Preparation Of Carbon Materials Research Articles

Preparation of microalgae-based carbon materials with Ni(OH)2 doping and their electrochemical performance

Supercapacitors are a new type of energy storage devices with many advantages. In this study a novel composite material named NiC were synthesized to improved their electrochemical performance in supercapacitors. It was composite of Ni(OH)2 and microalgae-based N-doped activated carbon materials. Activated carbon material prepared from defatted microalgae was excellent electrode material because of their nitrogen-rich characterization and porous structure. The Ni(OH)2 as a metallic material could provide considerable pseudo-capacitance for capacitors. In this study, Ni(OH)2 was successfully doped into carbon materials using a hydrothermal method at a temperature of 150 °C for 4 h. The flower-like structure of metallic materials was observed in SEM images and two forms of elemental Ni ions (Ni3+ and Ni2+) were detected in XPS. The porosity of the composite materials NiC was retained to some extent (specific surface area of 502 m2/g for sample NiC10). Moreover, the specific capacitance value of composite material NiC20 was increased by 190 % compared to its parent carbon material, indicating that the capacitive performance of the composite materials was significantly improved. The capacitance retention of NiC20//NiC20 in a two-electrode system was up to 75.29 % over 5000 cycles. This research will provide necessary information for high-performance electrochemical materials based on microalgae-based carbon materials.

Microstructure reconstruction via confined carbonization achieves highly available sodium ion diffusion channels in hard carbon

Hard carbon is considered as the main candidate negative electrode material for sodium-ion batteries (SIBs) due to its high stability and electrochemical performance. However, the complex carbon structure and composition of hard carbon are difficult to achieve precise control during the preparation process, which leads to difficulties in accurately determining the attribution of electrochemical behavior. Here, we propose a confined carbonization strategy to achieve microstructure reconstruction of hard carbon, characterized by the anchoring of polymers in the mesopores of porous carbon to generate ordered carbon structures at high temperatures. The stacking of ordered carbon on micropores in porous carbon achieves the transition from exposed pores to closed pores (nano cleithral pores). Through mechanism detection, it is found that the ordered carbon structure provides sub nanochannels for sodium ion migration, which contributes to high slope capacity. In addition, the nano cleithral pores are sites filled with sodium ions and provide high plateau capacity. Benefiting from theses available sodium ion transport channels, carbon materials have achieved a transition from surface-controlled process to diffusion-controlled process in the sodium storage process via confined carbonization. The as-prepared carbon delivers a superior capacity of 356.2 mAh g–1 (215.6 mAh g–1 for plateau capacity) at 20 mA g–1 with excellent rate and cycling performance. This work reveals the correlation between structure and electrochemical performance for carbon electrode, providing profound guidance for the precise preparation of high-performance carbon materials.

Preparation of nitrogen-doped lignin-based porous carbon materials and their application in a supercapacitor

Preparation of nitrogen-doped lignin-based porous carbon materials and their application in a supercapacitor

Co-crosslinking and anchoring strategy: One-step preparation of N-doped porous carbon for supercapacitors and zinc ion hybrid capacitors

Porous carbon has been widely used in aqueous capacitors due to its wide source, high stability, and controllable preparation. However, the two-step preparation strategy of carbonization and activation with complex operation and serious energy consumption severely limits its further application. In this paper, resorcinol/urea-furfural resin was successfully prepared by using cleaner and greener furfural as raw material and co-crosslinking with resorcinol and urea under the action of catalyst. It is noteworthy that during the curing process, KOH is uniformly anchored inside the resin, so the system only needs one-step high-temperature pyrolysis to obtain a N-doped ant-nest-like three-dimensional interconnected porous carbon material. Consequently, the porous carbon exhibited an impressive specific capacitance of 283F g−1. The assembled symmetrical device shows a capacitance retention of 92 % after 50 000 cycles, showing excellent cycle stability. In addition, the assembled zinc ion hybrid capacitor exhibits a capacitance of 138 mAh g−1 and an energy density of 111 Wh kg−1. The one-step carbonization-doping-activation strategy of this bottom-up in-situ anchoring activator will provide further insights into the hierarchical pore structure design of porous carbon and facilitate the simple and efficient preparation of carbon materials.

Preparation and Characterization of Urea-Modified Lignin-Derived Porous Carbon Materials and their CO<sub>2</sub> Adsorption Properties

Present study, activated carbon was precarbonised and chemically activated to prepare activated charcoal from different lignins , and their adsorption properties had been investigated. The influences of carbon source selection with urea modification on the CO2 adsorption performance of the materials were investigated. The selectivity, warmth of adsorption and cyclic steadiness of the materials had been in addition tested. The urea-modified porous carbon materials were prepared using dealkylated lignin (LCC), calcium lignosulfonate (CLS) and sodium lignosulfonate (SLS) as carbon precursors, KOH as activator and urea as nitrogen dopant. The CO2 adsorption values of the LCC-0.5N samples had been 5.52 mmol/g and 3.90 mmol/g at 1 bar, 273 K and 298 K, respectively, and were obtained in 10 successive adsorption-desorption cycles. The CO2 adsorption ability remained stable and greater than 110 mg/g after 10 consecutive adsorption-desorption cycles.

Pyrolysis combined with KOH activation to turn waste apple pruning branches into high performance electrode materials with multiple energy storage functions

In this paper, porous activated carbon is successfully prepared from waste apple pruning branches (PGZ), which demonstrates an ultra-high specific capacity of 505 F g −1 at a current density of 1 A g −1 with excellent rate performance (215 F g −1 at 50 A g−1). The assembled supercapacitor also exhibits excellent specific capacitance of 320 F g −1 (at 0.5 A g−1) and 160 F g −1 (at 20 A g−1), with a high energy density of 12.03 Wh kg −1 at a power density of 250.45 W kg −1 in 6 M KOH. In 1 M Na2SO 4 and 1 M Et4 NBF4/AC electrolytes, high energy densities of 18.8 Wh kg −1 and 44.1 Wh kg −1 could be achieved. It also exhibits high reversible lithium storage capacity of 636.2 mAh g −1 at 0.2 C and retains 390 mAh g −1 after 1000 cycles. Even at 0.8 C, the storage capacity is still as high as 327 mAh g −1, with 282 mAh g −1 retained after 1000 cycles. These excellent electrochemical properties are attributed to the hierarchical porous structure of the sample prepared under the optimum conditions. The large pores in the hierarchical structure will lead to high-speed capacitive properties due to their low ion transport resistance while the small mesopore and micropore provide a large electrode and electrolyte interface, which can facilitate charge transfer reaction. These outstanding performances highlights the first example of using waste apple pruning branches as a sustainable source of raw materials for the preparation of high value-added porous carbon materials with multiple energy storage functions.

Coconut Shell Carbon Preparation for Rhodamine B Adsorption and Mechanism Study.

Phosphoric acid is used as a chemical activator to prepare coconut shell carbon (PCSC), and for investigating rhodamine B (RhB) adsorption performance. The optimal conditions for the preparation of PCSC (calcined temperature, phosphoric acid concentration), and the influence of adsorption conditions (concentration, pH, etc.) on RhB and the recovery performance of optimal carbon are investigated. Experimental results show that when the amount of PCSC (600 °C, 2 h) is 0.2 g, the initial RhB concentration is 10 mg/L, pH = 6, and the adsorption time is 30 min, it can have 95.84% RhB adsorption efficiency. Liquid ultraviolet spectroscopy also supports this adsorption performance. Characterization data showed that hydroxyl and ester groups, aromatic structures, and PO43- existed on the surface of PCSC, and the amount decreased with increasing calcined temperature. PCSC has a BET (N2) surface area of 408.59 m2/g and has a micropore distribution, EDS-detected P content is 3.91%. SEM showed that the PCSC formed micropores which could better adsorb RhB. The kinetic and thermodynamic analysis of the adsorption of RhB by PCSC showed that the adsorption process was in accord with quasi-secondary kinetic equations and ΔGθ was between -1.65 and -18.75 kJ/mol. The adsorption was a physical adsorption and a spontaneous endothermic reaction, and the obtained PCSC sorption isotherms were classified as Langmuir-type. The RhB adsorption mechanism on PCSC includes pore diffusion, hydrogen bonding, and π-π conjugation. The PCSC prepared by H3PO4 modification has superior adsorption and recycling performance for RhB, providing a reference for the preparation of other biomass carbon materials for the treatment of dye wastewater.

Nanoporous carbon materials: modern production methods and applications

The review presents data on the nomenclature and production methods of the most intensively investigated classes of nanoporous carbon materials, which are increasingly used in science, medicine, and various fields of economy. The traditional activated carbons, which are produced by conventional biomass and fossil hydrocarbon processing methods, are compared with nanoporous carbon materials obtained using modern synthetic methods. Recommendations are given on the use of template synthesis to obtain carbon materials with a controlled nanoporosity. Self-template synthesis, in which environmentally benign and readily available organic salts can be used as precursors, is considered as a promising avenue of research. This approach markedly reduces the cost of template synthesis of nanoporous carbons and allows for the preparation of carbon materials with specific particle morphology from organometallic precursors. Methods for the preparation of functional materials with ordered architectures of micro- and mesopores are considered, including modern functionalization and doping approaches. A part of the review is devoted to advanced applications of nanoporous carbon materials such as water treatment, energy and hydrogen storage, separation of gas mixtures, development of catalysts and sensors, and solution of other significant problems. The conclusion summarizes the experience of application of various methods for the preparation of nanoporous carbon materials, identifies the most problematic issues of the development and practical use of these materials, and presents the authors' view on further development of this area of materials science.<br> The bliography includes 353 references.

Utilization of graphene nanoplatelets for friction coefficient reduction in NiCu/WC-12Ni composite materials

Graphene Nanoplates (GNPs), known for their outstanding performance, have found extensive applications in the preparation of metal composite carbon materials. In this investigation, a Directed Energy Deposition system was employed to effectively produce deposition specimens of NiCu/WC-12Ni + x wt% GNPs (x = 0, 0.5, 1.0, 1.5) composite material. The findings suggest that incorporating GNPs improved the microstructure of the NiCu/WC-12Ni deposited specimens, leading to a reduction in grain size with predominantly equiaxed and cellular grains. GNPs transformed into amorphous graphene spheres, uniformly distributed within the deposited structure. When 1 wt% GNPs were added, the average microhardness of the deposited specimens increased by approximately 15 %, the friction coefficient decreased from the original 0.318 to 0.257, and the wear rate decreased by 23.2 %. The primary wear mechanism observed was abrasive wear, demonstrating excellent wear resistance. Moreover, introducing a suitable quantity of graphene improved the electrochemical corrosion resistance of the deposited specimen.

Natural N/O/S co-doped defect-rich functional carbon materials for aqueous supercapacitors: Effect mechanism of N-containing functional groups on chemical activation

The efficient synthesis of porous carbons with a micro-mesoporous composite structure from low-cost, multi-source biomass was of significant importance for the fabrication of carbon-based supercapacitors. A novel method for the preparation of micro-mesoporous composite carbon materials by co-pyrolysis of multi-source biomass coupled with KOH activation was proposed in this study. The N, O and S co-doped micro-mesoporous composite carbon materials were synthesized using the bamboo and spiral algae as the precursors and KOH as the activator. Spiral algae, as the main source of heteroatoms, played multiple roles (pore forming agent, dopant and enhancer) in the co-pyrolysis process. The enhanced effect of heteroatom doping on KOH activation facilitated the formation of microporous structures. The KCA-500–2 exhibited a porous structure dominated by micropores, with a specific surface area (SSA) of 2421.85 m2/g. At 0.5 A/g, KCA-500–2 displayed an excellent capacitance of 460F/g and outstanding rate performance (73.5 %). The assembled aqueous symmetric supercapacitor (KCA//KCA) demonstrated a maximum energy density of 19.09 Wh/kg at a power density of 150 W/kg. In addition, KCA//KCA attained 97.96 % capacitance retention after 9,000 cycles. This work revealed the synergistic mechanism between N-containing functional groups and KOH activation, suggesting a theoretical guidance for the synthesis of high-performance supercapacitors.

One-step preparation of N-doped porous carbon materials with excellent microwave absorption properties based on methylene blue saturated wood-based activated carbon

One-step preparation of N-doped porous carbon materials with excellent microwave absorption properties based on methylene blue saturated wood-based activated carbon

Preparation of carbon materials by vapor deposition with Fe3+-Modified nickel foam from biomass pyrolysis gas

Biomass carbon materials have attracted attention in various fields due to their excellent properties. In this study, CH4 derived from biomass pyrolysis was utilized as a carbon source gas to synthesize carbon materials by chemical vapor deposition (CVD) in a two-stage reactor with purification system, with Fe3+-loaded nickel foam as the substrate under an argon atmosphere, using a self-designed experimental platform. The reaction process was optimized by examining the effects of the catalyst type, reaction temperature, reaction time, and gas flow rate on the structure and morphology of the carbon materials. The optimal preparation condition was to use FeCl3 ethanol solution as catalyst, with CH4 flow rate of 50 ml/min at 1000 °C for 25 min. The high quality carbon materials with uniform diameters (250–500 nm) were obtained on nickel foam substrate. The carbon materials obtained under optimal conditions were characterized and analyzed to investigate their excellent properties. Surface morphology and structure of as-formed carbon materials were characterized by SEM. The analysis of the XRD spectra and the Raman spectroscopy showed that the graphite diffraction peak (002) at 26.6°, the calculated intensity ratios for ID/IG and I2D/IG were 0.257 and 0.545, respectively, indicated high degree of graphitization and purity of the carbon materials. Furthermore, the growth mechanism of carbon materials on the nickel foam substrate was discussed.

Preparation and Performance Analysis of New Multi stage Porous Carbon Materials for Air Pollution Treatmentials on Atmospheric Pollution Sources under the Background of Carbon Peak and Carbon Neutrality

The adsorption of toxic and harmful gases through porous materials is an effective means of air pollution control. A multi-level porous carbon material with ultra-high-specific surface area was made based on rice husk biomass to improve the air pollution controlling efficiency and reduce its cost. The rice husk substrate was pretreated using T.viride spore suspension during the preparation of this material. This changes the proportion of various components in the matrix, thereby achieving an increase in the multi-level porous carbon material’s specific surface area. Its performance was analyzed through various means in the study. The results confirmed that when the activation treatment time was 60 minutes, the porous carbon material’s specific surface area was the highest, reaching 3714 m2/g. After 30 days of treatment with T.viride spore suspension, the cellulose content in rice husks decreased by about 40 g/kg. Compared to untreated porous carbon materials, after 20 days of treatment, the micropores and mesopores of these materials significantly increased. The research has successfully increased the multi-level porous carbon material’s specific surface area and achieved rapid absorption of atmospheric volatile organic compounds. The multi-level porous carbon material can enhance the air pollution controlling efficiency and reduce its cost.

Synthesis and Characterization of Nanocellulose/Polyacrylonitrile‐based Carbon Nanofibers: An Approach toward Low Cost and Sustainable Agro Waste based Carbon Nanomaterials

AbstractThe cost of polymer precursors and high energy need in carbonization for the preparation of carbon materials are two limiting factors in the commercialization of carbon‐based materials. In this study, carbon nanofiber films were prepared by adding a very small concentration of polymer polyacrylonitrile in nanocellulose (extracted from agro waste i.e., rice straws) with an overall aim of producing carbon nanomaterials with cost effective, renewable and sustainable carbon source. Polyacrylonitrile (PAN) added nanocellulose solution was drop‐casted to prepare Nanocellulose/Polyacrylonitrile‐based nanofibers film (NC/PAN). It was further stabilized in air atmosphere at 280 °C followed by carbonized in nitrogen atmosphere at 700 °C. It was found that addition of NC/PAN have 18 % lower activation energies than PAN. Results of tunneling electron microscopy showed that polyacrylonitrile/nanocellulose films carbonized at 700 °C temperature exhibited amorphous carbon nanofibers structure similar to bare polyacrylonitrile based carbon film carbonized at higher temperature of 1000 °C‐1200 °C. Furthermore, polyacrylonitrile/nanocellulose based carbon nanofibers have showed high degree of carbonization ((ID)/(IG)=0.87) as compared to bare polyacrylonitrile based carbon nanofibers film ((ID)/(IG)=1.02). This may be attributed to chiral nature of nanocellulose which served as a template to orientation of graphene planes and showed efficient carbonization.

Co3V2O8 composite carbon hollow spheres bidirectionally catalyze the conversion of lithium polysulfide to improve the capacity of lithium‐sulfur batteries

Although lithium‐sulfur batteries have a high theoretical energy density that is higher than lithium‐ion batteries, their development is limited by the slow kinetics of lithium polysulfide conversion. In this research, we utilize the excellent bidirectional catalysis and adsorption of lithium polysulfide by the bimetallic oxide Co3V2O8 composite carbon hollow sphere to address the kinetic obstacle of lithium‐sulfur battery. On the one hand, the carbon hollow sphere substrate provides a cavity that can hold a large amount of sulfur. On the other hand, it can limit the diffusion of lithium polysulfide by van der Waals forces. The combination of the above two points improves the capacity and stability of lithium‐sulfur batteries. It has a specific capacity of 1237.2 mAh g‐1 at 0.2 C current density and retains 603 mAh g‐1 after 100 cycles. At a high current density of 2 C, the specific capacity is 976.2 mAh g‐1. After 1000 cycles, it holds at 338.3 mAh g‐1, and the capacity retention rate per cycle is 99.89%. This work discovers the new potential of Co3V2O8 as an electrocatalyst and proposes a process that can widely prepare carbon materials with complex uniform distribution of electrocatalysts to achieve high specific capacity of lithium‐sulfur batteries.

Preparation of Al-doped carbon materials derived from artificial potassium humate prepared from waste cotton cloth and their excellent Cr(VI) adsorption performance

Millions of tons of cotton textile waste are generated annually worldwide, and most of it enters the municipal solid waste (MSW) stream for landfill or incineration disposal, resulting in a significant waste of resources and environmental pollution. This article developed an innovative low-temperature pyrolysis process for producing artificial humic acid (HA) from waste cotton textiles. Subsequently, Al3+ was introduced for a secondary pyrolysis to prepare an Al-doped biochar (Al/BC) with superior adsorption properties. The experimental results show that the presence of Al3+ has an important influence on the pyrolysis process of cotton fabric and the formation and structure of Al/BC. This is the first time to synthesize low-cost adsorbent by pyrolysis and aluminum mixing process of waste cotton cloth and explains the mechanism. This increased in defects (ID/IG = 0.76 to ID/IG = 0.92), a larger specific surface area (6.47 m2/g to 566.94 m2/g), and an increase in oxygen-containing functional groups (from none to C-O-C, OC-O, etc.) when compared to the undoped Al3+ biochar. The optimum Al3+-doped biochar (Al/BC-15) prepared with HA as a precursor exhibited a superior adsorption capacity for Cr(VI) of up to 176.23 mg/g, surpassing the results reported for similar materials in the literature. The adsorption mechanism of Cr(VI) is primarily based on physical adsorption, with some chemical adsorption. At a lower pH, the Al/BC-15 surface exhibits a high positive charge (46 mV). The Al3+-O-Cr(VI) association group is formed through rapid electrostatic attraction between C-Al and Cr(VI). Due to the strong positive electronegativity of Al3+ and the negative electronegativity of C in the vicinity of Al, Cr(VI) is further reduced to Cr(III) by C-Al. Therefore, the method proposed in this paper for preparing Al-doped carbon materials from waste cotton fabric offers a new approach and potential application for the production of high-performance adsorbent materials from waste cotton fabric.

Salt-separated strategy for construction of hollow carbon nanospheres with tunable size based on α-cyclodextrin

Hollow carbon nanospheres (HCNs) have attracted much attention in the field of science and technology for their excellent properties; however, developing a versatile synthesis strategy for the preparation of HCNs remains a great challenge. The successful manipulation of size and shell thickness of HCNs is essential to meet their structural varieties and practical applications. Herein, HCNs were prepared directly from the renewable α-Cyclodextrin (α-CD) by a novel and simple salt-separated strategy with direct carbonization method is reported. The synthesis differs from the traditional template method in that it is characterized by the introduction of salt for separation and protection, the carbonization does not require the passage of protective gas, and the salt can be recycled. Thus, this method is very cost-effective and environmentally benign. In addition, the HCNs size in this system can be adjusted on demand by simply adjusting the concentration of α-CD, thus realizing that the HCNs size is adjustable in the range of 90–700 nm and adjustable shell thickness in the range of 20–250 nm. This work provides a new insight into the preparation of high-performance carbon materials in an environmentally friendly manner.

Activation-free preparation of porous carbon fiber derived from phenolic resin for CO2 absorption

BackgroundIt is not uncommon to study the preparation of porous carbon materials for CO2 adsorption, but it is still a challenge to simultaneously achieve the good mechanical strength, porous structure, and efficient adsorption performance of porous carbon fibers. MethodsPorous carbon fibers with desirable morphology and selective CO2 adsorption were prepared using an activation-free method. The fibers were prepared through melt spinning of phenolic resin modified with polyvinyl butyral (PVB) and urea, followed by curing treatment, and then the pore structures were adjusted by controlling the carbonization temperature. Significant findingsThe porous carbon fibers prepared by carbonization at 900 °C not only had excellent CO2 adsorption (3.48 mmol/g) but also possessed desirable tensile strength (132 MPa). Those carbonized at 700 °C showcased CO2/N2 selectivity of 57 (Ideal adsorption solution theory (IAST), CO2: N2 =15:85), and tensile strength of 148 MPa, much higher than most fibers using other methods. The study revealed that the adsorption of CO2 was mainly performed by nitrogen-containing groups and physical function through pores ranging from 0.3 nm to 0.8 nm, and the micropores between 0.3 nm and 0.6 nm were conducive to the selective adsorption of CO2/N2.

Preparation of nitrogen-doped porous carbon from pyrolysis of light bio-oil pretreated poplar powder and its electrochemical performance

Biomass are widely used for the preparation of porous carbon materials (PCM). Therefore, there is considerable interest in how to obtain PCM with excellent electrochemical performance from biomass. Effective pretreatment methods can significantly improve the electrochemical performance of PCM. However, the low nitrogen content in most biomass limits its further application as electrode materials. Thus, this paper proposes a new method for preparing nitrogen-doped PCM. Nitrogen-doped PCM with outstanding performance were synthesized from poplar powder pretreated by light bio-oil in a ZnCl2/urea system. The findings indicate that adding urea notably enhanced nitrogen content in PCM surface, improving its electrochemical performance. When the mass ratio of ZnCl2, pretreated poplar powder and urea is 2:1:1 (PZN1-500), the nitrogen content of prepared PCM is 9.46 %. The maximum specific capacitance reaches 382.7 F/g at 0.5 A/g. Furthermore, the assembled symmetrical PZN1-500 supercapacitor possessed the energy density of 9.16 Wh kg−1 at 125 W kg−1 with the capacitance retention of 92.65 % after 10,000 cycles. The preparation strategy of nitrogen-doped PCM proposed in this study is helpful for the further development of supercapacitors and the high-value utilization of biomass.

Flexible electrode fabricated from molybdate-loaded silk fabric for hydrogen production

The broad use of the electrocatalytic hydrogen evolution reaction (HER) is impeded by challenges associated with the availability and high cost of precious metal-based catalysts. Carbon materials co-doped with transition metals and nitrogen have emerged as highly promising alternatives among non-precious metal-based electrocatalysts due to their advantageous features, such as cost-effectiveness, high activity, and excellent stability. This study focuses on incorporating low-cost sodium molybdate onto silk fabric, which serves as a sustainable precursor for the preparation of nitrogen-doped carbon material. This silk fabric is then carbonized to create a flexible electrode for electrocatalytic hydrogen evolution. The resulting electrode exhibits the in situ growth of Mo2C and MoO3, and this mechanism facilitates a smoother conduction path for electrons. The resulting electrode not only possesses flexible characteristics but also exhibits a large specific surface area. Transmission electron microscopy analysis reveals the presence of carbon quantum dots, which actively contribute to the heightened catalytic hydrogen evolution activity of the prepared electrode. Experimental findings unequivocally showcase the outstanding electrocatalytic hydrogen evolution capability and operational stability of the fabricated flexible electrode in acidic and alkaline environments. This work substantiates the efficacy of using low-cost sodium molybdate-loaded silk fabric as a catalyst precursor, thereby providing robust support for the design and implementation of non-precious metal-based electrocatalysts for the HER. This approach advances the development and broader application of carbon-free fuels.