Porous Nitrogen-doped Graphene Research Articles

Unveiling the Versatile Applications of Cobalt Oxide-Embedded Nitrogen-Doped Porous Graphene for Enhanced Energy Storage and Simultaneous Determination of Ascorbic Acid, Dopamine and Uric Acid

The advancement of electrode materials is essential for addressing the energy and biomedical challenges. A multi-functional approach was employed to create a new electrode material of cobalt oxide-embedded nitrogen-doped porous graphene (Co3O4@NpG) for sensing and energy storage applications. In the present study, we have fabricated a new electrochemical sensing platform based on Co3O4@NpG. The sensing performance and selective detection capability of the demonstrated sensor was optimized and tested by determining dopamine (DA), uric acid (UA), and ascorbic acid (AA) simultaneously in analyte fortified biological samples. The sensing response is noticed to be linearly dependent upon the concentration of AA, DA, and UA in the range of 0.1–450, 0.1–502, and 0.2–396 μM, respectively. This material also showed good electrochemical energy storage performance when assessed as a supercapacitor electrode. The Co3O4@NpG electrode material showcased a remarkable specific capacitance of 314.58 Fg−1, an energy density of 10.06 Wh kg−1 at a power density of 240 Wkg−1 at 0.5 Ag−1, in a 6 M KOH electrolyte, along with excellent long-term cycling stability. Hence, the material Co3O4@NpG stands out as a promising multifunctional electrode candidate, excelling in the precise simultaneous detection of critical biomolecules besides exhibiting superior energy storage performance.

Honeycomb-like MoCo alloy on 3D nitrogen-doped porous graphene for efficient hydrogen evolution reaction

Honeycomb-like MoCo alloy on 3D nitrogen-doped porous graphene for efficient hydrogen evolution reaction

Fe3C-Functionalized 3D Nitrogen-Doped Porous Graphene Nanocomposites as Anode Materials for Lithium-Ion Batteries

Fe₃C-Functionalized 3D Nitrogen-Doped Porous Graphene Nanocomposites as Anode Materials for Lithium-Ion Batteries

Facile synthesis of nitrogen-doped porous graphene for efficient adsorption of tetracycline: Behavior and mechanism

Developing economic and efficient adsorbents is critically important for antibiotic residual removal from contaminated water. Here, Nitrogen-doped porous graphene-like carbon (NPGC) adsorbents were successfully synthesized by self-blowing and doping method, where glucose was used as the carbon source, zinc nitrate was acted as the nitrogen source and the derived ZnO was as the porogen. The obtained NPGC possessed a graphene-like porous structure with moderate nitrogen doping. The removal capacity of NPGC was as high as 451.2 mg g−1 in 50 mg L−1 TC solution, which is much higher than graphene, carbon nanotubes, and activated carbon, due to the larger specific surface area and micro/mesopores on graphene sheets. The adsorption isotherms and kinetics for TC onto NPGC were well-fitted with Langmuir model and pseudo-second-order model. The adsorptive ability of NPGC increased linearly with the increasing graphitic N content due to the enhanced π-π interaction and hydrophobic effect between TC and NPGC. The NPGC also showed potential environmental application as revealed by anti-interference capacity in the interference (coexisting ions and humic acid) and reusability. This work not only provides a facile strategy to develop economic and scalable N-doped graphene, but also systematically studies the adsorption mechanism of TC onto N-doped carbon adsorbents.

First-principles study of nitrogen-doped porous graphene for Na+, K+, Mg2+, and Ca2+ cations adsorption

First-principles study of nitrogen-doped porous graphene for Na+, K+, Mg2+, and Ca2+ cations adsorption

Porous Nitrogen-Doped Crumpled Graphene Nanoparticles: A Metal-Free Nanozyme for Selective Detection of Dopamine in Aqueous Medium and Human Serum

Accurate detection of trace analytes in biological samples is essential for medical diagnostics but usually requires complex and expensive instruments. Nanozymes, a series of nanosized systems with a catalytic activity mimicking that of peroxidase enzymes, offer a useful alternative for the design of sensing devices. In this article, we describe the synthesis of porous 3D nitrogen-doped crumpled graphene nanoparticles (CGNPs) and their use as a platform for the sensitive detection of dopamine (DA) in complex biological media such as blood serum. CGNPs were prepared by doping graphene oxide (GO) using ammonium hydroxide in a hydrothermal treatment. This procedure leads to the crumpling of GO sheets into porous sphere-like nanoparticles, with a diameter of 34 ± 10 nm. These nanoparticles with high surface area and improved electronic properties proved very active for the oxidation of the peroxidase substrate 3,3′,5,5′- tetramethylbenzidine (TMB). Our sensing device relied on the scavenging of hydroxyl radicals by DA, resulting in a turn-off effect for TMB oxidation. The system selectively detected DA with a limit of detection of 1.15 μM and a linearity range of 1 to 20 μM. The system also possessed good selectivity for DA in the presence of various interfering species, as well as in human blood serum.

Kirigami-Inspired Thermal Regulator

One of the current challenges in nanoscience is tailoring phononic devices, such as thermal regulators and thermal computing. This has long been a rather elusive task because the thermal-switching ratio is not as high as electronic analogs. Mapping from a topological kirigami assembly, nitrogen-doped porous graphene metamaterials on the nanoscale are inversely designed with a thermal-switching ratio of 27.79, which is more than double the value of previous work. We trace this behavior to the chiral folding-unfolding deformation, resulting in a metal-insulator transition. This study provides a nanomaterial design paradigm to bridge the gap between kinematics and functional metamaterials that motivates the development of high-performance thermal regulators.

Anisotropic thermoelectric properties in hydrogenated nitrogen-doped porous graphene nanosheets.

By using density functional theory calculations combined with the nonequilibrium Green's function method and machine learning, we systematically studied the thermoelectric properties of four kinds of porous graphene nanosheets (PGNS) before and after nitrogen doping. The results show that the thermoelectric performance of porous graphene nanosheets along the armchair or zigzag chiral direction is improved due to the dramatically enhanced power factor caused by nitrogen doping. The calculated ZT values of nitrogen-doped porous graphene nanosheets are boosted by about one order of magnitude compared with those of undoped porous graphene nanosheets at room temperature. More importantly, an anisotropic thermoelectric transport is found in the nitrogen-doped porous graphene nanosheets. The results show that the ZT values of nitrogen-doped porous graphene nanosheets along the zigzag transport direction are nearly 11 times larger than those of them along the armchair transport direction. These results reveal that the thermoelectric properties of porous graphene nanosheets can be well regulated by nitrogen doping, and provide a good theoretical guidance for their application in thermoelectric devices.

Synthesis of NiCo-LDH@nitrogen-doped graphene hydrogel/nickel foam composites with 3D hierarchical structure for supercapacitors

Nickel-cobalt layered double hydroxide (NiCo-LDH)@N-GH/NF composites were prepared by a simple one-pot hydrothermal method on nickel foam (NF) substrates loaded with 3D porous nitrogen-doped graphene hydrogel (N-GH). 3D hierarchical structure has a positive role in promoting electrochemical performance. When used as supercapacitor electrodes, NiCo-LDH@N-GH/NF shows a specific capacity of 174.1 mAh·g−1 (specific capacitance of 1393F·g−1) at 1 mA·cm−2. The assembled NiCo-LDH@N-GH/NF//GH/CNT asymmetric supercapacitor (ASC) has a specific capacitance of 209F·g−1 (1 mA·cm−2). When the power density is 260 W·kg−1, the energy density reaches 63.33 Wh·kg−1.

Nitrogen-Doped Porous Core-Sheath Graphene Fiber-Shaped Supercapacitors.

In this study, a strategy to fabricate nitrogen-doped porous core-sheath graphene fibers with the incorporation of polypyrrole-induced nitrogen doping and graphene oxide for porous architecture in sheath is reported. Polypyrrole/graphene oxide were introduced onto wet-spun graphene oxide fibers by dip-coating. Nitrogen-doped core-sheath graphene-based fibers (NSG@GFs) were obtained with subsequently thermally carbonized polypyrrole/small-sized graphene oxide and graphene oxide fiber slurry (PPY/SGO@GOF). Both nitrogen doping and small-sized graphene sheets can improve the utilization of graphene layers in graphene-based fiber electrode by preventing stacking of the graphene sheets. Enhanced electrochemical performance is achieved due to the introduced pseudo-capacitance and enhanced electrical double-layered capacitance. The specific capacitance (38.3 mF cm−2) of NSG@GF is 2.6 times of that of pure graphene fiber. The energy density of NSG@GF reaches 3.40 μWh cm−2 after nitrogen doping, which is 2.59 times of that of as-prepared one. Moreover, Nitrogen-doped graphene fiber-based supercapacitor (NSG@GF FSSC) exhibits good conductivity (155 S cm−1) and cycle stability (98.2% capacitance retention after 5000 cycles at 0.1 mA cm−2).

Simultaneously speciation of mercury in water, human blood and food samples based on pyrrolic and pyridinic nitrogen doped porous graphene nanostructure

A rapid and efficient method based on a novel nitrogen-doped porous graphene nanostructure (NDPG) was used for the speciation of mercury in water and human blood samples by the CV-AAS. The mixture of the NDPG, ionic liquid, and acetone was rapidly injected into the human blood, water, and food samples for mercury separation by the cloud point assisted dispersive ionic liquid-micro solid-phase extraction (CPA-DIL-μ-SPE) at pH 7.5. The UV-microwave accessory converted the organic mercury (R-Hg) to inorganic mercury, and total mercury (TM) was determined. Finally, the organic mercury was calculated by subtracting the inorganic and entire mercury contents. By optimizing, the linear range, LOD, and enrichment factor were obtained (0.01–6.80 µg/L; 0.005–3.60 µg/L), (2.6 ng/L; 1.2 ng/L) and (9.8; 20.2) for the mercury species in human blood and water/food samples, respectively (Mean of RSD < 1.9 %). The CRM samples obtained the validation of the procedure.

Making a wearable supercapacitor based on highly porous 3D nitrogen-doped graphene

Making a wearable supercapacitor based on highly porous 3D nitrogen-doped graphene

Nitrogen-doped 3D porous graphene coupled with densely distributed CoOx nanoparticles for efficient multifunctional electrocatalysis and Zn-Air battery

Highly efficient and low-cost multifunctional electrocatalysts play a crucial role in energy storage and conversion systems. Herein, a new strategy is developed based on a structured precursor to design and fabricate a hierarchical porous nitrogen doped graphene coupled with densely distributed CoO/Co3O4 heterostructure that exhibits outstanding multifunctional activities. With rational hybridization of graphene and bimetallic nanoparticles, the as-obtained NGPC@CoOx integrated densely distributed CoO/Co3O4 active nanoparticles to 3D interconnected hierarchical N-doped graphene mesh, which gives rise to a multifaceted capability for electron/ion transfer and redox catalyzing. The NGPC@CoOx possesses excellent durability with a superior E1/2 of 0.86 V for oxygen reduction reaction (ORR), and a relatively low potential for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) of 1.61 V, and -0.162 V at 10 mA cm−2, respectively. Additionally, the superior cycling durability and high power density of NGPC@CoOx-based zinc-air batteries (184.4 mW cm−2) further confirm the potential application of prototype devices. This work introduces a new perspective on developing efficient multifunctional electrocatalysts with a well-designed 3D structure anchored with densely distributed nanoparticles towards energy storage and conversion technologies.

Rational design of highly efficient electrocatalytic single-atom catalysts for nitrogen reduction on nitrogen-doped graphene and g-C2N supports

Electrochemical N2 reduction reaction (NRR) is a very attractive route for ammonia production under ambient conditions. It is a challenging issue to develop efficient electrocatalysts in NRR process. Herein, we designed a series of NRR single-atom catalysts (SACs), namely, transition metal single-atom anchored on nitrogen-doped porous graphene with six-fold N6 cavity (TM@N6-G). Based on spin-polarized density functional theory (DFT) calculations, the stability and catalytic performance of TM@N6-G SACs were systemically investigated. Six promising catalysts (Nb, Mo, Tc, Ta, W, and Re@N6-G) are selected from 14 candidates by screening the free energy changes of the first and last electric chemical steps. Detailed NRR mechanism studies show that the six SACs have superior electrochemical NRR performance, especially W@N6-G, reaching low limiting potentials of −0.23 V. Furthermore, we extend the present study to another kind of graphitic carbon nitrides, g-C2N, which has a similar N6 cavity. Our calculations show that five TM@g-C2N SACs have good stability and high activity and selectivity for NRR. In addition, ΔG*NNH, dN-N, and ICOHP can be used as descriptors to understand the origin of NRR catalytic activity of these two kinds of catalysts. The present work may provide valuable clues for exploring promising and efficient NRR electrochemical catalysts.

Bimetallic nitrogen-doped porous graphene for highly efficient magnetic solid phase extraction of 5-nitroimidazoles in environmental water

In this work, Fe/Ni bimetallic nitrogen-doped porous graphene (Fe/Ni-NPG) nanomaterials with rich pores, strong magnetism and good reusability were successfully prepared by one-step combustion and can be used as magnetic solid phase extraction (MSPE) adsorbents for the determination of 5-nitroimidazoles (5-NDZs) in environmental water samples. The dispersion and active sites of the materials were increased by the introduction of nitrogen. The adsorption behavior of Fe/Ni-NPG for 5-NDZs was investigated, which corresponds to the quasi-second-order kinetics and Langmuir adsorption model. The π-π electron donor-acceptor interaction (π-π EDA), hydrogen bond and electrostatic interaction between Fe/Ni-NPG and 5-NDZs are the main factors that help to obtain excellent adsorption properties. Several important conditions of MSPE are systematically optimized. Under the optimal MSPE conditions, the linear range of DMZ was 0.6–500 μg/L, the linear range of TNZ and ONZ was 0.7–500 μg/L, and the correlation coefficient R2 ≥ 0.9991. The limit of detection was 0.18–0.2 μg/L, the limit of quantification was 0.6–0.7 μg/L, and the RSDs of intraday and interday precision were 1.58%–4.66% and 3.77–9.69%, respectively. In the three spiked actual environmental water samples, the recovery was 78.05%–107.05% (RSDs<7.82%). The results show that this method based on Fe/Ni-NPG provides an accurate and reliable way to detect 5-NDZs in environmental water.

Porous nitrogen-doped graphene nanofibers comprising metal organic framework-derived hollow and ultrafine layered double metal oxide nanocrystals as high-performance anodes for lithium-ion batteries

The growth of unique nanostructures with multicomponent systems is a renowned strategy for developing advanced materials for various energy storage applications. Herein, we utilize a facile approach to synthesize multicomponent high-performance nanofibers as anodes that comprises hierarchically porous and self-supporting N-doped reduced graphene oxide (N-doped rGO) matrix grafted with metal-organic framework (MOF)-derived hollow and ultrafine layered double metal (Ni and Co) oxide (LDO) nanocrystals [P-(Ni, Co)O/rGO NFs]. The porous and highly conductive N-doped rGO scaffold not only provides structural integrity but also offers short Li-ion diffusion pathways along with enormous conductive channels for rapid charge transfer during cycling. The hollow and ultrafine LDO nanocrystals also provide sufficient space for rapid reaction sites and to absorb the severe volume stress generated during repeated charge-discharge cycles owing to their rich oxidation states. The Li-cell utilizing the P-(Ni, Co)O/rGO NFs as anodes exhibits overall enhanced electrochemical performance with prolonged cycling stability (907 mA h g−1 at the end of 500th cycle) and a satisfactory high-rate capability (519 mA h g−1 at 5.0 A g−1).

Polypyrrole-Wrapped SnS2 Vertical Nanosheet Arrays Grown on Three-Dimensional Nitrogen-Doped Porous Graphene for High-Performance Lithium and Sodium Storage

Polypyrrole-Wrapped SnS₂ Vertical Nanosheet Arrays Grown on Three-Dimensional Nitrogen-Doped Porous Graphene for High-Performance Lithium and Sodium Storage

A novel artificial peroxisome candidate based on nanozyme with excellent catalytic performance for biosensing

Artificial peroxisome is of critical importance to supersede natural peroxisome in fabricating protocell system and disease treatment. Nevertheless, developing feasible artificial peroxisome with various stable functions remains a monumental challenge. Nanozyme with multiple enzyme-like activities can mimic natural enzymes in peroxisome, which make it a prospective candidate for artificial peroxisome design. Herein, we prepared a nanozyme with multiple peroxisomal-like activities – Pd nanoparticles functionalized nitrogen-doped porous carbon-reduced graphene oxide (PdNPs/N-PC-rGO). Due to its sandwich-like structure, the incorporation of N heteroatoms and the synergistic effect between PdNPs and N-PC-rGO bi-support, the PdNPs/N-PC-rGO exhibited triple peroxisomal-like activities including oxidase (OXD), peroxidase (POD) and catalase (CAT), leading it a promising alternative for artificial peroxisome exploration. Furthermore, the PdNPs/N-PC-rGO showed high electrocatalytic activity, which could be employed for the detection of electrochemical active substances reduced glutathione (GSH). The PdNPs/N-PC-rGO modified electrode displayed a wide concentration range from 70 nM to 1500 μM, with a very low detection limit of 9.8 nM (S/N = 3). Therefore, PdNPs/N-PC-rGO was a promising nanozyme for various biotechnological applications such as artificial organelles, biosensing, cytoprotection, disease diagnosis and treatment.

Nitrogen and molybdenum co-doped CoP nanohoneycombs on 3D nitrogen-doped porous graphene as enhanced electrocatalyst for oxygen evolution reaction

The four-electron transfer process involved in anodic oxygen evolution reaction (OER) of electrocatalytic water splitting causes the sluggish kinetics and significantly limiting the efficiency of energy conversion. It's urgent to explore low-cost, efficient and stable electrocatalysts for OER. In the work, we design the nitrogen and molybdenum co-doped CoP with nanohoneycombs structure on three-dimensional (3D) nitrogen-doped porous graphene (N/Mo–CoP@NPG) as an efficient OER electrocatalyst. The N/Mo–CoP@NPG delivers the current density of 10 mA cm−2 at a low overpotential value of 201 mV in 1.0 M KOH, meanwhile the electrocatalytic activity shows no obvious degradation after 50 h. The NPG substrate provides plentiful ligaments for growth of N/Mo–CoP nanohoneycombs and 3D network for rapid electronic transfer. Additionally, doping N and Mo atoms into CoP synergistically modifies the micromorphology and electronic structure, benefiting the electrocatalytic ability. This work offers a promising strategy to improve the electrocatalytic activity of transition metal phosphides.

Embedding Pt-Ni octahedral nanoparticles in the 3D nitrogen-doped porous graphene for enhanced oxygen reduction activity

Due to its better corrosion resistance and higher mechanical strength, 3D graphene is considered as a promising support for oxygen reduction reaction (ORR) electrocatalysts. However, the chemical inertness nature of graphene makes it difficult for Pt-based catalysts to anchor on. Compared with the spherical catalyst, although the Pt-based octahedral catalyst possesses higher mass activity (MA), it has fewer active sites per unit mass due to its larger size, which further hinders the application of 3D graphene as the support of Pt-based octahedral catalyst. Herein, we developed a facile and effective one-step hydrothermal method to fabricate nitrogen-doped porous graphene (NPG). The carbon material with an interconnected 3D framework and submicron macropores was then used to support Pt-Ni octahedral nanoparticles (NPs). The nitrogen not only increase the number of defects, but also improves the distribution of Pt-based octahedral catalysts on the graphene. The electrochemical surface areas (ECSA) of Pt-Ni/NPG reaches 5.5 times that before N-doping. Relative to commercial Pt/C (JM), Pt-Ni/NPG exhibits 6.8-fold enhancement in MA for 725.2 mA mgPt−1 at 0.9 VRHE. Particularly, Pt-Ni/NPG showed only 8.6% loss in MA after 8000 cycles of the accelerated durability test, as compared to a sharp decrease of 56.2% for Pt/C after only 4000 cycles. In the accelerated durability test of carbon support, Pt-Ni/NPG also exhibited good durability relative to Pt-Ni/C. These results indicate that the Pt-based octahedral catalyst supported on NPG is expected to be applied to proton exchange membrane fuel cells (PEMFCs).