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Pure nanometals have poor adsorption capacity due to their agglomeration in aqueous solution. In this study, biochar (Bc) prepared by the pyrolysis of rosin and coated on bentonite (Bt) was designed to support and disperse nanoscale α-Fe2O3 (Bt/Bc/α-Fe2O3). The generation of α-Fe2O3 nanoparticles and the pyrolysis of rosin on the surface of Bt were accomplished in a one-step heating route. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the pyrolysis of rosin into biochar and the production of α-Fe2O3 in the composite. Besides, scanning electron microscopy (SEM) images showed good dispersion of α-Fe2O3 nanoparticles on the biochar surface. This adsorbent demonstrated fast Cr(vi) adsorption property with a Cr(vi) removal efficiency of 95% within one minute and high Cr(vi) adsorption capacity with a maximum Cr(vi) removal up to 81.7 mg g−1 based on the Langmuir model. The remarkable improvement of Cr(vi) adsorption on Bt/Bc/α-Fe2O3 was attributed to the good dispersion of α-Fe2O3 nanoparticles by the biochar network in comparison with other similar adsorbents. In addition, Bt/Bc/α-Fe2O3 maintained high Cr(vi) adsorption capacity under both acidic and basic conditions. This indicated that Bt/Bc/α-Fe2O3 can be used for fast Cr(vi) removal from wastewater or emergent Cr(vi) leakage due to its facile preparation and high efficiency in a wide range of pH. [ABSTRACT FROM AUTHOR]

NiS/g-C 3 N 4 /SrTiO 3 (NS/CN/STO) composites were prepared using a facile hydrothermal method. The synergistic effect of g-C 3 N 4 /SrTiO 3 (CN/STO) heterojunction and NiS cocatalyst enhanced the photocatalytic hydrogen evolution activity of NS/CN/STO. A hydrogen production rate of 1722.7 μmol h -1  g -1 was obtained when the 2%NiS/20%g-C 3 N 4 /SrTiO 3 (2NS/20CN/STO) was used for the photocatalytic hydrogen evolution in the presence of methanol used as a sacrificial agent under UV-vis light irradiation; the photocatalytic hydrogen production rate of 2NS/20CN/STO is 32.8, 8.9 and 4.2 times the value of that obtained with pure g-C 3 N 4 , SrTiO 3 and 20%g-C 3 N 4 /SrTiO 3 (20CN/STO), respectively. Moreover, in photoelectrochemical investigations when compared with 20CN/STO, SrTiO 3 and g-C 3 N 4 , 2NS/20CN/STO exhibited significant photocurrent enhancement. The heterojunction and cocatalyst in NS/CN/STO improved the charge separation efficiency and the lifetime of the charge carriers, leading to the enhanced generation of electrons for photocatalytic hydrogen production., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Hierarchical ZnO hollow spheres (400-500 nm in diameter) consisting of ZnO nanoparticles with a diameter of approximately 15 nm have been successfully prepared by a facile and rapid sonochemical process. The formation of hierarchical ZnO hollow spheres is attributed to the oriented attachment and subsequent Ostwald ripening process according to time-dependent experiments. The as-prepared ZnO hollow spheres are used as a photoanode in dye-sensitized solar cells and exhibit a highly efficient power conversion efficiency of 4.33%, with a short-circuit current density of 9.56 mA cm(-2), an open-circuit voltage of 730 mV, and a fill factor of 0.62 under AM 1.5 G one sun (100 mW cm(-2)) illumination. Moreover, the photovoltaic performance (4.33%) using the hierarchical ZnO hollow spheres is 38.8% better than that of a ZnO nanoparticle photoelectrode (3.12%), which is mainly attributed to the efficient light scattering for the former.