Carbon Materials Research Articles

Multi-shell bowl-like carbon microspheres for lightweight and broadband microwave absorption

Carbon materials have made significant progress in the field of microwave absorption (MA), but achieving wide effective absorption bandwidth (EAB) at low filler content still remains a great challenge. In this work, we design multi-shell bowl-like mesoporous carbon microspheres (MBMCs) by a facile hard template method for efficient MA. It is demonstrated that the spacing between inner and outer shell and second shell thickness play a vital role on the configuration of carbon microspheres. By controlling the second addition of silica template, the microstructure of carbon microsphere evolves from spherical to bowl shape geometry. Expanded shell spacing is beneficial for forming bowl-like microsphere. The dielectric loss and MA properties are highly associated with the configuration of MBMCs. Well-proportioned MBMCs with appropriate shell spacing present wide EAB of 7.3 GHz under a low filling ratio of 12 wt.%. This work paves a new way to broaden EAB and lower filling content of carbon materials via asymmetric multilayer microstructure design.

Reusable metal-free mesoporous carbon-catalyzed reductive N-formylation of nitroarenes and quinolines

The high-value transformation of nitrogen-containing compounds through a facile, cost-effective, and eco-friendly one-pot strategy holds significant importance. However, this process typically involves the use of metal catalysts and is limited by low activity as well as the requirement of high temperature and pressure. Herein, we describe a general and efficient metal-free N-doped mesoporous carbon material using well-defined ligand 1,10-phenanthroline as the precursor and silica colloid as the hard template. Formic acid is both a reducing agent and a formylation reagent, and structurally distinct mono- or multi-substituted nitroarenes and quinolines can be selectively N-formylation in a one-pot method. The catalyst can be easily recovered without observable loss of efficiency for ten consecutive uses. The control experiments and density functional theory (DFT) calculations indicate that formic acid mainly obtains active hydrogen in the form of O–H bond cleavage, which benefits from the strong adsorption and enhanced activity generated by the interaction between graphitic nitrogen species in the catalyst and formic acid. The excellent catalytic performance of the meso-phen-X catalyst is attributed to the synergistic effect of graphitic N and large specific surface area, providing a promising method for the development of non-metallic catalyst-modified carbon materials.

Green self-templated synthesis of P-doped mesoporous carbon from dual sodium salts with improved average pore size for capacitive deionization

Mesoporous carbon materials hold significant potential in capacitive deionization (CDI) technology owing to expansive accessible surface area, more adaptable pore structure, excellent conductivity properties and effective surface modification and functionalization. While templating is a common method for synthesizing mesoporous carbons, the commonly used hard and soft templating approaches among them suffer from the challenges of expensive precursors and templating agents, complex procedures, secondary contaminants and difficulties in template removal. In contrast, the self-templating method not only circumvents the traditional template removal or combustion steps but also eliminates the use of organic solvents and hazardous chemicals, thus minimizing environmental impact. In this paper, we have successfully synthesized phosphorus-doped mesoporous carbon with a large average pore size (paver) using a green and convenient self-templating method employing dual sodium salts of sodium alginate (SA) and sodium phytate (SP). Compared to single SA (6.76 nm) or SP (3.74 nm) self-templated carbonization, the average pore size of carbon materials obtained from dual self-templated carbonization with a proportional mixture (12.97 nm) is significantly improved. The larger average pore size provides a greater surface area for electrode-electrolyte interactions, allowing for easier access and faster diffusion of ions into the pores, thereby enhancing the electrochemical and capacitive deionization properties of the material. The resulting material demonstrates promising electrochemical and desalination performance as evidenced by possessing a specific capacitance of 175.8 A/g and an adsorption capacity of 19.65 mg/g, underlining its potential for application in capacitive deionization utilizing mesoporous carbon materials with large average pore size.

Toward Superior Stiffness in Carbon: The Interplay between Bond Strength and Anisotropic Response.

Carbon's ability to form diverse structures with varying hybridizations motivates the search for novel materials surpassing diamond's exceptional mechanical rigidity. We analyze previously predicted superhard phases and find that some exhibit average bond stiffness and density higher than those of diamond, hinting at potentially superior stiffness. However, these structures show a lower bulk modulus. We delve into this contradiction and demonstrate that it stems from the structures' anisotropic response to isotropic deformation. The concept of strain anisotropy is introduced to quantify this phenomenon. Our findings reveal a key connection between bond stiffness and bulk modulus in carbon materials, highlighting the importance of considering anisotropic behavior for a comprehensive understanding of the mechanical properties.

Magnetically separable sorbent based on activated carbon derived from a new precursor Rhizoclonium hookeri for facile oil spill clean-up

A huge quantity of synthetic toxic materials ends-up in water bodies causing long-lasting environmental and economic impacts due to catastrophic oil spill. Exploring marine algae as sorbent materials for oil spill remediation is a relatively new area and holds great potential. Herein, macroalgae Rhizoclonium hookeri (RH) derived magnetically recoverable RH-activated carbon (RHAC@Fe3O4) composite has been proposed as an innovative and robust strategy for oil spill clean-up. The application of RHAC@Fe3O4 composite was investigated for oil removal by varying time (10–60 min), dosage (0.2–1 g) and temperature (20, 30, 40 °C) to ascertain its optimal performance using both unused and used motor oil. Characterization studies showed that KOH activation resulted in developing pore structure and surface functionalities in the algal biochar. The percentage of oil uptake from simulated oil spill was over 90 % in 30 min at room temperature using 0.8 g composite. Moreover, Fe3O4 loading onto carbon material allowed magnetic separation as a convenient alternative to filtration for the recovery of oil laden composite. Apart from superior oil removal ability, synthesized composite demonstrated robust performance up to four cycles in synthetic sea water matrices. Comparative study revealed better oil sequestration efficiency of RHAC@Fe3O4 (93 %) as compared to its precursors, i.e. algal biochar (71 %) and AC (88 %). Based on these findings, it is advocated that designed RHAC@Fe3O4 composite being eco-friendly, economical and readily recoverable with enhanced oil uptake ability could potentially be an innovative platform for oil spill clean-up applications.

Enhancing performance of Si/C composite anode in high energy density lithium-ion batteries with CMC-CPAM-SBR binder

Abstract The utilization of polymeric binders is indispensable in the implementation of silicon/carbon anode materials in high-energy-density lithium-ion batteries (LIBs). This necessity arises from their pivotal function in upholding structural integrity. However, current water-based binders solely focus on binder adhesion, neglecting the crucial interaction with the carbon material. In this work, a composite binder (CMC-CPAM-SBR) was constructed by combining Styrene Butadiene Rubber (SBR) with cationic polyacrylamide (CPAM) network binder with self-healing carboxymethyl cellulose (CMC). This innovative binder formulation was designed to enhance the performance of Si@C/graphite composite anodes. A capacity retention rate of 92.86% was achieved after 100 cycles, which represents the improvement over the performance of electrodes utilizing the CMC-CPAM binder, which only retained a capacity of 84.53% after the same number of cycles. A full battery with a capacity of 1992.8 mAh was designed, and the battery capacity remained at 80.6% of its capacity after completing 500 cycles. This research presents an effective technique for manufacturing high-performance anode materials.

Synthesis of hierarchical carbon Nanofibers-CoNi/C composites for enhanced microwave absorption efficiency

Developing lightweight, highly absorption and broadband microwave absorbents to combat severe electromagnetic radiation pollution poses a significant challenge. In this study, we designed a novel chain-like CNFs-CoNi/C nanocomposite by in-situ growth of bimetallic MOFs on the CNFs followed by calcination. The resulting CoNi/C composite with hollow structure was uniformly distributed along the 1D CNFs. The unique porous structure and heterogeneous interface derived from MOFs facilitated efficient scattering and multiple reflections of microwaves. By harnessing interfacial polarization loss, dipole polarization loss, and conduction loss mechanisms synergistically, the chain-shaped porous multi-stage CNFs-CoNi/C composite exhibited exceptional microwave absorption performance at a filling ratio of 10 %. It achieves a maximum reflection loss of −70 dB and an absorption bandwidth (EAB) for RL ≤ -10 exceeding 4.82 GHz with a corresponding thickness as low as 1.25 mm. This study introduced a lightweight and highly absorptive material that offers valuable insights into developing high-performance electromagnetic wave absorbing materials through organic composite comprising MOF and carbon materials.

High-performance rechargeable zinc-air batteries enabled by cobalt iron anchored on nitrogen-doped carbon matrix as bifunctional electrocatalyst

Developing efficient bifunctional oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) electrocatalysts is potential ways for achieving high rechargeable zinc-air (Zn-air) battery performance. Herein, we report an iron (II) acetate-assisted strategy to synthesize Co3Fe7-NC-OAc catalyst with cobalt iron (Co3Fe7) alloy anchored on nitrogen-doped carbon (NC) matrix, which can serve as efficient ORR/OER bifunctional electrocatalysts for rechargeable Zn-air batteries. Apart from alloying with Co to form ORR/OER active Co3Fe7 nanoparticles, the incorporation of iron (II) acetate has expanded the pore size inside the Co3Fe7-NC-OAc catalyst to serve as gas transfer channels, and has induced synergetic electronic coupling between Co3Fe7 nanoparticles and NC matrix for boosting catalytic activity. Therefore, Co3Fe7-NC-OAc exhibits favorable ORR activity with a most positive half-wave potential of 0.90 V vs. RHE, fast ORR kinetics with a highest kinetic current density of 57.4 mA cm−2 at 0.85 V vs. RHE, and fast O2 diffusion and transport that enables smaller mass transport overpotential at high current density up to 800 mA cm−2. Additionally, Co3Fe7-NC-OAc can catalyze OER with low overpotential of 310 mV at 10 mA cm−2. When employed as air electrode for Zn-air batteries, Co3Fe7-NC-OAc achieve high peak power densities of 193 mW cm−2 and 587 mW cm−2 in liquid and solid-state Zn-air batteries. The liquid battery also exhibits high specific capacity and remarkable cycling performance. This work opens up a new opportunity for developing highly efficient bifunctional electrocatalysts for Zn-air battery applications.

MOFs-derived copper selenides nanoparticles implanted in carbon matrix for broadband electromagnetic wave absorption

Selenide-based functional composites materials demonstrated tunable dielectric properties and heterogeneous interface design, which has been widely studied in electromagnetic (EM) wave absorption field. Herein, Metal-organic frameworks (MOFs) derived carbon coating copper selenide (Cu2-XSe@C) composites were successfully fabricated by using the Cu-MOFs as precursor. After reacting with the gaseous Se in the selenization annealing process, the metal host was converted into the Cu2-XSe nanoparticles, where embodied in the carbon matrix transformed from the organic linker. Based on the tunning dielectric property and building heterogeneous interface, MOFs-derived Cu2-XSe@C composites displayed outstanding EM wave absorption performance. Though the conduction loss, interfacial and dipole polarization behaviors, the minimum reflection loss (RLmin) value of Cu2-XSe@C-600 composites reached to −74.3 dB at 11.7 GHz when the thickness is 2.0 mm. The efficient absorption bandwidth (EAB) can be regulated via controlling the applied thickness. When the thickness is 2.3 mm, above-mentioned Cu2-XSe@C-600 got the broadest absorption performance with the EAB of 5.5 GHz from the 7.7–13.2 GHz, covering the whole X-band. Therefore, MOFs-derived selenide-based composites shed a new design strategy for constructing broadband EM wave absorption, especially in radar stealth applications.

Effective activation of PMS by encapsulating monodispersed Fe3O4 within N, S heteroatoms co-doped carbon chamber for ROX removal dominated by the non-radical pathway

Developing the eco-friendly catalyst-adsorption iron-based materials with improved catalytic activity and minimal Fe leaching is fascinating for roxarsone (ROX) removal. Herein, Fe3O4 nanoparticles were encapsulated in flexible N, S-modified carbon chamber (Fe3O4@NS4C) through the “hydrothermal + pyrolysis” process to form a catalyst with multi-active sites. ROX could be degraded nearly 100 % at pH 5.0 − 11.0 and secondary inorganic As species concentration is lower than 0.09 mg/L by efficient adsorption. Especially, the Fe ion leaching concentration in Fe3O4@NS4C/PMS after ROX removal is decreased to 0.08 mg/L. Combined with quenching experiment, EPR, Raman spectroscopy and electrochemical analysis, the non-radical activation mechanism dominated by 1O2 and electron transfer was determined. The synergistic interaction between the N doped sites and the S anchored sites within the carbon matrix not only improves the adsorption of PMS on the catalyst but also facilitates the direct activation of PMS to 1O2, while the surface electron transfer improves the Fe2+/Fe3+ redox cycling in PMS activation. The active sites of ROX attacked by 1O2 were examined through Fukui function computations. Combined with HPLC-MS, the ROX degradation pathway was determined, and the toxicity of intermediates was evaluated. Furthermore, the removal performance of ROX in Fe3O4@NS4C/PMS system was also assessed in different environment for practical application, indicating that the advantages in the synergy between N, S co-doping carbon chamber and encapsulated iron oxide for water purification.

EVALUATION OF CARBONATED PRODUCT FROM MINERAL CARBONATION OF MINING WASTE FOR CARBON SEQUESTRATION

Mining operations generate significant quantities of waste containing alkaline earth silicates, which are valuable for carbon sequestration. Hence, the goal of this study is to assess the possibility of using mining waste to store carbon through a process of mineral carbonation. The study tested mineral carbonation under low reactivity conditions, including ambient pressure and low temperature, to evaluate the effect of pH levels on process efficiency. The samples were discovered to have an alkaline pH, suggesting that they were suitable for mineral carbonation reactions from the beginning. The carbonation process of the mineral was conducted at different pH levels of 8, 10, and 12. The findings showed that the carbonation efficiency was approximately 3%, with the highest level observed at pH 12. Through thermogravimetric analysis, it was observed that there was a multi stage transformation of minerals, which indicated the formation of carbonates containing iron and magnesium. The process captured approximately 33 and 39 g of CO2/kg. The process indicates that mine waste can be used as a source material for mineral carbonation, as demonstrated by the formation of iron and calcium carbonate products. This research demonstrates that mine waste has the potential for long-term carbon storage, offering a beneficial method for waste management and carbon capture strategies.

Preparation of Ni-Cu-C composite catalysts prepared from mixed nickel and copper hydroxides for selective hydrogenation of 4-nitrophenol

A high-performance Ni-Cu-C composite catalyst was prepared from mixed nickel hydroxide and copper hydroxide, which were obtained by coprecipitation, by thermal treatment with acetylene-containing gas at 120 °C followed by hydrogen reduction at 180 °C. The characterization results of XRD, TEM, XPS, and H2-TPR measurements confirmed the presence of nickel carbide (Ni3C), copper carbide (CuxC), Cu, and Ni in the matrix of amorphous carbon in the composite catalyst. The mild preparation temperature and the porous carbon shell layers prevented the nano-sized particles from aggregation. The formation of interstitial Ni3C and CuxC significantly enhanced the dissociation of molecular hydrogen, accelerating the selective hydrogenation of 4-nitrophenol (4-NP) to yield 4-aminophenol (4-AP) at relatively mild conditions (80 °C and 1.0 MPa hydrogen pressure). The catalytic performance of the composite catalysts depended strongly on the Ni/Cu molar ratio, with an optimal Ni/Cu molar ratio of 4. In addition, the composite catalyst showed high conversion and selectivity to the corresponding aniline in the selective hydrogenation of other nitroarenes, including nitrobenzene, 4-nitrotoluene, 4-nitrochlorobenzene, 4-nitrobenzaldehyde, 4-nitroacetophenone, and 2-nitroaniline. The catalyst offers a novel approach to rational design and preparation of high-performance abundant metal catalysts for selective hydrogenation of nitroarenes.

Preparation of broad-bandwidth porous carbon electromagnetic wave absorption materials from agricultural waste corncob

Developing advanced electromagnetic wave-absorbing materials tend to focus on the characteristics of low cost, renewability, environmental friendliness, strong absorption, wide bandwidth, and lightweight. This paper described the preparation of porous carbon electromagnetic wave-absorbing materials with strong absorption, broad bandwidth and thin thickness by one-step charring of corncob, an agricultural waste. The corncob porous carbon (CPC) materials were prepared when the charring temperature was 600 °C, the charring time was 3 h and the activator ratio was 0.25:1. The obtained CPC exhibited porous microstructure with average pore size of approximately 1 μm. Its specific surface area was 713.971 m2·g−1, with pore volume of 0.289 mL·g−1 and high degree graphitization. CPC showed excellent electromagnetic wave absorption performance with minimum reflection loss (RL min) of −38.21 dB and effective absorption bandwidth (EAB) of 5.6 GHz at a relatively thin thickness of 2.0 mm. CPC was capable of absorbing 99.9 % of electromagnetic wave (EMW).

Development and properties of cost-effective self-sensing Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) incorporating steel slags

This study examined the electrical and self-sensing capacities of ultra-high performance fiber-reinforced concrete （UHPFRC） with and without steel slag powder. The inclusion of steel slags provides a reliable way to enhance the electrically conductive and self-sensing capabilities of UHPFRC, which is composed of cement, silica fume, and steel fiber. The conductibility of UHPFRC and its response to external loading were investigated. Additionally, through 3D analysis of fiber structure and pore distribution, the conductive mechanisms were revealed. The results show that the addition of steel slags powder (SSP) can improve both mechanical properties and flowability. The maximum fractional change in electrical resistivity under compressive and flexural loads reached 37.6 % and 54.1 %, respectively. However, the conductive model under compressive loading differs from that under flexural loading. Furthermore, an analysis of carbon emissions and material costs revealed that using SSP reduced carbon emissions by 45.2–96.4 % and lowered costs by 41.8–88.8 %, making this approach both economically and environmentally advantageous.

Characteristics and evaluation of recycled waste PVCs as a filler in composite structures: Validation through simulation and experimental methods

Solar Cell as a renewable energy utilization in today's era is considered a suitable choice due to encompass sustainability, environmental preservation, and energy processing efficiency. Solar cells have a finite lifespan that need replacement to maintain energy absorption efficiency. Unfortunately, discarded materials are often underutilized or improperly disposed of. In this study, used photovoltaic solar cell materials are explored as reinforcements in composites. The results showed that 4 % cell filler specimen exhibited highest ultimate tensile strength (UTS) with 51.43 MPa. Followed by Compression strength with 35.38 MPa and flexural strength with 45.54 MPa. SEM/EDS analysis of PV filler specimens revealed the dominance of Carbon (C) and Silica (Si) materials, comprising over 60 %. FT-IR analysis indicated varying compound bond intensities affecting polymerization and material strength under applied forces. Simulation results showed a difference of <2 % when compared to experimental testing outcomes. The current study benefited in environmental conservation efforts through waste reduction and the reuse of recycled materials and are listed in several applications such as in wind turbine, structures, lightweight laminates, automotive structures, and sport equipment.

Development of hydrophilic carbon fiber textiles using seed-assisted hydrothermal deposition of ZnO nanostructures for enhanced interfacial interaction in CFRP composites

Two-step hydrothermal deposition of zinc-oxide (ZnO) nanorods was used to functionalize carbon fiber textiles in order to produce increased hydrophilicity on fiber surface. On carbon fiber textiles, tightly packed ZnO nanorods developed after five seed cycles and 5 h of growth treatment in a 30 mM precursor salt based on the hydrothermal synthesis. Extensive characterizations have been performed on field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Energy-dispersive X-ray spectroscopy, High resolution transmission electron microscopy, Photoluminescence spectroscopy, and Raman spectroscopy to assess the different aspects such as structural, morphological, elemental, and wettability of the plain and ZnO-modified carbon fiber textiles. ZnO nanomaterial having hexagonal nanorods shape and wurtzite crystalline structure were uniformly deposited on the fabrics. Owing to the wettability study, ZnO prisms improved the hydrophilicity of virgin carbon fiber textiles to enable strong bonds with polymer matrix. The findings highlight the significant improvement in the static water contact angle as a result of the samples' ZnO coating's ability to reduce surface free energy. The improved hydrophilicity in carbon fiber may enhance the bonding between carbon fibers and matrix materials in composite materials. Hydrophilic carbon fibers are more easily wetted by the matrix materials, allowing for better penetration of the matrix into the fiber structure.

S-N co-doped porous carbon as metal-free ORR electrocatalysts in zinc-air batteries

The implementation of zinc-air batteries (ZABs) requires the creation of economically feasible electrocatalysts for the oxygen reduction reaction (ORR) process. In this work, sulfur-nitrogen co-doped porous carbon materials (S-N-PC) were synthesized using a straightforward approach including ball milling followed by calcination without solvent. The optimized S-N-PC 1000 demonstrates exceptional ORR performance in 0.1 M KOH, with a half-wave potential of 0.870 V that outperforms commercial Pt/C. Furthermore, it exhibits remarkable durability and exceptional methanol resistance. The S-N-PC 1000 performs excellent performance as an air cathode in ZABs, exhibiting a peak power density of 159.26 mW cm−2 and outstanding stability for up to 720 h. Additionally, the energy efficiency decreases by only 2.52 % after undergoing more than 2000 cycles of charging and discharging at 5 mA cm−2. This study offers a novel concept for the development of eco-friendly porous carbon catalysts for ZABs.

Polymerized lignin based carbon nanofiber for high-performance energy generator and storage

Lignin is an ideal precursor for the preparation of lignin-based materials. However, the lack of molecular weight, thermal stability and spatial configuration of lignin hinder the practical application of lignin in lignin-based carbon materials. Herein, a novel and effective strategy for preparing high-performance lignin-based carbon nanofibers (CFs) is designed. Lignin samples with different chemical structures are prepared by polymerization modification and fractionation. This strategy completely gets rid of the dependence on petroleum-based polymers in the electrospinning process, and makes the lignin-based CFs show good performance in energy storage, temperature sensor, and moisture power generation. The specific capacitance and energy of lignin-based supercapacitors reach 357.2 F/g and 31.5 Wh/kg, respectively. The CFs exhibit good flame retardancy and thermal sensitivity, and the response time is 1 s. In addition, moisture power generators assembled with CFs exhibit great potential. The output voltage of moisture power generators has a linear relationship with the number of devices. With the increase of series equipment, the output voltage of 5 series moisture power generators is 4.7 V. This work provides a new approach to prepare high-performance lignin-based carbon nanofibers, which has a good application prospect in the fields of energy storage, sensing and power generation.

Catalytic effects of structural design in N-modified carbon materials for the hydrochlorination of acetylene

Catalytic effects of structural design in N-modified carbon materials for the hydrochlorination of acetylene

Porous nitrogen-doped carbons derived from poultry feathers for electrochemical capacitors

The synthesis of a nitrogen doped carbon material (NDCM) from the ball-milling and chemical activation of high temperature carbonised waste chicken feathers is reported. Synthesised NDCMs with nitrogen content ranging from 2.2 to 6.6 wt% were analysed via a range of physio and electrochemical characterisation methods. The effects of carbonisation temperature, mechanical milling and chemical activation were evaluated on specific capacitance and charge retention. Electrochemical testing demonstrated that the optimised NDCM (carbonised at 700 °C followed by ball milling and chemical activation) possessed a specific capacitance of 195 F g−1 at 1 A g−1 current density. At the higher current density of 40 A g−1 89 % of the capacitance is retained. Moreover, this material showed a cycle life of 1000 galvanostatic charge/discharge cycles with a 1 % loss in capacitance at a current density of 5 A g−1.