No abstract

No abstract

Graphitic-C3N4 nanosheets (CN)/ZnO photocatalysts (CN/ZnO) with different CN loadings were successfully prepared via a simple precipitation-calcination in the presence of exfoliated C3N4 nanosheets. Their morphology and structure were thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL). The results showed that hexagonal wurzite-phase ZnO nanoparticles were randomly distributed onto the CN nanosheets with a well-bonded interface between the two components in the CN/ZnO composites. The performance of the photocatalytic Cr(VI) reduction indicated that CN/ZnO exhibited better photocatalytic activity than pure ZnO under visible-light irradiation and the photocatalyst composite with a lower loading of CN sheets eventually displayed higher activity. The enhanced performance of CN/ZnO photocatalysts could be ascribed to the increased absorption of the visible light and the effective transfer and separation of the photogenerated charge carriers.

To enhance the ability to remove mercury(II) from aqueous media, an Fe 3 O 4 magnetic nanocomposite (PPy-GO) composed of polypyrrole (PPy) and graphene oxide (GO) was synthesized in situ and characterized via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), zeta potential analysis, vibrating sample magnetometer (VSM) and the Brunauer-Emmett-Teller (BET) method. The performance of the magnetic PPy-GO for adsorbing mercury(II) from water along with the effects of solution pH, adsorbent dosage, coexisting ions, reaction time and temperature were studied in detail. The adsorption kinetics, isotherms and thermodynamics were investigated in detail to gain insights into the adsorption process. The results show that the BET surface area of the magnetic PPy-GO reached 1737.6 m 2 g À1. The Langmuir capacity of the magnetic PPy-GO for mercury(II) adsorption was 400.0 mg g À1 at 300 K and pH 7 AE 0.1.After adsorption, the magnetic PPy-GO nanocomposite could be efficiently separated from water via a magnetic field. The adsorption process was endothermic and spontaneous and occurred in accord with the Langmuir and pseudo-second-order models. The overall adsorption of mercury(II) not only involved chemisorption, but was also partially governed by intra-particle diffusion. Data from the preliminary application of magnetic PPy-GO to remove heavy metals from real electroplating effluent indicated a high removal efficiency of over 99% for mercury(II). Finally, a possible adsorption mechanism was discussed. All data showed that the magnetic PPy-GO material is a promising adsorbent to remove mercury(II) from aqueous media.

No abstract

can suppress the polysulfide shuttling and exhibit excellent redox electrocatalytic properties for lithium polysulfides decomposition. The batteries with heterostructure-modified separators show a high initial discharge capacity of 1068.4 mAh g −1 at 0.5 C, excellent rate performances (719.6 mAh g −1 at 5C), and a remarkable cycling ability. Even with a high sulfur loading of 6.4 mg cm −2 , the pouch cell can deliver an areal capacity of 5.54 mAh cm −2 at 0.2 C. This work not only provides a new route for preparing SA-catalysts, but also sheds new lights into engineering electronic structures of heterointerfaces for developing high-performance Li-S batteries.

No abstract

No abstract