Diamond and Related Materials最新文献

The rapid advancement of carbon nanotube (CNT) synthesis through the Floating Catalyst Chemical Vapor Deposition (FC-CVD) process has propelled the field of carbon nanomaterials to new heights. Nevertheless, transitioning from laboratory-scale success to industrial production demands a comprehensive understanding of the process, optimization of diverse parameters, and the design of a suitable reactor. The necessity for enhanced efficiency, improved control, and continuous synthesis is a crucial prerequisite for the industrial adoption of the process. Recent advancements in the process have significantly altered the trajectory toward CNT fiber production, underscoring the importance of a systematic analysis that delves into every aspect of recent developments. This in-depth review extensively covers the notable progress achieved in the synthesis of CNT fibers and fabrics using the FC-CVD process. Here, a comprehensive analysis of the engineering challenges associated with controlled synthesis is provided, and a forward-looking perspective is offered through proposed future research strategies to advance the synthesis process. The successful production of CNT-based macroscopic materials has revitalized R&D efforts in nanoscience, making these materials suitable for various applications. Two of the most promising fields where CNT fibers and fabrics demonstrate high potential are the fabrication of flexible smart wearable sensors and flexible electrodes for next-generation energy storage devices. We briefly discuss these two applications, focusing on how they are influenced by the synthesis process and the method of self-assembly. The insights provided in this review aim to be a valuable guide for researchers and engineers involved in the design and optimization of reactors. The ultimate objective is to facilitate the widespread commercialization of CNT fiber and fabric and their seamless integration into various industrial applications.

Graphene has attracted attention as a new transparent conductive film (TCF) because of its transparency, stability, strength, and versatility. However, it has a higher resistance than conventional TCFs. Recently, vapor transport intercalation with doping effect materials has been investigated to reduce the resistivity of graphene. Studies have revealed a correlation between the stacking structure and the intercalation efficiency, which favors smaller interactions between the graphene layers. In this study, polycrystalline graphene, which consists of small domains, grown by chemical vapor deposition is stacked in three layers using a layer-by-layer method, and the graphene layers are intentionally randomly stacked to suppress the interlayer interactions. Intercalation of FeCl₃, which has p-type doping effects, into randomly stacked three-layer graphene (3LG) significantly reduces the sheet resistance (Rs) of 3LG from 500 to 41 Ω/sq. Interestingly, Raman mapping of the G peak shift of FeCl₃ intercalated into randomly stacked 3LG indicates that in-plane intercalation proceeds homogeneously, even though strong interlayer interactions such as AB stacking are observed in some parts of 3LG. This study reveals that a randomly stacked polycrystalline graphene layer is advantageous for intercalation.

Diamond-like carbon (DLC) films are widely used to improve the tribological properties of key components in internal combustion engines. However, their performance can be significantly affected by the service environment, which may impact engine reliability. This study investigates the impact of various media and friction pairs on the tribological behavior of molybdenum-doped DLC (Mo-DLC) films. The results demonstrate that Mo-DLC films exhibit excellent tribological properties across different media, showcasing their adaptability to various conditions. The lubrication mechanism varies with media viscosity: in methanol, Mo-DLC films operate under boundary lubrication conditions, leading to a relatively high wear rate of approximately 5.2 × 10⁻⁸ mm³/N·m. Conversely, in diesel and polyalphaolefin-based oil (PAO), where fluid dynamic lubrication occurs, wear rates are significantly lower, at 4.4 × 10⁻⁸ mm³/N·m and 3.1 × 10⁻⁸ mm³/N·m, respectively. In addition, the friction pair significantly influences the tribological performance of the Mo-DLC film. When paired with D-GCr15 in methanol, Mo-DLC films exhibit a low friction coefficient of 0.09 and a wear rate of 1.6 × 10⁻⁸ mm³/N·m, respectively. However, when coupled with N-GCr15, the increased surface roughness extends the running-in period and raises the friction coefficient in methanol. These findings offer valuable theoretical insights and practical guidance for optimizing DLC films in internal combustion engines.

Currently, the most common process for manufacturing brazed cubic boron nitride (CBN) tools is vacuum brazing using Cu-based active filler alloys. However, the high brazing temperature of Cu-based alloys and the long heating time in a vacuum furnace inevitably cause severe thermal damage, thereby compromising the mechanical properties of the brazed CBN abrasives. In this study, CBN abrasives were brazed using low-temperature Sn-Cu-Ti filler alloys in a continuous tunnel furnace. The final contact angles of the Sn-Cu-Ti filler alloys on the surfaces of the brazed CBN abrasives were determined at 650 °C. When the Ti content in the alloy was 4 %, the final contact angle was 37.2° and the CBN maintained a good exposure height and achieved a firm holding force. The interfacial microstructure was analysed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). It was found that a layer of needle-like compounds, primarily comprising TiB₂ and TiN, with an approximate thickness of 5 μm, was formed at the interface, indicating the formation of a chemical–metallurgical bond between the Sn-Cu-Ti alloy and CBN abrasive. The residual stresses and mechanical properties of brazed CBN abrasives with Sn-Cu-Ti and traditional Cu-based alloys were measured and compared. The results showed that compared to the brazed CBN with the Cu-based alloy, the average residual stress of the brazed CBN with the Sn-Cu-Ti alloy was reduced by 25.2 %, while the compressive strength and impact toughness increased by 25.3 % and 13.8 %, respectively. The experimental results provide new insights into reducing thermal damage to CBN for improving the processing performance of brazed CBN tools.

The advancement of high-speed growth technology for large-scale single-crystal diamonds is desired. In the widely used microwave plasma chemical vapor deposition method, the gas temperature in the plasma atmosphere significantly contributes to the generation of reactive radicals and enhancement of crystal growth. However, the impact of electron-dominated reactions in the plasma on the crystal growth remains unclear. In this study, we actively controlled the plasma environment by adding argon gas and adopting microwave pulse modulation to generate the plasma. We estimated the gas temperature and electron density of the plasma using optical emission spectroscopy. Our results implied that an increase in gas temperature alone hardly explained the enhancement of the growth rate by the argon addition or pulse modulation. In addition to the increase in the electron density due to the argon addition and pulse modulation, gas-phase chemical reaction calculations showed that the radical production enhancement became remarkable under an electron density higher than a threshold (10¹⁷ m⁻³). Therefore, the enhancement of the growth rate mentioned above may be attributed to electron-dominated reactions in the discharge region. These findings suggest that increasing the electron density can further improve the growth rate and potentially enable diamond synthesis at lower temperatures than traditional methods.

The dual osmium/boron doped/co-doped armchair single walled carbon nanotubes (SWCNTs) have been explored for hydrogen storage applications via ab-initio method. We thoroughly screen dual osmium/boron doping at two different opposite positions in SWCNTs and analyze bond distances, binding energy, band gaps, electrophilicity, density of states, adsorption energies, adsorption enthalpy, Gibbs free energy and storage capacity. The results summit Osmium doped CNTs as hopeful nominees for hydrogen storage applications. The findings indicates that Osmium atoms doping in opposite sides of CNT along with boron atoms at ortho position (2Os-2BCNT) show 1.95 wt% gravimetric hydrogen storage capacity at 298.15 Kelvin temperature and 1 atm pressure. Furthermore, the feasibility of doped SWCNTs have been explored for storage applications by performing average Van't Hoff desorption temperature calculations and molecular dynamics simulations for 2Os-2BCNT at maximum desorption temperature and 1 atm pressure.

The depletion of fossil fuel reservoirs has led to a serious concern related to the energy industry, with by-products generated from their combustion harming the environment. Hence, it is crucial to find an alternative to fossil fuels that has large reserves. The spinel is an efficient class that can provide reliable source of fuel by coupling with graphitic carbon nitride (g-CN). Herein, we hydrothermally developed the non-transition metal-based spinel with g-CN composite for oxygen evolution reaction (OER) activity. The resulting samples were thoroughly characterized using various analytical techniques. All characterizations verify the phase structure of the SrBi₂O₄/g-CN composite. The nitrogen (N₂) adsorption-desorption isotherm indicated a mesoporous structure based on the adsorption isotherm. In addition, the integration of unique-shaped nanoparticles decorated on graphitized carbon nitride nanosheets helps in reducing initial potentials for the OER procedure. Due to their unique mesoporous configuration, SrBi₂O₄/g-CN catalysts illustrate remarkable electrical conductivity and electrocatalytic activity. The SrBi₂O₄/g-CN composite exhibited less overpotential (η) of 193 mV at current density (Cd) of 10 mA/cm² compared to SrBi₂O₄. The SrBi₂O₄/g-CN composite revealed remarkable durability and lesser Tafel value of 33 mV/dec. All of the outstanding results obtained from the electrochemical activity suggest as potential electrocatalyst and it can be employed in future energy conversion and water related applications.

The integration of activated carbon with chitosan (CS) for dye removal offers a multitude of benefits, making this hybrid material a promising and efficient solution for water purification. Activated carbon (C) was synthesized from fruit wastes and then mixed with CS for the preparation of chitosan‑carbon nanocomposite (CSCNC) using ball milling technique. XRD and ATR-FTIR techniques affirmed the preparation of CSCNC. Additionally, the findings obtained from TEM and SEM analyses signifying the deposition of activated carbon onto the surface of CS. The majority of particle size and polydispersity index (PdI) for CSCNC were found to be 162.8 nm and 0.483, respectively as displayed from DLS technique. The current research work was examined the adsorption and desorption behaviors of Methylene Blue (MB) using CSCNC. Adsorption experiments reveal a time-dependent process characterized by an initial rapid phase and gradual approach to equilibrium, with the pseudo-second-order kinetics model providing the best fit. The adsorption capacity exhibited a rising pattern as pH increased, reaching its peak value of 912.4 mg/g. Both Langmuir and Freundlich isotherm models explained the equilibrium relationship between MB and the nanocomposite, offering insights into maximum adsorption capacity and surface characteristics. Desorption studies explored the nanocomposite's regenerative potential under varying conditions. The findings contributed to the sustainable design of water treatment technologies, emphasizing the nanocomposite's efficiency, scalability, and regenerative capabilities.

This study investigates the effect of laser surface treatment on spark plasma sintered (Zr-Ta-W-Ti)C-SiC (ZTaWT-S) based high entropy ceramic (HEC) composites, reinforced with multiwalled carbon nanotubes (CNT) (ZTaWT-SC), graphite (ZTaWT-SG), and graphene nanoplatelets (GNP) (ZTaWT-SGNP). The increased hardness of the laser-treated composites (25–33 GPa) when compared to that of untreated composites (23–28 GPa) is attributed to the high compressive residual stresses, ranging from 1400 to 2900 MPa. The laser-treated ZTaWT-SGNP composite exhibited a minimum scratch wear rate of ∼0.9 × 10⁻¹ mm³/N.m, representing a 57 % and 73 % reduction compared to the untreated ZTaWT-SGNP and the laser-treated ZTaWT-S, respectively. ZTaWT-SGNP composite demonstrated the best resistance to damage accumulation, due to the synergistic effects of laser treatment and GNP reinforcement, enhancing its suitability for extreme environments.

In the present study, carbon dots (C-dots) were synthesized using a simple and uncomplicated pyrolysis method at 250 °C with varying duration of 1 h, 2 h, and 3 h, utilizing Pennisetum glaucum as the biomass precursor to break down methylene blue (MB) and Rose Bengal (RB) dyes under UV light exposure. Various analytical techniques, including X-ray diffraction (XRD), UV–visible spectroscopy, high-resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared spectroscopy (FT-IR), and vibrating-sample magnetometer (VSM), were utilized to investigate the chemical, optical, electronic, surface morphological, and magnetic characteristics of the C-dots produced. These C-dots are crystalline, nearly spherical, and have particle sizes ranging from 4.73 nm to 12.44 nm. FTIR analysis identified the functional groups present on the surface of the C-dots. Additionally, the band gap energy of the C-dots reduced from 2.82 eV to 2.40 eV with an increase in pyrolysis time. They are effective for cleaning dye-polluted wastewater and demonstrate high photocatalytic performance. When exposed to UV light, the synthesized particles achieved impressive photocatalytic degradation of 94.80 % for MB and 91.80 % for RB dyes.