X and Ku radar frequency band. Combined with the analysis of the electronic and surface structures of NiFe@N–C/rGO composites, the formation energy and dipole moment were calculated to reveal the mechanism of EMWs absorption within them. The results show that the N-doped structure is more stable than the vacancy modification, where the pyridinic-N is the source of dipole relaxation polarization under high-frequency electromagnetic field. The combination of experimental and theoretical research reveals the inherent mechanism of EMWs attenuation in as-prepared composites, paving an inspirational route for controllable high performance absorbing materials.