Graphene-like Carbon Research Articles

Synthesis of ultra-thin graphene-like nanosheets from lignin based on evaporation induced self-assembly for supercapacitors

Graphene-like carbon materials are widely used in power devices due to their excellent structural characteristics. In this study, ultra-thin graphene-like nanosheets (LGLNs) with rich surface wrinkles were prepared by classical evaporation induced self-assembly (EISA) using lignin biomass as carbon precursor, followed by chemical activation with KHCO3. The obtained LGLN900 material calcined at 900 °C had a thickness of ca. 3 nm, a large specific surface area of 2886 m2 g−1 with a high specific pore volume of 2.10 cm3 g−1. In addition, a large number of wrinkles on the surface of LGLN900 endows its effective compression resistance. When the LGLN900 material was used as electrode material of supercapacitor, a high specific capacitance of 388 F g−1 was obtained at 0.2 A g−1 current density in 6 M KOH aqueous solution, and 269 F g−1 specific capacitance could be at remained at 40 A g−1. The supercapacitor assembled with LGLN900 afforded a specific energy density of (11.0–13.7) Wh kg−1 at a power density of (128.8–6465) W kg−1. This work provides a facile and green strategy for the synthesis of highly wrinkled ultra-thin graphene-like nanosheets from sustainable biomass resources, which should have wide applications in adsorption, catalysis and energy storage.

Highly porous biobased graphene-like carbon adsorbent for dye removal: Preparation, adsorption mechanisms and optimization

Dyes containing wastewater are generally produced in enormous quantities by the textile, dyeing, paper and pulp, tannery, and paint industries. Adsorption is used widely for dye removal because it is easily applied, non-toxic, inexpensive, and highly efficient. Graphene and graphene-based materials are attractive adsorbents, owing to their high specific surface areas and strong π–π interactions. However, graphene production process is demanding, costly, and requires several toxic chemicals. Thus, uncomplicated, and economical graphene-like carbon preparation by biomass pyrolysis has attracted attention. In this study cellulose-derived graphene-like carbon (CGLC) was obtained by pyrolyzing cellulose with FeCl3/ZnCl2. FeCl3 facilitates the synthesis of CGLC via the template effect, while ZnCl2 can produce a porous structure. The CGLC produced was characterized using the Brunauer–Emmett–Teller method, scanning electron microscopy, X-ray diffraction, Raman, Fourier transform infrared, and X-ray photoelectron spectroscopic analyses. We confirmed that the CGLC had a low ID/IG of 0.64 and a crystalline structure when cellulose was pyrolyzed with FeCl3. In addition, ZnCl2 produced a porous CGLC with high specific surface areas (2069.22 m2 g−1). The CGLC was then used for adsorptive cationic and anionic dye (Rhodamine B and Congo Red) removal to investigate its applicability as an adsorbent. The maximum CGLC adsorption capacities for Rhodamine B and Congo Red were 572.8 and 220.7 mg g−1, respectively, which indicate that CGLC can remove both cationic and anionic dyes. The adsorption mechanism may involve physical adsorption, such as π–π interactions and van der Waals bonds.

Ultra-thin highly-wrinkled graphene-like nanosheets for supercapacitor electrodes via 4-nitrocatechol and solvent-induced self-assembly

Graphene-like carbon materials are in high demand due to their potential applications in power devices. However, conventional synthesis of graphene-like materials causes repacking to occur during high-pressure compression steps resulting in low surface areas and unfavorable structures for mass transfer. Herein, ultra-thin wrinkled graphene-like nanosheets (GNs) were prepared simply via classical evaporation induced self-assembly (EISA) of 4-nitrocatechol as carbon precursor. Combination of EISA and subsequent KHCO3 activation and calcination at 900 °C (GN-900) afforded materials with thicknesses of (2–3) nm, specific surface areas of 3300 m2 g−1 with specific pore volumes of 2.34 cm3 g−1 under optimum conditions. When GN-900 was evaluated as an electrode material, a specific capacitance of 367 F g−1 was achieved at 0.2 A g−1 current density in 6 M KOH aqueous solution with a rate capability of 228 F g−1 at 40 A g−1. Supercapacitors assembled with GN-900 had specific energy densities of 11.5 Wh kg−1 at power densities of 89.8 W kg−1. Moreover, capacitance retention was greater than 98% after 3000 cycles at 10A g−1. Materials prepared with the proposed methods in this study were determined to be structurally stable and to exhibit favorable electrochemical performance for present and near-future supercapacitor applications.

Theoretical exploration of the structural, electronic and optical properties of g-C3N4/C3N heterostructures.

Integration of graphene-like carbon nitride materials is essential for nanoelectronic applications. Using density-functional theory (DFT), we systematically investigate the structural, electronic and optical properties of a s-triazine-based g-C3N4/C3N heterostructure under different modified conditions. The g-C3N4/C3N van der Waals heterostructure (vdWH) formed has an indirect bandgap with type-II band alignment and the band structures can be tuned from type-II band alignment to type-I band alignment by applying biaxial strains and external electric fields (Efield). Compared to single transition metal (TM) atoms at g-C3N4/C3N surfaces, the TM atoms anchored in the interlayer region exhibit more stability, and the corresponding bandgaps are changed from 0.19 eV to 0.61 eV. In addition, the g-C3N4/C3N heterostructure has a strong absorption coefficient in the ultraviolet-visible light region along the x direction. It is found that compressive strain has a large influence on the absorption coefficient of the g-C3N4/C3N system. With the increased compressive strain, the absorption spectra in the visible light region disappeared. Tensile strain has a slight effect on the absorption range, but causes a red shift of the absorption spectrum. In comparison, the light absorption coefficient of the g-C3N4/C3N system remains almost unchanged under the Efield conditions. In summary, the formation of a s-triazine-based g-C3N4/C3N heterostructure has shown potential for applications in nanoelectronic and optoelectronic devices.

Synthesis of magnetic graphene-like carbon nitride-cobalt ferrite (g-C3N4/CoFe2O4) nanocomposite for sonocatalytic remediation of toxic organic dyes.

A novel magnetic g-C3N4/CoFe2O4 nanocomposite was successfully synthesized by a simple hydrothermal method and applied as a new graphene-like carbon nitride-based sonocatalyst for sonodegradation of pollutant dyes. The as-prepared samples were characterized by using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS), BET surface area measurements and photoluminescence (PL) spectroscopy. The results indicate that the nanocomposite sample is composed of spherical CoFe2O4 nanoparticles adhered to g-C3N4 naosheets. The g-C3N4/CoFe2O4 nanocomposites were used as a new magnetically separable sonocatalyst in H2O2-assisted sonodegradation of methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes in aqueous media. The results showed complete degradation (ca. 100%) of dyes within short times (30-35 min). The sonocatalytic activity of graphitic carbon nitride (g-C3N4) was greatly enhanced with CoFe2O4 modification. Trapping experiments indicated that the g-C3N4/CoFe2O4 nanocomposites serves as a generator of hydroxyl radical (˙OH) via activation of H2O2 for degradation of dyes under ultrasound irradiation. Furthermore, the magnetic sonocatalyst can be separated from solution by an external magnet and reused several times without observable loss of activity. The possible mechanism of sonocatalytic activity was also proposed according to experimental results.

Hierarchical porous nitrogen-doped carbon nanosheets derived from zinc-based bioMOF as flexible supercapacitor electrode

We propose an efficient and flexible supercapacitor electrode material based on hierarchically structured nitrogen-doped graphene-like carbon nanosheets (H-NCNs) with accordion-like shape. H-NCNs were obtained by pyrolyzing zinc-based biometal–organic frameworks (Zn-bioMOFs) and using urea as nitrogen source at high temperature (800 °C) under nitrogen atmosphere, and Zn-bioMOFs were synthesized using biomass molecules, i.e., curcumin. Inheriting from the features of Zn-bioMOF, H-NCNs showed hierarchical structures and unique accordion-like morphology. By changing the urea dosage, the nitrogen-doping degree and porosity of H-NCNs were regulated, optimizing the supercapacitive performance. H-NCNs-8 prepared with Zn-bioMOF/urea mass ratio of 1:8 exhibited high specific capacitance and superior rate capability (293 F g−1 at 0.25 A g−1 and 188 F g−1 at 50 A g−1). The H-NCNs-assembled symmetric supercapacitor offered long cycle life of over 40,000 cycles at 2 A/g and high energy density of 17.6 Wh kg−1 at 250 W kg−1, outperforming most carbon nanomaterial-related ones. Accordingly, the proposed flexible interdigital solid microsupercapacitor demonstrated high areal capacitance, high areal energy densities, and long cycle stability. The present work can provide promising application prospects of MOFs in the field of supercapacitors and flexible electronics.

One-Step Synthesized Iron-Carbon Core-Shell Nanoparticles to Activate Persulfate for Effective Degradation of Tetrabromobisphenol A: Performance and Activation Mechanism.

Tetrabromobisphenol A (TBBPA), as an emerging endocrine disrupter, has been considered one of the persistent organic contaminants in water. It is urgently necessary to develop an efficient technique for the effective removal of TBBPA from water. Herein, a one-step hydrothermal synthesis route was employed to prepare a novel iron-carbon core-shell nanoparticle (Fe@MC) for effectively activating persulfate (PS) to degrade TBBPA. Morphological and structural characterization indicated that the prepared Fe@MC had a typical core-shell structure composed of a 5 nm thick graphene-like carbon shell and a multi-valence iron core. It can be seen that 94.9% of TBBPA (10 mg/L) could be degraded within 30 min at pH = 7. This excellent catalytic activity was attributed to the synergistic effect of the porous carbon shell and a multi-valence iron core. The porous carbon shell could effectively prevent the leaching of metal ions and facilitate PS activation due to its electron transfer capability. Furthermore, numerous micro-reaction zones could be formed on the surface of Fe@MC during the rapid TBBPA removal process. Radical quenching experiments and electron paramagnetic resonance (EPR) technology indicated that reactive oxygen species (ROS), including OH, SO4-, O2-, and 1O2, were involved in the TBBPA degradation process. Based on density functional theory (DFT) calculation, the carbon atoms linked by phenolic hydroxyl groups would be more vulnerable to attack by electron-rich groups; the central carbon was cracked and hydroxylated to generate short-chain aliphatic acids. The toxicity evaluation provides clear evidence for the promising application potential of our prepared material for the efficient removal of TBBPA from water.

CoSe-catalyzed growth of graphene sheath to construct CNF@graphene-CoSe cable/sheath heterostructure for high-performance Lithium–Sulfur batteries

Advanced hierarchical hybrid nanostructures of polar, conductive and catalytic chemical traps/carbon with rationally tailored components, structures, and chemistries are important in determining the performance of lithium-sulfur (Li–S) batteries. Herein we propose a facile strategy to prepare 3D-structured CNF@graphene-CoSe (CNF@GL-CoSe) cable/sheath heterostructure with the in-situ formed CoSe as a catalyst for graphene-like carbon growth and Se as a catalyst promoter. The architecture integrates high electrical conductivity, effective ion transport, notable polysulfide entrapment, and polysulfide redox kinetics, availing lithium/sulfur conversion when applied as an interlayer in a Li–S battery. As expected, the battery delivered a low decay of 0.053% per cycle over 700 cycles at 1 C. The capacity even remained 649.4 and 524.5 mA h g−1 at 4 and 6 C, respectively. Furthermore, an areal capacity of about 3 mA h cm−2 at 0.1 C after long-term tests can still maintain with sulfur loading of 4.5 mg cm−2.

In situ Self-Catalyzed Growth of Manganese-Embedded 3D Flakes-Coated Carbon Rod as an Efficient Oxygen-Reduction Reaction Catalyst of Zinc-Air Batteries.

The in situ self-catalyzed growth of manganese-embedded 3D flakes-coated carbon rods (GFC) as an efficient oxygen-reduction reaction (ORR) catalyst of Zinc-air batteries is described for the first time. By optimizing the amount of Mn in the precursor, a series of 3D graphene-like flakes-coated carbon rods were synthesized. GFC with a doping amount of Mn of 10 % (GFC-10) exhibits excellent ORR performance with an onset potential of 0.94 V (vs. reversible hydrogen electrode). The Zinc-air battery is constructed with GFC-10 as the cathode catalyst, and it exhibits a peak power density of 128.9 mW cm-2 and a cycling stability of 75 h at a current density of 10 mA cm-2 , which are superior to the commercial 20 wt% Pt/C-based Zinc-air battery. Interestingly, the introduction of Mn facilitates the self-catalyzed growth of carbon rods, and the change of Mn amount can effectively regulate the morphology of materials. The improved ORR performance of the catalyst is ascribed to the synergistic effect of unique hierarchical porous structure, high-charge transport capacity, abundant carbon defects/edges and Mn-Nx sites. This research provides a new avenue to fabricating highly active Mn-based electrocatalysts for renewable energy systems.

Microwave-assisted preparation of novel graphene-like carbon material from waste bamboo for high-performance supercapacitors

Microwave-assisted preparation of novel graphene-like carbon material from waste bamboo for high-performance supercapacitors

In Situ Exfoliated Graphene-Like Carbon Nanosheets Strongly Coupled with the Biochar Tube as the Cathode for an Application-Ready Zn-Air Battery

In Situ Exfoliated Graphene-Like Carbon Nanosheets Strongly Coupled with the Biochar Tube as the Cathode for an Application-Ready Zn-Air Battery

Effectiveness of Bio-Waste-Derived Carbon Doping on De-Icing Performance of an Electrically Resistant Concrete

This paper proposes a modified carbon-based concrete filler composition, which can potentially be used as a self-de-icing pavement. Carbon fibers (CNFs), graphene-like porous carbon (GLC), and a CNF/GLC composite were developed to reinforce concrete with the aim to improve its electrical conductivity and mechanical properties. The effect of the CNF and GLC loadings on the electrical conductivity of the filled concrete was evaluated in a climatic chamber at temperatures simulating water-freezing conditions on a concrete road. The results show that even a negligible loading (0.2 wt.%) of concrete with CNF/GLC results in a dramatic decrease in its resistance when compared to the same loadings for CNF and GLC added separately. Depending on the number of fillers, the temperature of the modified concrete samples reached up to +19.8 °C at low voltage (10 V) at −10 °C, demonstrating the perspective of their heat output for anti-icing applications. Additionally, this study shows that adding 2.0 wt.% of the CNF/GLC composite to the concrete improves its compressive strength by 33.93% compared to the unmodified concrete.

Ni-O4 as Active Sites for Efficient Oxygen Evolution Reaction with Electronic Metal-Support Interactions.

Precise adjustment of the metal site structure in single-atom catalysts (SACs) plays a key role in addressing the oxygen evolution reaction (OER). Herein, we report the synthesis of O-doped Ni SACs anchored on porous graphene-like carbon (Ni-O-G) using molten salts (ZnCl2 and NaCl) as templates, in which the unique Ni-O4 structure serves as the active sites. Ni-O-G, with an overpotential of only 238 mV (@ 10 mA cm-2), is one of the more advanced catalysts. An array of characterizations and density functional theory calculations show that the Ni-O4 coordination enables Ni to be closer to the Fermi level compared to traditional Ni-N4, enhancing the electronic metal-support interaction to facilitate OER kinetics. Thus, this work offers an alternative strategy for the structural modulation of Ni SACs and the effect of different coordination elements with the same atomic coordination structure on the intrinsic OER activity.

Graphene and graphene-like carbon nanomaterials-based electrochemical biosensors for phytohormone detection

Graphene and graphene-like carbon nanomaterials-based electrochemical biosensors for phytohormone detection

Effect of Preparation Method on the Activity of Fe2O3-NiO/γ-Al2O3 Catalyst in Decomposition of Methane

The effect of method preparation on the activity of Fe2O3-NiO/γ-Al2O3 catalyst was investigated in process decomposition of methane. Fe2O3-NiO/γ-Al2O3 catalyst was prepared by impregnation and solution combustion methods. The samples were characterized by X-ray phase analysis (XRD), temperature-programmed hydrogen reduction (TPR-H2), BET and Raman spectroscopy. It has been shown that the method of preparation plays an important role in regulating the textural and morphological properties of catalysts and provides a difference in their catalytic activity. The synthesis of the Fe2O3-NiO/γ-Al2O3 catalyst by the solution combustion method, in comparison with the capillary impregnation method, leads to the formation of a large amount of FeNi and FeAl2O4 solid solutions, which ensured good catalytic activity at high temperatures. The Fe2O3-NiO/γ-Al2O3 catalyst synthesized by the solution combustion method demonstrated good activity with a hydrogen yield of 52% within 150 min of the reaction without any deactivation. According to the results of Raman spectroscopy, graphene-like carbon was obtained on the surface of the catalysts. On the catalyst of Fe2O3-NiO/γ-Al2O3 (СI) synthesized by capillary impregnation, 4‒5 layer graphene on Fe2O3-NiO/γ-Al2O3 (SC)-6-7 layer graphene is formed.

Engineering the electronic structure of high performance FeCo bimetallic cathode catalysts for microbial fuel cell application in treating wastewater

The development of high-performance, strong-durability and low-cost cathode catalysts toward oxygen reduction reaction (ORR) is of great significance for microbial fuel cells (MFCs). In this study, a series of bimetallic catalysts were synthesized by pyrolyzing a mixture of g-C3N4 and Fe, Co-tannic complex with various Fe/Co atomic ratios. The initial Fe/Co atomic ratio (3.5:0.5, 3:1, 2:2, 1:3) could regulate the electronic state, which effectively promoted the intrinsic electrocatalytic ORR activity. The alloy metal particles and metal-Nx sites presented on the catalyst surface. In addition, N-doped carbon interconnected network consisting of graphene-like and bamboo-like carbon nanotube structure derived from g-C3N4 provided more accessible active sites. The resultant Fe3Co1 catalyst calcined at 700 °C (Fe3Co1-700) exhibited high catalytic performance in neutral electrolyte with a half-wave potential of 0.661 V, exceeding that of the commercial Pt/C (0.6 V). As expected, the single chamber microbial fuel cell (SCMFC) with 1 mg/cm2 loading of Fe3Co1-700 catalyst as the cathode catalyst afforded a maximum power density of 1425 mW/m2, which was 10.5% higher than commercial Pt/C catalyst with the same loading (1290 mW/m2) and comparable to the Pt/C catalyst with 2.5 times higher loading ( 1430 mW/m2). Additionally, the Fe3Co1-700 also displayed better long-term stability over 1100 h than the Pt/C. This work provides an effective strategy for regulating the surface electronic state in the bimetallic electro-catalyst.

Preparation and mechanism of biomass-derived graphene-like Li+/Na+ battery anodes controlled by N/O functional groups and interlayer spacing

The universal electrode material can be applied to the traditional Li-ion battery of the emerging alkaline ion battery at the same time, providing a new idea for the development of energy storage systems (EESs). In this study, a porous graphene-like biomass carbon material anode was prepared by chemical blowing strategy and KOH activation method. As the anode of both Li/Na ion batteries, it has excellent cycle stability and extremely high-rate cycle performance. Under the charge-discharge rate of 0.2c, the reversible capacity of Li-ion battery assembled by anode material was 953.2 mA g −1 , and that of Na-ion battery was 378.2 mA g −1 . Under the condition of 10c, the reversible capacity was 352.6 mA g −1 and 127.6 mA g −1 . Its excellent electrochemical performance can be attributed to its wide interlayer spacing, rich pore structure and N/O double doping, and its pseudocapacitance mechanism is conducive to the diffusion of alkaline ions. First-principles calculations further show that its doped structure is beneficial to promote ion adsorption and improve the conductivity of the material. This work has promoted the development of sustainable energy storage materials and provided new ideas for the development of carbon-based anode materials. The porous graphene-like biomass carbon material anode was prepared by chemical blowing strategy and KOH activation method. Combining the effect of interlayer spacing regulation and doped N/O functional group, this carbon-based material has displayed excellent electrochemical performance. When used as anode for lithium-ion batteries, the reversible capacity was 953.2 mA g −1 under 0.2c, and that of Na-ion battery was 378.2 mA g −1 . Under 10c, the reversible capacities of Li-ion and Na-ion batteries were 352.6 mA g −1 and 127.6 mA g −1 . First-principles calculations show that the doped structure is beneficial to promote ion adsorption and improve the conductivity of the material. • Under 0.2c, the reversible capacity of Li-ion battery assembled by anode material was 953.2 mA g −1 , and that of Na-ion battery was 378.2 mA g −1 . • Under 10 c, the reversible capacities of Li-ion and Na-ion batteries were 352.6 mA g −1 and 127.6 mA g −1 . • First-principles calculations show that the doped structure is beneficial to promote ion adsorption and improve the conductivity of the material.

3D graphene-like oxygen and sulfur-doped porous carbon nanosheets with multilevel ion channels for high-performance aqueous Zn-ion storage

Zinc-ion hybrid capacitors (ZIHC) demonstrate impressive charge-storage performance and intrinsic safety due to the inherited superiorities of aqueous rechargeable batteries and supercapacitors. However, the promotion of electrochemical performance is usually hindered by the cathode materials that fail to hold high energy density and rate capability of ZIHC. The optimization of porous carbon cathodes into a hierarchical structure is an efficient strategy to break the bottlenecks of ZIHC. Herein, a metal oxide space-confined strategy is proposed to build 3D graphene-like porous carbon nanosheets (3DPC) with doping of O and S heteroatoms by using low-cost aromatic hydrocarbons as precursors. It is found that the obtained 3DPC consists of micro-, mseo- and macropores and further delivers a high specific surface area of 2813 m2 g−1 with a total pore volume of 1.82 cm3 g−1. Specifically, such a well-defined hierarchical porosity of 3DPC coupled with rich O and S heteroatoms enables sufficient multilevel ion transport channels and large accessible surface sites to capture the Zn2+ ions. As a proof of concept demonstration, the assembled aqueous ZIHC by employing the 3DPC cathode exhibits a desirable capacity of 194 mAh g−1 at 0.5 A g−1 with a superior rate capability of 53% at 30 A g−1 and excellent cycling stability of over 88% after 15000 cycles. Moreover, the remarkable electrochemical performance of the 3DPC cathode can be well-preserved in the case of a quasi-solid-state ZIHC device under various harsh bent states, highlighting the promising application in flexible and wearable energy storage.

Biomass-derived graphene-like carbon nanoflakes for advanced supercapacitor and hydrogen evolution reaction

It is valuable that graphene-like carbon materials are prepared from the biomass resources due to their unique two-dimensional structure, heteroatom enriched, and high specific surface area. Herein, we use egg white and graphene oxides as precursor and employ post-hydrothermal carbonization approach, freeze-drying technique, carbonization, and activation methods by KOH to prepare the graphite carbon nanoflakes with Fe7C3 @graphite carbon nanoflakes hybrid materials. Morphology tests imply that the formation of graphite carbon nanoflakes are mainly depended by activation step, it implies that carbon flakes are exfoliated via introducing K+ into carbon layers and further destroying the van der Waals force (VDWF). As a result, this hybrid materials exhibit an attractive capacitance (528 mF·cm−2 @1 mA·cm−2) and durability (91 @10 mA·cm−2, 4000 cycles). For hydrogen evolution reaction (HER), the as-collected samples also deliver a low overpotential and remarkable stability. We believe that the as-obtained hybrid materials have a greatly application value in energy storage devices.

Perforated nitrogen-rich graphene-like carbon nanolayers supported Cu-In catalyst for boosting CO2 electroreduction to CO

The combination of a powerful CO2-enriching carrier and robust active component provides a new idea for the construction of efficient catalysts for electrocatalytic CO2 reduction. Herein, novel perforated nitrogen-rich graphene-like carbon nanolayers (PNGC) are prepared from biomass derivatives, which promotes the oriented deposition of In-doped Cu2(OH)3(NO3) nanosheet patches. A robust Cu-In/PNGC composite catalyst is then obtained via simple in-situ electrochemical reduction. Unsurprisingly, Cu-In/PNGC exhibits a CO Faradaic efficiency (FECO) of 91.3% and a remarkable CO partial current density (jCO) of 136.4 mA cm−2 at a moderate overpotential of 0.59 V for electrocatalytic CO2 reduction reaction (CO2RR). DFT calculations and experimental studies indicate that the strong carrier effect of PNGC makes PNGC carried Cu-In nanosheets improved the adsorption capacity of CO2 gas, reconfigured electronic structure, and reduced free energy of key intermediate formation, thereby the CO2 activation and conversion are promoted.