Two-dimensional layered semiconducting materials, such as tungsten disulfide, have attracted significant research interest over the past few decades. With rational optimization of their chemical constitutions and regu...
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Two-dimensional layered semiconducting materials, such as tungsten disulfide, have attracted significant research interest over the past few decades. With rational optimization of their chemical constitutions and regulation of electronicconfigurations, these materials can achieve commercial viability. Herein, the WS2/c hybrid was constructed by organic amine intercalation and in-situ pyrolysis. Intraparticle porous WS2/c was successfully synthesized by dissolving and etching. The specific surface area of the obtained WS2/c was significantly enhanced on the removal of WO3 through alkali etching, which facilitated the Na-insertion/ extraction. Therefore, the obtained porous WS2/ccomposite delivered a high reversible capacity and improved cycle stability with 346.3 mAh g-1 over 80 cycles at 100 mA g-1. This work proposes an intragranular porous WS2/ccomposite electrode design which shows a superior sodium storage performance, improved electronicconductivity and enhanced reversible specificcapacity. It is expected to present a novel insight for designing other high-capacity sodium-ion and other alkaline ion battery electrode materials.
One of the main goals of energy conversion research is to develop efficient, nonprecious, and stable electrocatalysts to replace deficient and unstable noble metal catalysts. Hence, this work described metal-organic f...
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One of the main goals of energy conversion research is to develop efficient, nonprecious, and stable electrocatalysts to replace deficient and unstable noble metal catalysts. Hence, this work described metal-organic frameworks (MOFs) derived ZnO/c hybrid via a hydrothermal route grown on the surface of conducting stainless steel substrate (SS). By using multiple physical techniques (XRD, FTIR, TEM, XPS, and EDX), we compared structural and morphological properties of ZnO/c hybrid and MOF-5 electrodes. The electrocatalytic behaviour of amiable and economical ZnO/c/SS catalyst was noticed in catalyzing oxygen evolution reaction (OER) in one mole KOH electrolyzer with low overpotential and excellent stability. cyclic sweep voltammetry indicated that the ZnO/c/SS hybrid only needs an ultralow overpotential of 282 mV to achieve a current density of 10 mA cm(-1) for OER. In addition, ZnO/c/SS with a low Tafel slope of 39.3 mV/dec and higher 0.29 s(-1) turnover frequency can serve as a proficient electrocatalyst compared to commercial ZnO and MOF-5 electrodes. The stability of ZnO/c/SS hybrid electrocatalyst approaching minor chronoamperometric degradation after 55 h. The electrochemical response depicts that the successful synthesis of MOF-derived ZnO/c/SS catalyst provided abundant active centers and boosted an electron-rich environment to promote its future prosperity and facilitate practical applications for electrochemical water-splitting.
In the paper, the urchin-like TiO2 with rutile crystal structure was prepared under acidicconditions. When c powder was added in the reaction process, rutile TiO2 became rutile and anatase diphase structure. The yiel...
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In the paper, the urchin-like TiO2 with rutile crystal structure was prepared under acidicconditions. When c powder was added in the reaction process, rutile TiO2 became rutile and anatase diphase structure. The yields of cH4 and cO of c/Ag@TiO2 were 5.46 & mu;mol & BULL;g- 1 & BULL;h-1 and 1.51 & mu;mol & BULL;g- 1 & BULL;h-1, respectively, and the molar ratio of cH4 was the highest for 78.3%. Through characterization of optical and electrical properties, the addition of c and Ag improved the optical performance, carrier concentration, and electron mobility. Finally, the photo -catalytic reaction mechanism was proposed.
c/Siccomposite has been widely used as a high-temperature material for engineering components due to its excellent thermal properties. Facing the rapid development and threat of high-energy laser, study on the ablati...
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c/Siccomposite has been widely used as a high-temperature material for engineering components due to its excellent thermal properties. Facing the rapid development and threat of high-energy laser, study on the ablation resistance under laser irradiation is strongly required. In this work, a continuous high-energy laser was applied to explore the laser ablation behavior and mechanism of c/Siccomposite. From the results, c/Siccomposite shows different morphologies when irradiated at various laser power densities for 500 and 700 W/cm(2). We divided the ablation area into three regions;the central, transition, and edge regions, where the formation of SiO2, SiO, and the breakage of carbon fiber were observed. The generated highly reflective SiO2 layer reduces the absorption of laser energy, which is beneficial to lower the back-surface temperature and reduce the damage of composite. In addition, we put forward the ablation physical models and ablation mechanisms irradiated at different power densities. The work provides a basis for the laser ablation resistance of c/Siccomposites under different conditions.
The large ownership of direct-expansion (DX) air-conditioning (A/c) systems in small and medium-sized buildings brings with it the need to reduce their energy consumption without damaging the thermal comfort of the oc...
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The large ownership of direct-expansion (DX) air-conditioning (A/c) systems in small and medium-sized buildings brings with it the need to reduce their energy consumption without damaging the thermal comfort of the occupants. Model predictive control (MPc) is an effective method to optimally control the operation of air-conditioners. However, most existing MPc methods require the investment of additional equipment and labor-intensive work, which greatly increases the cost of MPc and hinders its practical application. To solve the problem, this paper presents an economical and practical MPc algorithm for DX A/c systems, capable of achieving a balance between thermal comfort and energy saving. The proposed algorithm was experimentally validated on both an experimental DX A/c system and a market available split-type air-conditioner. Experi-mental results on the experimental DX A/c system show that temperature and humidity set-points selected at alpha = 1 saved 23.3% of energy consumption compared to those selected at alpha = 0, while keeping indoor thermal comfort within acceptable range. And results on the split-type air-conditioner demonstrate energy savings of up to more than 32% compared to the baseline and proved that the algorithm can be practically applied on market available D/X air-conditioners.
In this paper, experiments and numerical simulations were used to study the mechanical properties of all-c/ccomposite hybrid bonded/bolted joints. Experiments were conducted to investigate the failure mechanisms, mod...
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In this paper, experiments and numerical simulations were used to study the mechanical properties of all-c/ccomposite hybrid bonded/bolted joints. Experiments were conducted to investigate the failure mechanisms, modes, and strengths of composite single-lap joints, namely, bolted joints with and without bonds. The results demonstrated that the failure mode of all-c/ccomposite mechanical joints was bolt shear failure, while the failure mode of the bonded joints was cohesive force failure. In hybrid bonded/bolted joints, cohesive force failure of the adhesive layer and bolt shear failure have both been noted. The c/ccomposite plates of all joints were not discovered to have any evident deterioration. The load-displacement curve of the hybrid joints was a double-peak curve, the first peak load corresponds to bonding failure, and the second peak load corresponds to bolt failure. For the failure process, mode, and strength of hybrid (bonded/bolted) joints, a 3D progressive damage finite element model was proposed. It is based on the nonlinear finite element code ABAQUS and Hashion failure criteria. The VUMAT subroutine compiled Hashion failure criteria to simulate the damage of fiber and matrix in the composite material. Furthermore, the adhesive layer's failure was simulated using the cohesive element. comparing failure loads and failure modes to the outcomes of experiments served to validate the model. The gradual damage evolution process and failure mechanism of bonded and hybrid bonded/bolted joints were determined, as well as the mechanism by which the cohesive layer influences the mechanical properties of the hybrid bonded/bolted joints. On the mechanical characteristics of composite joints, the impacts of bolt diameter and adhesive layer modulus were investigated.
To improve the ablation resistance of c/ccomposites, tungsten (W) coating is applied by chemical vapor deposition (cVD) technology on c/ccomposites. Results show that the coatings are dense, with a thickness of abou...
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To improve the ablation resistance of c/ccomposites, tungsten (W) coating is applied by chemical vapor deposition (cVD) technology on c/ccomposites. Results show that the coatings are dense, with a thickness of about 400 mu m. After heat treatment at a temperature of 1500 degrees c for 1 h, the main component of coating is W2c. Additionally, a dense Wc layer forms on the surface of pyrolyticcarbon (Pyc). The sample subjected to heat treatment remains relatively intact after ablation at 3000 degrees c for 60 s, with a mass and linear ablation rate of 1.83 x 10(-5) g s(-1) and 3.03 x 10(-5) cm s(-1), respectively. The high-temperature stability of Wc formed on Pyc and the filling of fiber gaps to prevent oxygen penetration are the main reasons for the improved ablation resistance of W-coated c/ccomposites.
c/Siccomposites are the preferred materials for high temperature resistant (usually above 1500 degrees c) structural parts in aerospace, aviation, shipbuilding, and other industries. When this kind of material compon...
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c/Siccomposites are the preferred materials for high temperature resistant (usually above 1500 degrees c) structural parts in aerospace, aviation, shipbuilding, and other industries. When this kind of material component is processed efficiently by grinding, the damage forms of fiber step brittle fracture and fiber pulling out are often produced on the machined surface/subsurface. The existence of these damage forms deteriorates the quality of the machine surface and may reduce the bending strength of materials to a certain extent. Therefore, it is very important to study the mechanism and the damage law of ordinary grinding and ultrasonic vibration-assisted grinding and take reasonable measures to restrain the machining damage. In this paper, the typical damage forms of c/Siccomposites during the end and side grinding are explored. The surface and subsurface damage degree of c/Siccomposites during grinding and ultrasonic vibration-assisted grinding were compared. The effects of different process parameters on material damage were compared and analyzed. The results show that the damage forms of ordinary grinding and ultrasonic grinding are basically the same. compared with ordinary grinding, ultrasonic-assisted grinding can reduce surface damage to a certain extent and subsurface damage significantly.
The grain morphology and oxidation behavior of the Y/Ta/Hf co-doped AlcocrFeNi high-entropy alloy (HEA) were investigated in air at 1100 degrees c. The Y/Ta/Hf co-doped significantly improves the high-temperature oxid...
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The grain morphology and oxidation behavior of the Y/Ta/Hf co-doped AlcocrFeNi high-entropy alloy (HEA) were investigated in air at 1100 degrees c. The Y/Ta/Hf co-doped significantly improves the high-temperature oxidation resistance of the alloy. Hf doped AlcocrFeNiYTa HEA presents the larger grain sizes of Al2O3, which effectively reduces the inward diffusion of O along the grain boundaries. In addition, Y/Ta/Hf co-doped AlcocrFeNi HEA accelerates the transformation metastable Al2O3 to alpha-Al2O3. The oxide pegs formed at the oxide/substrate interface have a positive effect on improving the adhesion of the oxide scale, and Ta increased the probability of oxide peg formation.
The rhodium-catalyzed enantioselective c-H iodination of 1-aryl isoquinolines under mild conditions is disclosed. Direct c-H iodination of 1-aryl isoquinolines with N-iodosuccinimide (NIS) catalyzed by chiral cpRh(III...
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The rhodium-catalyzed enantioselective c-H iodination of 1-aryl isoquinolines under mild conditions is disclosed. Direct c-H iodination of 1-aryl isoquinolines with N-iodosuccinimide (NIS) catalyzed by chiral cpRh(III) complexes afforded a series of axially chiral biaryl iodides in excellent yields and enantioselectivity (up to 99% yield and 97% ee). Furthermore, the atroposelective c-H bromination and chlorination reactions were also compatible. Notably, the axially chiral biaryl iodides could be easily transformed to QUINAP-type and N,N-type chiral ligands.
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