Ultrathin Porous Carbon Research Articles

Construction of NiCo2O4 nanorods into 3D porous ultrathin carbon networks for high-performance asymmetric supercapacitors

Rational design of electrode architecture and utilization of distinct components are effective strategies to further enhance the performance of supercapacitors. In this work, a novel hybrid heterostructure consisting of NiCo2O4 nanorods with diameter between 10 nm and 20 nm grown on three-dimensional porous carbon (3D-OPC) is successfully fabricated via a simple direct nucleation on 3D-OPC matrix under hydrothermal conditions. The merits of highly conductive porous carbon and short ion transport channels in NiCo2O4 nanorods together with the synergistic effect between NiCo2O4 and 3D-OPC result in a higher specific capacitance of 1297 F g−1 at 0.5 A g−1 and enhanced rate capability (1253.6 Fg−1 at 5 A g−1) compared with urchin-like NiCo2O4. Moreover, an asymmetric supercapacitor device using hybrid NiCo2O4/3D-OPC and porous carbon as electrodes delivers a high energy density of 29.23 Wh kg−1 at 1.55 kW kg−1, outstanding power density (7.75 kW kg−1 at 27.38 Wh kg−1), and good cycling stability (capacitance retention of 87.6% after 3000 cycles at 1 A g−1), making it as one of the most promising candidates for electrochemical energy storage.

Ultrathin Honeycomb-like Carbon as Sulfur Host Cathode for High Performance Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries have attracted great interest because of its high theoretical capacity (1675 mA h g–1). However, the low electrical conductivity of sulfur, dissolution of polysulfides, and structural collapse of electrode limit its practical application. Here an ultrathin honeycomb-like porous carbon derived from loofah sponge and doped with nitrogen (PCLSN) is prepared as a stable host for sulfur nanoparticles. Attributed to the integrated honeycomb structure, hierarchical porosity, ultrathin honeycomb walls, and synergistic effects between physical and chemical adsorption of polysulfides, the developed PCLSN@S cathode achieves a high initial specific capacity of 1379 mA h g–1 at 0.1 C, outstanding cyclability with a small capacity decay rate of 0.044% per cycle over 970 cycles at 2 C, excellent rate performance with a high capacity of 664 mA h g–1 at 3 C, and high sulfur content of PCLSN@S up to 76.1%. Our approach provides a promising route to design other 3D porous structures for high ...

Cobalt and nitrogen codoped ultrathin porous carbon nanosheets as bifunctional electrocatalysts for oxygen reduction and evolution

Development of efficient, low-cost, and durable electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is scientifically and technologically important for the conversion and storage of renewable energy. Herein, cobalt and nitrogen codoped ultrathin porous carbon nanosheet (Co-N-PCN) is developed by directly carbonizing the graphene oxide sandwiched cobalt ion adsorbed polyaniline-co-polypyrrole (PACP) precursors. The nitrogen-rich PACP favors the formation of abundant Co-Nx-C active species, while the 2D ultrathin nanosheet structure ensures the high exposure of the generated Co-Nx-C active sites to the electrolyte. In addition, the sandwiched graphene acts as the conductive backbone to facilitate fast charge transfer and enhance the electrode conductivity. Benefiting from the synergistic effect, the Co-N-PCN presents superior electrocatalytic properties with low overpotentials and favorable kinetics to Pt and RuO2 as a bifunctional electrocatalyst for ORR and OER. Remarkably, the potential difference of OER and ORR (ΔE = Ej=10 - E1/2) is as low as 0.81 V in 0.1 M KOH, indicating the Co-N-PCN outperforms most of the previously reported bifunctional electrocatalysts.

Potassium compound-assistant synthesis of multi-heteroatom doped ultrathin porous carbon nanosheets for high performance supercapacitors

Two-dimensional (2D) porous carbon materials have attracted great attentions as high-performance electrodes for supercapacitors due to their large aspect ratio and high surface area. Generally, micropore-dominant 2D carbon materials have higher densities than hierarchically porous 3D carbon materials, which can provide a new possibility of greatly enhancing the volumetric capacitance. Herein, we propose a facile and low-cost synthesis method of biomass-derived porous carbon nanosheets (PCNSs) with the assistance of the KOH derived potassium compounds using fish scale as precursor. The PCNS obtained at 600 °C possesses ultrathin nanosheet structure (with thickness of 3–5 nm), micropore-dominate porosity (with specific surface area of 962 m2 g−1), rich surface heteroatoms (14.64 at% for O, 5.05 at% for N and 0.92 at% for S) and high compacting density (1.06 g cm−3), which endow the electrodes with high gravimetric/volumetric capacitance performance in three-electrode and two-electrode systems.

Self-assembled porous Fe3O4/C nanoclusters with superior rate capability for advanced lithium-ion batteries

Porous Fe3O4/C nanoclusters composed of nanopores with an average size of 7.1 and ~ 2 nm thick carbon layers inlaid homogenously with ~ 5.1 nm Fe3O4 nanocrystals are successfully prepared for the first time via a hydrothermal process using iron chloride hexahydrate, tri-sodium citrate, polyvinylpyrrolidone, glucose and sodium carbonate as starting materials. The obtained powders were systematically characterized by XRD, FESEM, TEM, BET and Raman techniques. It has been found that the self-aggregation of glucose molecules and Fe(OH)3 nanoparticles via the molecular chain entanglements between molecules during the condensation and carbonization of glucose should be responsible for the formation of the precursory agglomerates, which are then turned into the porous Fe3O4/C nanoclusters with complex microstructures. These porous Fe3O4/C nanoclusters used as an anode material for lithium-ion batteries exhibit a high reversible capacity of 997.6 mAh g−1 after 200 cycles at 1 A g−1, and a high-rate delivery of 807.6 mAh g−1 after 500 cycles at 4 A g−1. The superior performance of Fe3O4/C nanoclusters is mainly attributed to the local dynamic confinement of tiny Fe3O4 nanoparticles in the ultrathin porous carbon matrix.

A Molecular Pillar Approach To Grow Vertical Covalent Organic Framework Nanosheets on Graphene: Hybrid Materials for Energy Storage.

Hybrid 2D-2D materials composed of perpendicularly oriented covalent organic frameworks (COFs) and graphene were prepared and tested for energy storage applications. Diboronic acid molecules covalently attached to graphene oxide (GO) were used as nucleation sites for directing vertical growth of COF-1 nanosheets (v-COF-GO). The hybrid material has a forest of COF-1 nanosheets with a thickness of 3 to 15 nm in edge-on orientation relative to GO. The reaction performed without molecular pillars resulted in uncontrollable growth of thick COF-1 platelets parallel to the surface of GO. The v-COF-GO was converted into a conductive carbon material preserving the nanostructure of precursor with ultrathin porous carbon nanosheets grafted to graphene in edge-on orientation. It was demonstrated as a high-performance electrode material for supercapacitors. The molecular pillar approach can be used for preparation of many other 2D-2D materials with control of their relative orientation.

Hierarchically porous Zn-Co-O NCs-in-carbon hollow microspheres with high rate-capacity and cycle stability as anode materials for lithium-ion batteries

Zn-Co-O/C hollow microspheres composed of center hole with an average size of 400 nm and ∼30 nm thicked porous carbon walls inlaid homogenously with ∼5.2 nm Zn-Co-O nanocrystals are successfully prepared for the first time via a Na-citrate mediated solvothermal method and a subsequent annealing process of Zn-Co-ethylene glycolate (Zn-Co-EG) precursor. The obtained powders were systematically characterized by XRD, IR, FESEM, TEM, BET and Raman techniques. The data indicate that the polymerization reaction of Zn-Co-EG crystals confined by Na-citrate should be responsible for the formation of the hollow microspherical precursors, which are then converted into the hierarchically porous Zn-Co-O/C hollow microspheres with complex microstructures after annealing at 450 °C for 3 h. These porous Zn-Co-O/C hollow microspheres used as an anode material for lithium-ion batteries exhibit a high reversible capacity of 991.7 mAh g−1, 81.6% of the second cycle discharge capacity after 200 cycles at 1 A g−1, and a high-rate delivery of 823.4 mAh g−1 after 1000 cycles at 4 A g−1. The superior performance of Zn-Co-O/C hollow microspheres is mainly attributed to the local dynamic confinement of tiny Zn-Co-O nanoparticles in the ultrathin porous carbon matrix.

Ultrathin Nitrogen-Doped Carbon Coated with CoP for Efficient Hydrogen Evolution

Searching for non-noble-metal-based electrocatalysts with high efficiency and durability toward the hydrogen evolution reaction (HER) is vitally necessary for the upcoming clean and renewable energy systems. Here we report the synthesis of CoP nanoparticles encapsulated in ultrathin nitrogen-doped porous carbon (CoP@NC) through a metal–organic framework (MOF) route. This hybrid exhibits remarkable electrocatalytic activity toward the HER in both acidic and alkaline media, with good stability. Experiments and theoretical calculations reveal that the carbon atoms adjacent to N dopants on the shells of CoP@NC are active sites for hydrogen evolution and that CoP and N dopants synergistically optimize the binding free energy of H* on the active sites, which results in a higher electrocatalytic activity in comparison to its counterparts without nitrogen doping and/or CoP encapsulation.

Porous ultrathin carbon nanobubbles formed carbon nanofiber webs for high-performance flexible supercapacitors

Porous ultrathin carbon nanobubbles formed carbon nanofiber webs exhibit 94.1% capacitance retention after 35 000 cycles at a current density of 10 A g−1.

Insight into highly efficient simultaneous photocatalytic removal of Cr(VI) and 2,4-diclorophenol under visible light irradiation by phosphorus doped porous ultrathin g-C3N4 nanosheets from aqueous media: Performance and reaction mechanism

Carbon nitride (g-C3N4) has attracted great attention for its wide applications in hydrogen evolution and photocatalytic degradation. In this study, phosphorus doped porous ultrathin carbon nitride nanosheets (PCN-S) were prepared successfully via the element doping and thermal exfoliation method. The prepared PCN-S was characterized by XRD, SEM, TEM, N2-adsorption-desorption measurement, FT-IR, XPS, UV–vis diffuse reflectance spectra, photoluminescence (PL), photocurrent response (I-t) and EIS. The results show that PCN-S owns regular crystal structure of g-C3N4, large specific surface areas and nanosheet structure with lots of in-plane pores on its surface, excellent chemical stability, and broad light response to the whole visible light region, which was attributed to the doping of phosphorus element. Under visible light irradiation, the photocatalytic reduction of Cr(VI) over different samples indicated that the P doping and porous nanosheet structure play an important role for the enhanced performance of PCN-S. The reason was that P element doping can broaden the visible light response region, and large specific surface areas from the porous nanosheet structure can provide quantities of active sites for the photocatalytic reaction. Then the detailed study on the PCN-S for simultaneous photocatalytic reduction of Cr(VI) and oxidation of 2,4-diclorophenol (2,4-DCP) was conducted. The experiments results show that low pH value and enough dissolved oxygen were found to promote Cr(VI) reduction and 2,4-DCP oxidation. The detailed photocatalytic mechanism was proposed. The strategies used in this study could provide new insight into the design of g-C3N4 based materials with high photocatalytic activity, and present potential for the treatment of Cr(VI)/2,4-DCP or other mixed pollutants in wastewater.

Template-free synthesis of ultrathin porous carbon shell with excellent conductivity for high-rate supercapacitors

The ultrathin porous carbon shell with the thickness of about 10 nm has been fabricated by a facile method using sodium citrate as carbon precursor without any activation. The electric conductivity of the material is as high as 7.12 S/cm, which contributes to a good rate performance for supercapacitor electrode without any conductive additive. When tested in 6 M KOH by three-electrode system, the C-700 sample exhibits specific capacitance of 251 F g−1 at 1 A g−1, high rate capability with the specific capacitance of 228 F g−1 at 20 A g−1, only a loss of 3% after 10000 cycles at a current density of 3 A g−1. Non aqueous performance was tested in 1 M TEA-BF4/acetonitrile, the material can deliver an energy density of 12–17 Wh kg−1 in a two-electrode system. Apparently, the porous carbon with ultrathin structure can provide low-resistant pathways and short ion diffusion channels for energy storage. Therefore, the ultrathin porous carbon shell would be a promising material particularly for applications where high power output performances are required.

Carbon-Encapsulated Co3O4 Nanoparticles as Anode Materials with Super Lithium Storage Performance.

A high-performance anode material for lithium storage was successfully synthesized by glucose as carbon source and cobalt nitrate as Co3O4 precursor with the assistance of sodium chloride surface as a template to reduce the carbon sheet thickness. Ultrafine Co3O4 nanoparticles were homogeneously embedded in ultrathin porous graphitic carbon in this material. The carbon sheets, which have large specific surface area, high electronic conductivity, and outstanding mechanical flexibility, are very effective to keep the stability of Co3O4 nanoparticales which has a large capacity. As a consequence, a very high reversible capacity of up to 1413 mA h g−1 at a current density of 0.1 A g−1 after 100 cycles, a high rate capability (845, 560, 461 and 345 mA h g−1 at 5, 10, 15 and 20 C, respectively, 1 C = 1 A g−1), and a superior cycling performance at an ultrahigh rate (760 mA h g−1 at 5 C after 1000 cycles) are achieved by this lithium-ion-battery anode material.

Ultrafast permeation of water through protein-based membranes

Pressure-driven filtration by porous membranes is widely used in the production of drinking water from ground and surface water. Permeation theory predicts that filtration rate is proportional to the pressure difference across the filtration membrane and inversely proportional to the thickness of the membrane. However, these membranes need to be able to withstand high water fluxes and pressures, which means that the active separation layers in commercial filtration systems typically have a thickness of a few tens to several hundreds of nanometres. Filtration performance might be improved by the use of ultrathin porous silicon membranes or carbon nanotubes immobilized in silicon nitride or polymer films, but these structures are difficult to fabricate. Here, we report a new type of filtration membrane made of crosslinked proteins that are mechanically robust and contain channels with diameters of less than 2.2 nm. We find that a 60-nm-thick membrane can concentrate aqueous dyes from fluxes up to 9,000 l h(-1) m(-2) bar(-1), which is approximately 1,000 times higher than the fluxes that can be withstood by commercial filtration membranes with similar rejection properties. Based on these results and molecular dynamics simulations, we propose that protein-surrounded channels with effective lengths of less than 5.8 nm can separate dye molecules while allowing the ultrafast permeation of water at applied pressures of less than 1 bar.

Metal-dispersed porous carbon films as electrocatalytic sensors

The attractive features of ultrathin porous carbon films have been coupled with the efficient catalytic action of dispersed metal particles. In particular, loading of these submicrometer foams with ruthenium or platinum centers offers a dramatic increase in the electron transfer rates of important redox systems, such as NADH, uric acid, ascorbic acid, acetaminophen, hydrazine or hydrogen peroxide. Characterization of the electrocatalytic behavior (with respect to the pH, scan rate or metal loading) and the attractive low-potential analytical (sensing) performance are reported. Scanning electron microscopy sheds useful insights into the distribution of the metals within the porous electrode matrix.

Ultrathin Porous Carbon Films as Amperometric Transducers for Biocatalytic Sensors

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUltrathin Porous Carbon Films as Amperometric Transducers for Biocatalytic SensorsJoseph. Wang, Qiang. Chen, Clifford L. Renschler, and Christine. WhiteCite this: Anal. Chem. 1994, 66, 13, 1988–1992Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Published inissue 1 July 1994https://doi.org/10.1021/ac00085a011RIGHTS & PERMISSIONSArticle Views249Altmetric-Citations36LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts