Porous Graphene-like Carbon Research Articles

Porous Graphene-like Carbon from Fast Catalytic Decomposition of Biomass for Energy Storage Applications.

A novel carbon material made of porous graphene-like nanosheets was synthesized from biomass resources by a simple catalytic graphitization process using nickel as a catalyst for applications in electrodes for energy storage devices. A recycled fiberboard precursor was impregnated with saturated nickel nitrate followed by high-temperature pyrolysis. The highly exothermic combustion of in situ formed nitrocellulose produces the expansion of the cellulose fibers and the reorganization of the carbon structure into a three-dimensional (3D) porous assembly of thin carbon nanosheets. After acid washing, nickel particles are fully removed, leaving nanosized holes in the wrinkled graphene-like sheets. These nanoholes confer the resulting carbon material with ≈75% capacitance retention, when applied as a supercapacitor electrode in aqueous media at a specific current of 100 A·g–1 compared to the capacitance reached at 20 mA·g–1, and ≈35% capacity retention, when applied as a negative electrode for lithium-ion battery cells at a specific current of 3720 mA·g–1 compared to the specific capacity at 37.2 mA·g–1. These findings suggest a novel way for synthesizing 3D nanocarbon networks from a cellulosic precursor requiring low temperatures and being amenable to large-scale production while using a sustainable starting precursor such as recycled fiberwood.

A Potassium Formate Activation Strategy for the Synthesis of Ultrathin Graphene-like Porous Carbon Nanosheets for Advanced Supercapacitor Applications

Ultrathin graphene-like porous carbon nanosheets (GPCNSs) have been proved to be promising candidates for electrochemical energy storage application in view of their extremely large accessible surf...

Controlling synthesis of nitrogen-doped hierarchical porous graphene-like carbon with coral flower structure for high-performance supercapacitors

In this work, nitrogen-doped hierarchical porous graphene-like carbon (NCFC) with coral flower structure is synthesized by an eco-friendly and inexpensive template carbonization method, with cellulose acetate (CA) as carbon precursor, MgO as template, and urea as nitrogen agent. The as-synthesized NCFC features loose coral flower composed of ultra-thin graphene-like sheets and has a high specific surface area of 937 m2 g−1. As the electrode material for supercapacitors, the NCFC shows a high capacitance of 333 F g−1 at 1 A g−1 in 1 mol L−1 H2SO4 electrolyte and a good rate performance (the specific capacitance at 10 A g−1 retains 84% relative to 1 A g−1), and excellent cycle stability with 100% capacitance retention after 10,000 cycles. The symmetric supercapacitor (SSC) was assembled by using NCFC in 1 mol L−1 H2SO4 electrolyte. The device exhibits the maximum energy density of 21 W h kg−1 at a power density of 750 W kg−1 in a potential window of 0 to 1.4 V. Our work is expected to pave a new way for scale-up production of high-performance graphene-like carbon from natural cellulose with a simple, eco-friendly, and low-cost method.

Graphene like Porous Carbon Sheets Derived from Hibiscus Cannabinus As a Versatile Electrochemical Energy Storage Material

In recent years, energy storage devices such as supercapacitors (SC) and Li-ion batteries (LIB) have attracted worldwide interest due to their critical role in replacing the conventional fuels in the transportation sector and also owing to their promising electro-chemical characteristics like long cycle life, high energy density, high power density and low toxicity [1]. In LIBs and SCs, carbon electrode material is arguably an important component and plays a pivotal role in the device performance. However, development of low cost carbon electrode materials with improved energy density and long cycle stability are the great challenges to meet the increasing demands of upcoming electric vehicle technology. Various carbon materials, such as activated carbon, mesoporous carbon, graphene and carbon nanotubes have been extensively studied as electrode materials. However, there are certain limitations using these materials for commercial applications due to their inappropriate pore structure, high cost, tedious synthesis conditions etc. [2]. Graphene-like porous carbon sheets (GPCSs) have recently been viewed as the outstanding electrode materials for high rate electrochemical storage devices such as supercapacitors and Li-ion batteries because the 2D porous carbon sheets can integrate the high conductivity as well as high porosity to promote the facile diffusion of both ion transport and electron transfer. Herein, synthesizing graphene like porous carbon sheets from a renewable biomass waste (Hibiscus cannabinus sticks) is of great importance in lowering the production costs and also promoting environmental protection. The relationship between structure of the GPCS-X (X represents the concentration of activation agent) and its electrochemical performance at different concentration of activating agent is explored in detail. The resulting porous carbon sheets possesses excellent textural parameters with a high specific surface area of 2308 m2/g, highly ordered graphitic carbon with a ID/IG ratio of 0.315 which is confirmed by BET, Raman, HR-TEM (Figure 1a and 1b) etc. While being used as supercapacitor application, the GPCS electrode exhibits a high specific capacitance of 240 F/g at 1A/g, excellent rate capability (84% capacity retention at 50 A/g) and also shows outstanding cyclic stability (92% capacitance retention after 25,000 cycles) in aqueous electrolyte. When tested in organic electrolyte with an extended voltage window, the electrode exhibits symmetric charge-discharge profiles as shown in figure 1c. Also, for Li-ion battery application, GPCS electrode material as shown in figure in 1d displayed a high reversible capacity (1050 mAh/g at 100 mA/g), excellent rate performance (230 mAh/g at 5000 mA/g), and good cycling stability (72% capacitance retention after 400 cycles). The excellent electrochemical performance of GPCS electrode material can be attributed to the high electrical conductivity of the graphene network along with high specific surface area. These results demonstrate a facile, low-cost, eco-friendly design of electrode materials for energy storage applications. Figure 1 (a) FE-SEM and (b) HR-TEM images of GPCS material (c) Charge-Discharge profiles for Supercapacitor application and (d) Rate comparison for Li-ion battery application.

Monodisperse multicore-shell SnSb@SnOx/SbOx@C nanoparticles space-confined in 3D porous carbon networks as high-performance anode for Li-ion and Na-ion batteries

Tin-based materials have attracted intensive attention as promising high-capacity anodes for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). However, they suffer from serious capacity fading owing to the inherent huge volume changes and sluggish kinetics. Herein, we propose a facile and scalable self-assembly NaCl template-assisted in situ catalytic strategy for preparing monodisperse multicore–shell SnSb@SnOx/SbOx@C nanoparticles (10–30 nm) space-confined in three-dimensional (3D) graphene-like porous carbon networks. In the unique nanostructure, the synergistic effect of Sn and Sb and abundant free space provided by porous carbon network effectively relieves the volume change, the amorphous SnOx/SbOx shell enhances the interface interaction between SnSb and carbon as well as facilitates ion diffusion, the graphitic carbon shells and the 3D graphene-like carbon network with high mechanical flexibility not only inhibits the aggregation and pulverization of SnSb, but also improves the integrity and conductivity of electrode. Thus, the nanocomposite electrode deliver a high specific capacity, superior rate capability (337.3 mAh g−1 and 244.3 mAh g−1 at 5 A g−1 for LIBs and SIBs, respectively), and excellent cycling stability (capacity retention of 93% after 200 cycles at 1 A g−1 for LIBs; capacity retention of 80% after 500 cycles at 2 A g−1for SIBs). This work provides new strategy for the design and fabrication of nanocomposite with robust interface interaction for electrochemical energy conversion and storage application.

Co0.85Se on three-dimensional hierarchical porous graphene-like carbon for highly effective oxygen evolution reaction

Designing an efficient, cheap and abundant catalyst for oxygen evolution reaction (OER) is crucial for the development of sustainable energy sources. A novel catalyst which could be a promising candidate for such electrocatalysts is described. Co0.85Se supported on three-dimensional hierarchical porous graphene-like carbon (HPG) exhibits outstanding catalytic performances for OER in alkaline medium. It is found that the onset overpotential is 311 mV on the Co0.85Se/HPG electrode, which is more 28 and 41 mV negative than that on the Co/HPG and Co3O4/HPG electrodes. What's more, the value of Tafel slope is 61.7 mV dec−1 and the overpotential at the current density of 10 mA cm−2 is 385 mV on this electrode. The Co0.85Se/HPG of this work is an appealing electrocatalyst for OER in basic electrolyte.

Facile and Scale Synthesis of Co/N/S-Doped Porous Graphene-Like Carbon Architectures as Electrocatalysts for Sustainable Zinc-Air Battery Cells

Developing low cost and efficient electrocatalysts for oxygen reduction reaction (ORR) is largely beneficial for preparing regenerative zinc-air batteries. Herein, ultrasmall cobalt nanoparticles w...

Facile large-scale synthesis of macroscopic 3D porous graphene-like carbon nanosheets architecture for efficient CO2 adsorption

Chemisorption of CO2 by amine-based solid adsorbents is an effective approach to reduce the greenhouse effect. However, the scalable fabrication of excellent materials with superior CO2 adsorption capacity and outstanding cycle performance remains a big challenge. Here we demonstrate a unique architecture of macroscopic 3D porous graphene-like carbon nanosheets (3D-PGCNs) through a simple one-step carbonization of a mixture of melamine and natural soybean oil. The key feature of 3D-PGCNs is that the formed ultrathin graphene-like carbon nanosheets have crumpled morphology and 3D interconnected macropore structure, leading to a high pore volume (3.48 cm3 g−1) with capable of loading large amount of amine species. As a result, the 3D hybrid (3D-PEI-PGCNs) impregnated with 40 wt% polyethyleneimine (PEI) exhibits a high CO2 adsorption capacity of 117 mg g−1 at 75 °C with excellent cycling stability. This work provides a new strategy for the simple, cost-effective and scalable synthesis of efficient and stable CO2 capture sorbents.

Graphene-like porous carbon nanostructure from Bengal gram bean husk and its application for fast and efficient adsorption of organic dyes

Graphene-like porous carbon nanostructure (BGBH-C-K) is prepared using the Bengal gram bean husk (BGBH) as agro-waste biomass via alkali-activation. Abundance of micropores in the BGBH-C-K furnished high pore volume (0.834 cm3.g−1) and surface area (1710 m2.g−1). The π-electron rich graphitic domains, remarkable textural properties, thorough distribution of micro and meso pores, and presence of oxygen functionalities as deduced by HRTEM, XPS, FTIR, and N2 adsorption-desorption isotherm promise the potential of BGBH-C-K for adsorption of organic dyes. The experimental data revealed excellent adsorption capacity of BGBH-C-K for methylene blue (469 mg.g−1; cationic dye) and methyl orange (418 mg.g−1; anionic dye). The π-π interaction, hydrogen linkage, electrostatic interaction, and trapping of dye molecules on the structural defects facilitate the adsorption of organic dyes by the BGBH-C-K. The adsorption capacity and efficiency are collectively monitored by textural and chemical properties of adsorbents along with size, shape, and charge of dye molecules. The finding revealed the remarkable capability of BGBH-C-K as a dye scavenger for efficient removal from industrial wastewater.

MnO2 Nanostructures Deposited on Graphene-Like Porous Carbon Nanosheets for High-Rate Performance and High-Energy Density Asymmetric Supercapacitors

Graphene-like porous carbon nanosheets (GPCNs) have been proved to have great potential in high-rate performance supercapacitors. However, the relatively low specific capacitance and low working vo...

Three-dimensional graphene-like porous carbon nanosheets derived from molecular precursor for high-performance supercapacitor application

Newly three-dimensional (3-D) graphene-like carbon nanosheet network is synthesized by a simple and efficient buried-protection KOH activation technology with a surfactant (Tween-20) as carbon source (molecular precursor). The as-synthesized material possesses favorable three-dimensional network structure and hierarchical porous structure (with a specific surface area of 2017.3 m2 g−1). As a promising supercapacitor electrode, a relatively high specific capacitance of 316.8 F g−1 at a current density of 1 A g−1 in 1 mol L−1 KOH aqueous solution, along with good cycling stability (with a 92.5% retention rate after 2000 cycles) are demonstrated for the as-prepared electrode. The 3-D graphene-like carbon nanosheet network material exhibits ideal capacitive behavior indicating a promising electrode material for high-performance supercapacitors.

Graphene like porous carbon with wood-ear architecture prepared from specially pretreated lignin precursor

3D graphene (or graphene-like porous carbon) is prepared from precursor lignin separated and purified from alkaline pulp black liquor. The lignin is pretreated using rapid freeze-dry technique for the porous, soft and dispersive microstructure. A special temperature control program is designed to keep the porous structure of lignin particles in the carbonization and graphitization process, avoiding agglomeration. The 3D graphene from lignin consist of curve graphene sheets in dimensions around dozen micrometers, which merge each other with clear dihedral angle and form wood-ear like architecture, different from fullerene like carbon crystals. The porous carbon is characterized and analyzed with FTIR, Raman, XRD, SEM, TEM, XPS, and SSA. A possible chemical mechanism in the synthesis of 3D graphene from lignin precursor is proposed. The aromatic groups and alkane fragments in lignin are decomposed during pyrolysis under high temperature, then the benzene rings compose the graphene sheets, and the sp3 free carbon atoms join the graphene sheets with chemical bonds along the framework of lignin polymer, forming the self-supporting and self-constructing 3D graphene, or porous carbon.

Pd Nanoparticles Confined in the Porous Graphene-like Carbon Nanosheets for Olefin Hydrogenation.

As a novel type of defective graphene, porous graphene has been considered an excellent support material for metal clusters, as the interaction between defective carbon atoms surrounded with the metal nanoparticles (NPs) is very different from that on the ordinary supported catalyst. In this work, we reported a facile three-step method to confine the Pd NPs and grow the graphene-like carbon nanosheets (GLCs) in the same interlayer space of the layered silicate, generating embedded Pd NPs in the pores of porous GLCs in situ. The Pd@GLC nanocomposite exhibited not only high activity and stability than the common commercial Pd/C catalyst for the hydrogenation of olefins but also superior ability of resisting high temperature, which benefitted from the two-dimensional structure of layered GLCs, the confinement of Pd, and the increased edge and defect of the unsaturated carbon atoms in GLCs.

Interconnected nitrogen and sulfur co-doped graphene-like porous carbon nanosheets with high electrocatalytic activity as counter electrodes for dye-sensitized and quantum dot-sensitized solar cells

Interconnected nitrogen and sulfur co-doped graphene-like porous carbon nanosheets (NSGPCSs) are facilely produced by thermal annealing methyl orange (MO) doped polypyrrole (PPy) nanotubes at the presence of KOH under N2 atmosphere at 700 °C. The pyrolysis of PPy combined with the dedoping of PPy nanotubes derived from the interactions between KOH and MO lead to transforming 1D PPy nanotubes into 2D graphene-like carbon nanosheets. The as-prepared NSGPCSs have high specific surface area (up to 1744.98 m2 g−1) and hierarchical porosity, and are investigated as the counter electrodes for dye-sensitized and quantum dot-sensitized solar cells. The unique characteristics such as co-doping of nitrogen and sulfur heteroatoms, high specific surface area, and interconnected graphene-like nanosheets with hierarchical porosity render NSGPCSs a promising electrode material for photoelectrochemical cells. Electrochemical investigations indicate that NSGPCS electrodes display excellent electrocatalytic activity for the regeneration of the I−/I3− and polysulfide electrolytes. As a result, the dye-sensitized solar cell based on NSGPCS electrode achieves a conversion efficiency of 8.21%, which is very close to that of the cell based on conventional Pt electrode (8.61%). The efficiency of the quantum dot-sensitized solar cell assembled with NSGPCS counter electrode is significantly higher than that of the cell assembled with Pt counter electrode, and comparable to that of the cell assembled with PbS counter electrode.

Synthesis of porous graphene-like carbon materials for high-performance supercapacitors from petroleum pitch using nano-CaCO3 as a template

Porous graphene-like carbon materials (PGCMs) for supercapacitors were synthesized from petroleum pitch by a nano-CaCO3 template strategy combined with KOH activation. The PGCMs were characterized by TEM, XPS, Raman spectroscopy and N2 adsorption. Results show that their specific surface areas are 1542-2305 m2·g−1, depending on the template/pitch ratio, KOH/pitch ratio and activation temperature. The PGCMs feature interconnected graphene-like carbon layers with abundant small pores. The optimum supercapacitor electrode is produced when the PGCM is synthesized with a template/pitch ratio of 1.5, a KOH/pitch ratio of 1.5 at 850 °C for 1h. It has a specific capacitance of 293 F·g−1 at a current density of 0.05 A·g−1, an excellent rate capability with a capacitance of 231 F·g−1 at a current density of 20 A·g−1 and an outstanding cycling stability with a 97.4% capacitance retention after 7000 cycles in a 6 M KOH aqueous electrolyte. It also exhibits a high specific capacitance of 267 F·g−1 at a current density of 0.05 A·g−1, and a high energy density of 148.3 Wh·kg−1 at a power density of 204.2 W·kg−1 in a BMIMPF6 ionic liquid electrolyte. This is a possible method for the synthesis of PGCMs for high-performance supercapacitors.

Graphene-like porous carbon nanosheets derived from salvia splendens for high-rate performance supercapacitors

Graphene-like porous carbon nanosheets (GPCNs) have recently been viewed as the outstanding electrode materials for high-rate-performance supercapacitors because the 2D nanosheets can integrate high conductivity and high aspect ratio together to promote both ion transport and electron transfer. The fabrication of GPCNs from sheet-like plant raw materials is of great importance to lowering production cost and simultaneously to promoting environment protection. Herein, we demonstrate the utilization of salt sealing strategy to fabricate GPCNs with flower petals as the precursor. The petals of salvia splendens are firstly crushed and sealed in NaCl crystal. After pyrolysis at the optimal temperature, salvia splendens-derived, O/N-codoped GPCNs are obtained by washing off NaCl with water. The resulting GPCNs possess a relatively high specific surface area and a moderate O, N contents. Owing to these characteristics, the GPCNs-based supercapacitor exhibits high rate capability (88.6% and 83.4% capacity retention from 1 to 100 A g−1 in 6 M KOH and 1 M Na2SO4 solutions, respectively) and excellent stability. Taking into account the species diversity, renewability, and abundance of plant raw materials, they can serve as a novel kind of precursors for the fabrication of heteroatom-doped GPCNs for high-rate-performance supercapacitors.

Graphene-like porous carbon from sheet cellulose as electrodes for supercapacitors

Graphene, a single layer of carbon atoms arranged in an hexagonal lattice, has attracted a lot of well-deserved attention due to its high surface area and excellent electrochemical properties. However, graphene is easy to aggregate and has poor volumetric performance when used as electrode material. Here, dense graphene-like porous carbon (GPC) with hierarchical pore structure was fabricated from sheet cellulose made by milling of bleached kraft pulp. The unique pore structure gave rise to specific surface area value of up to 2045 m2/g, providing aboundant storage sites and channels for electrolyte species. The gravimetric (353 F/g) and volumetric (309.7 F/cm3) specific capacitance at 1 A/g were obtained in 6 M KOH aqueous electrolyte. The gravimetric and volumetric specific energy density of the symmetrical supercapacitor were 120.1 Wh/kg and 80.4 Wh/L, respectively, in an ionic liquid electrolyte in acetonitrile. These excellent performances make this material potentially useful for diverse energy storage devices.

Pd–Mn3O4 on 3D hierarchical porous graphene-like carbon for oxygen evolution reaction

A 3D hierarchical porous graphene-like carbon (3D HPG) has been studied as conducting support for Pd and Mn3O4 nanoparticles. The Pd–Mn3O4 supported on 3D HPG demonstrates as an excellent catalyst for oxygen evolution reaction (OER) in alkaline medium. The Pd–Mn3O4(wt 2:1)/HPG catalyst shows a low onset potential of 0.497 V and achieves a high current density of 5.3 mA cm−2 at 0.7 V (vs. SCE). The outstanding electrocatalytic activity is attributed to a synergistic effect between Pd and Mn3O4, and the 3D HPG enhances conductivity for charge transport and gives more active sites for the OER reaction.

Carbon nitride template-directed fabrication of nitrogen-rich porous graphene-like carbon for high performance supercapacitors

Facile yet rationally designed strategy for advanced electrode material synthesis is pivotal for energy storage. Herein, we report an protocol for g-C3N4 template-directed in-situ fabricating nitrogen-rich porous graphene-like carbon sheets (NPGCs) by using plasma-enhanced chemical vapor deposition followed with high-temperature pyrolysis process, which totally avoids the postsynthetic template-removal. The resultant NPGCs integrate a range of intriguing features including highly conductive interconnected structure (693 S m−1), abundant mesoporous with ultrahigh pore volume (4.35 cm3 g−1), large specific surface area (1277 m2 g−1), high N doping (8.75 wt%), and good wettability. As supercapacitor electrode, the NPGCs exhibit a quite encouraging specific capacitance of 261 F g−1 at 1 A g−1, excellent rate capability (189 F g−1 even at 100 A g−1), and outstanding cycle performance (97% capacitance retention at 10 A g−1 after 20000 cycles), which outperforms most carbon-based materials reported to date. Moreover, the assembled supercapacitors deliver a high power density of 28.4 kW kg−1 with a energy density of 6.53 Wh kg−1 at 100 A g−1. Our work is expected to open up new avenues for developing efficient nitrogen-doped porous carbon materials in a facile and viable way.

Facile synthesis of porous graphene-like carbon nitride nanosheets with high surface area and enhanced photocatalytic activity via one-step catalyst-free solution self-polymerization

Porous graphite carbon nitride nanosheets (g-C3N4) are achieved via one-step catalyst-free solution self-polymerization from a single melamine precursor. The resultant porous g-C3N4 nanosheets with the best photodegradation capacity provided the surface area of 669.15m2/g, which is superior to the surface area of any other porous g-C3N4 reported. Results showed enhanced adsorption and degradation capacity of methyl orange (MO) under UV-visible light irradiation (λ>350nm) compared to bulk g-C3N4. The MO oxidation of the porous g-C3N4 nanosheets is driven mostly by the participation of holes, and secondly by O2− and OH radicals. This approach shed lights on porous g-C3N4 production simply by self-polycondensation of single functional monomer. It also provided a low-cost and eco-friendly method to facilely mass-produce g-C3N4 nanosheets with high surface area for many potential applications.