Conductive polymeric composites (CPC) incorporating carbon nanotubes (CNT) and carbon fibers (CF) offer promising potential in self-heating applications due to their superior electrical and thermal properties. This study investigates the synergistic effects of CNT and CF on the electrical conductivity and heat-generation capabilities of CNT/polydimethylsiloxane (PDMS) nanocomposites. Three CF lengths (0.1 mm, 3 mm, and 6 mm) were systematically evaluated to establish hierarchical conductive networks. The incorporation of 6 mm CF into CNT/PDMS composites resulted in a 72% increase in electrical conductivity compared to composites with 0.1 mm CF. Despite these enhancements in electrical performance, the heat-generation capabilities, based on simulations and experimental validation, showed minimal dependence on CF length. A micromechanics-based numerical approach was used to compare and validate the experimental findings, identifying limitations in current analytical models, especially in predicting the heat-generation behavior.
Polyethylene (PE) is one of the most widely used plastics, and vast amounts of waste PE are either buried or incinerated, leading to environmental concerns. Significant research efforts have focused on converting waste PE into carbon materials, particularly as carbon anodes for lithium-ion batteries (LIBs). However, most previously developed PE-based carbon anodes have underperformed compared to graphite-based commercial anode materials (CAM). In this study, LIB anode materials were prepared based on both commercial high-density polyethylene (CPE) and waste high-density polyethylene (WPE). Through thermal oxidative stabilization and high-temperature graphitization, both CPE and WPE were successfully transformed into highly crystalline carbon materials comparable to CAM. However, despite the high crystallinity, both CPE and WPE derived carbon contained significant number of fine particles and exhibited a broad particle size distribution. When used as an anode for LIBs, fine particles led to unwanted side reactions, resulting in an initial coulombic efficiency (ICE) of around 85%, which is lower than the ICE value of 92.5% observed in CAM. To tackle the low ICE problem, recarbonization after coal tar (CT) coating was adopted as a mean to induce secondary particle formation. After CT coating, the average particle size increased, and the size distribution became narrower. Although CT coating reduced the crystallinity slightly, the overall level remained comparable to that of CAM. As a result, the CT-coated graphitized CPE (GCPE@10CT) and CT-coated graphitized WPE (GWPE@10CT) exhibited performance comparable to CAM as LIB anodes, achieving an ICE of over 93% and a capacity of approximately 349 mAh g− 1.
Carbon nanotube (CNT) fibers were synthesized in this study under a hydrogen atmosphere using the floating-catalyst chemical vapor deposition (CVD) technique. Acetone, ferrocene, and thiophene served as the sources of carbon, catalyst, and promoter, respectively. By adjusting the amount of thiophene, the sulfur molar ratio in the CVD reactor was varied to study its impact on the morphology and composition of the CNT fibers. Raman and TEM analyses showed that the structural properties of the CNTs, especially the production of single-walled CNTs (SWCNTs) with a high Raman IG/ ID ratio of approximately 23.8, can be finely tuned by altering the sulfur content, which also affects the accumulation of spherical carbonaceous particles. Moreover, it was established that the electrical conductivity of the CNT fibers is significantly influenced by their specific components—SWCNTs, multi-walled CNTs (MWCNTs), and spherical carbonaceous particles. The ratios of these components can be adjusted by modifying the molar ratios of catalyst and promoter in the precursor mixture. Remarkably, SWCNTs with enhanced crystallinity were found to substantially improve the electrical conductivity of the CNT fibers, despite the presence of numerous spherical carbon impurities.
To optimize the electrochemical properties of Ni-rich cathode materials, CPAN@SC-NCM811 is prepared via surface modification of single-crystalline LiNi0.8Co0.1Mn0.1O2 cathode material by adding 1, 2 and 3 wt.% of polyacrylonitrile, respectively. Significantly, the results obtained from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) verify the successful synthesis of CPAN@SC-NCM811 cathode, which exhibits better electrochemical properties compared to SC-NMC811. After thorough milling and calcination of 2 wt.% polyacrylonitrile with SC-NCM811, the initial discharge specific capacity of prepared S2 sample is 197.7 mAh g− 1 and the capacity retention reached 89.2% after 100 cycles at a rate of 1.0 C. Furthermore, the S2 sample exhibits superior rate performance compared to the other three samples, in which these superior electrochemical properties are largely attributed to the optimal ratio of conductive cyclized polyacrylonitrile coatings. Overall, this work offers guidelines for modifying the surface of SC-NCM811 cathode materials for lithium-ion batteries with exceptional cycling and rate performance.
In this study, we developed electrochemical sensors based on the composite of hydroxylated multiwalled carbon nanotubes (MWCNT-OH) and graphene for paraoxon-ethyl detection as pesticide residues in agricultural products. Chemical treatment was employed to produce MWCNT-OH from pristine MWCNT and its composite with graphene was subsequently characterized using FTIR, Raman spectroscopy, FESEM-EDX, TEM, and XPS techniques. The MWCNT-OH/graphene composite was employed as an electrode modifier on the glassy carbon electrode (GCE) surface, and its electroanalytical performances were studied using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. It was revealed the optimum composition ratio between MWCNT-OH and graphene was 2:8, for paraoxon-ethyl detection at pH 7. This could be attributed to the enhanced electrocatalytic activity in the MWCNT-OH/graphene composite which displayed a linear range of paraoxon-ethyl concentration as 0.1–100 μM with a lower detection limit of 10 nM and a good sensitivity of 1.60 μA μM cm− 2. In addition, the proposed sensor shows good reproducibility, stability, and selectivity in the presence of 10 different interfering compounds including other pesticides. Ultimately, this proposed sensor was tested to determine the paraoxon-ethyl concentrations in green apples and cabbage as samples of agricultural products. The obtained concentrations of paraoxon-ethyl from this proposed sensor show no significant difference with standard spectrophotometric techniques suggesting this sensing platform might be further developed as a rapid detection of pesticide residue in agricultural products.
The prime objective of this computational study was to develop a highly accurate potential for the use of molecular dynamics (MD) simulations of carbon nanotubes (CNTs). This potential was generated using ab initio MD (AIMD) simulations based on density functional theory (DFT). Subsequently, we constructed machine-learned interatomic potentials (MLIPs) based on moment tensor potential (MTP) descriptors using AIMD trajectories as training data. The performance of the developed MLIPs was evaluated by conducting the MD simulations of the stress–strain responses of single-walled CNTs (SWCNTs) and defected SWCNTs (D-SWCNTs) under tensile loading. Furthermore, this work includes extensive MLIP-based MD simulations to examine the influence of diameter and chirality, temperature, and defect concentration on the fracture characteristics and Young’s modulus of SWCNTs. The findings demonstrate the computational reliability and transferability of the MLIPs in predicting the mechanical properties of SWCNTs through MD simulations performed over a temperature range of 1 K to 2000 K. The observed stiffnesses correspond to Young’s modulus ranging from 1.61–0.53 TPa with a mean value of 0.936 TPa for different SWCNTs with diameters ranging from 1.1–2.89 nm and temperatures spanning from 1 to 2000 K, exhibiting a noticeable dependence on chirality.
Manganese dioxide, functioning as a cathode material for aqueous zinc-ion batteries (AZIBs), demonstrates a variety of benefits, such as elevated theoretical specific capacity, outstanding electrochemical performance, environmental compatibility, ample resource availability, and facile modification. These advantages make MnO2 one of the cathode materials that have attracted much attention for AZIBs. Nevertheless, manganese dioxide cathode in practical applications suffers from structural instability during the cycling process because of sluggish electrochemical kinetics and volume expansion, which hinder their large-scale application. Doping and compositing with conducting frameworks is an effective strategy for improving structural stability. Herein, homogeneously in situ growth of Yttrium-doped MnO2 nanorods on conductive reduced graphene oxide (Y-MnO2/rGO), were synthesized through a straightforward hydrothermal method. The Y-MnO2/rGO electrodes have an ultra-long cycle life of 179.2 mA h g− 1 after 2000 cycles at 1 A g− 1 without degradation. The excellent structural stability is attributed to the cooperative effect of yttrium doping and compositing with rGO, which is an effective approach to enhance the stability and mitigate the Jahn–Teller distortion associated with Mn ions.
In the pursuit of achieving in-situ real-time detection of methanol production rate during the photocatalytic reduction of CO2, we developed a methanol sensor using a copolymer-coated fiber Bragg gratings. The theoretical model of methanol measurement by sensor was established. The effect of methanol-selective sensitive material and its thickness on the performance of the sensor were investigated. Humidity and temperature interference to sensor measurements was compensated. Furthermore, TiO2 photocatalyst was prepared and the photocatalytic reactor was constructed. The methanol production rate in the photocatalytic CO2 reduction process was monitored by the prepared sensor in-situ. The results highlight that the fiber Bragg grating methanol sensor with 600 nm-thick poly(N-isopropylacrylamide)/polymethyl-methacrylate coating showed a high sensitivity, lower limit of detection, fast response and recovery speed, and high selectivity. The methanol generation rate of TiO2 photocatalytic reduction of CO2 measured by gas chromatograph and prepared fiber Bragg grating methanol sensor was 1.42 and 1.53 μmol/g-cat·h, respectively, the error of the two detection methods was 7.86%. This highlights the efficacy of the developed fiber Bragg grating methanol sensor for real-time in-situ detection of the methanol production rate during the photocatalytic reduction of CO2.
Inspired by the recycling approach of electronic waste, within this research paper, we extracted exhausted materials from spent primary zinc batteries and then annealed them in a modified condition, forming a ZnMn2O4/ C composite with a uniform nanoparticles’ porous morphology. The produced material has been examined as a supercapacitor active one, which showed promising electrochemical properties for supercapacitor application. At a current density of 3 A g− 1, it exerted a comparatively significant capacitance of 1696.88 F g− 1 along with a capacity of 807 C g− 1. Furthermore, the fabrication of a flexible all-solid-state symmetric supercapacitor prototype has been accomplished. It exhibited promising initial results that carried a specific energy of 76.75 Wh kg− 1 at a specific power of 333.86 W kg− 1. After 3000 cycles, it maintained an acceptable capacity. Thus, this eco-friendly approach can successfully convert the spent battery material to new value-added materials for supercapacitors in the clean energy area.
Electrochemical treatment has a significant effect on the properties of carbon fibers (CFs). In this study, the effect of mild electric field action on the microstructure and properties of polyacrylonitrile (PAN)-based high-modulus CFs (HMCFs) and high-strength CFs (HSCFs) was investigated. Under the action of a mild electric field, CFs did not show obvious defects, but their microstructure, mechanical properties and electrical properties were affected. For HMCFs, the graphitization degree in both axial and radial directions of the fibers had a decreasing trend, the grain spacing increased, and the grain size and degree of orientation decreased, which led to a decrease in the tensile strength, tensile modulus and axial conductivity. However, for HSCFs, the pattern of change was exactly opposite to that of HMCFs. The results of this study can provide useful guidance for optimizing the production process and surface modification of CFs.
Waste utilization is not only a way to protect the environment and realize green chemistry, but also a means to create novel materials. In this study, based on waste grape seeds as the biowaste-derived carbon dots (G-BCDs), a straightforward one-pot green method was employed for the rapid detection of folic acid (FA). Owing to the internal filter effect and the static mixing quenching mechanism, the sensing principle of G-BCDs was effectively quenched by FA. The results showed fluorescence at an emission wavelength of 415 nm upon excitation at 330 nm with a quantum yield of 1.5%. Particularly, the FA sensing assay obtained a broad linear range of 2–220 μM and the limit of detection was 0.48 μM. In addition, the fluorescence probe was successfully utilized for detecting FA in tablets, blood, and urine samples, yielding desirable results, which indicated promising applications in the fields of biological and pharmaceutical analysis.
Transition metal/porous carbon composite is good electrode candidate since porous carbon provides high surface porosity which promotes the access of electrolyte ions, and transition metal enables redox reactions to improve specific capacitance and energy density. In this study, iron/carbon nanofiber (CNF) composite electrodes were prepared by grafting ferrocenecarboxaldehyde to the CNFs which were fabricated by electrospinning and thermal treatment of polyacrylonitrile (PAN). The presence of iron on the CNF surface was confirmed by SEM/EDS, ICP-MS and XPS. Electrochemical performance was evaluated using a three-electrode cell with 1 M Na2SO4 as an electrolyte. Iron-grafted CNFs exhibited a high specific capacitance of 358 F g− 1 and an energy density of 49.7 Wh kg− 1 at 0.5 A g− 1, which is significantly higher than those for untreated CNFs (68 F g− 1 and 9.4 Wh kg− 1). This demonstrates that this iron/CNF composite is promising candidate for supercapacitor electrode with outstanding energy storage performance.
Self-assembled organic layers containing various functional groups between graphene layers were examined as gas barrier films. The formation of well-defined self-assembled layers of functionalized alkane molecules on graphene was confirmed by scanning tunneling microscopy (STM). The roles of these organic layers as gas barrier films could be quantitatively deduced by comparing their water vapor transmission rate (WVTR). The formation of self-assembled layers dramatically improved gas barrier properties by primarily blocking defects and gas molecule pathways. For functionalized alkanes containing hydrophilic groups, more enhanced gas barrier properties were observed compared to those with hydrophobic groups. These results clearly indicate that the primary role of the organic layers in gas barrier films is to block defects and the pathways of water molecules, with a secondary role of delaying the movement of water molecules through hydrogen bonding interactions.
The study presents a framework for the sustainable carbon-based nanomaterials, focusing on Carbon Nano Tubes (CNTs). The framework integrates performance, hazard, and economic considerations toward the development of CNT-enabled products. Through Life Cycle Analysis (LCA) and environmental degradation studies, the research highlights the energy-intensive nature of CNT production, the persistence of CNTs in the environment, and the associated ecotoxicity risks. Functionalization of CNTs is emphasized as a crucial strategy to enhance biodegradability and reduce toxicity. The study also addresses the economic trade-offs, noting that while CNTs offer superior functional performance, their high production costs and energy demands must be carefully managed. The proposed framework aims to ensure that CNTs maximize their benefits while minimizing their environmental and health impacts, thereby supporting the sustainable advancement of carbon nanomaterials in various applications. The study found that CNT production is highly energy-intensive, but scaling up can improve efficiency. CNTs persist in the environment, with partial degradation, indicating potential long-term ecological risks. Functionalization enhances biodegradability and reduces toxicity, helping to balance performance with sustainability.
This study details the synthesis and characterization of phosphorus-sulfur co-doped graphitic carbon nitride quantum dots (PSQ) and their integration into g-C3N4 (CN) to form PSQ/CN composites for the enhanced photocatalytic reduction of Cr(VI) and fluorescence detection. Incorporating PSQ into CN was found to significantly improve light absorption, narrow the band gap, and enhance charge separation efficiency. Notably, the composite material exhibits superior photocatalytic performance, especially in acidic environments. Photocatalytic assessments utilizing Cr(VI) demonstrated that the PSQ/ CN composite outperformed both undoped and singly doped materials, indicating its superior photocatalytic activity. Additionally, phosphorus-sulfur co-doping markedly increased the fluorescence quantum yield of PSQ. The fluorescence intensity exhibited a linear decrease with increasing Cr(VI) concentrations, enabling sensitive and selective detection of Cr(VI) with a detection limit as low as 1.69 μmol/L. Collectively, the PSQ/CN composite and PSQ highlight their potential for photocatalysis and fluorescence-based detection of Cr(VI), providing high sensitivity, selectivity, and synergistic interactions within the composite material.
A novel, ultra-high sensitivity electrochemical aptamer biosensor (EAB) was fabricated by immobilising gold nanoparticles (Au) on a nano-confined interface of N-doped carbon nanofibers/carbon fibers (N-CNFs/CFs). Gold nanoparticle-thiol (Au–S) conjugates, coupled with aptamer-specific recognition technology, were used to immobilise aflatoxin B1 (AFB1). The nanoconfined interface of N-CNFs/CFs provides more binding sites for Au with its unique spatial structure and electroactive surface area, enhancing the electrochemical performance of the matrix. Compared to the existing sensor detection limit, the limit of detection(LOD) of the EAB was approximately 6.4 pg/mL. The dynamic detection ranged from 10.0 to 1.0 × 108 pg/ mL. Furthermore, AFB1 was also successfully detected in Chinese Materia Medica decoction pieces(CMMDP) using the prepared EAB, with recoveries ranging from 96.18 to 112.87%. These results demonstrate the proposed EAB’s potential as a reliable tool for rapid and efficient detection of AFB1 in complex matrices.