This study aims to investigate the effect of meniscus curvature on the permeability of the micro-post arrays, which are widely used for applications of microfluidics. An analytical model that accounts for the meniscus curvature is developed. The model considers two common array types: quadratic and hexagonal arrays. The permeability of micro-post arrays is estimated using the capillary rate of rise experiment and numerical simulation. The results obtained from the analytical model match the experimental and numerical results within the error of 5% over the range of parameters commonly found in microfluidic applications (0.06 < d * < 0.6 and H * > 0.2), where d * and H * are the post-diameter and the post-height, respectively, which are normalized by the pitch. Based on the analytic results, the effects of the post-diameter, post-height and the contact angle on the permeability of post-arrays are investigated. It is shown that the previous permeability models based on the flat meniscus assumption overestimate the experimental value by 26% for the quadratic array and 24% for the hexagonal array when cos θ = 1, d * = 0.5 and H * =1. The effect of the meniscus curvature is shown to become more pronounced as the contact angle or the post-height decreases.

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A zero-dimensional/two-dimensional heterostructure consists of binary SnO 2 –ZnO quantum dots (QDs) deposited on the surface of graphitic carbon nitride (g-C 3 N 4 ) nanosheets. The so-called SnO 2 –ZnO QDs/g-C 3 N 4 hybrid was successfully synthesized via an in situ co-pyrolysis approach to achieve efficient photoactivity for the degradation of pollutants and production of hydrogen (H 2 ) under visible-light irradiation. High-resolution transmission electron microscopy images show the close contacts between SnO 2 –ZnO QDs with the g-C 3 N 4 in the ternary SnO 2 –ZnO QDs/g-C 3 N 4 hybrid. The optimized hybrid shows excellent photocatalytic efficiency, achieving 99% rhodamine B dye degradation in 60 min under visible-light irradiation. The enriched charge-carrier separation and transportation in the SnO 2 –ZnO QDs/g-C 3 N 4 hybrid was determined based on electrochemical impedance and photocurrent analyses. This remarkable photoactivity is ascribed to the “smart” heterostructure, which yields numerous benefits, such as visible-light-driven fast electron and hole transfer, due to the strong interaction between the SnO 2 –ZnO QDs with the g-C 3 N 4 matrix. In addition, the SnO 2 –ZnO QDs/g-C 3 N 4 hybrid demonstrated a high rate of hydrogen production (13 673.61 μmol g –1 ), which is 1.06 and 2.27 times higher than that of the binary ZnO/g-C 3 N 4 hybrid (12 785.54 μmol g –1 ) and pristine g-C 3 N 4 photocatalyst (6017.72 μmol g –1 ). The synergistic effect of increased visible absorption and diminished recombination results in enhanced performance of the as-synthesized tin oxide- and zinc oxide-modified g-C 3 N 4 . We conclude that the present ternary SnO 2 –ZnO QDs/g-C 3 N 4 hybrid is a promising electrode material for H 2 production and photoelectrochemical cells.

This paper reports the solvothermal synthesis of MoS2nanoflowers and nanosheets. The nanoflowers have a mean diameter of about 100 nm and were obtained using thioacetamide (C2H5NS) as a sulfur source. The few layered nanosheets were obtained using thiourea (CH4N2S) as a sulfur source. The obtained powders were characterized using powder X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The lubricating effect of MoS2nanoflowers and nanosheets were analyzed using four-ball test, the topography of the wear scar was analyzed using SEM, EDS, and 3D surface profilometry. The relationship between the tribological properties and morphology of the materials was determined. It is observed that the engine oil containing the MoS2nanomaterials penetrated more easily into the interface space, and it formed a continuous film on the interface surface. The tribological performance showed that the synthesized nanosheets had superior antiwear and friction-reducing properties as a lubrication additive compared with nanoflowers. Also, the wear scar of balls lubricated with nanoflowers revealed a larger diameter compared to nanosheets. In conclusion, nanosheets dispensed in oil have better tribological performance compared to nanoflowers oil in terms of capability to reduce friction.

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Core-shell heterostructures have attracted considerable attention owing to their unique properties and broad range of applications in lithium ion batteries, supercapacitors, and catalysis. Conversely, the effective synthesis of Bi2S3 nanorod core@ amorphous carbon shell heterostructure remains an important challenge. In this study, C@Bi2S3 core-shell heterostructures with enhanced supercapacitor performance were synthesized via sacrificial- template-free one-pot-synthesis method. The highest specific capacities of the C@Bi2S3 core shell was 333.43 F g−1 at a current density of 1 A g−1. Core-shell-structured C@Bi2S3 exhibits 1.86 times higher photocatalytic H2 production than the pristine Bi2S3 under simulated solar light irradiation. This core-shell feature of C@Bi2S3 provides efficient charge separation and transfer owing to the formed heterojunction and a short radial transfer path, thus efficiently diminishing the charge recombination; it also facilitates plenty of active sites for the hydrogen evolution reaction owing to its mesoporous nature. These outcomes will open opportunities for developing low-cost and noble-metal-free efficient electrode materials for water splitting and supercapacitor applications.

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