Mesoporous Carbon Nanosheets Research Articles

Self-deposition for mesoporous carbon nanosheet with supercapacitor application

Porous carbon sheets have wide application prospects in many fields, especially in energy storage of supercapacitor due to the features combining both 2D structure and porous architectures. Herein, a self-deposition approach is proposed to obtain N-doped mesoporous carbon nanosheets (N-MCNs), using 3-aminophenol (3-AF) as precursor and Mg(OH)2 sheet as hard template. This process realizes the direct carbon formation using 3-AF monomer as carbon precursor under the catalysis of hard template avoiding the polymerization and utilization of solvent. The mass ratio of 3-AF to Mg(OH)2 plays an important role in determining the pore structures and the resulting capacitance behavior. The results show that N-MCNs with a mass ratio of 3-AF and Mg(OH)2 of 1:1 have good electrochemical behavior for supercapacitors. This N-MCNs based electrode exhibits a high capacitance of 240 F·g−1 at 1 A·g−1, good rate performance (75.4% retention ratio at 20 A·g−1), and high cycling stability with 98.3% initial capacitance retained after 10000 cycles. Symmetric supercapacitors on N-MCNs achieve energy density of 18.2 W·h·kg−1 and power density of 0.4 kW·kg−1 operated within a wide potential range of 0–1.6 V in 1.0 mol·L−1 Na2SO4 solution, exhibiting its potential for electrode materials with high performance.

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.

Two-dimensional mesoporous nitrogen-rich carbon nanosheets loaded with CeO2 nanoclusters as nanozymes for the electrochemical detection of superoxide anions in HepG2 cells

Two-dimensional (2D) porous carbon-based composite nanosheets loaded with metal oxide nanoclusters are expected to be promising electrocatalysts for high-performance electrochemical sensors. However, for this complicated composite material, strict reaction conditions and complex synthesis steps limit its general application in electrochemical detection. Here we present a facile method to fabricate 2D mesoporous nitrogen-rich carbon nanosheets loaded with CeO2 nanoclusters (2D-mNC@CeO2), for fabricating superoxide anions (O2•−) electrochemical sensor. The method is based on block copolymers self-assembly and the affinity of polydopamine to metal ions to obtain organic-inorganic hybrid, which can be directly converted into 2D-mNC@CeO2 through carbonization strategy without structural deterioration. Characterizations demonstrate that the 2D-mNC@CeO2 owned the 2D N-doped carbon structure with an interlinked hierarchical mesoporous and the uniformly dispersed CeO2 nanoclusters on the surface. Benefitted from the unique structure, the 2D-mNC@CeO2 shortens electron transfer distance, enhances mass transfer efficiency, exposes numerous active sites, and obtain a high Ce3+/Ce4+ ratio for improving electrocatalytic performance. The 2D-mNC@CeO2/SPCEs sensors for O2•− detection has a detection limit of 0.179 μM (S/N = 3) and sensitivity of 401.4 μA cm-2 mM-1. The sensors can be applied to capture electrochemical signals of O2•− released from HepG2 cells, demonstrating the application potential of the sensors to monitor O2•− in biological fields.

Urea-Mediated Monoliths Made of Nitrogen-Enriched Mesoporous Carbon Nanosheets for High-Performance Aqueous Zinc Ion Hybrid Capacitors.

Aqueous zinc ion hybrid capacitors (aZHCs) are of great potential for large-scale energy storage and flexible wearable devices, of which the specific capacity and energy density need to be further enhanced for practical applications. Herein, a urea-mediated foaming strategy is reported for the efficient synthesis of monoliths consisting of nitrogen-enriched mesoporous carbon nanosheets (NPCNs) by prefoaming drying a solution made of polyvinylpyrrolidone, zinc nitrate, and urea at low temperatures, foaming and annealing at high temperatures, and subsequent acid etching. NPCNs have a large lateral size of ≈40µm, thin thickness of ≈55nm, abundant micropores and mesopores (≈3.8nm), and a high N-doping value of 9.7 at.%. The NPCNs as the cathode in aZHCs provide abundant zinc storage sites involving both physical and chemical adsorption/desorption of Zn2+ ions, and deliver high specific capacities of 262 and 115 mAh g-1 at 0.2 and 10 A g-1 , and a remarkable areal capacity of ≈0.5 mAh cm-2 with a mass loading of 5.3mg cm-2 , outperforming most carbon cathodes reported thus far. Moreover, safe and flexible NPCNs based quasi-solid-state devices are fabricated, which can withstand drilling and mechanical bending, suggesting their potential applications in wearable devices.

3D holey hierarchical nanoflowers assembled by cobalt phosphide embedded N-doped carbon nanosheets as bifunctional electrocatalyst for highly efficient overall water splitting

With the increasing energy and environmental crisis, exploring convenient and general strategies for constructing of highly active, stable, and cost-effective bifunctional electrocatalysts for overall water splitting are exceedingly desirable yet still challenging. Herein, 3D hierarchical mesoporous cobalt phosphide embedded N-doped carbon nanoflowers (CoP@NCNFs) are successfully constructed with ultrathin nanosheets by phosphatingof the cobalt coordination polymer nanoflowers (CoCPNFs). By virtue of their unique architecture and particular composition, the obtained CoP@NCNFs reveal extraordinary performance with ultralow overpotentials and small Tafel slopes for both OER (291 mV at 10 mA cm−2; 75 mV dec−1) and HER (166 mV at 10 mA cm−2; 76 mV dec−1) in alkaline medium. In particular, CoP@NCNFs can act as both anode and cathode to perform overall water splitting, and the assembled device only needs a cell voltage as low as 1.59 V to achieve the current density of 10 mA cm−2. Simultaneously, the CoP@NCNFs also exhibit admirable durability (at least 15 h) throughout the water splitting process. These remarkable electrocatalytic performances could be attributed to the synergistic effect of highlyactive CoP NPs and conductive mesoporous N-doped carbon nanosheets, which effectively improved the surface contact between catalyst and electrolyte, mass diffusion, and stability.

Micelle-templating interfacial self-assembly of two-dimensional mesoporous nanosheets for sustainable H2O2 electrosynthesis

In this report, we demonstrated a feasible micelle-templating interfacial self-assembling (MTISA) strategy for the controllable synthesis of mesoporous nanosheets with various chemical composition, including polymer, carbon, nitrogen-doped carbon and silica. Micelle-templates derived from the mixture surfactants of F127 and FC4 regulated the polymerization reaction at the water-oil interface, resulting in the formation of mesoporous resorcinol-formaldehyde resin nanosheets (MRFNS). After carbonization, mesoporous carbon nanosheets (MCNS) with thickness of ∼21.5 nm, hierarchical porous structure, and high specific surface area of 740 m2 g−1 can be obtained. Furthermore, our approach can be extended to prepare other 2D mesoporous materials with component of aminophenol-formaldehyde resin and inorganic SiO2 by simply replacing the precursor from resorcinol to aminophenol, or tetraethyl orthosilicate. Besides, the formation mechanism of mesoporous nanosheets through MTISA approach was systematically investigated by variation of the synthesis parameters. Owing to the accessible mesoporous structures with 2D morphology, the MCNS demonstrated efficient and stable H2O2 production both in alkaline and neutral electrolytes. The present synthesis strategy might pave the way to tune the architecture of mesoporous materials through a facile and universal approach.

A Spatial Confinement Strategy for Micelle-Size-Mediated Synthesis of Mesoporous Carbon Nanosheets with Efficient Capacitive Response

A Spatial Confinement Strategy for Micelle-Size-Mediated Synthesis of Mesoporous Carbon Nanosheets with Efficient Capacitive Response

Data-driven design and controllable synthesis of Pt/carbon electrocatalysts for H2 evolution

SummaryTo achieve net-zero emissions, a particular interest has been raised in the electrochemical evolution of H2 by using catalysts. Considering the complexity of designing catalyst, we demonstrate a data-driven strategy to develop optimized catalysts for H2 evolution. This work starts by collecting data of Pt/carbon catalysts, and applying machine learning to reveal the importance of ranking various features. The algorithms reveal that the Pt content and Pt size have the greatest impact on the catalyst overpotentials. Following the data-driven analysis, a space-confined method is used to fabricate the size-controllable Pt nanoclusters that anchor on nitrogen-doped (N-doped) mesoporous carbon nanosheet network. The obtained catalysts use less platinum and exhibit better catalytic activity than current commercial catalysts in alkaline electrolytes. Moreover, the data formed in this work can be used as feedback to further improve the data-driven model, thereby accelerating the development of high-performance catalysts.

N, S co-doped magnetic mesoporous carbon nanosheets for activating peroxymonosulfate to rapidly degrade tetracycline: Synergistic effect and mechanism

Heteroatoms doped carbon materials are widely used in the advanced oxidation process (AOPs) to remove organic pollutants in water due to the synergies effect between different heteroatoms. In this study, a novel kind of N, S co-doped magnetic mesoporous carbon nanosheets (Fe@NS-C) was prepared by simple one-step pyrolysis. Further, the influence of doping amount of S (L-methionine) and N (melamine) on catalytic activity was studied, the optimized sample Fe@NS-C-2-12/PMS showed a satisfying degradation ( 91.07%) for high concentrations of tetracycline (80 mg/L TC) in 10 min, which was attributed to the proper ratio of S content to N content (S(at.%)/ N(at.%)= 0.2097) in the sample could better play its synergistic effect by XPS analysis. The Fe@NS-C-2-12/ PMS system also exhibited satisfactory degradation effects in a wide pH range (3−10) and the existence of inorganic ions and humic acid. Then, the degradation mechanisms were mainly through the non-radical pathway (1O2 and electron transfer) and the major active sites were pyridinic N compared to thiophene S, CO, and Fe-Nx. This study could inspire the design of high-performance active and low-cost heteroatomic doping nano-magnetic catalysts for PMS-based waste treatment.

Biomass derived Fe,N-doped carbon material as bifunctional electrocatalysts for rechargeable Zn-air batteries

The development of affordable and perdurable electrocatalysts for oxygen reduction/evolution reaction (ORR/OER) has been considered as an alternative to address the global energy crisis and grievous environmental pollution. Therefore, exhaustively developing low-cost bifunctional electrocatalysts is of significance especially derived from the ubiquitous carbonous biomass materials. Here, an advanced catalyst of Fe, N-dual doped mesoporous and microporous carbon nanosheets (Fe-MNC) is synthesized by using Fe-pyridine coordination complex as the sources of Fe, N and corn stalk soot as the support. The Fe-MNC possesses vigorous electrocatalytic performance for ORR with an E1/2 of 0.85 V. Moreover, for OER, the overpotential is as low as 309 mV at the current density (j) of 10 mA cm−2 and the Tafel slope is 127 mV dec−1. What's more, a rechargeable Zn-Air battery is constructed based on Fe-MNC as the air cathode. This work not only establishes an easy access and sustainable way to produce a cost-cutting and highly efficient ORR/OER catalyst, but also paves a new way for a greater value-added utilization of biomass carbon for sustainable energy conversation.

The free-standing cathode fabricated with nano-CoSe2 embedded in mesoporous carbon nanosheets towards high performance Li/SeS2 batteries

SeS2, a substitute to S with slightly lower theoretical capacity (1124 mAh g−1) but much improved electric conductivity, requires host with special design to alleviate shuttle effect, accommodate volume variation and ensure fast redox kinetics. Herein, a facile synthesis method via hydrothermal reaction was introduced to fabricate a 3D hierarchical structure composite with CoSe2 nano-particles uniformly distributed in mesoporous carbon nanosheets standing on carbon fiber cloth (marked as [email protected]2). As a whole substrate, the mesopores of [email protected]2 can physically restrain the intermediates migration and accommodate the volume variation, while the CoSe2 can chemically adsorb the intermediates and catalyze their conversion to Li2S/Li2Se efficiently. The [email protected]2 exhibits stronger affinity to polysulfides/polyselenides than the contrast sample [email protected] in the soaking experiment. In addition, the chemical absorption to the polysulfides/polyselenides generated by CoSe2 was further proved via the XPS analysis. Furthermore, the [email protected]2-SeS2 cathode presents 3 times higher exchange current density than the [email protected]2 cathode, suggesting the previous one holds much faster charge-transfer kinetics. Therefore, when tested at 1.0 A g−1, the free-standing [email protected]2-SeS2 cathode presents high initial capacity up to 943.4 mAh g−1 with an outstanding coulombic efficiency. In addition, this cathode exhibits excellent rate performance, delivering 735.9, 677.8, 640.3 and 610.5 mAh g−1 when cycled at 1.0, 2.0, 3.0 and 4.0 A g−1, respectively. This easy fabrication method to obtain a composite with rational design may provide a novel approach for the development of next generation rechargeable batteries.

Magnetic mesoporous carbon nanosheets derived from two-dimensional bimetallic metal-organic frameworks for magnetic solid-phase extraction of nitroimidazole antibiotics

We prepared two-dimensional (2D) bimetallic metal-organic frameworks (Ni-ZIF-8) nanosheets by a simple solvent-free method at room temperature. The morphology and composition of Ni-ZIF-8 can be controlled through adding different amounts of Ni. And then, the 2D magnetic mesoporous nanosheets (Ni/ZnO@C) were synthesized by directly pyrolyzing Ni-ZIF-8 under argon atmosphere and explored as magnetic solid phase extraction (MSPE) adsorbents for the determination of nitroimidazole antibiotics (NIABs). Magnetic Ni nanoparticles embedded in carbon nanosheets uniformly resulted in high magnetization saturation of Ni/ZnO@C for easy separation. The Ni/ZnO@C can form hydrogen bond and π-π interaction with three NIABs resulting from their rich N-H containing imidazole, π-electron. Due to the high specific surface area and high mass transfer rate of 2D Ni/ZnO@C, the materials showed satisfactory adsorption capacity and rapid adsorption kinetics for NIABs. A rapid and effective method of Ni/ZnO@C-MSPE combined with high-performance liquid chromatography was proposed for the determination of NIABs. Several main parameters affecting MSPE were investigated. Under the optimal conditions, wide linear was achieved ranging from 0.1 to 500 µg⋅L−1 with a low detection limit of 0.025-0.05 µg⋅L−1. The established method has been successfully applied to analyze NIABs from environmental water samples with satisfactory recovery from 74.33 to 105.71%.

SnS Nanoparticles Grown on Sn-Atom-Modified N,S-Codoped Mesoporous Carbon Nanosheets as Electrocatalysts for CO2 Reduction to Formate

Electrochemical conversion of carbon dioxide (CO2) to formate provides a method for the synthesis of valuable fuels and chemical products. Herein, SnS nanoparticles were grown in situ on Sn-atom-modified N,S-codoped mesoporous carbon nanosheets. As a result, a novel nanohybrid (NH) catalyst named SnS/Sn-NSC NH was obtained for CO2 electroreduction for formate production. In the obtained NHs, the synergistic effect of SnS nanoparticles (∼2.2 nm) with Sn atoms in the carbon matrix and the 3D hierarchical porous structure could provide more active sites and shorten the diffusion pathway, thereby improving the performance of CO2 reduction. The SnS/Sn-NSC NH showed a high Faradaic efficiency (FE) of formate of 91% at a low potential of −0.7 V (vs reversible hydrogen electrode, RHE). In particular, the SnS/Sn-NSC NH demonstrated a favorable FEformate value of over 80% over a wide potential range. On the basis of spectroscopic characterizations, electrochemical tests, and CO2 adsorption analyses, the origin of the enhanced catalytic performance was suggested. This work offers an efficient strategy to construct 3D hierarchical SnS/Sn-NSC NHs for enhancing formate productivity through CO2 electrocatalytic reduction.

Nitrogen and phosphorus co-doped mesoporous carbon nanosheets derived from bagasse for lithium-ion batteries

N,P co-doped bagasse-based sheet-like mesoporous carbon (NP-BC) for lithium-ion battery anode material was prepared using bagasse and NH4H2PO4 as raw material. Compared with primary bagasse carbon (BC), the specific surface area and the lattice spacing of the NP-BC increased from 1307.21 to 2118.59 m2/g and from 0.34 to 0.385 nm, respectively. The first discharge specific capacity also increased from 1186.59 to 2347.56 mAh/g at 0.05 A/g, and the reversible capacity increased more than twice.

One-step synthesis of nitrogen and sulfur co-doped mesoporous graphite-like carbon nanosheets as a bifunctional material for tetracycline removal via adsorption and catalytic degradation processes: Performance and mechanism

In this study, nitrogen and sulfur co-doped mesoporous graphite-like carbon nanosheets (NS-MGCNS) were synthesized via a facile pyrolysis method. The as-prepared sample at a calcined temperature of 800 °C (NS-MGCNS-800) exhibited remarkably outstanding removal capacity for tetracycline (TC). About 94.5% of TC (20 mg/L) was removed within 60 min via the synergistic effect of adsorption and catalytic degradation processes. Pseudo-second-order adsorption plot and Langmuir models fitted well with the adsorption process. The maximum adsorption capacity of NS-MGCNS-800 was 91.57 mg/g through π-π interactions. Besides, NS-MGCNS-800 could activate persulfate (PS) for TC degradation with the pseudo-first-order degradation reaction rate constant of 0.144 min−1, which was 51.4, 24.0, and 1.3-fold as high as that over graphitic carbon nitride (CN), pure carbon (C), and nitrogen doped carbon nanosheets (N-CNS), respectively. Meanwhile, NS-MGCNS-800 possessed superior reusability for removing TC with the removal efficiency of over 87% after 5 cycles. Quenching tests, electron spin resonance spectroscopy (ESR), and electrochemical measurement revealed that radical and non-radical pathways were involved in the NS-MGCNS-800/PS/TC system. More importantly, by means of experimental methods and density functional theory (DFT) calculations, the introduction of sulfur could significantly adjust the electron density of the carbon lattice though the synergistic effect of nitrogen doped carbon nanosheests, promoting the TC adsorption and PS activation of NS-MGCNS-800. Finally, TC intermediates were detected and six possible degradation pathways of TC were proposed. Consequently, this study not only developed a high-performance bifunctional graphite-like carbon nanomaterial, but also provided a new direction for removing the trace antibiotics in environmental remediation.

Nitrogen and phosphorus co-doped ultrathin carbon nanosheets as superior cathode catalysts for Zn–air batteries

Nitrogen and phosphorus co-doped mesoporous ultrathin carbon nanosheets prepared by a NaCl template method present outstanding ORR activity and can be used as superior cathode catalysts for Zn–air batteries.

Synthesis of core–shell Co@S-doped carbon@ mesoporous N-doped carbon nanosheets with a hierarchically porous structure for strong electromagnetic wave absorption

Electromagnetic wave absorbents with hierarchically porous and core–shell structures have significantly positive influence on the electromagnetic wave absorption because of the enhanced interfacial polarization.

Topological defect-containing Fe/N co-doped mesoporous carbon nanosheets as novel electrocatalysts for the oxygen reduction reaction and Zn-air batteries.

Developing effective electrocatalysts for the oxygen reduction reaction is of great significance for clean and renewable energy technologies, such as metal-air batteries and fuel cells. Defect engineering is the central focus of this field because the overall catalytic performance crucially depends on highly active defects. For the ORR, topological defects have been proven to have a positive effect. However, because preparation and characterization of such defects are difficult, a basic understanding of the relationship between topological defects and catalytic performance remains elusive. In this study, topological defect-containing Fe/N co-doped mesoporous carbon nanosheets were synthesized using azulene-based sandwich-like polymer nanosheets as the precursor. As electrocatalysts, such porous carbon nanosheets exhibited promising ORR activity, methanol tolerance ability, and stability with a half-wave potential of 841 mV under alkaline conditions, which is superior to those of most of the reported porous carbons. As the air cathode for Zn-air batteries, the catalyst exhibited a peak power density of 153 mW cm-2 and a specific capacity of 628 mA h g-1,which were higher than those of a Pt/C-based Zn-air battery. Density functional theory calculation further proved the positive effect of topological defects on the oxygen reduction activity. These results indicate that bottom-up topological defect engineering could be a new and promising strategy for developing high-performance electrocatalysts.

Cobalt–Iron nanoparticles encapsulated in mesoporous carbon nanosheets: A one-pot synthesis of highly stable electrocatalysts for overall water splitting

Advancement of cost-effective, highly efficient and non-noble metal-based bifunctional electrocatalysts is considered an attractive approach to overcome the energy defect and environmental pollution challenges. Herein, this study presents a simple one-pot approach to synthesize cobalt-Iron nanoparticles encapsulated in mesoporous carbon nanosheets (Co3Fe7@CNSs) by the pyrolysis method. The Co3Fe7@CNSs-750/4h electrocatalyst exhibits a notable performance, low overpotential of 181 and 301 mV at a current density of 10 mA cm−2 and small Tafel slope of 124.8 and 38.59 mV dec−1, large active surface area 18.20 and 21.18 mF cm−2, and low charge transfer resistance 4.92 and 9.42 Ω for hydrogen and oxygen evolution reactions, respectively, in 1.0 M KOH. Overall water splitting, with the set-up of two-electrode cells acquires the 10 mA cm−2 of current density at 1.610 V in 1.0 M KOH. The combined structure of cobalt-iron nanoparticles encapsulated in carbon nanosheets; it could enhance the surface area and, provide more active sites that improve the overall catalytic activity. Not only this but also the synergistic effect due to different temperature treatments which significantly influenced the structural formation. However, the major involvement of this study is concerned with the production of economical non-noble metal-based electrocatalysts at an industrial scale for renewable energy to sustainability.

Sub-nanometric Manganous Oxide Clusters in Nitrogen Doped Mesoporous Carbon Nanosheets for High-Performance Lithium-Sulfur Batteries.

The greatest challenge for lithium-sulfur (Li-S) batteries application is the development of cathode hosts to address the low conductivity, huge volume change, and shuttling effect of sulfur or lithium polysulfides (LiPs). Herein, we demonstrate a composite host to circumvent these problems by confining sub-nanometric manganous oxide clusters (MOCs) in nitrogen doped mesoporous carbon nanosheets. The atomic structure of MOCs is well-characterized and optimized via the extended X-ray absorption fine structure analysis and density functional theory (DFT) calculations. Benefiting from the unique design, the assembled Li-S battery displays remarkable electrochemical performances including a high reversible capacity (990 mAh g-1 after 100 cycles at 0.2 A g-1) and a superior cycle life (60% retention over 250 cycles at 2 A g-1). Both the experimental results and DFT calculations demonstrate that the well-dispersed MOCs could significantly promote the chemisorption of LiPs, thus greatly improving the capacity and rate performance.