Graphitic Carbon Nanosheets Research Articles

Facile synthesis of graphitized carbon nanosheets from Chlorella with multiple Fe active sites to modify separator for efficient Li-S batteries

Li-S battery as an alternative to next-generation battery systems suffers from electrical insulating properties of sulfur, “shuttle effects” and slow kinetics of lithium polysulfides (LiPSs). Separator modification via catalysts with multiple scales of active sites are great potential; however, the preparation of such a kind of catalysts is still complex and tedious. Here, we developed a facile pyrolysis strategy to fabricate multiple Fe active sites on N-doped porous graphitized carbon nanosheets (Fe-NG) from Chlorella, including atomically dispersed Fe single atoms, Fe nanoclusters and carbon-coated Fe nanoparticles, which enhanced the affinity to LiPSs and accelerated their conversion kinetics. As Fe-NG was utilized to modify the separators, the resulting Li-S battery demonstrated an initial discharge capacity of 1062.1 mAh g−1 at 1 C and maintained at 678 mAh g−1 after 500 cycles with the average capacity decay rate of 0.072 % per cycle. This work provides a rational design and large-scale preparation routes for separator modifying catalysts with heterogeneous active species on biomass-derived carbons.

Hydrothermal synthesis of CoSnO3 nanocubes-incorporated graphitic carbon nitride for the efficient photodegradation of organic dye and antibiotic drug

In this work, an eco-friendly, low-cost, facile synthesis of CoSnO3/g-C3N4 using an in-situ hydrothermal method by incorporating graphitic carbon nanosheets. In as-prepared nanocomposite, the CoSnO3 nano cubes strongly attached to graphitic carbon nanosheets due to the ionic interaction which leads to improved catalytic activity, conductivity and stability. The as-synthesized nanocomposite was characterized by various spectral, structural and optical studies and it was applied for the photocatalytic degradation of organic dye-methylene blue (MB) and antibiotic drug-norfloxacin (NOR). From DRS-UV analysis, CoSnO3 exhibit a bandgap of 2.93 eV, g-C3N4 and CoSnO3/g-C3N4 has 2.84 eV and 1.95 eV, respectively. The nanocomposite demonstrates admirable degradation efficiency of 95.24 % for Methylene blue within 50-min and 95.99 % for Norfloxacin within a 70-min period under visible-light active conditions and surpass the performance of pure CoSnO3 and g-C3N4 due to the synergetic acceleration of heterojunction. The results have demonstrated that the CoSnO3/g-C3N4 nanocomposite exhibits significant potential as a photocatalyst for the degrading NOR antibiotic and MB dye. Liquid chromatography–mass spectrometry (LC-MS) analysis identified four potential routes for the degradation intermediates of norfloxacin. Moreover, the nanocomposite material exhibits long term stability, durability and good bio comfortability.

Nitrogen configuration modulation of porous graphitic carbon nanosheets for superior capacitive energy storage

Carbon nanosheets with layer-stacked porous structures and surface functionalized groups are beneficial for efficient ion storage in supercapacitor electrode materials, but achieving high cost-effectiveness and controllable surface groups remains a significant challenge. Herein, the biomass-derived chitosan and sodium alginate are selected as raw materials for self-assembly reaction with phytic acid as a cross-linking agent. The protonated chitosan and sodium alginate form a cross-linked network structure through hydrogen bonding and electrostatic adsorption, which is subsequently carbonized and activated to synthesize porous graphitic carbon nanosheets (PNPCN-X). PNPCN-X realizes an efficient distribution of porous and graphitic structures. It's noteworthy that phytic acid facilitates the fixation of N atoms, and various N configurations can be adjusted by altering the content of phytic acid. Optimized PNPCN-1.5 exhibits a high content of structurally stable pyridinic-N and graphitic-N configurations, which are confirmed to serve as active sites substantially augmenting the ion adsorption capacity through Density Functional Theory (DFT) calculations. Benefiting from its exceptional physicochemical properties, PNPCN-1.5 achieves 322 F g−1 as electrode materials in the three-electrode system, while the symmetrical supercapacitor assembled with EMIMBF4 electrolyte attains 56.29 W h kg−1. Furthermore, various kinetic analyses extensively elucidate its capacitance distribution characteristics and ion diffusion rates.

FeNi Prussian blue analogues on highly graphitized carbon nanosheets as efficient glucose sensors

FeNi Prussian blue analogues on highly graphitized carbon nanosheets as efficient glucose sensors

Porous and graphitic carbon nanosheets with controllable structure for zinc-ion hybrid capacitor

The imbalances of storage capacity and reaction kinetics between carbonaceous cathodes and zinc (Zn) anodes restrict the widespread application of Zn-ion hybrid capacitor (ZIHC). Structure optimization is a promising strategy for carbon materials to achieve sufficient Zn2+ storage sites and satisfied ion–electron kinetics. Herein, porous graphitic carbon nanosheets (PGCN) were simply synthesized using a K3[Fe(C2O4)3]- and urea-assisted foaming strategy with polyvinylpyrrolidone as carbon precursor, followed by activation and graphitization. Sufficient pores with well-matched pore sizes (0.80–1.94 nm) distributed across the carbon nanosheets can effectively shorten mass-transfer distance, promoting accessibility to active sites. A partially graphitic carbon structure with high graphitization degree can accelerate electron transfer. Furthermore, high nitrogen doping (7.2 at.%) provides additional Zn2+ storage sites to increase storage capacity. Consequently, a PGCN-based ZIHC has an exceptional specific capacity of 181 mAh g−1 at 0.5 A g−1, superb energy density of 145 Wh kg−1, and excellent cycling ability without capacity decay over 10,000 cycles. In addition, the flexible solid-state device assembled with PGCN exhibits excellent electrochemical performances even when bent at various angles. This study proposes a straightforward and economical strategy to construct porous graphitic carbon nanosheets with enhanced storage capacity and fast reaction kinetics for the high performance of ZIHC.

Electrochemical Nanoaptasensor Based on Graphitic Carbon Nitride/Zirconium Dioxide/Multiwalled Carbon Nanotubes for Matrix Metalloproteinase-9 in Human Serum and Saliva.

In this study, a nanocomposite was synthesized by incorporating graphitic carbon nanosheets, carboxyl-functionalized multiwalled carbon nanotubes, and zirconium oxide nanoparticles. The resulting nanocomposite was utilized for the modification of a glassy carbon electrode. Subsequently, matrix metalloproteinase aptamer (AptMMP-9) was immobilized onto the electrode surface through the application of ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride-N-hydroxysuccinimide (EDC-NHS) chemistry. Morphological characterization of the nanomaterials and the nanocomposite was performed using field-emission scanning electron microscopy (FESEM). The nanocomposite substantially increased the electroactive surface area by 205%, facilitating enhanced immobilization of AptMMP-9. The efficacy of the biosensor was evaluated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimal conditions, the fabricated sensor demonstrated a broad range of detection from 50 to 1250 pg/mL with an impressive lower limit of detection of 10.51 pg/mL. In addition, the aptasensor exhibited remarkable sensitivity, stability, excellent selectivity, reproducibility, and real-world applicability when tested with human serum and saliva samples. In summary, our developed aptasensor exhibits significant potential as an advanced biosensing tool for the point-of-care quantification of MMP-9, promising advancements in biomarker detection for practical applications.

RuCo clusters stabilized by Co single atoms: alloying effect and small size effect facilitate hydrogen electrocatalysis kinetics

The development of efficient catalysts is essential to promote slow hydrogen reaction kinetics in alkaline solutions. Herein, an ultrathin ZIF-derived efficient HOR/HER electrocatalyst, with Co single-atom-anchored RuCo clusters on N-doped graphitized carbon nanosheets (RuCo/SANC NS), is designed and constructed by a step-by-step calcination strategy. In the RuCo/SANC NS, Co atoms dispersed in carbon nanosheets induce the formation of ultrasmall RuCo clusters and stabilize the RuCo clusters. Abundant coordinatively unsaturated Ru sites are formed on the surface of RuCo clusters due to the small size effect. The electronic structure of the Ru site is regulated by the alloying effect with Co, optimizing the adsorption energy to *H and *OH and accelerating the HER/HOR kinetics. The RuCo/SANC NS catalyst exhibits excellent mass activity with HER of 13.58 A/mgRu and HOR of 3.85 A/mgRu, which are about 35.35 and 48.13 times that of Pt/C.

Fabrication of N-doped graphitic carbon nanosheets via reaction between CaC2 and g-C3N4 as promising Li-ions battery anode

Nitrogen-doped carbon materials have attracted much attention for energy storage. Herein, we synthesize nitrogen-doped graphitic carbon nanosheets (NGCN) via a simple reaction between g-C3N4 and CaC2. The NGCN product integrates various features including high nitrogen content (3.98 at.%), large surface area (72.96 m2 g−1) and high graphitization degree (interplanar spacing, 0.335 nm). When served as anode material in Li-ions batteries, the NGCN exhibits a quite encouraging reversible capacity of 475 mAh g−1 at a current density of 500 mA g−1, with a capacity retention of 98.5 % after 1000 cycles. It also has an acceptable rate capability (238 mAh g−1 at 5000 mA g−1). This work promises an efficient route to convert sustainable carbon sources into nitrogen-doped graphitic carbon nanosheets with excellent electrochemical performances for energy storage.

Novel strategy for efficient conversion of biomass into N-doped graphitized carbon nanosheets as high-performance electrode material for supercapacitor

The transformation of low-cost, renewable and eco-friendly biomass into energy conversion or storage materials with high energy density is one of the effective means to alleviate the energy crisis. In this study, a scalable route was proposed to synthesize porous, hetero-atom doped graphitized carbon nanosheets from the biomass-fish scales, and the as-prepared material was further used to construct a high-performance electrode for supercapacitor application. The synthesized N-doped graphitized carbon nanosheets (GNC-900) exhibit an average scale of 1–2 μm in size and hierarchical porous structure with a specific surface area of 1261.5 m2 g−1. The results of cyclic voltammetry (CV) and galvanostatic charge-discharge show that GNC-900 owns the quasi-electric double layer capacitance behavior in 6.0 M KOH electrolyte due to the presence of heteroatoms, and it exhibits a distinguished specific capacitance value of 448 F g−1 at a current density of 1 A g−1 in three-electrode cell. The CV curves at different scan rates reveal that this electrode has superior reversible stability and rapid response. Meanwhile, it delivers a high energy density of 57.7 Wh kg−1 at a power density of 999 W kg−1 in a two-electrode system. This novel and low-cost strategy provides an effective route to transform fish scales into highly valuable electrode materials in energy storage fields.

Oxygen-terminated vanadium carbide with graphitic carbon nitride nanosheets modified electrode: A robust electrochemical platform for the sensitive detection of antibiotic drug clioquinol

Engineering the electrocatalyst's nanostructure is key-factor in constructing a high-performance electrochemical sensor. The MXene vanadium carbide (V8C7Tx; VC) nanosheets encapsulating graphitic carbon nanosheets nanocomposite (VC/g-CN NSs NC) as an effective electrocatalyst for detecting clioquinol (CQL) is reported here. The interconnected VC and g-CN nanosheets form a very effective conductive network. The high concentration of O-terminated functional groups in the oxidized VC and the abundant surface area of g-CN contribute to the enhanced electrocatalytic effectiveness of the nanocomposite. The synergistic interaction between the VC NSs and g-CN NSs creates a nanocomposite ideal for CQL detection because it offers many active sites with a fast electron transfer rate. A lower oxidation potential and higher peak current responsiveness distinguish the proposed drug sensor from previously described CQL sensors. Under optimal conditions, the constructed sensors showed strong analytical performance, as shown by a low detection limit of 2.2 nM, high sensitivity of 15.6 µA µM−1 cm−2, a broad linear range of 0.3–220 µM, and significant recovery outcomes in the analysis of real samples. Thus, the VC/g-CN NSs NC material has promise for use in high-performance electrochemical applications.

Co/N nanoparticles supported on a C3N4/polydopamine framework as a bifunctional electrocatalyst for rechargeable zinc-air batteries

• An electrocatalyst with Co NPs on a graphitized N -doped carbon framework are prepared. • The synthetic strategy avoids the excessive growth and aggregation of metal nanoparticles. • The catalyst has an improved ORR and OER activity compared with Pt/C and Ir/C, respectively. • The synthetic catalyst-containing ZABs present an outstanding discharging performance. Metal N -doped carbons (M N C) and specifically cobalt-based N -doped carbons (Co N C) have attracted extensive attention as suitable multifunctional catalysts. Their high catalytic activity, originating from the strong coupling effect of Co with N, lead to the formation of active sites with suitable binding energies for promoting the discharging and charging reactions. Herein, we propose the synthesis of an efficient bifunctional electrocatalyst (ZIFCNDA) prepared by the introduction of Co ions during the polymerisation of dopamine, which lead to the direct doping of a carbon framework and the localized growth of Co-based MOFs polyhedrons, generating Co-based nanoparticles (Co NPs) upon pyrolysis. The C 3 N 4 -controlled polydopamine growth formed thin graphitized carbon nanosheets which can facilitate the transfer of electrons to the catalytically active sites. The ZIFCNDA catalyst was able to efficiently catalyse both the oxygen reduction (ORR) and oxygen evolution (OER) reactions). The ZAB containing the developed catalyst presented a stable discharge voltage of 1.1 V at a high current density of 10 mA cm −2 with higher stability and longer cycle life compared to their counterparts constructed using Pt/C and Ir/C in air–cathode. This study illustrates a platform to enhance the catalytic activity of the ORR and OER catalyst via promoting the formation of well distributed cobalt active sites, achieved due to the insertion of cobalt ions during the polymerization process of dopamine, instead of on a previously prepared framework and their application for rechargeable metal–air batteries.

A robust in-situ catalytic graphitization combined with salt-template strategy towards fast lithium-ions storage

Lithium-ion hybrid supercapacitors (LIHSs) have received significant attention in electrochemical energy-related areas. However, the sluggish anode kinetics hinders the improvement of power density and cycling stability. Herein, an in-situ catalytic graphitization with a salt-template strategy was applied to prepare the porous graphitic carbon nanosheets. The results demonstrated that the addition of KCl led to a higher specific surface area and higher porous structure. The as-prepared potassium-induced porous graphitic carbon flakes (PPGCs) exhibited an electrochemical plateau capacity of 240.1 mAh g −1 and an electrochemical slope capacity of 129.0 mAh g −1 . PPGCs also delivered superior rate performance of 60.8 mAh g −1 even at 5.0 A g −1 , which was much better than graphitic carbon flakes (GCFs) and potassium-induced graphitic carbon flakes (PGCFs). When assembled into LIHSs devices with commercial activated carbon, the energy density reached 75.6 Wh kg −1 , and the power density was as high as 5.05 kW kg −1 . After 10,000 cycles at 5.0 A g −1 , the energy density was maintained at 39.2 Wh kg −1 , revealing excellent long-term cycling performance. This work may provide a promising solution to obtain graphitic carbon with a high graphitization degree and highly porous structure. • In-situ catalytic graphitization incorporated into salt-template strategy was developed. • Porous graphene-like graphitic carbon nanosheets were achieved successfully. • The effect of KCl added before and after hydrothermal procedure was illustrated. • The energy density reached 75.6 Wh kg −1 with 68.4% retention after 10,000 cycles.

Bifunctional electrocatalyst with CoN3 active sties dispersed on N-doped graphitic carbon nanosheets for ultrastable Zn-air batteries

Realizing large-scale production of low-cost bifunctional catalysts is pivotal to promoting the practical application of Zn-air batteries. Herein, we successfully constructed unique bifunctional CoN3 catalytic sites atomically dispersed on N-doped graphitic carbon nanosheets (CoSA/NCs), which enable Zn-air batteries with ultrahigh durability for over 6000 cycles (~ 2000 h). The 2D carbon construction and single-atom Co formation were achieved simultaneously in salt-assisted process employing CoCl2. CoCl2 serves as a recyclable template, a pore-making agent, and a catalyst for graphitization, which effectively enables the catalyst with abundant active sites catalyze ORR and OER. Our experimental and theoretical modeling results confirm that of CoN3 surpasses CoN4 in term of the ORR and OER catalytic activity. The Zn-air battery based on CoSA/NCs catalyst exhibits a high peak power density of 255 mW cm−2. With unparalleled catalytic performance and low production cost, this catalyst paves the way for the potential large-scale application of Zn-air batteries.

New nitrogen-doped graphitic carbon nanosheets with rich structural defects and hierarchical nanopores as efficient metal-free electrocatalysts for oxygen reduction reaction in Zn-Air batteries

Carbon materials are highly promising alternative metal-free catalysts for oxygen reduction reaction (ORR), an important element reaction involved in various energy storage/conversion processes, while controllable and fine structural and morphological tunning is key for maximizing the catalytic performance. Here, we report the rational design of hierarchical porous graphitic carbon nanosheets with rich defects (d-pGCS) based on a facile two-step thermal treatment route, delivering superior catalytic ORR performance in alkaline electrolytes. The second thermal treatment is critical in creating such structural defects and nanopores. Through optimizing synthesis parameters, d-pGCS-1000 exhibits outstanding electrocatalytic ORR performance in terms of positive onset potential (0.95 V), half-wave potential (0.82 V), and limiting current density (6.02 mA cm−2). As a proof-of-concept, the obtained Zn-air battery delivers a large open-circuit voltage (1.42 V), high peak power density (182.8 mW cm−2), high specific capacity (773 mAhgZn−1), and good rate performance. Such results are comparable to or even better than the Pt/C-based Zn-air battery.

Atomically-dispersed Mn-(N-C2)2(O-C2)2 sites on carbon for efficient oxygen reduction reaction

Owing to their ultimate mass-catalytic activity, simple active site configuration and readily tunable electronic structures, transition-metal single atoms (SAs) on carbon support have emerged as a new category of electrocatalysts for oxygen reduction reaction (ORR). Here, we exemplify the use of atomically dispersed Mn with N, O heteroatoms-coordinated Mn sites to enhance alkaline ORR performance. A combined sol-gel/carbonization approach is developed to controllably anchor Mn-SAs onto graphitic carbon nanosheets via a hybridized N, O coordination configuration of Mn-(N-C2)2(O-C2)2 (denoted as Mn-SA@CNSs). The obtained Mn-SA@CNSs exhibits superior alkaline ORR electrocatalytic activity with a half-wave potential of 0.88 V vs. RHE in 0.1 M KOH. The rechargeable Zn–air battery assembled using Mn-SA@CNSs air cathode can readily attain a high power density of 177 mW cm−2 with a narrow voltage gap of 0.76 V at 5 mA cm−2. Density functional theory calculations unveil that altering the coordination environment of Mn-SAs from N-coordinated Mn-(N-C2)4 to N-/O-coordinated Mn-(N-C2)2(O-C2)2 alters the d-band electronic structures and regulates the binding strength of ORR intermediates on Mn-SA sites to dramatically reduce the energy barrier and enhance ORR activity. The exemplified hybridization coordination approach in this work would be applicable to alter the electronic structures of other transition-metal SAs for ORR and other reactions.

High-temperature deoxygenation-created highly porous graphitic carbon nanosheets for ultrahigh-rate supercapacitive energy storage

Developing carbon-based supercapacitors with high rate capability is of great importance to meet the emerging demands for devices that requires high energy density as well as high power density. However, it is hard to fabricate a nanocarbon with high electro-active surface area meanwhile maintaining superior conductivity to ensure the high rate capability since excellent conductivity is usually realized by high temperature graphitization, which would lead to the structural collapse and sintering resulting in low surface area. Herein, we reported a highly porous graphitic carbon nanosheet with an unprecedented rate capability of 98% of its initial capacitance from 0.5 to 50 A/g for ultrahigh-rate supercapacitive energy storage. These hierarchical mesoporous carbon nanosheets (HMCN) were fabricated by a template induced catalytic graphitization approach, in which sheet-like Mg(OH)2 was employed as catalytic template in situ catalytically polymerizing of catechol and formaldehyde and catalytically graphitizing of the formed carbon skeleton. Upon the co-effect of template (avoiding the sintering) and the deoxygenation (creating the pores) during the high temperature graphitization process, the obtained HMCN material possesses nanosheet morphology with highly porous graphitic microstructure rich in mesoporosity, large in surface area (2316 m2/g), large in pore volume (3.58 cm3/g) and excellent in conductivity (109.8 S/cm). In 1.0 M TEABF4/AN, HMCN exhibits superior supercapacitive performance including large energy density of 52.2 Wh/kg at high power density of 118 kW/kg, long-cycling stability and excellent rate capability, making HMCN a promising electrode material for supercapacitor devices.

Impacts of Metal-Support Interaction on Hydrogen Evolution Reaction of Cobalt-Nitride-Carbide Catalyst.

Cobalt-nitride-carbide (Co-N-C) catalysts are promising cost-efficient transition metal catalysts for electrocatalytic hydrogen evolution, but few works investigate the metal–support interaction (MSI) effect on hydrogen evolution reaction (HER) performance. Herein, efficient Co-N-CX catalysts with controllable MSI between encapsulated Co nanoparticles and nitrogen-doped graphitic carbon nanosheets were synthesized via a facile organic–inorganic hybridization method. Results demonstrate that the Co-N-C0.025M catalyst with the coexistence of single-atom Co sites and Co nanoparticles prepared by 0.025 M cobalt nitrate shows excellent HER performance, achieving a low overpotential of 145 mV to reach 10 mA cm−2 in 0.5 M sulfuric acid, which is mainly because the optimal MSI, which leads to a moderate hydrogen adsorption energy and improved electroactive sites, not only facilitates the charge transfer to improve the HER kinetics, but also improves the durability of the catalyst by Co-N bond anchoring and encapsulation of active Co species. This work provides guidance to further reveal the influence of MSI on their catalytic activity.

Sustainable development of graphitic carbon nanosheets from plastic wastes with efficient photothermal energy conversion for enhanced solar evaporation

Plastic wastes are converted into two-dimensional carbon nanosheets with a graphitic-like structure and interlayer channels for improved solar evaporation performance.

Novel co-doped iron oxide and graphitic carbon nanosheets on biochar for arsenite removal from contaminated water: Synthesis, applicability and mechanism

Arsenite (AsIII) is the most toxic form of arsenic in drinking water, but AsIII removal is still a challenge. In this study, α-Fe2O3-doped graphitic carbon nanosheets were coated on the surfaces of coconut biochar backbone to remove AsIII from contaminated water. The properties of the composites and the efficiency of AsIII treatment were measured by modern techniques and methods, such as XPS, SEM-EDS, ICP–MS, BET analyses. The novel composites enhance AsIII removal capacity by up to 99.85%, and exhibited high effectiveness for AsIII removal over a large pH range from 3 to 9. In addition, XPS analysis revealed that the FeCl3-derived composites have the ability to oxidize AsIII into AsV species on the composite surfaces due to its catalytic properties. The novel composites can be considered adsorbents that can treat a large AsIII concentration range to obtain safe aqueous As levels according to the WHO guidelines for drinking water.

Coordination regulated pyrolysis synthesis of ultrafine FeNi/(FeNi)9S8 nanoclusters/nitrogen, sulfur-codoped graphitic carbon nanosheets as efficient bifunctional oxygen electrocatalysts

Design of advanced carbon nanomaterials with high-efficiency oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities is still imperative yet challenging for searching green and renewable energies. Herein, we synthesized ultrafine FeNi/(FeNi)9S8 nanoclusters encapsulated in nitrogen, sulfur-codoped graphitic carbon nanosheets (FeNi/(FeNi)9S8/N,S-CNS) by coordination regulated pyrolyzing the mixture of the metal precursors, dithizone and g-C3N4 at 800 °C. The as-prepared FeNi/(FeNi)9S8/N,S-CNS exhibited distinct electrocatalytic activity and stability for the ORR with positive onset (Eonset) and half-wave (E1/2) potentials (Eonset = 0.97 V; E1/2 = 0.86 V) and OER with the small overpotential (η = 283 mV) at 10 mA cm−2 in the alkaline media, outperforming commercial Pt/C and RuO2 catalysts. This research provides some constructive guidelines for preparing efficient, low-cost and stable nanocatalysts for electrochemical energy devices.