Diamond and Related Materials最新文献

Biomass-derived porous carbon possesses several advantageous characteristics, such as low cost, inherent properties, and a controllable structure, making it an ideal electrode material for Zn-ion hybrid supercapacitors (ZIHSs). In this investigation, we used cattail leaves (CLs) as the carbon source and employed carbonization and activation techniques to fabricate porous carbon. We aimed to explore the correlation between the morphology, oxygen content, and defects in porous carbon derived from CLs under varying K₂CO₃ ratios. Remarkably, when the K₂CO₃/carbon ratio was adjusted to 2:1, the resulting porous carbon from CLs exhibited outstanding electrochemical performance in ZIHSs. These ZIHSs, functioning in an aqueous electrolyte, displayed impressive rate capability, achieving 158.3 mAh g⁻¹ at 0.1 A g⁻¹ and 60.2 mAh g⁻¹ at 20 A g⁻¹, along with a high energy density of 119.5 Wh kg⁻¹. Furthermore, they exhibited exceptional long-term durability with nearly 100 % coulombic efficiency over 10,000 cycles. Additionally, a quasi-solid-state ZIHSs device demonstrated satisfactory specific capacity (148.54 mAh g⁻¹ at 0.1 A g⁻¹) and maintained stability under various orientations. The abundant, renewable, and cost-efficient biomass-derived carbon obtained in this study serves as a valuable guide for the development of portable energy storage devices that are both low in cost and high in performance, thereby contributing to sustainable energy solutions.

We report a high growth rate (37 μm/min) synthesis of vertically aligned carbon nanotube (VACNT) forest, achieving remarkable height exceeding a millimetre with good crystallinity. VACNTs with few numbers of walls have been grown over Fe–Co/Al₂O₃/SiO₂ coated Si wafer using the water assisted atmospheric pressure chemical vapour deposition (WACVD) method. The key to this success lies in the synergistic combination of a bimetallic catalyst (Fe-Co) with buffer Al₂O₃ layer and the WACVD method. Notably, the VACNT forest, synthesised at optimized conditions can be directly used without the need for additional post-growth purification processes, eliminating the risk of potential damage to the CNTs. Finally, the VACNT forest exhibits excellent areal capacitance of 133.33 mF/cm² at a current density of 1 mA/cm² with outstanding cyclic stability of 130 % @ 3000 cycles.

This article investigates how the presence of polyvinylpyrrolidone (PVP) affects the dielectric properties and proton conductivity of phosphoric acid (PA) doped PVdF/PVP-based composite polymer electrolytes supported by graphene oxide (GO). In the study, insights into the structural, morphological, and thermal characteristics of the proposed composite electrolytes are obtained using characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Proton conductivity and dielectric measurements are carried out across a frequency and temperature range (20 Hz-1 MHz, 300–420 K). We conduct in-depth discussions on the dielectric properties, including AC conductivity (σ_ac), dielectric permittivity (ε′), imaginary permittivity (ε″), and loss tangent (tanδ) of the polymer electrolytes. While GO enhances the thermomechanical properties, the highest proton conductivity values are observed for (PVdF₇₀/PVP₃₀)-GO and (PVdF₅₀/PVP₅₀)-GO electrolytes, reaching 4.4 × 10⁻⁵ and 6.1 × 10⁻⁴ S/cm respectively. The dielectric measurements revealed a significant increase in the dielectric constant (ε′) and dielectric loss (ε″) values for the composite membranes, especially at lower frequencies and higher temperatures. For instance, the (PVdF₅₀/PVP₅₀)-GO composite exhibited ε′ values of 8.8 × 10⁶, 1.99 × 10⁵, and 77.38 at frequencies of 20 Hz, 1 kHz, and 1 MHz, respectively, at 300 K, and 7.38 × 10⁶, 2.76 × 10⁴, and 430.5 at 420 K. The ε″ values at 300 K for the same composite were 16.18 × 10⁶, 7.25 × 10⁵, and 1.09 × 10³, respectively, at the same frequencies. (PVdF₅₀-PVP₅₀)-GO exhibits the lowest relaxation time (τ) and the highest proton conductivity at ambient temperature. These findings underscore the intricate interplay between PVP content, dielectric properties, and proton conductivity, providing valuable insights for the advancement of polymer electrolyte materials. This study contributes to our understanding of PA-doped (PVdF_x/PVP_y)-GO electrolytes, with implications for electronic and energy storage devices.

Biomass contained significant amounts of lignin, cellulose and hemicellulose and these high crystallinity results in sub-optimal electrochemical properties. Herein, a hydrothermal method was employed to intentionally weaken the structural integrity of hemp fibers and eliminate cellulose impurities. After undergoing KOH activation, the resulting product achieved a maximum specific surface area of 1644.3 m² g⁻¹. In a three-electrode test, the specific capacitance of this electrode material was 255.6 F g⁻¹ at a current density of 1 A g⁻¹, representing a nearly double enhancement over the non-hydrothermally treated sample. Furthermore, the assembled symmetric supercapacitor has a specific capacitance of 56.9 F g⁻¹ at 1 A g⁻¹ and a capacitance retention of 102 % after 10,000 charge/discharge cycles (10 A g⁻¹). Its maximum power density was 725 W kg⁻¹ at an energy density of 16.6 Wh kg⁻¹. The desirable capacitive properties indicated that the hydrothermal pretreatment method was expected to have wider applications in the preparation of other biomass-based electrode materials.

Accurate electrochemical detection of glyphosate (GLY) presents significant challenges due to its non-electroactive nature on conventional electrode materials. To address this challenge, copper-modified electrodes have been developed to form a complex with GLY, enhancing detection capabilities. In this study, we propose an innovative material: copper-modified carbon nanotubes on a glassy carbon electrode (Cu/CNT/GCE). The detection mechanism of GLY using Cu/CNT/GCE involves the formation of a copper-GLY complex, which inhibits the electrochemical response of copper, proportionally to the GLY concentration. This effect is enhanced by the synergistic interaction between copper and carbon nanotubes, increasing the electrochemical stability and detection capacity of the system. To evaluate the electrochemical performance of Cu/CNT/GCE, cyclic voltammetry was performed at different electrolyte concentrations and pH levels. Square wave voltammetry was employed for the electrochemical quantification of GLY, showing a linear correlation between GLY concentration and the inhibition of the copper response. The proposed sensor exhibited a low limit of detection (0.098 ppm) and a limit of quantification (0.326 ppm). Furthermore, the electrode demonstrated long-term stability, retaining 95 % of its signal after one year of storage. This stability is attributed to the carbon nanotube support, which prevents corrosion of copper particles. Recovery values ranged from 94 to 106 % for Citromax™ and Orium™ glyphosate with precision. The method showed excellent selectivity for GLY detection, even in the presence of other herbicides such as diuron and oryzalin. These properties suggest that Cu/CNT/GCE presents promising features for the electrochemical monitoring of GLY in diverse environmental samples.

In this study, Fe-based diamond composites with various Ni–Cr–Mo–Si–B prealloy additives were prepared using hot-press sintering, and the effects of the Ni–Cr–Mo–Si–B content on the relative density, bending strength, Rockwell hardness, and frictional wear properties of the Fe–Cu–Co–Sn matrix were investigated. Additionally, the effect of the composition of the Ni–Cr–Mo–Si–B additives on the interface between the matrix and diamond was studied. The Ni and Cr in the additives facilitated a tight bonding interface without notable gaps between the diamond and Fe–Cu–Co–Sn matrix. Considering the overall performance of the materials, the optimal addition of Ni–Cr–Mo–Si–B was determined to be 10 %, which resulted in notably improved comprehensive performance indicators of the Fe-based diamond composite materials. For example, diamond drill bits made with this formulation exhibited a wear ratio of 1600 mm/g and a penetration rate of 29.21 mm/min, representing increases of 29 % and 44.96 %, respectively, compared to those of drill bits without Ni–Cr–Mo–Si–B additives. Developing high-performance diamond drill bits with increased ROP and extended service lives to enhanced performance, efficiency, and cost-effectiveness in drilling operations across different industries, ranging from mining and construction to oil and gas exploration.

The wastewater discharged from the plating process contains highly toxic transition metals. To decontaminate plating wastewater, we investigated the deactivation of complex formation via the anodic oxidation of three complexing agents — (ethylenediaminetetraacetic acid (EDTA), gluconic acid (GA), and triethanolamine (TEA)) — on a boron-doped diamond (BDD) electrode. The performance of the BDD electrode was compared with those of existing electrodes: a Pt electrode, an IrO₂ electrode, and a PbO₂ electrode. Compared with the Pt and IrO₂ electrodes, the BDD electrode achieved higher deactivation rates of GA and TEA. Moreover, we investigated the decomposition products of the complexing agents and the variation in the total organic carbon content during the electrooxidation. The BDD electrode rapidly oxidized the formic acid generated as the decomposition product and achieved the complete mineralization of EDTA after 8 h of anodic oxidation and GA and TEA after 12 h. These results indicate that anodic oxidation on a BDD electrode is a suitable method for treating plating wastewater containing complexing agents.

Carbon nanostructures represent cutting-edge nanomaterials poised to replace thermionic emitters in electron emission devices, offering a pathway to miniaturization. Carbon nanotubes (CNTs) and graphene (Gr) stand out for their exceptional electronic and structural properties, making them superior candidates for such applications. This study introduces an in-situ synthesis method for synthesizing a nanostructured composite of Gr-CNT by precisely controlling ammonia (NH₃) gas flow. The nanocomposite samples, prepared at varying NH₃ gas flow rates, were characterized using FESEM and Raman spectroscopy, revealing the formation of flower-like Gr nanoflakes and spiral-threaded CNT profiles. The presence of D and G bands, along with the D′, 2D and D + G bands in the Raman spectra, confirms the successful growth of the Gr-CNT field emitters. The electron field emission properties were significantly improved, leading to reduced turn-on $\left(E_{\mathrm{to}},2.48\to 1.95V/\mathrm{\mu m}\right)$ and threshold $\left(E_{\mathrm{th}},2.9\to 2.32V/\mathrm{\mu m}\right)$ fields, respectively. Notably, increasing NH₃ gas flow rates enhanced the macroscopic emission current density $\left(J_M,174\to 797\mathrm{\mu A}/{\mathrm{cm}}^2\right)$ become maximum at 40 sccm (standard cubic centimeters per minute) due to increased CNT protrusions. Repeatability tests and analyses of emission current stability demonstrated superior performance compared to pristine Gr field emitters. Increased protrusions density, reduced contact resistance, and a lesser screening effect are responsible for this enhanced stability. Additionally, the prepared field emitters were considered suitable for practical applications based on the scaled barrier field values extracted from the emission experiments, which satisfied the necessary criteria.

Centrifugal spinning is a promising technique to design nanostructured electrodes with tunable morphology and structure. Carbon nanofibers are commonly used as anodes for sodium ion batteries (SIBs) and supercapacitors owing to high electrical conductivity, high porosity and large interlayer spacing. Herein, a facile and low-cost strategy is presented to fabricate carbon nanofibers via a fast and safe centrifugal spinning and heat treatment. Moreover, triple doping was employed by using ionic liquids to further improve electrochemical properties of carbon nanofiber electrodes for SIBs and supercapacitors. The morphology of triple doped carbon nanofibers (TDCNFs) were studied by using scanning electron microscopy (SEM) and tunneling electron microscopy (TEM). Heteroatom doping was seen from SEM EDX images. Larger interlayer spacing was observed from XRD pattern of TDCNFs. Self-standing, binder free TDCNF electrodes delivered the high reversible capacity of over 350 mAh/g at 100 mA/g with excellent cycling stability in 200 cycles compared to that of CNF electrodes (150 mAh/g). TDCNFs were also used in two-electrode supercapacitors and high capacitance of around 225 F/g was observed with excellent capacitance retention in 10,000 cycles. This work reports a promising way to prepare carbon nanofibers with tunable morphology and various compositions which could be applicable for different energy storage applications.

Recently, Graphyne-based gas sensors have drawn a lot of interest. One kind of Graphene with acetylene bonds connecting its hexagons is Graphyne. In this study, the density functional theory (DFT) method was used to investigate the physical parameters of the surface adsorption of CO₂, NO, O₂, F₂, and Cl₂ molecules on the α-Graphyne nanosheet, taking into account van der Waals (vdW) interactions through the use of the SIESTA computational code. Gas molecules have adsorbed and optimized in two vertical and horizontal states from the side of its different atoms, at different distances and sites relative to the α-Graphyne sheet. After optimization and finding the adsorption energy, the best adsorption sites, equilibrium distance of the molecule from the surface, electronic structure, charge transfer rate, and bandgap changes were calculated. It was observed that the changes in the electronic structure after the adsorption of CO₂ and F₂ gas molecules are negligible and the structure remained zero-gap semiconductors. The adsorption of CO₂ and F₂ molecules on the α-Graphyne nanosheet is physisorption while the adsorption of NO, O₂, and Cl₂ is chemisorptions type. Graphyne sheet acts as electron acceptors for all considered molecules except F₂ molecule. The higher the charge transfer between the molecule and the sheet, the higher the reactivity and sensitivity of Graphyne sheets to Cl₂, O₂, and NO molecule detection. The electronic properties of α-Graphyne are more sensitive to adsorption of Cl₂, O₂, and NO molecules than that of F₂ and CO₂. Hence, α-Graphyne can be a desirable and promising material for sensing these gas molecules in practical applications.