Carbon Layer Research Articles

Boosting piezocatalytic efficiency: Thin carbon layer-modified ZnO for superior rhodamine B degradation

This study aims to enhance the piezocatalytic activity of ZnO by modifying it with a thin carbon layer (TCL). The composite catalysts were synthesized using a simple hydrothermal method. The tightly adhered TCL served as an effective electron transfer medium, enabling the rapid migration of piezoinduced charge carriers from the ZnO to the catalyst surface, thereby facilitating the catalytic degradation of Rhodamine B (RhB). The optimized TCL/ZnO sample exhibits an RhB degradation rate 13.4 times higher than that of pure ZnO. This work demonstrates that TCL/ZnO has significant potential in piezocatalytic water purification and offers new insights into the design of efficient piezocatalytic materials.

Multi-interfaced FeCoNi@C/carbon cloth composites for eliminating electromagnetic wave pollution

To tackle the increasing electromagnetic pollution, new and efficient electromagnetic wave absorption (EWA) and shielding (EWS) materials are urgently needed. Multi-component synergism and complex microstructure design are effective measures to improve the EWA and EWS properties. However, how to implement the above designs still faces huge challenges. Herein, multi-interface carbon-coated FeCoNi nanoneedles grown on carbon cloth (FeCoNi@C/CC) were synthesized by a combination of hydrothermal process and chemical vapor deposition (CVD) technology with the concept of “green synthesis”. Using acetylene as the carbon source and atmosphere, the FeCoNi ternary hydroxide can be transformed into a multiple magnetic component (Fe3O4, Ni, and Co metals) by simple annealing. Simultaneously, a uniform carbon layer is formed on the surface, resulting in a composite system with a variety of heterogeneous interfaces and loss mechanisms. Additionally, the dielectric and magnetic loss capacities can be effectively adjusted by changing the temperature of CVD. The optimized FeCoNi@C/CC as filler exhibits remarkable EWA performance with a minimum reflection loss of −69.3 ​dB at a thickness of 1.82 ​mm and a maximum effective absorption bandwidth of 6.80 ​GHz. Moreover, the composites as an integrated component also show a fascinating electromagnetic interference shielding efficiency of 42.2 ​dB. This work provides a guide for the structural design of high-performance electromagnetic protection materials with multi-heterogeneous interfaces.

Exploring the metallurgical coke thermal properties in viewpoint of experiment and molecular simulation

The Chinese standard method of GB/T 4000–2017 was unable to accurately measure the coke thermal properties in the large blast furnace. Therefore, the coke compressive strength (CCS) test at a high temperature was designed to examine the coke thermal properties. Then, the large-scale coke model (sp2C17421sp3C6579) was established. After, the ReaxFF molecular dynamics simulations were implemented to mimic the coke solution loss (CSL) and the CCS at the high temperature. It was found that the adsorption energy and the diffusion energy of micropores were greater than those of mesopores and macropores, indicating that the CSL reaction mainly happened in the coke micropore. It was discovered that the CSL reaction mechanism was the sp3 C oxidization mechanism with the transient state of ketene structure. And, it was detected that the CCS process was divided into the plastic deformation, the instantaneous fracture and the elastic deformation and yield, which was caused by the local reconstruction, the overall folding and the center stretching of carbon layer, respectively. By comparing simulated results with experiments, it was proved that obtained mechanisms were valid. The proposed experimental and simulated methods provided a novel method to measure and understand the coke thermal properties.

Synergistic effect of coal gangue on intumescent flame retardants

Abstract In order to improve the flame retardant properties of wood plywood, intumescent flame retardant coatings were prepared using melamine, borate, pentaerythritol and urea as the basic formulations and gangue as a modified additive. The flame retardancy of the samples was characterized using a cone calorimeter, scanning electron microscope, X-ray diffraction and thermogravimetric analysis. In addition, the study investigated the effect of gangue content on the properties of the prepared coatings. The results show that the doping of gangue in intumescent flame retardant coatings can improve the flame retardant effect of the coatings. Specifically, when the mass fraction of gangue was 8 wt%, the exothermic rate, total smoke production and total exothermic amount of the coating were significantly reduced. Moreover, the addition of gangue promoted the formation of a continuous and dense carbon layer structure during the combustion process of the coating, which produced a molten substance that effectively isolated oxygen and heat, thus strengthening the fire-retardant and heat-insulating properties of the coating. The results of this study provide valuable insights into the development of flame retardant coating formulations for wood plywood.

Core/shell Ni@C particle-supported N-doped carbon with hollow capsules for efficient electrocatalytic reduction of oxygen

To replace the noble metal catalysts for oxygen reduction reaction (ORR), a Ni@C-supported N-doped carbon material (Ni@C/NC) is in-situ prepared via one-step pyrolyzing the polymerizable ionic liquid of vinyl imidazole combined with Ni(NO3)2. Systemic investigations demonstrate that these nanosized Ni particles are tightly wrapped with a thin carbon layer to form the core/shell structure, meanwhile carbon capsules are synchronously yielded on the carbon matrix. As a result, both the carbon shell and the carbon capsule jointly increase the active sites of the Ni@C/NC, while the carbon shell also contributes the fast electron-transfer from Ni particle. Compared with the normal Ni-supported carbon catalyst, the Ni@C/NC shows the respectable ORR performance with the onset and half-wave potentials of 0.96 and 0.84 VRHE. After the long-term electrocatalysis (10 h), the Ni@C/NC is found to possess the great structural and electrocatalytic stabilities, which maintains 93 % of the initial current density and the well-dispersed and uniform Ni@C particles. Subsequently, a Zn-Air battery with the Ni@C/NC cathode is assembled and exhibits a peak power density of 200 mW cm−2. Therefore, the as-obtained Ni@C/NC with the high electroactivity and stability can be expected as an ideal candidate to apply in the metal-air batteries and fuel cells in the future.

Cellulose Nanofiber-Based Nanocomposite Films with Efficient Electromagnetic Interference Shielding and Fire-Resistant Performance.

Cellulose nanofiber (CNF) has been widely used as a flexible and lightweight polymer matrix for electromagnetic shielding and thermally conductive composite films because of its excellent mechanical strength, environmental performance, and low cost. However, the lack of flame retardancy seriously hinders its further application. Herein, renewable and biomass-sourced l-arginine (AR) was used to surface-modify ammonium polyphosphate (APP) and an environmentally friendly biobased flame retardant was synthesized by the coordination of zinc sulfate heptahydrate (ZnSO4·7H2O), which was named AAZ. AAZ was deposited on the surface of CNF by electrostatic adsorption and Zn2+ complexation. The biobased compatibilizer Triton X-100 was employed to assist the exfoliation of graphene nanoplatelets (GNPs) and their dispersion in the CNF matrix. Due to the formation of a dense lamellar layer resembling a shell structure, the CNF/GNPs composite films with a tensile strength of 52 MPa were obtained via vacuum-assisted filtration. Because the phosphorus-containing group produces a protective layer of PxOy compound and promotes the formation of a carbon layer by CNF and the combustion releases ammonia gas, the fire-resistant performance of the composite films was greatly improved. Compared with the pure CNF film, the composite film exhibits 33% reduction in PHRR value and 40% reduction in THR. In addition, the CNF/GNPs composite film with 20 wt % GNPs possessed high conductivity (2079.2 S/m) and electromagnetic interference (EMI) shielding effectiveness (37 dB). The ultrathin CNF/GNPs composite films have excellent potential for use as efficient flame retardant and EMI shielding materials.

Upcycling of waste photovoltaic silicon: Co-MOF derived coating layer enhanced lithium storage

Large amounts of silicon waste (W-Si) powders or ingots from the photovoltaic (PV) industry can be recycled as the improved raw negative electrode material in Lithium-ion batteries. Herein, Co-MOFs (ZIF-67) is produced in the form of small particles which turns into the uniform coating layer on the surface of micro-sized W-Si by solvent evaporation, and then ZIF-67 is carbonized to form nitrogen-doped carbon (NC) layer and carbon nanotubes (CNTs). Finally, W-Si/NC/Co/CNTs composites are formed. The continuous and uniform NC layer and CNTs formed by the catalyzation of Co on the surface of the silicon particles can inhibit the volume expansion of silicon during the charge and discharge process, showing the reversible discharge capacity of 1039 mAh g−1 after 100 cycles. The rate performance is also improved due to the high conductivity composite structure. This work can provide a choice for the composite of MOF and micro-silicon, and the meaning guidance for the application of silicon waste from PV industry.

Surface engineering of carbon nanotube-carbon fiber networks for enhanced strength in additive manufacturing of nylon composites

This work quantifies the impact of chemical functionalization of carbon nanotubes and carbon fibres on the interfacial shear strength, tensile and interlaminar shear strength properties of additively manufactured nylon composites. The surface chemistry of functionalized carbon materials was evaluated through infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Single carbon fibre was dip-coated in a suspension of nanotubes and embedded into a nylon matrix. The fibres were pulled out to measure the interfacial shear strength, and the fibres with attached neat, carboxylated, and silanized nanotubes increased it by up to 67 %, 112 %, and 216 %, respectively. Composite samples were manufactured using a novel hybrid additive manufacturing method, which was able to deposit nylon layers and a suspension containing carbon reinforcement. The use of chemically functionalized nanotubes in the suspension led to carbon layers that improved tensile strength by 49 % and tensile modulus by 126 % over neat nylon. Functionalization of carbon reinforcement increased the interlaminar shear strength by up to 63 %. Overall, this paper demonstrates the importance of chemical modification in composite materials containing a large interface area of carbon materials.

Facile synthesis of N-doped porous CoO@C nanocubes as anode with superior lithium storage

N-doped porous CoO@C nanocubes were fabricated using a hydrothermal method and annealing process. The uniform wrapped carbon layer effectively mitigates the volume changes during electrochemical reactions. Moreover, the porous carbon layer enhances the electrical conductivity and promotes Li ion diffusion. Therefore, the as-prepared CoO@C nanocubes maintian a capacity of 565 mA h/g at 0.2 A/g after 100 cycles. This stabilization ability is attributed to the introduction of carbon layer and its porous structure, which buffers the volume expansion of cobalt oxide, and increases the surface area and active sites.

Tuning Morphologies of Metal-Organic Framework-Derived Ni3P/Ni Carbon Nanocomposites for Water Oxidation.

The oxygen evolution reaction (OER) frequently acts as a kinetic bottleneck in various energy storage and conversion systems. Effective electrocatalysts for the OER play a crucial role in reducing the reaction barrier and expediting the reaction. Multicomponent transition metal phosphides (TMPs) have garnered an extensive amount of attention as a result of their exceptional performance in the OER. Here, we present a direct method for preparing two intrinsic morphologies of metal-organic frameworks (MOFs), barrel-like BMM-10 and pancake-like BMM-10(Ac), achieved by establishing a protonation/deprotonation equilibrium with varying NO3-/Ac- ratios. The BMM-10(Ac)-C catalyst was synthesized via heat treatment of the BMM-10(Ac) precursor, exhibiting superior OER performance. It realized an overpotential of 286 mV at a current density of 10 mA cm-2, with a Tafel slope of 111.17 mV decade-1 and a current retention of 98.03%. This improvement arises from the synergistic interaction between Ni3P/Ni nanoparticles and the partially graphitic carbon layer, augmenting the exposure of active sites. Furthermore, alterations in the morphological features of MOF-derived Ni3P/Ni carbon nanocomposites adjusted the active electrochemical surface area, thereby modulating the overall OER performance of the corresponding TMP carbon nanocomposites. This methodology can be extended to control the morphology of other MOFs and their derivatives, providing innovative avenues for the design and synthesis of new MOF-based TMP nanomaterials.

Mechanical Compression‐Enabled Carbon‐Based Perovskite Solar Cells with Enhanced Efficiency and Stability

Carbon electrode‐based perovskite solar cells (C‐PSCs) without hole transport layer (HTL) have been emerging as a promising low‐cost photovoltaic technology with excellent stability for commercialization. However, the loose physical contact between the carbon electrode and perovskite layer, as well as the relatively poor conductivity of the carbon film, contributes mainly to the large gap in the power conversion efficiency (PCE) between C‐PSCs and the metal (Ag, Au, etc.,) electrode‐based counterparts. To this end, a simple but effective mechanical compression strategy for efficient C‐PSCs is developed. The mechanical compression densifies the porous carbon electrode for high film conductivity and also provides intimate contact between carbon and perovskite layers for fast charge extraction. Consequently, the resulting HTL‐free C‐PSCs using MAPbI3 (MA = methylammonium) absorber yield a PCE of 15.29%, corresponding to a 27.6% improvement compared to the counterpart without mechanical pressing treatment. Moreover, the compacted carbon film also serves as an enhanced barrier against the intrusion of water and oxygen, and the unencapsulated device retains 88.9% of its initial PCE after 1000 h of aging in ambient conditions with 35 ± 2% humidity. This work paves a simple and effective way toward efficient and stable C‐PSC.

Positron unveiling high mobility graphene stack interfaces in Li-ion cathodes

Carbon-based coatings in Li-ion battery cathodes improve electron conductivity and enable rapid charging. However, the mechanism is not well understood. Here, we address this question by using positrons as non-destructive probes to investigate nano-interfaces within cathodes. We calculate the positron annihilation lifetime in a graphene stack LiCoO2 heterojunction using an ab initio method with a non-local density approximation to accurately describe the electron-positron correlation. This ideal heterostructure represents the standard carbon-based coating performed on cathode nanoparticles to improve the conduction properties of the cathode. We characterize the interface between LiCoO2 and graphene as a p-type Schottky junction and find positron surface states. The intensity of the lifetime component for these positron surface states serves as a descriptor for positive ion ultra-fast mobility. Consequently, optimizing the carbon layer by enhancing this intensity and by analogizing Li-ion adatoms on graphene layers with positrons at surfaces can improve the design of fast-charging channels.

State change of Na clusters in hard carbon electrodes and increased capacity for Na-ion batteries achieved by heteroatom doping

Although heteroatom doping is an effective method to improve the capacity of hard carbon (HC) anodes in Na-ion batteries (NIBs), the complicated structure of HC leads to uncertainty when understanding the effects of heteroatom doping on sodium storage. This study shows the effects of phosphorus and sulfur doping to HC on sodium storage using solid-state NMR to improve the capacity of HC prepared by the carbonization of resorcinol formaldehyde (RF) resin at 1100 °C. Heteroatom doping increased the battery capacity of the HC, especially the plateau capacity, but the interlayer distance of the carbon layers in the HC did not expand considerably. 23Na solid-state NMR revealed that heteroatom doping facilitates the formation of quasi-metallic sodium clusters, thereby contributing to the plateau capacity increase. The metallicity of the sodium clusters in heteroatom-doped HC samples was controlled by the amount of doped-phosphorous. XPS and 31P NMR detected various phosphorus sites such as phosphine and phosphine oxide in the carbon structure.

A dual-layer solid electrolyte interphase enhances interfacial chemistry stability in aqueous aluminium metal batteries

Aqueous aluminum metal batteries (AAMBs) have garnered significant attention owing to the abundance of aluminum, high volumetric energy density (8040 mAh cm−3, approximately four times that of lithium metal anodes), and chemical inertness. However, profound issues such as surface corrosion and the side reaction of hydrogen evolution severely impede the advancement of AAMBs. Here, we report the in-situ formation of a dense inorganic AlF3 + Al/Zn-CO3 + flexible carbon shell solid-electrolyte interface (SEI) on the surface of an Al electrode through hydrothermal and electrochemical activation in a dilute aqueous solution of Al(OTf)3-Zn(NO3)2. Experimental evidence demonstrates that the electrically insulating Al/Zn-NO3 layer initially forms on the Al negative electrode surface through self-polymerization reactions of Al with Zn2+ and NO3– under sealed heating conditions. Subsequent electrochemical activation leads to the decomposition of CF3SO3- to form conductive AlF3 + Al/Zn-CO3, while in situ generation of a flexible carbon layer occurs internally on the surface. The inorganic inner layer facilitates the diffusion of Al ions, while the organic carbon shell suppresses water permeation and maintains the stability of the SEI structure. The in-situ formed SEI enables the Al//Ti battery to achieve a high Coulombic efficiency (CE) of 98.9 % over 100 cycles. Constructing the Al//β-MnO2 battery yields a high energy density of 216 Wh kg−1, with the capacity retention remaining stable at 83.6 % after 700 cycles.

Synthesis of nitrogen-doped amorphous carbon nanotubes from novel cobalt-based MOF precursors for improving potassium-ion storage capability

Amorphous carbon materials with sophisticated morphologies, variable carbon layer structures, abundant defects, and tunable porosities are favorable as anodes for potassium-ion batteries (PIBs). Synthesizing amorphous carbon materials typically involves the pyrolysis of carbonaceous precursors. Nonetheless, there is still a lack of studies focused on achieving multifaceted structural optimizations of amorphous carbon through precursor formulation. Herein, nitrogen-doped amorphous carbon nanotubes (NACNTs) are derived from a novel composite precursor of cobalt-based metal–organic framework (CMOF) and graphitic carbon nitride (g-CN). The addition of g-CN in the precursor optimizes the structure of amorphous carbon such as morphology, interlayer spacing, nitrogen doping, and porosity. As a result, NACNTs demonstrate significantly improved electrochemical performance. The specific capacities of NACNTs after cycling at current densities of 100 mA/g and 1000 mA/g increased by 194 % and 230 %, reaching 346.6 mAh/g and 211.8 mAh/g, respectively. Furthermore, the NACNTs anode is matched with an organic cathode for full-cell evaluation. The full-cell attains a high specific capacity of 106 mAh/gcathode at a current density of 100 mA/g, retaining 90.5 % of the specific capacity of the cathode half-cell. This study provides a valuable reference for multifaceted structural optimization of amorphous carbon to improve potassium-ion storage capability.

The development of bend clamp of carbon-based fiber offshore gas lift pipelines: A primary experimental approach

The work reports the proposed development of the laminated carbon fiber-reinforced polymer composites (CFRP), at a uniaxial angle as a primary bend clamp material assembly of the offshore gas lift pipelines. Generally, the clamps are utilized to repair the defect of the metallic pipelines due to their practical and mechanical strength. The existing bend clamp model poses challenges especially when applied to the J-tube bending side due to mechanical buckling and corrosion. This study evaluates the effect of laminated CFRP subjected to uniform uniaxial and in-plane compression on API 5 L X52. Several tests, including tensile, bend, and impact tests, are chosen to assess the effect of multiple and thick carbon layers to improve the clamp's mechanical properties. Scanning electronic microscope (SEM) intends to reveal the surface characterization of carbon fiber clamp. The result shows that laminated carbon fiber increases the durability and mechanical properties of the bend clamp for two weeks. The tensile test result shows that the uniaxial orientation has the highest tensile strength of about 2000N and is affected by the strong interfacial bond between the fiber and metal layers. The high impact energy of 2242 ± 0.001 J of the same orientation shows the stability of the clamp under unprecedented dynamic load and enhances the safety. The SEM result at uniaxial shows the resistance towards fracture has increased and was initiated from the air pocket in the composite.

An in situ exploration of how Fe/N/C oxygen reduction catalysts evolve during synthesis under pyrolytic conditions

In pursuing cheap and effective oxygen reduction catalysts, the Fe/N/C system emerges as a promising candidate. Nevertheless, the structural transformations of starting materials into Fe- and N-doped carbon catalysts remains poorly characterized under pyrolytic conditions. Here, we explore the evolution of Fe species and track the formation of Fe–N4 site development by employing diverse in-situ diagnostic techniques. In-situ heating microscopy reveals the initial formation of FeOx nanoparticles and subsequent internal migration within the carbon matrix, which stops once FeOx is fully reduced. The migration and decomposition of nanoparticles then leads to carbon layer reconstruction. Experimental and theoretical analysis reveals size-dependent behavior of FeOx where nanoparticles below 7 nm readily release Fe atoms to form Fe–N4 while nanoparticles with sizes >10 nm tend to coalesce and impede Fe–N4 site formation. The work visualizes the pyrolysis process of Fe/N/C materials, providing theoretical guidance for the rational design of catalysts.

Effect of asphaltene content in petroleum residues on carbon layer properties and the electrochemical performance of SiOx as an anode in lithium-ion batteries

Effect of asphaltene content in petroleum residues on carbon layer properties and the electrochemical performance of SiOx as an anode in lithium-ion batteries

Fabrication of green montmorillonite modified bio-based rigid polyurethane foam with improved flame retardancy and enhanced mechanical properties

A low-carbon and sustainable green rigid polyurethane foam was prepared by compounding montmorillonite (MMT) with homemade barium phytate (BAPA). The flame retardancy, thermal stability and mechanical properties of the modified RPUFs investigated using the limiting oxygen index (LOI) method, cone calorimetry (CONE) and thermogravimetry. The results showed that the BAPA/MMT2 composite containing 2 wt% MMT had the highest LOI (25.1 %), and its peak heat release rate (PHRR) and total heat release (THR) were reduced by 14.33 % and 34.68 %, respectively, compared with that of the BAPA/MMT0 material without added MMT. In addition, the smoke production rate (SPR) and total smoke release (TSR) were reduced by 20.54 % and 30.77 %, respectively. BAPA/MMT2 had good flame retardancy and smoke suppression effect. The mechanical properties of BAPA/MMT2 with 2 wt% MMT were improved. The flame retardant mechanism confirmed that BAPA and MMT synergistically improved the quality of the carbon layer. At the same time, phosphorus-containing compounds (PO·), CO2 and water vapor were produced, which diluted the combustible gas in the gas phase and inhibit the flames spread. The current results provided a new strategy for the preparation of high-performance RPUFs.

Magnetic Nitrogen-Doped Fe<sub>3</sub>C@ c Catalysts for Efficient Activation of Peroxymonosulfate for Degradation of Organic Pollutants

Recoverable and stable nanocatalysts are essential for peroxymonosulfate - based advanced oxidation processes (AOPs) in wastewater purification treatment. In this paper, Fe3C nanorods @ nitrogen-doped carbon composites (N-Fe3C@C) with core-shell architecture were fabricated by the co-precipitation and calcination methods, and characterized and analyzed in terms of their crystal structure, microscopic morphology, and surface chemical elements. In addition, N-Fe3C@C-4 degraded 85.36% of tetracycline in 10 min under PMS, which was much higher than the catalytic ability of Fe3O4 (42.03% in 10 min). Both the active radical trapping and EPR experiments verified that 1O2 played a key role for degradation of organic dyes in PMS system. The investigation on the degradation mechanism revealed that the presence of the carbon layer facilitated to adsorb TC, accelerate free radical generation and promote the redox cycle of Fe2+/Fe3+ in the nanocatalyst. This study offers novel ideas for multifunctional catalysts for advanced wastewater purification treatment.