查看更多>>摘要：? 2022 Elsevier B.V.This paper describes a new method of modified carbon nanotubes (CNTs) by ethylene grafting or silicon coating. The thermal conductivity of paraffin is enhanced by the modified CNTs. The influence of modification on the dispersion stability of CNTs and the thermal conduction performance of paraffin are studied. Fourier transform infrared spectroscopy, scanning electron microscopy, thermal constant analyzer are used to analyze the composites. The results indicate that CNTs have been modified successfully. The dispersion stability of CNTs is significantly improved by polyethylene grafting or silicon coating. The thermal conductivity of paraffin phase change material is enhanced by 84.6% with the modified CNTs. The prepared paraffin/CNTs phase change materials show good thermal conductivity.
查看更多>>摘要：? 2022MnO2 as the cathode material of Zinc-ion batteries (ZIBs) has attracted great attention. In order to further improve the performance of ZIBs, MnO2 hollow nanorobs and carbon nanotubes (CNTs) are compounded to obtain α-MnO2/CNTs nanocomposites in which robs and tubes are entangled with each other and present the cross-linked reticular structure. This structure of α-MnO2/CNTs electrode is obtained through hydrothermal strategy and provides large space for the volume variation of MnO2 during the charge and discharge process. The α-MnO2/CNTs composite displays an excellent initial discharge capacity of 302 mAh·g?1 at 100 mA·g?1, and keeps 116 mAh·g?1 at 2000 mA·g?1 (78.4% retention after 2000 cycles). This composite provides a new way for the further application of ZIBs.
查看更多>>摘要：? 2022 Elsevier B.V.Owing to the need for new-generation energy storage equipment and industrial application, the development of carbon electrode materials with comprehensive electrochemical performances and convenient production processes has become a top priority. In this study, N/P/O doped carbon materials are prepared using a simple one-step method with 4-(2,4,6-tricarboxylphenyl)-2,2′:6′,2″-terpyridine (TT) as a raw material. Owing to the doping of many heteroatoms, particularly phosphorus atoms, the optimized TT(Zn/P)-700 exhibits a large specific surface area (2164.7 cm2/g), proper pore distribution from micropore to macropore, and high degree of graphitization. These structural and morphological features ensure excellent comprehensive capacitance performance, such as a high specific capacitance (366.25 F/g at 0.5 A/g), and high specific energy (73.25 Wh/kg at 300 W/kg). In addition, the specific capacitance of the symmetric supercapacitor assembled with TT(Zn/P)-700 electrode reaches 143.3 and 121.7 F/g at specific currents of 0.5 and 10 A/g, respectively. The specific current is increased 20 times, and the capacitance retention rate reaches 84.9%, improving the rate performance. When the specific power increases to 150 and 3000 W/kg, the specific energy reaches 7.17 and 6.08 Wh/kg, respectively. After 5000 charge/discharge cycles, the capacitance retention rate is 92.7%. These high-performance N/P/O-doped carbon electrode materials demonstrate great potential in industrial applications and new-generation energy storage equipment.
查看更多>>摘要：? 2022 Elsevier B.V.In the scenario, a novel Ce2(WO4)3/ZnO@GO (CWZG) nanocomposite (NCs) were constructed by an easier hydrothermal technique. The crystalline phase and the structure of the material were characterized by the Powder X-Ray diffraction analysis (P-XRD), Scanning electron microscopy (SEM) analysis; the presenting elements for synthesized materials were confirmed by EDAX spectroscopy analysis. The corresponding band energy value and the adsorption value for the degradation of the pollutants were examined by UV–Visible spectroscopy and DRS-UV spectroscopic techniques. In this process, the CWZG catalyst has higher photocatalytic performance in the visible region toward the decomposition of ciprofloxacin (CIP), methylene blue (MB) and amaranth dye (AM) with above 95% efficiency. The CWZG NCs have better catalytic performance and high stability even after more than four repeating recycle tests. The plausible degradation mechanism of the pollutants degradation reaction was examined by the Reactive Oxidative Species (ROS) test. Besides, the CWZG nanocomposite exhibits a superior capacitance of 114 Fg?1 than the other host materials. This superior electrochemical performance redox reactivity of the prepared material denotes the significance in photocatalytic applications. The above results strongly testify to the fact that CWZG nanocomposite may be a good photocatalytic material for environmental use.
查看更多>>摘要：? 2022 The AuthorsSemiconductor based photocatalysis is considered as a promising route for remediation of polluted water. However, there is still intensive research to overcome high recombination rate of electrons and holes, and low reaction rate, limiting large-scale applications. Therefore, it is crucial to focus on the fabrication of the optimal photocatalysts which could be practically utilized. In this contribution, we propose a composite composed of ultrasmall TiO2 nanoparticles embedded in silica/carbon matrix. This molecular hybrid was fabricated via anchoring a (3-aminopropyl) triethoxysilane on a surface of TiO2 and then the composite was encapsulated in a carbon sphere-like structure formed with biocompatible glucose as carbon precursor. As a result, such a system exhibited impressive photocatalytic activity in the degradation of methylene blue as a model hazardous organic dye. Among examined catalysts, the sample calcinated at 500 °C showed the highest photocatalytic efficiency (~100% photodegradation under UV light after 120 min and ~11.0–fold higher reaction rate constant in comparison to pristine TiO2) and the most enhanced photocurrent response upon irradiation with light 388 nm (~0.74 μA, which is 1.37–fold more compared with TiO2). Therefore, we provide new insights into the fabrication of carbon-based inorganic composite, which have great potential in water treatment.
查看更多>>摘要：? 2022 Elsevier B.V.Boron–nitrogen co-doped diamond (BNDD) nanostructures are grown in situ on a boron-doped diamond (BDD) film, and the effects of B and N doping on the BNDD-layer morphology and composition are systematically investigated. A competitive control mechanism of BNDD etching and growth under the synergistic action of the B and N atoms is revealed and, hence, a controllable preparation process for porous BNDD films and BNDD nanosheets on BDD is proposed. In an NaCl aqueous solution, the positive-potential window of the BNDD electrode reaches 0–1.2 V, the negative-potential window reaches ?1.6–0 V, and the working voltage of the constructed capacitor reaches 2.8 V. The proposed capacitor exhibits a high power density of 21,458.33 μW cm?2 at 0.02 μW h cm?2 energy density, and a high energy density of 0.42 μWh cm?2 at 1224.22 μW cm?2 power density. Furthermore, the BNDD-based capacitor demonstrates excellent stability, with 104.8% capacitance retention and 101.2% Coulombic efficiency after 50,000 cycles. The capacitor filters alternating-current (AC) signals in a wide frequency range of 50 Hz–1 MHz, with an output-signal voltage loss of 0.17–0.48 V. The proposed aqueous BNDD-based capacitor has considerable application potential in the filtering of broadband and high-frequency AC signals.
查看更多>>摘要：? 2022This present study describes the first electrochemical investigation of caspofungin, which is a semisynthetic echinocandin class of antifungal drug. For this purpose, an electrochemically pretreated (anodically and subsequently cathodically) boron-doped diamond (BDD) electrode was used. The cyclic voltammetric scans showed a single oxidation step that is irreversible and controlled by a dual mechanism of adsorption and diffusion. For the optimization of experimental conditions, the influence of the electrode pretreatment, pH of the supporting electrolyte, concentration of cationic surfactant cetyltrimethylammonium bromide (CTAB), accumulation variables, and instrumental parameters was examined on the current response of caspofungin. The improved sensitivity of the voltammetric measurements was observed due to the synergistic effect of CTAB on the adsorption capacity of BDD electrode in alkaline pH conditions. Employing square-wave adsorptive stripping voltammetry (using open-circuit accumulation for 60 s), the oxidation signal at around +0.45 V allowed to the determination of caspofungin in Britton-Robinson buffer at pH 11.0 containing 1 × 10?4 M CTAB. The process could be used in the concentration range from 2.06 × 10?7 to 1.03 × 10?5 M (from 0.25 to 12.5 μg mL?1 as acetate salt) with a detection limit of 5.27 × 10?8 M (0.064 μg mL?1 as acetate salt). A technique developed here was used successfully to determine caspofungin concentration in commercial parenteral dosage formulations.
查看更多>>摘要：? 2022In this work, diamond and diamond/graphite composite coatings were obtained on the surfaces of TC4 (Ti-6Al-4V) alloy by high-frequency induction heating the preplaced powders in argon. The microstructures of the composite coatings were studied by scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer, and the wear resistance of coatings was assessed by rubber wheel abrasion test. The results showed that the composite coatings had good metallurgical bonding with the substrates. TiC and ZrC particles in-situ generated in diamond/graphite composite coating improved the wear resistance of alloy matrix, but the free graphite weakened the wear-resistant structure of the coating. In the wear tests, abrasive wear was the main wear mechanism for diamond composite coating and diamond/graphite composite coating. Beside the elements of brazing alloy, carbon, aluminum and oxygen were the main elements detected at the surfaces of the two coatings.
查看更多>>摘要：? 2022 Elsevier B.V.Herein, a zero-dimensional graphene quantum dots (GQD) anchored on reduced graphene oxide (rGO) sheets were synthesized by hydrothermal method. CuS and GQD anchored rGO sheet (GRGS/CuS) composite was prepared by simple spin coating and thermal sulfidation techniques and used as counter electrode (CE) material for CdS quantum dot sensitized solar cell (QDSSC). The morphological studies of GRGS/CuS composite revealed the presence of spherical graphene quantum dots and microflower structured CuS on rGO sheet matrix. This microflower morphology provided more reactive sites for the electrolyte reduction and GQD/rGO in the composite acted as an effective conducting matrix to transport the charge carriers. The synergistic effect of GQD/rGO and CuS in the composite resulted in reduced charge transfer resistance and multi fold times increased the power conversion efficiency of GRGS/CuS composite than the bare counter electrodes. This work has opened up new opportunities to use GRGS/CuS composite material as a promising counter electrode, since it has the potential to enhance the performance of solar cells.
查看更多>>摘要：? 2022Biochar containing graphene (BCG) was synthesized using the precursor of bamboo biomass and K2CO3 as the activating agent utilizing microwave heating with short duration. The biochar had a typical graphene structure with abundant micropore and extremely high surface area up to 1565 m2/g. The activating agent K2CO3 played an important role in the catalytic graphitization, facilitating transformation of amorphous carbon into graphene like carbon. The adsorption experiment exhibited an excellent adsorption capacity of BCG for methylene blue (MB), with a maximum adsorption capacity of 1100 mg/g. The adsorption process was governed both by physical and chemical adsorption. The work further presents the mechanism of activation, adsorption isotherms, adsorption kinetics, adsorption thermodynamics. The experimental resulted proved the successful and fast preparation methodology for graphene contained carbon materials by microwave heating.
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