Carbon fibers (CFs) with different tensile moduli of 280–384 GPa were applied to investigate the relationship between crystalline structure and compressive failure. The carbon chemical structure and crystalline structure were studied by Raman, highresolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The correlation between compressive strength and crystalline structure was investigated. The results showed that the transition point between medium and high tensile modulus was around 310 GPa, and within the range of medium modulus, the compressive strength of CFs improved with the increase of tensile modulus, and the compressive strength also improved with the increase of crystal thickness Lc, crystal width La, and crystal plane orientation; In the high modulus range, the correlation law was opposite, which was mainly influenced by the grain boundary structure. CFs with tensile modulus lower than 310 GPa exhibited bucking and kinking fracture under compressive loading, while shear fracture was observed for CFs with tensile modulus higher than 310 GPa.

Diamond/SiC composites were prepared by vacuum silica vapor-phase infiltration of in situ silicon–carbon reaction, and the thermophysical properties of the composites were modulated by controlling diamond graphitizing. The effects of diamond surface state and vacuum silicon infiltration temperature on diamond graphitization were investigated, and the micromorphology, phase composition, and properties of the composites were observed and characterized. The results show that diamond pretreatment can reduce the probability of graphitizing; when the penetration temperature is greater than 1600 °C, the diamond undergoes a graphitizing phase transition and the micro-morphology presents a lamellar shape. The thermal conductivity, density, and flexural strength of the composites increased and then decreased with the increase of penetration temperature in the experimentally designed range of penetration temperature. The variation of thermal expansion coefficients of composites prepared with different penetration temperatures ranged from 0.8 to 3.0 ppm/K when the temperature was between 50 and 400 °C.

A simple and effective method was developed to prepare fluorescent carbon quantum dots (CQDs) for the detection of Fe3+ and Cu2+ in aqueous solution. The water-soluble CQDs with the diameter around 2–5 nm were synthesized using anthracite coal as the precursor. In addition, the as-prepared CQDs exhibits sensitive detection properties for Fe3+ and Cu2+ metal cations with a detection limit of 18.4 nM and 15.6 nM, respectively, indicating that the coal-derived CQDs sensor is superior for heavy metal recognition and environmental monitoring.

Graphene-based solar cells and supercapacitors integrated into photosupercapacitors represent a pioneering advancement. These devices leverage the exceptional properties of graphene, such as high conductivity and large surface area, to enhance both solar energy conversion and energy storage. The integration of these technologies into photosupercapacitors creates a multifunctional device capable of harnessing solar energy and storing it efficiently. This innovative approach holds promise for sustainable and versatile energy solutions, marking a significant step towards developing efficient and compact energy storage systems. This integration addresses the intermittent nature of solar power generation by providing a continuous and reliable power supply through energy storage. Supercapacitors are one such energy device with a high-power density and excellent specific capacitance which is integrated will a dye-sensitized solar cell (DSSC) comprising a single system of photosupercapacitor. A novel electrode material of NiO/CuO/Co3O4/rGO was synthesized which serves as the Pt-free counter electrode of DSSC and working or storage electrode of supercapacitor later was used as the intermediate electrode and storage electrode of a photosupercapacitor. The integrated photosupercapacitor device had a photovoltage of 0.81 V with arealspecific capacitance, energy and power density of 190.12 mF cm− 2, 17.325 μW h cm− 2 and 0.162 mW cm− 2, respectively. The device self-discharged in 385 s with an overall conversion efficiency of 2.17%, resulting in a self-charged energy device.

Nitrogen-doped carbon nanomaterials (N-CNMs) were prepared using Ni(NO3)2 as a catalyst in the laminar diffusion flame. Doping the structure of carbon nanomaterials (CNMs) with nitrogen can significantly change the characteristics of CNMs. The purpose of this research is to study the effect of adding ammonia ( NH3) on the evolution of CNMs structure in the laminar flame of ethylene. Raman analysis shows that the intensity ratio ( ID/IG) of the D-band and G-band of N-CNMs increases and then decreases after the addition of NH3. The intensity ratio is a maximum of 0.99, which has a good degree of disorder and defect density. The binding distribution of nitrogen was analyzed by X-ray photoelectron spectroscopy (XPS), and a correlation was found between the amount of nitrogen and the morphology of N-CNMs. Nitrogen atoms predominantly present in the forms of pyrrolic-N, pyridinic-N, graphitized-N and oxidized-N, with a doping ratio of nitrogen atoms reaching up to 2.44 at.%. This study found that smaller nickel (Ni) nanoparticles were the main catalysts for carbon nanotubes (CNTs), and their synthesis followed the ‘hollow growth mechanism’ and carbon nanofibers (CNFs) were synthesized from larger Ni nanoparticles according to the ‘solid growth mechanism’. Furthermore, a growth mechanism for the synthesis of bamboolike CNTs using a specific particle size of the Ni catalyst is proposed. It is noteworthy that the synthesis and modulation of high-performance N-CNMs by flame method represents a simple and efficient approach.

Gold nanoparticles (Au NPs) decorated carbon nanofibers (CNFs) have been prepared by an electrospinning approach and then carbonized. The prepared Au-CNFs were employed to modifying a screen printed electrode (SPE) for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Au NPs are uniformly dispersed on carbon nanofibers were confirmed by the structure and morphological studies. The modified electrodes were tested in cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CA) to characterize their electrochemical responses. Compared to bare SPE, the Au-CNFs/SPE had a better sensing response to AA, DA, and UA. The electrochemical oxidation signal of AA, DA and UA are well separated into three distinct peaks with peak potential separation of 280 mV, 159 mV and 439 mV between AA-DA, DA-UA and AA-UA respectively in CV studies and the corresponding peak potential separation in DPV studies are 290 mV, 166 mV and 456 mV. The Au-CNFs/SPE has a wide linear response of AA, DA and UA in DPV analysis over the range of 5–40 μM ( R2 = 0.9984), 2–16 μM ( R2 = 0.9962) and 2–16 μM ( R2 = 0.9983) with corresponding detection limits of 0.9 μM, 0.4 μM and 0.3 μM at S/N = 3, respectively. The developed modified SPE based sensor exhibits excellent reproducibility, stability, and repeatability. The excellent sensing response of Au-CNFs could reveal to a promising approach in electrochemical sensor.

We investigated the effects of supercritical-CO2 treatment on the pore structure and consequent H2 adsorption behavior of single-walled carbon nanohorns (SWCNHs) and SWCNH aggregates. High-resolution transmission electron microscopy and adsorption characterization techniques were employed to elucidate the alterations in the SWCNH morphology and aggregate pore characteristics induced by supercritical-CO2 treatment. Our results confirm that supercritical-CO2 treatment reduces the interstitial pore surface area and volume of SWCNH aggregates, notably affecting the adsorption of N2 (77 K), CO2 (273 K), and H2 (77 K) gasses. The interstitial porosity strongly depends on the supercritical-CO2 pressure. Supercritical-CO2 treatment softens the individual SWCNHs and opens the core of SWCNH aggregates, producing a partially orientated structure with interstitial ultramicropores. These nanopores are formed by the diffusion and intercalation of CO2 molecules during treatment. An increase in the amount of H2 adsorbed per interstitial micropore of the supercritically modified SWCNHs was observed. Moreover, the increase in the number and volume of ultramicropores enable the selective adsorption of H2 and CO2 molecules. This study reveals that supercritical-CO2 treatment can modulate the pore structure of SWCNH aggregates and provides an effective strategy for tailoring the H2 adsorption properties of nanomaterials.

Si-based anodes are promising alternatives to graphite owing to their high capacities. However, their practical application is hindered by severe volume expansion during cycling. Herein, we propose employing a carbon support to address this challenge and utilize Si-based anode materials for lithium-ion batteries (LIBs). Specifically, carbon supports with various pore structures were prepared through KOH and NaOH activation of the pitch. In addition, Si was deposited into the carbon support pores via SiH4 chemical vapor deposition (CVD), and to enhance the conductivity and mechanical stability, a carbon coating was applied via CH4 CVD. The electrochemical performance of the C/Si/C composites was assessed, providing insights into their capacity retention rates, cycling stability, rate capability, and lithium-ion diffusion coefficients. Notably, the macrostructure of the carbon support differed significantly depending on the activation agent used. More importantly, the macrostructure of the carbon support significantly affected the Si deposition behavior and enhanced the stability by mitigating the volume expansion of the Si particles. This study elucidated the crucial role of the macrostructure of carbon supports in optimizing Si-based anode materials for LIBs, providing valuable guidance for the design and development of high-performance energy-storage systems.

Crystalline heptazine carbon nitride (HCN) is an ideal photocatalyst for photocatalytic ammonia synthesis. However, the limited response to visible light has hindered its further development. As a noble metal, Au nanoparticles (NPs) can enhance the light absorption capability of photocatalysts by the surface plasmon resonance (SPR) effect. Therefore, a series of Au NPs-loaded crystalline carbon nitride materials (AH) were prepared for photocatalytic nitrogen fixation. The results showed that the AH displayed significantly improved light absorption and decreased recombination rate of photo-generated carriers owing to the introduction of Au NPs. The optimal 2AH (loaded with 2 wt% Au) sample demonstrated the best photocatalytic performance for ammonia production with a yield of 70.3 μmol g− 1 h− 1, which outperformed that of HCN. This can be attributed to the SPR effect of Au NPs and alkali metal of HCN structure. These findings provide a theoretical basis for studying noble metal-enhanced photocatalytic activity for nitrogen fixation and offer new insights into advances in efficient photocatalysts.

Graphitic nitrogen-doped carbon film/nanoparticle composite, in which the films were wrapped and separated by the nanoparticles, was prepared through a simple co-calcination route. Due to its unique porous structure and improved nitrogen content, the as-prepared electrode material could exhibit high specific capacitances of 317.5 F g− 1 at 0.5 A g− 1 and 200.0 F g− 1 at 20 A g− 1, and stable cycling behavior with no capacitance decline after 10,000 cycles in three-electrode system. When assembled in two-electrode capacitor, its specific capacitance could be well kept at 265.5 F g− 1 at 0.5 A g− 1, and thus the supercapacitor with a high energy density of 9.22 Wh kg− 1 was obtained. The superior energy storage properties of the as-prepared material indicate its promising application as high-performance carbon-based electrode for supercapacitors.

Coal tar pitch is a raw material that can be made from various carbon materials such as activated carbon, carbon fiber, and artificial graphite through heat treatment. In particular, it is an important raw material used as a binder and impregnated pitch when manufacturing carbon composite materials. In order to improve the physical properties of such a carbon composite material, the content of β-resin is an important factor. Although β-resin plays the role of a binder, it also corresponds to fixed carbon, so it can determine the physical properties after carbonization. In this study, we compared the physical properties of coal tar pitch various temperature ramping rate, and found through Py-GC/MS analysis that intermediate materials were generated by heteroatoms such as oxygen and nitrogen. MALDI-TOF/MS analysis revealed that these intermediate materials overlapped with the molecular weight region of β-resin. Therefore, the content of β-resin is in the following order: 430–5 (12.8 wt%), 430–10 (10.2 wt%), and 430–2 (6.3 wt%), and when 430–5 is used as a binder, the highest density appeared at 1.75 g/cm3. However, such intermediate materials undergo thermal decomposition even at temperatures above 900 °C. As a result, after carbonization, 430–5 had a density of 1.60 g/cm3, which was similar or lower than that of 430–2 (1.72 → 1.63 g/ cm3) and 430–10 (1.73 → 1.61 g/cm3). From these results, it is expected that if the heteroatom content is distributed in an appropriate amount and the heating rate is well controlled, it will be possible to maintain a high density even after carbonization while ensuring a high beta-resin content.

In recent years, the search on fabrication of highly efficient, stable, and cost-effective alternative to Pt for the hydrogen evolution reaction (HER) has led to the development of new catalysts. In this study, we investigated the electrocatalytic HER activity of the Toray carbon substrate by creating defect sites in its graphitic layer through ultrasonication and anodization process. A series of Toray carbon substrates with active sites are prepared by modifying its surface through ultrasonication, anodization, and ultrasonication followed by anodization procedures at different time periods. The anodization process significantly enhances the surface wettability, consequently resulting in a substantial increase in proton flux at the reaction sites. As an implication, the overpotential for HER is notably reduced for the Toray carbon (TC-3U-10A), subjected to 3 min of ultrasonification followed by 10 min of anodization, which exhibits a significantly lower Tafel slope value of 60 mV/dec. Furthermore, the reactivity of the anodized surface for HER is significantly elevated, especially at higher concentrations of sulfuric acid, owing to the enhanced wettability of the substrate. The lowest Tafel slope value recorded in this study stands at 60 mV/dec underscoring the substantial improvements achieved in catalytic efficiency of the defect-rich carbon materials. These findings hold promise for the advancement of electrocatalytic applications of carbon materials and may have significant implications for various technological and industrial processes.

Complex structure constituting of several layers of heteroatom-doped N-CDs are used as a main sensing film along with aluminum electrodes in conductometric gas sensing system for sensitive and selective monitoring of CO2 and CO gases diluted with normal air, which are extensively prevalent in the atmosphere primarily due to the industrial revolution, locomotives, and numerous natural phenomena’s and the limit of detection (LOD) turned out to be 400 ppm and 30 ppm, respectively, with 20% relative humidity at 30 °C and pressure 1 (atm) which are good for healthy air quality checks. The sensor performance was satisfactory and bidirectional at ambient room temperature (30 °C) and pressure (1 atm) conditions but the relative humidity (50%) at 30 °C had a detrimental impact on the sensing responses, therefore intermittent heating at 80 °C for several minutes between the sensing responses was provided to the sensing chip or one should use gas filter membranes to block humidity, thereby maintaining its constant performance with great ease and accuracy. The cyclic voltammetry revealed well-defined oxidation and reduction peaks, with excellent stability and reversibility. In a nutshell, heteroatom-doped N-CDs’ nanocomposite material can revolutionize in a better environmental pollution monitoring by sensing gases in an extensively lesser response and recovery times.

Silicon carbide (β-SiC) was synthesized through an improved sol–gel method, then Ni/SiC catalysts were prepared using a hydrothermal method. The catalysts were characterized using TEM, H2- TPR, CO2- TPD and N2- TPD, etc. The results showed that the synthesized β-SiC had a large specific surface area, promoting the dispersion of Ni species and thus exposing more active sites. The interaction between Ni species and β-SiC contributed significantly to catalytic performance. Furthermore, the strong alkalinity of catalyst could adjust the bond energy of the active metal and N (M–N), which were conducive to desorption of the recombinant N2 from the metal surface, promoting to ammonia decomposition. Among the Ni/SiC catalysts, 30Ni/SiC-700 synthesized with the Ni loading of 30 wt% and calcination temperature of 700 °C, exhibited the optimal ammonia conversion rate of 93.4% at 600 °C under the space speed of 30,000 mL∙gcat −1∙h−1, and demonstrated a long-term stability, suggesting a very promising catalyst in ammonia decomposition.

With the continuing advances in technology, electrical energy storage has become increasingly important. Among storage devices supercapacitors’ distinct qualities, such as a long lifespan, quick charge/discharge speeds, and high-power density, make them viable substitutes for traditional batteries. In this study a simple hydrothermal method was used to synthesize a h-MoO3/graphene oxide (GO) composite for such applications. The crystal structure, morphology, and chemical bonding were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Raman spectroscopy. XRD confirmed the hexagonal crystal structure, and no changes were observed after GO incorporation. The FESEM images revealed that the nanosheets of GO and hexagonal rods MoO3 were well coupled with the GO sheets. The electrochemical properties of the pure h-MoO3 and h-MoO3/GO composites were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The nanocomposite electrode demonstrated a specific capacitance of 134 Fg-1 at a current density of 3 mA/cm-2, an energy density of 26.8 Wh/kg-1, and power density of 560 W/kg-1 in an aqueous acidic electrolyte 1 M H2SO4, which is notably higher than that of pure MoO3. This indicates the promising electrochemical performance of MoO3/GO composite for supercapacitor applications. The enhanced capacitive performance may have resulted from the decrease in the charge transfer resistance (Rct), calculated from the Nyquist plot. Furthermore, the composite material exhibited stability and a capacitive retention of 76 % after 1,000 cycles. This confirms the benefits of incorporating GO to enhance material retention for better long-term results. The results of this study demonstrate its potential to advance energy storage technology. Maintaining the hexagonal crystal structure of h-MoO3 while incorporating GO improves the composite’s structural stability, an important factor for reliable long-term use. Moreover, the observed reduction in crystallite size due to the presence of GO suggests improved electrochemical performance.

Magnons have unique properties, including long propagation length, and can exist in insulators. Magnon valve structures, which consist of two magnetic insulating layers, offer a promising approach for advanced magnetoresistive randomaccess memory (MRAM) technology and an alternative to the limitations of traditional electronic devices. In this study, we investigate a magnon valve structure that incorporates a platinum (Pt) spacer between two magnetic insulator layers, specifically yttrium iron garnet (Y3Fe5O12, YIG). Structural characterization of the YIG/Pt/YIG magnon valve was carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM), confirming the high-quality growth of the multilayer structure. The magnon valve behavior was assessed through vibrating sample magnetometry (VSM) and spin Seebeck effect (SSE) measurements. Our results demonstrate magnon valve behavior, which becomes apparent as the Pt spacer reaches a thickness sufficient to decouple the magnetization of the YIG layers. The magnon valve ratio of the magnon valve can be modulated, and clarity of the those states can be enhanced.

This study investigates the development of risedronate (RSD)-incorporated polycaprolactone (PCL)/chitosan composite films for potential use in drug delivery systems aimed at bone repair. PCL and chitosan were blended in varying ratios (25 %, 50 %, 75 % PCL), and their miscibility, morphology, and hydrophilicity were analyzed. The effects of incorporating RSD at different concentrations (10-7 to 10-4 M) on MG63 preosteoblast cell proliferation and differentiation were also evaluated. The results demonstrated that blending of the hydrophobic PCL with hydrophilic chitosan was challenging, due to poor miscibility and phase separation. Optimal blending conditions and drying temperatures were essential for homogeneous film formation. The incorporation of RSD influenced cellular behavior, with 50 % PCL showing the most effective cell proliferation and moderate hydrophilicity. However, higher RSD concentrations (10-4 M) inhibited proliferation, while lower concentrations (10-7 M) promoted it. RSD also enhanced osteoblast differentiation, as evidenced by increased alkaline phosphatase (ALP) activity, particularly in 75 % PCL films. These findings suggest that adjusting the PCL/chitosan ratio and RSD concentration can optimize drug release and cellular responses, making this composite system a promising candidate for bone tissue engineering applications.

This study investigates the performance characteristics of electrodeposited (ED) silver nanowires (AgNWs) networks as transparent conducting electrodes (TCEs) considering Cu(In,Ga)Se2 (CIGS) thin-film solar cells. The electrodeposition process uniformly deposits silver onto a network of spin-coated AgNWs, resulting in the enlargement of individual nanowire diameters and the formation of stronger interconnections between the AgNWs. This structural enhancement significantly improves both the electrical conductivity and thermal stability of the ED AgNW networks, making them more efficient and robust for practical applications in solar cells. The study comprehensively examines the optoelectronic properties of the ED AgNW networks, encompassing total and specular transmittance, transmission haze values, and sheet resistance, with varying durations of silver electrodeposition. Additionally, this study presents the current density (J)-voltage (V) characteristics of CIGS thin-film solar cells employing the ED AgNW TCEs, revealing how electrodeposition duration impacts overall device performance. These findings offer valuable insights for optimizing TCEs in not only thin-film solar cells but also in other optoelectronic devices, highlighting the potential for improved long-term stability across various applications without compromising performance.

Nanoparticles, especially those derived from plant extracts, are becoming increasingly popular as a bio-based, environmentally friendly alternative to conventional technologies. The Maui rose, a flowering plant with medicinal and therapeutic properties, is one of the most important of these materials because its extract component has antibacterial, antioxidant and anti-inflammatory biological activity. In this work, we report on synthesizing and characterizing iron oxide nanoparticles (Fe2O3) extracted from flower plants (Borago), to create persistent and environmentally friendly antibacterial agents. As part of the chemical formation process, Fe2O3 nanoparticles were extracted from specific flower plants utilizing a series of carefully regulated chemical reactions. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) of the samples were studied. The nanoparticles produced were analyzed using common microbiological methods and studies (EDS). The antibacterial activity of the Fe2O3 nanoparticles and their effect on a range of microorganisms were evaluated. The results demonstrated that Fe2O3 nanoparticles were successfully synthesized with a specific crystal structure and good anti-bacterial activities.

During the period of 1959 to 1984, North Korean false propaganda led over 90,000 ethnic Koreans and their families to migrate from Japan to North Korea. Once in North Korea, the migrants suffered severe discrimination and human rights abuses. For decades, there was little prospect of justice for these abuses. In recent years, however, survivors of this migration who escaped North Korea have renewed efforts to gain some type of recognition and compensation. This note reviews three of these attempts: lawsuits in Japanese and South Korean courts, as well as a petition that was brought before the Korean Truth and Reconciliation Commission. While each of these avenues has helped bring to light the truth of North Korean deception, more work remains to be done with respect to collecting compensation.