Nitrogen-doped Graphene Aerogel Research Articles

A Prussian blue route to nitrogen-doped graphene aerogels as efficient electrocatalysts for oxygen reduction with enhanced active site accessibility

Developing high-performance nonprecious-metal electrocatalysts for the oxygen reduction reaction (ORR) is crucial for a variety of renewable energy conversion and storage systems. Toward that end, rational catalyst design principles that lead to highly active catalytic centers and enhanced active site accessibility are undoubtedly of paramount importance. Here, we used Prussian blue nanoparticles to anchor Fe/Fe3C species to nitrogen-doped reduced graphene oxide aerogels as ORR catalysts. The strong interaction between nanosized Fe3C and the graphitic carbon shell led to synergistic effects in the ORR, and the protection of the carbon shell guaranteed stability of the catalyst. As a result, the aerogel electrocatalyst displayed outstanding activity in the ORR on par with the state-of-the-art Pt/C catalyst at the same mass loading in alkaline media, good performance in acidic media, and excellent stability and crossover tolerance that rivaled that of the best nonprecious-metal ORR electrocatalysts reported to date.

Hierarchically porous nitrogen-doped graphene aerogels as efficient metal-free oxygen reduction catalysts

Nitrogen-doped graphene aerogels with hierarchically porous architectures (N-Gs) are fabricated through the co-assembly of graphene oxide and o-phthalonitrile in a solvothermal process and the thermal treatment of the obtained composites at different temperatures. The structural characterizations indicate that both mesopores and macropores exist in the monolithic N-Gs. More importantly, the architectures, porosities and compositions show obvious dependence on the thermal treatment temperature. As the metal-free catalyst for oxygen reduction reaction in basic media, the sample thermally treated at 750°C shows the best catalytic performances among the three N-Gs, which is owing to its advantages in the surface areas and content of active N species.

Three-Dimensional Porous LiFePO4 Cathode Composite Decorated By Nitrogen-Doped Graphene Aerogel for Ultrafast Lithium Storage

Being a candidate of Lithium-ion batteries (LIBs) cathode material, olivine structured LiFePO4 (LFP) has various advantages, however, the major problems associated with LFP still lie in the fact of its poor electric conductivity and low Li+ diffusivity along the [010] direction only[1-2]. Based on this viewpoint, we wrapped (010) facet orientated LFP nanoplatelets (LFP NPs) with N-doped graphene aerogel (N-GA) to prepare a porous N-GA modified LFP composite (LFP@N-GA) through a facile electrostatic attraction treatment combined with a self-assembly process. In such a composite as shown in Figure. 1a-1i, LFP NPs are well surrounded by a N-GA constructed bicontinuous conductive network, which effectively facilitate both Li+and electron transport, and thus, effectively reducing the polarization[3-4]. Electrochemical test results demonstrated that the LFP@N-GA composite electrode indeed exhibited a ultrahigh rate capability (78 mAh·g−1at 100 C) and a stable cyclability (90% capacity retention over 1000 cycles at 10 C), as shown in Figure. 1j and 1k[5-6]. Such a LFP@N-GA cathode material may advance the development of high-power LIB for EVs and HEVs, and the preparation method is independent from the morphology and the synthesis process of the electrochemically active material, and therefore, compatible with many other energy-storage materials for different applications. Figure 1.Characterization and electrochemical performance of LFP@N-GA composite: (a, b) SEM images at different magnification. (c-h) TEM and HRTEM images. Inset of d: FFT pattern of the HRTEM image, where B denotes the beam direction, indicating the (010) facet orientation. (i) HAADF-STEM image and elemental mapping results of LFP@N-GA. (j) and (k) Rate and cycling performance. Reference ： [1]Padhi A. K., Nanjundaswamy K. S., et al., J. Electrochem. Soc., 1997, 144, 1188-1194. [2]Wang B., Xu B., et al., Nanoscale, 2014, 6 (2): 986-995. [3]Wang B., Wang Q., et al., RSC Adv., 2013, 3 (43): 20024-20033. [4]Wang B., Wang S., et al., Mater. Lett., 2014, 118: 137-141. [5]Wang B., Al A. W., et al., Energy Environ. Sci., 2015, 8 (3): 869-875. [6]Wang, B.; Wang D., et al., J. Mater. Chem. A, 2013, 1 (1): 135-144. Figure 1

Nitrogen-Doped Porous Carbon/Graphene Aerogel with Much Enhanced Capacitive Behaviors

Hierarchically porous hybrids of strongly coupled nitrogen-doped porous carbons and graphene aerogel (NPC-GA) are fabricated through the solid-state oxidation polymerization and carbonization of m-phenylenediamine on the interconnected macroporous frameworks of GA. The hierarchically porous hybrids provide abundant storage sites and short transport paths for electrolyte ions. By adjusting the pyrolysis temperature, the specific surface areas and nitrogen content of NPC-GA can be easily modified, further influencing the electrochemical performance of the hybrids. In a three-electrode system, NPC-GA electrode shows high specific capacitance of 608Fg−1 at 0.1Ag−1 in 1M H2SO4. An all-solid-state flexible supercapacitor based on NPC-GA delivers superior energy density (12.4 Wh Kg−1) and power density (2432W Kg−1) as well as good cycling stability (92% specific capacitance retention after 10 000 cycles).

Ultra-fine Pt nanoparticles supported on 3D porous N-doped graphene aerogel as a promising electro-catalyst for methanol electrooxidation

Three dimensional porous nitrogen-doped graphene aerogel (3D-NGA) was successfully fabricated via a combined hydrothermal self-assembly, thermal treatment and template-removing process. The as-synthesized Pt/3D-NGA catalysts exhibit an interconnected 3D porous structure, high N-doped level and uniform dispersion of Pt NPs. In studying the electrocatalytic performance of samples towards methanol electrooxidation, we found that Pt/3D-NGA hold a high electrochemical active surface area (ECSA) of 90.7m2g−1 and better catalytic activity as well as stability compared to Pt/G and Pt/3D-GA catalysts. Our studies provide a simple approach to synthesize 3D metal or metal oxide/graphene-based composites, holding great potential for fuel cell applications.

Nitrogen-Doped Graphene Aerogels with Three Dimensional Architectures for Multifunctional Applications in Supercapacitor and Absorption

Nitrogen-Doped Graphene Aerogels with Three Dimensional Architectures for Multifunctional Applications in Supercapacitor and Absorption

Boosting Power Density of Microbial Fuel Cells with 3D Nitrogen-Doped Graphene Aerogel Electrode.

A 3D nitrogen‐doped graphene aerogel (N‐GA) as an anode material for microbial fuel cells (MFCs) is reported. Electron microscopy images reveal that the N‐GA possesses hierarchical porous structure that allows efficient diffusion of both bacterial cells and electron mediators in the interior space of 3D electrode, and thus, the colonization of bacterial communities. Electrochemical impedance spectroscopic measurements further show that nitrogen doping considerably reduces the charge transfer resistance and internal resistance of GA, which helps to enhance the MFC power density. Importantly, the dual‐chamber milliliter‐scale MFC with N‐GA anode yields an outstanding volumetric power density of 225 ± 12 W m−3 normalized to the total volume of the anodic chamber (750 ± 40 W m−3 normalized to the volume of the anode). These power densities are the highest values report for milliliter‐scale MFCs with similar chamber size (25 mL) under the similar measurement conditions. The 3D N‐GA electrode shows great promise for improving the power generation of MFC devices.

Electrosorption of Lead Ions by Nitrogen-Doped Graphene Aerogels via One-Pot Hydrothermal Route

We present an efficient Pb2+ electrosorption by nitrogen-doped graphene aerogels (NGAs) prepared by one-pot hydrothermal synthesis of nitrogen-doped graphene hydrogels (NGHs) followed by freeze-drying treatment. Pb2+ can be effectively removed by the as-prepared NGAs at an applied negative potential, and the removal mechanisms include (1) electrostatic attraction derived from external electric field, (2) electrostatic attraction caused by intrinsic charges on NGAs and Pb2+, (3) large specific surface area (SBET) of NGAs, and (4) coordination between doped nitrogen atoms and Pb2+. More importantly, after a simple and convenient electrodesorption treatment, the NGAs exhibit promising performance in recyclable electrosorption, and the removal ratio (%R) of Pb2+ decreases only ∼5% after successive 100 cycles, which is significantly superior to conducting polymer and conducting polymer/reduced graphene oxide (rGO) composites-based electrosorption.

Preparation of preferentially exposed poison-resistant Pt(111) nanoplates with a nitrogen-doped graphene aerogel.

A poison-resistant and highly catalytically active Pt(111) lattice on ultrathin Pt nanoplates (Pt(111)NPTs) with a large ratio (28%) of surface active to sum Pt atoms is obtained with a dense small pore N-atom doped aerogel (NGA) featuring a large specific surface area and high N content in the graphene skeleton.

A novel biosensor nanomaterial for the ultraselective and ultrasensitive electrochemical diagnosis of the breast cancer-related BRCA1 gene

Supramolecular ionic liquids grafted on nitrogen-doped graphene aerogels (SIL-g-(N)GAs) were used as a novel electrochemical DNA biosensor for the direct detection of the breast cancer-related BRCA1 gene.

One-pot hydrothermal synthesis of platinum nanoparticle-decorated three-dimensional nitrogen-doped graphene aerogel as a highly efficient electrocatalyst for methanol oxidation

Pt nanoparticle-decorated nitrogen-doped 3D graphene aerogel (PtNPs/3DNGA) composites were prepared through a one-pot hydrothermal approach and show superior catalytic activity in methanol oxidation.

Silver nanoparticles supported on a nitrogen-doped graphene aerogel composite catalyst for an oxygen reduction reaction in aluminum air batteries

A facile one-step hydrothermal method to prepare the Ag/N-RGO composite as an efficient ORR electrocatalyst.

Fabrication of pore-rich nitrogen-doped graphene aerogel

Porosity tuning of NGAs by tailoring GONSs yields the pore-richest NGA with the best mechanical stability and electrocatalytic biosensing activity using the smallest sonicated GONSs and DA with high N content and 3D crosslinking capability.

Low-thermal-conductivity nitrogen-doped graphene aerogels for thermal insulation

N-doped graphene aerogels with low thermal conductivity were prepared for the first time.

Effect of Boron-Doping on the Graphene Aerogel Used as Cathode for the Lithium-Sulfur Battery.

A porous interconnected 3D boron-doped graphene aerogel (BGA) was prepared via a one-pot hydrothermal treatment. The BGA material was first loaded with sulfur to serve as cathode in lithium-sulfur batteries. Boron was positively polarized on the graphene framework, allowing for chemical adsorption of negative polysufide species. Compared with nitrogen-doped and undoped graphene aerogel, the BGA-S cathode could deliver a higher capacity of 994 mA h g(-1) at 0.2 C after 100 cycles, as well as an outstanding rate capability, which indicated the BGA was an ideal cathode material for lithium-sulfur batteries.

A novel electrochemical DNA-sensing nanoplatform based on supramolecular ionic liquids grafted on nitrogen-doped graphene aerogels

In this paper, the application of supramolecular ionic liquids grafted on nitrogen-doped graphene aerogels (SIL-g-(N)GAs), a novel electrode system, for the preparation of electrochemical DNA sensing platform is proposed. The super dispersion of SIL-g-(N)GAs in water makes it an ideal candidate for biological purposes such as gene delivery. In fact, SIL-g-(N)GAs/glassy carbon working electrode (GCE) can realize the simultaneous detection of all four DNA bases in double-stranded DNA without a prehydrolysis step. On the SIL-g-(N)GAs/GCE, due to the presence of SIL on the surface of three-dimensional nitrogen-doped graphene, the anchoring of the DNA probe can be achieved by electrostatic association of SIL cations with the DNA backbone readily. So, herein we report a novel strategy for DNA hybridization without any electroactive tags or intercalators and suggest the potential applications of SIL-g-(N)GAs/GCE in the label-free electrochemical detection of DNA hybridization or DNA damage for further research. Moreover, the influence of potentially interfering substances on the determination of DNA is investigated.

A hybrid-assembly approach towards nitrogen-doped graphene aerogel supported cobalt nanoparticles as high performance oxygen reduction electrocatalysts

As a novel electrocatalyst for oxygen reduction reaction (ORR), nitrogen-doped graphene aerogel supported cobalt nanoparticles (Co-NGA) is archived by a hybrid-assembly of graphene oxide (GO), o-phthalonitrile and cobalt acetate and the following thermal treatment. The hybrid-assembly process successfully combines the ionic assembly of GO sheets and Co ions with the coordination between o-phthalonitrile and Co ions, which can be converted to nitrogen doped carbon and Co nanoparticles in the pyrolysis process under nitrogen flow. Remarkable features of Co-NGA including the macroporous graphene scaffolds, high surface area, and N/Co-doping effect can lead to a high catalytic efficiency for ORR. As the results, the composites pyrolyzed at 600°C (Co-NGA600) shows excellent electrocatalytic activities and kinetics for ORR in basic media, which are comparable with those of Pt/C catalyst, together with superior durability.

3D nitrogen-doped graphene aerogel: A low-cost, facile prepared direct electrode for H2O2 sensing

A facile, template-free and low-cost strategy has been developed to construct a 3D nitrogen (N) doped graphene aerogel (GA) by the incorporation of dopamine (DA). 3D-NGA can be served as a highly efficient electrocatalyst in the reduction of H2O2, which is then applied in the nonenzymatically electrochemical determination of H2O2. The structure and morphology of hollow 3D-NGA were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Electrocatalytic activity of 3D-NGA was investigated by cyclic voltammetry (CV) and chronoamperometry, exhibiting a direct for the reduction of H2O2 at −0.5V. This constructing sensor was applied in detection of H2O2 with a detection limit of 0.05mM, a linear detection range from 0.2 to 35mM. Due to superior catalytic performance and low cost of 3D-NGA electrode, it shows great potential in applications for direct sensing of H2O2.

Nitrogen-doped graphene aerogels as anode materials for lithium-ion battery: Assembly and electrochemical properties

Three-dimensional nitrogen-doped graphene aerogel (N-GA) is facilely synthesized via a hydrothermal method combined with freeze drying. When it is used as an anode for lithium-ion battery, N-GA possesses larger surface area (SBET=379.1m2g−1), higher reversible capacity (535.3mAhg−1 in the 100th cycle ) and more stable cycling performance compared with those of pristine GA, which could result from the structural defects caused by the nitrogen doping.

Integrated 3D porous C-MoS2/nitrogen-doped graphene electrode for high capacity and prolonged stability lithium storage

Scrupulous design and fabrication of advanced anode materials are of great importance for developing high-performance lithium ion batteries. Herein, we report a facile strategy for construction of free-standing and free-binder 3D porous carbon coated MoS2/nitrogen-doped graphene (C-MoS2/N-G) integrated electrode via a hydrothermal-induced self-assembly process. The preformed carbon coated MoS2 is strongly anchored on the porous nitrogen-doped graphene aerogel architecture. As an anode for lithium ion batteries, the C-MoS2/N-G electrode delivers a high first discharge capacity of 1600 mAh g−1 and maintains 900 mAh g−1 after 500 cycles at a current density of 200 mA g−1. Impressively, superior high-rate capability is achieved for the C-MoS2/N-G with a reversible capacity of 500 mAh g−1 at a high current density of 4000 mA g−1. Furthermore, the lithium storage mechanism of the obtained integrated electrode is investigated by ex-situ X-ray photoelectron spectroscopy and transmission electron microscopy in detail.