Structure Of Carbon Materials Research Articles

Selective adsorption of high ionization potential value organic pollutants in wastewater

It is imperative to devise effective removal strategies for high ionization potential (IP) organic pollutants in wastewater as their reduced electron-donating capacity challenges the efficiency of advanced oxidation systems in degradation. Against this backdrop, leveraging the metal-based carbon material structure meticulously, we employed metal-pyridine-N (M-N-C, M=Fe, Co, and Ni) as the electron transfer bridge. This distinctive design facilitated the ordered transfer of electrons from the adsorbent surface to the surface of high IP value pollutants, acting as a "supplement" to compensate for their deficient electron-donating capability, thereby culminating in the selective adsorption of these pollutants. Furthermore, this adsorbent also demonstrated effective removal of trace emerging contaminants (2 mg/L), displayed robust resistance to various salts, exhibited reusability, and maintained stability. These findings carry substantial implications for future carbon-based material design, offering a pathway toward exceptional adsorption performance in treating water pollution.

Basic magnesium carbonate template assisted co-carbonization of potassium citrate toward hierarchical porous carbon for supercapacitors

Hierarchical porous carbon (HPC) as the ideal host material for supercapacitors has received extensive attention. However, traditional methods of fabricating HPC often rely on organic macromolecules and complex procedures. Herein, a simple and straightforward approach is developed for the synthesis of HPC through basic magnesium carbonate template assisted co-carbonization of potassium citrate. Potassium citrate can be effectively embedded and encapsulated with basic magnesium carbonate due to the large bulk density difference between them. In the pyrolysis process, the carbon-containing small molecules produced by the pyrolysis of potassium citrate are deposited on the surface of MgO surface obtained from the decomposition of basic magnesium carbonate, and the etching reaction of potassium salt, CO2 and primary carbon structure occurs. The competitive rate of carbon deposition reaction and etching reaction can be easily controlled by changing the ratio of potassium citrate and basic magnesium carbonate. The obtained carbon materials show the morphology changes of nanoparticle accumulations, discontinuous carbon frames and carbon planar blocks, and the hierarchical porous structure of carbon materials can also be controlled in a wide range. HPC-2 exhibits the morphology of nanoparticle accumulation and generates abundant meso-macropores, which accelerates the rapid transport of electrolytic ions. The micropores inside the nanoparticles provide an accessible room for ionic adsorption. Benefited from this unique microstructural framework, HPC-2 shares a high capacitance of 305.5Fg-1 at 0.5Ag-1 and 173.1Fg-1 at 50Ag-1. Furthermore, the assembled symmetric supercapacitors exhibit a high energy density and power density than YP-50F throughout the test range. The versatility of this synthetic strategy provides an insight into directional tailoring fine pore structure and micro-morphology of carbon materials based on small molecule deposition.

Disordered carbon structures enhance capacitive storage

Electrochemical energy storage (EES) is one of the key technologies in global research, focusing on the efficient storage and utilization of electrical energy generated from intermittent sources. The development of EES systems with high energy and power density is essential for meeting future energy demands electrochemical capacitors, such as capacitors, are capable of storing electrical energy obtained from intermittent sources and enabling the rapid energy transfer and transformation. Among these, electrical double-layer capacitances (EDLCs) within porous carbon materials (Fig. 1a), are commercially popular due to their excellent conductivity and relatively low cost. Despite their advantages, the complex structure of nanoporous carbon materials challenges in optimizing supercapacitor performance. While previous research has suggested that adjusting the pore size of nanoporous in carbon materials can enhance capacitive performance [1], conflicting reports and the lack of a definitive correlation between capacitance and pore size remain issues [2]. Understanding the relationship between the structure of carbon materials and their capacitance is crucial for the design of devices with high energy density effectively.

Basic magnesium carbonate template assisted co-carbonization of potassium citrate toward hierarchical porous carbon for supercapacitors

Hierarchical porous carbon (HPC) as the ideal host material for supercapacitors has received extensive attention. However, traditional methods of fabricating HPC often rely on organic macromolecules and complex procedures. Herein, a simple and straightforward approach is developed for the synthesis of HPC through basic magnesium carbonate template assisted co-carbonization of potassium citrate. Potassium citrate can be effectively embedded and encapsulated with basic magnesium carbonate due to the large bulk density difference between them. In the pyrolysis process, the carbon-containing small molecules produced by the pyrolysis of potassium citrate are deposited on the surface of MgO surface obtained from the decomposition of basic magnesium carbonate, and the etching reaction of potassium salt, CO2 and primary carbon structure occurs. The competitive rate of carbon deposition reaction and etching reaction can be easily controlled by changing the ratio of potassium citrate and basic magnesium carbonate. The obtained carbon materials show the morphology changes of nanoparticle accumulations, discontinuous carbon frames and carbon planar blocks, and the hierarchical porous structure of carbon materials can also be controlled in a wide range. HPC-2 exhibits the morphology of nanoparticle accumulation and generates abundant meso-macropores, which accelerates the rapid transport of electrolytic ions. The micropores inside the nanoparticles provide an accessible room for ionic adsorption. Benefited from this unique microstructural framework, HPC-2 shares a high capacitance of 305.5Fg-1 at 0.5Ag-1 and 173.1Fg-1 at 50Ag-1. Furthermore, the assembled symmetric supercapacitors exhibit a high energy density and power density than YP-50F throughout the test range. The versatility of this synthetic strategy provides an insight into directional tailoring fine pore structure and micro-morphology of carbon materials based on small molecule deposition.

Design and physical property study of seven novel carbon allotropes by Random methods combined group and Graph theories

Carbon materials are important semiconductor materials. For enriching the structure of carbon materials, the eight novel carbons with R-3m phase are predicted by using Random methods based on Group and Graph theories. Among these allotropes, one (R-3m/C−8(-|-)) was excluded through stability criterion, and the others new carbon structures meet all stability conditions, including thermal stability, dynamical stability, mechanical stability, and thermodynamic stability. According to two empirical hardness model criteria, all the hardness of seven novel carbon allotropes are above 50 GPa. Particularly, R-3m/C, R-3m/C−2(-|-), R-3m/C−3(-|-), R-3m/C−6(-|-), and/R−3(-|-)m/C−7(-|-) belong to superhard materials. Electronic band structures of these materials are demonstrated by HSE06 hybrid functional, where R-3m/C, R-3m/C−2(-|-), R-3m/C−3(-|-), R-3m/C−4(-|-), R-3m/C−6(-|-), and/R−3(-|-)m/C−7(-|-) are wide band gap semiconductors, while R-3m/C, R-3m/C−2(-|-) are quasi-direct band gap structures. The R-3m/C−4(-|-) exhibits the greatest elastic anisotropy in elastic modulus. There materials with different crystalline phase structures are characterized by using X-ray diffraction spectroscopy. Here, the predicted new allotropes with excellent physical properties provide theoretical guidance for further development and expansion of carbon material applications.

Production of C-SiO_2 Composite from Waste Plant Raw Materials and Its Use as a Filler of Structural Carbon Materials

Production of C-SiO_2 Composite from Waste Plant Raw Materials and Its Use as a Filler of Structural Carbon Materials

Influence of the Nitrogen Precursor in the Development of N-Functionalities in a Mesoporous Carbon Material and Its Effect on the Li–S Cells’ Electrochemistry

Li–S batteries are positioned as a strong alternative for efficient energy storage due to their high theoretical energy density and their theoretical specific capacity (1675 mA h g−1) compared to current Li-ion batteries; however, their commercialization is affected by the rapid decay of the specific capacity as a consequence of the different species of lithium polysulfides that are generated during the charge–discharge processes. The use of nitrogen-doped mesoporous carbon materials has been shown to have the ability to confer electronic conductivity to sulfur and retain the lithium polysulfide species. However, there are not enough studies to help understand how the type of nitrogen precursor influences the development of specific nitrogen functionalities to favor the retention of lithium polysulfide species. This work seeks to determine the effect of the use of different nitrogen precursors on the structural changes of the mesoporous carbon materials prepared, and thus evaluate the electrochemical behavior of Li–S cells correlating the type of nitrogen functionality generated when the precursor is variated with the charge/discharge capacity developed during the cell operation. For this study, different carbon materials were prepared by the variation of the nitrogen source (melamine, ethylenediamine, and hexadecylamine) to obtain a N-doped mesoporous carbon with different distributions of nitrogen functionalities in its structure. The use of the primary amine ethylenediamine as a nitrogen precursor in the formation of structured carbon materials favored elemental sulfur infiltration into its pores, resulting in the maximum sulfur content within the pores and interacting with the carbonaceous matrix (78.8 wt.%). The carbon material prepared with this precursor resulted in a higher content of N-pyridinic functionality, which, combined with the high content of N-pyrrolic, resulted in the highest specific discharge capacity at 0.1 C after 100 cycles when compared to cells assembled with materials derived from the use of melamine and hexadecylamine precursors. The cell assembled with the electrode formed from ethylenediamine as a nitrogen precursor presented an initial discharge capacity of 918 mA h g−1 with a Coulombic efficiency of ~83.4% at 0.1 C after 100 cycles.

Biochar with enhanced performance prepared based on “graphite-structure regulation” conjecture designed to effectively control water pollution

In this work, corn straw was used as raw material, Hummers method and activation were used to adjust the graphite structure in biochar, and preparing straw based biochar (H-BCS) with ultra-high specific surface area (3441.80 m2/g), highly total pore volume (1.9859 cm3/g), and further enhanced physicochemical properties. Compared with untreated straw biochar (BCS), the specific surface area and total pore volume of H-BCS were increased by 47.24 % and 55.85 %, respectively. H-BCS showed good removal ability in subsequent experiments by using chloramphenicol (CP), hexavalent chromium (Cr6+), and crystal violet (CV) as adsorption models. In addition, the adsorption capacities of H-BCS (CP: 1396.30 mg/g, Cr6+: 218.40 mg/g, and CV: 1246.24 mg/g) are not only higher than most adsorbents, even after undergoing 5 cycles of regeneration, its adsorption capacity remains above 80 %, indicating significant potential for practical applications. In addition, we also speculated and analyzed the conjecture about the “graphite-structure regulation” during the preparation process, and finally discussed the possible mechanism during the adsorption processes. We hope this work could provide a new strategy to solve the restriction of biochar performance by further exploring the regulation of graphite structure in carbon materials.

N, S co-doped coal-based hard carbon prepared by two-step carbonization and a molten salt template method for sodium storage

Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g-1 at 20 mA g-1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g-1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.

How hetero-single-atom dispersion reconstructed electronic structure of carbon materials and regulated Fenton-like oxidation pathways

Single-atom catalysts (SACs) have emerged as competitive candidates for Fenton-like oxidation of micro-pollutants in water. However, the impact of metal insertion on the intrinsic catalytic activity of carrier materials has been commonly overlooked, and the environmental risk due to metal leaching still requires attention. In contrast to previous reports, where metal sites were conventionally considered as catalytic centers, our study investigates, for the first time, the crucial catalytic role of the carbon carrier modulated through hetero-single-atom dispersion and the regulation of Fenton-like oxidation pathways. The inherent differences in electronic properties between Fe and Co can effectively trigger long-range electron rearrangement in the sp2-carbon-conjugated structure, creating more electron-rich regions for peroxymonosulfate (PMS) complexation and initiating the electron transfer process (ETP) for pollutant degradation, which imparts the synthesized catalyst (FeCo-NCB) with exceptional catalytic efficiency despite its relatively low metal content. Moreover, the FeCo-NCB/PMS system exhibits enduring decontamination efficiency in complex water matrices, satisfactory catalytic stability, and low metal leaching, signifying promising practical applications. More impressively, the spatial relationship between metal sites and electron density clouds is revealed to determine whether high-valent metal-oxo species (HVMO) are involved during the decomposition of surface complexes. Unlike single-type single-atom dispersion, where metal sites are situated within electron-rich regions, hetero-single-atom dispersion can cause the deviation of electron density clouds from the metal sites, thus hindering the in-situ oxidation of metal within the complexes and minimizing the contribution of HVMO. These findings provide new insights into the development of carbon-based SACs and advance the understanding of nonradical mechanisms underpinning Fenton-like treatments.

Bio-based sunflower carbon/polyethylene glycol shape-stabilized phase change materials for thermal energy storage.

The exploitation of shape-stabilized phase change materials with high thermal conductivity and energy storage capacity is an effective strategy for improving energy efficiency. In this work, sunflower stem carbon/polyethylene glycol (SS-PEG) and sunflower receptacle carbon/polyethylene glycol (SR-PEG) shape-stabilized phase change materials, utilizing sunflower stem and receptacle biomass carbon with high specific surface area and pore volume obtained by carbonization as frameworks and polyethylene glycol as an energy storage material, were prepared by the vacuum impregnation method. The ability to load polyethylene glycol into the pore structure of carbon materials in different sunflower parts was mainly investigated, and the micro-morphology, compositional structure and thermal properties were characterized and analyzed using SEM, IR spectroscopy, XRD, DSC and TG techniques. The results showed that the carbonized sunflower stems maintained the sieve pore structure, and the carbonized sunflower receptacle was a macroporous structure containing a large number of three-dimensional interconnections. At the same time, the interaction between polyethylene glycol and each carbon material occurred through physisorption. The melting enthalpies of SS-PEG and SR-PEG shape-stabilized phase change materials were 153.4 J g-1 and 171.5 J g-1, respectively, and the loading rates reached 81.9% and 91.5%, with initial thermal decomposition temperatures (T 5%) of 344 °C and 368 °C.

Controllable synthesis of electric double-layer capacitance and pseudocapacitance coupled porous carbon cathode material for zinc-ion hybrid capacitors.

The designability of the porous structure of carbon material makes it a popular material for zinc-ion hybrid capacitors (ZIHCs). However, the micropore confinement effect leads to sluggish kinetics and is not well resolved yet. In this work, a pore-size controllable carbon material was designed to enhance ion accessibility. The experimental and calculated results revealed that suitable pore sizes and defects were beneficial to ion transfer/adsorption. Meanwhile, oxygen-containing functional groups could introduce a pseudocapacitance reaction. Its large specific surface area and interconnecting network structure could shorten the ion/electron transfer length to reach high ion adsorption capacity and fast kinetic behavior. When used as a zinc-ion hybrid capacitor cathode material, it showed 9.9 kW kg-1 power density and 100 W h kg-1 energy density. Even at 5 A g-1, after 50 000 cycles, there was still 93% capacity retention. Systemic ex situ characterization and first-principles calculations indicated that the excellent electrochemical performance is attributed to the electric double layer capacitance (EDLC) - pseudocapacitance coupled mechanism via the introduction of an appropriate amount of oxygen-containing functional groups. This work provides a robust design for pore engineering and mechanistic insights into rapid zinc-ion storage in carbon materials.

Biomass‐Derived Carbon Materials for the Adsorption of Organic Pollutants

AbstractWith the development of economy and increasing environmental awareness, how to effectively remove organic pollutants in wastewater is a research hotspot. Adsorption is one of the effective methods, and the adsorption material is the key factor to determine the efficiency. In this review, biomass‐derived carbon materials as adsorbents of organic pollutants and the adsorption mechanism are discussed in depth. The effects of carbonization and activation on the morphology and structure of carbon materials; the modification strategies of carbon adsorbents, the adsorption performance of biomass‐derived carbon materials for organic pollutants are described and illustrated; the future work of the biomass‐derived carbon materials is proposed.

Enhancement of gelatinization on electrochemical performance of corn starch-based porous carbon as electrode material in supercapacitors

Biomass-based porous carbon is extensively utilized as an electrode material for double-layer supercapacitors due to its cost effectiveness and wide availability. However, it is still a challenge to construct reasonable pore structures to prepare biomass porous carbon materials with excellent electrochemical properties. In this work, corn starch was chosen as carbon source to prepare porous carbon materials through gelatinization, pre-carbonization and activation. The impact of gelatinization temperature on the pore structure and electrochemical properties of carbon materials was thoroughly investigated. With the increase of gelatinization temperature, the small mesoporous ratio in the carbon materials firstly increases and then decreases, which is positively correlated to the changes of specific capacitance. Among all samples tested, the corn starch-based porous carbon (SAC-85-R6A7) prepared by gelatinizing at 85 °C followed by pre-carbonizing at 600 °C and activating at 700 °C exhibits exceptional electrochemical characteristics with a specific capacitance up to 386.43 F g−1 at 0.5 A g−1 and a retention rate of 75.81 % even at 20 A g−1. Due to its wide voltage window range from 0 to 1.1 V, the two-electrode device for SAC-85-R6A7//SAC-85-R6A7 shows an outstanding energy density of 12.94 Wh kg−1 at a power density of 277.33 W kg−1 and still retains an energy density value as substantial as 10.75 Wh kg−1 even though at 6.45 kW kg−1, and presents a capacity retention of 95.33 % after 10,000 cycles at 5 A g−1, the coulomb efficiency close to 100 %. The change of gelatinization temperature optimizes the pore size structure of the carbon material, further promotes the rapid penetration of electrolyte ions, and improves the electrochemical performance.

Preparation and properties of high porosity activated carbon material used as electrode material

The hemp straw based activated carbons catalyzed by phosphotungstic acid were prepared by hydrothermal carbonization and KOH activation. The electrochemical characterization of activated carbon had been examined using cyclic voltammetry and galvanostatic charge-discharge technique. At the current density of 1 A g−1, the specific capacitance of activated carbon material doped with phosphotungstic acid (HSAC-P) was 138 F g−1, which was higher than the HSAC (93 F g−1 at the current density of 1 A g−1). The porous structure of carbon material could increase its specific surface area and improve its performance in electrochemistry.

Novel Isomer of Volleyballene Sc20C60.

The Stone-Wales defect is a well-known and significant defective structure in carbon materials, impacting their mechanical, chemical, and electronic properties. Recently, a novel metal-carbon nanomaterial named Volleyballene was discovered, characterized by a C-C bond bridging two carbon pentagons. Using first-principles calculations, a stable Stone-Wales-defective counterpart of Volleyballene, exhibiting Th symmetry, has been proposed by rotating the C-C bond by 90°. Although its binding energy per atom is slightly higher than that of Volleyballene (ΔEb = 0.009 eV/atom), implying marginally lower structural stability, it can maintain its bond structure until the effective temperature reaches about 1500 K, indicating greater thermodynamic stability. Additionally, its highest vibration frequency is 1346.2 cm-1, indicating a strong chemical bond strength. A theoretical analysis of the Sc20C60 + Sc20C60 binary systems highlights that the stable building block may be applied in potential nanoassemblies.

Synthesis of metal-free nitrogen-doped mesoporous carbon nanosheets with reference to molecular self-assembly for efficient peroxymonosulfate activation

The application of metal-free carbon materials in Sulfate radical-based advanced oxidation processes (SR-AOPs) has attracted great attention. In SR-AOPs, porosity and active sites are the keys for nitrogen-doped carbon materials to exhibit high catalytic activity. In this paper, melamine and gallic acid were selected as raw materials, preparing metal-free nitrogen-doped carbon materials by using the molecular self-assembly synthesis method. The catalysts with different structural morphology and surface chemistry were obtained by controlling the pyrolysis temperature. It proposed the formation mechanism of nitrogen-doped mesoporous carbon nanosheets (NMC). The pyrolysis temperature was critical for the regulation of surface properties as well as the structure of carbon materials. It was found that NMC-800 exhibited fluffy and porous microstructure, and various active sites on the surface of the catalyst, including graphite N, pyridine N and CO. In the NMC-800/PMS system, the SMX degradation efficiency and corresponding rate constant could achieve 90.3 % and 0.1705 min−1, respectively. Besides, the degradation pathways and intermediate products of SMX were discussed by the analysis of quenching experiments, electron spin resonance (ESR) and liquid chromatography-mass spectrometry (LC-MS).

Regulating the intrinsic electronic structure of carbon nanofibers with high-spin state Ni for sodium storage with high-power density

Carbon nanofibers (CNFs) with high specific surface area show great potential for sodium storage as a hard carbon material. Herein, CNFs anchored with Ni nanoparticles (CNFs/Ni) were prepared through chemical vapor deposition and impregnation reduction methods, in situ growing on the three-dimensional porous copper current collector (3DP-Cu). The coupling effect of high-spin state Ni nanoparticles leads to the increase of defect density and the expansion of lattice spacing of CNFs. Meanwhile, the 3DP-Cu ensures a high loading capacity of CNFs and short ion/electron transport channels. As an integral binder-free anode, the 3DP-Cu/CNFs/Ni exhibits excellent electrochemical performance, which demonstrates a high specific capacity with 298.5 mAh g–1 at 1000 mA g–1 after 1500 cycles, and a high power density with 200 mAh g–1 over 1000 cycles at 5000 mA g–1. Density functional theory calculation results show that the high-spin state Ni regulates the electronic structure of CNFs, which significantly reduces the adsorption energy for Na+ (–2.7 Ev) and thus enables high-rate capability. The regulation of the electronic structure of carbon materials by high-spin state metal provides a new strategy for developing high-power carbonaceous anode materials for sodium-ion batteries.

Application of pitch-based multi cavity carbon microsheets in capacitive deionization removal of NO3–

Capacities deionization (CDI) denitrification technology has attracted considerable attention, and electrode materials with nitrate adsorption properties have become a research hotspot. In this study, a multi cavity carbon microsheets (MCCM-5) was prepared using a hard template method and low-cost nitrated pitch as a carbon source. The results of the electrosorption experiments showed that the material had an excellent capacity of NaNO3 (45 mg g−1). Furthermore, although the actual specific surface area and specific capacitance of MCCM-5 are lower than those of hierarchical porous carbon materials (HPCM-1), MCCM-5 exhibit lower diffusion and charge-transfer resistances, resulting in a better denitrification performance. The adsorption capacity of MCCM-5 for NaNO3 was twice that HPCM-1 and 11.8 times that of commercial activated carbon, which is superior to the material properties reported thus far. Our analysis indicated that the material combined the advantages of both a layered structure and hierarchical pores. First, the uniformly distributed hierarchical pores in the layered structure enhanced the ion concentration potential. Second, the layered structure provided good ion diffusion channels, thereby increasing the effective adsorption area of the material. DFT calculation shows that the carbon cavity structure enriched in the material shows a stronger adsorption capacity for NO3–, which can promote the electron transfer process during NO3– adsorption. This study shows that a precise regulation of the carbon material structure can be achieved by adjusting the size of the template material and carbonization conditions to obtain a higher adsorption capacity and provides a new idea for the structural optimization of electrode materials.

Metal–Organic Framework‐Derived N‐Doped Carbon with Controllable Mesopore Sizes for Low‐Pt Fuel Cells

AbstractMesoporous structure of carbon materials plays an important role in electrocatalyst design. Constructing carbon supports with tunable mesopores has long been a challenge. Herein, the elaborate regulation of mesopores in N‐doped carbon materials is reported by pyrolyzing energetic metal‐triazolate (MET) frameworks with different particle sizes and at different ramp rates. Higher thermal transfer rates brought about by smaller particle size and higher ramp rate lead to more violent decomposition with a large number of gases producing, which in turn result in larger mesopores in the derivatives. Consequently, a series of N‐doped carbon materials with controllable mesopores are obtained. As a proof‐of‐concept, ultrafine Pt nanoparticles are enveloped inside these mesopores to acquire high‐performance electrocatalysts for oxygen reduction reaction. The optimized catalyst achieves high mass activity of 1.52 A mgPt−1 at 0.9 ViR‐free and peak power density of 0.8 W cm−2 (H2‐Air) with an ultralow Pt loading of 0.05 mgPt cm−2 at cathode in fuel cells, highlighting the great advantages of MET‐derived carbon materials with controllable mesopores in the preparation of advanced electrocatalysts.