Herein, a magnetically separable reduced graphene oxide (rGO)-supported CoFe 2 O 4 –TiO 2 photocatalyst was developed by a simple ultrasound-assisted wet impregnation method for efficient photocatalytic H 2 production. Integration of CoFe 2 O 4 with TiO 2 induced the formation of Ti 3+ sites that remarkably reduced the optical band gap of TiO 2 to 2.80 eV from 3.20 eV. Moreover, the addition of rGO improved the charge carrier separation by forming Ti–C bonds. Importantly, the CoFe 2 O 4 –TiO 2 /rGO photocatalyst demonstrated significantly enhanced photocatalytic H 2 production compared to that from its individual counterparts such as TiO 2 and CoFe 2 O 4 –TiO 2 , respectably. A maximum H 2 production rate of 76 559 μmol g –1 h –1 was achieved with a 20 wt % CoFe 2 O 4 - and 1 wt % rGO-loaded TiO 2 photocatalyst, which was approximately 14-fold enhancement when compared with the bare TiO 2 . An apparent quantum yield of 12.97% at 400 nm was observed for the CoFe 2 O 4 –TiO 2 /rGO photocatalyst under optimized reaction conditions. This remarkable enhancement can be attributed to synergistically improved charge carrier separation through Ti 3+ sites and rGO support, viz., Ti–C bonds. The recyclability of the photocatalyst was ascertained over four consecutive cycles, indicating the stability of the photocatalyst. In addition, it is worth mentioning that the photocatalyst could be easily separated after the reaction using a simple magnet. Thus, we believe that this study may open a new way to prepare low-cost, noble-metal-free magnetic materials with TiO 2 for sustainable photocatalytic H 2 production.

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Zinc oxide (ZnO) nanostructures were synthesized and their photocatalytic activity was evaluated using methylene blue (MB) as a model pollutant. Ethylenediamine (EDA) was used as a passivating agent to control the morphology and size of the ZnO nanostructures. In the absence of EDA, agglomerated ZnO nanoparticles were obtained. The addition of EDA at varying concentrations considerably influenced the morphological size. The as-prepared samples were extensively characterized using various techniques. The morphology- and size-dependent photocatalytic degradation of MB was studied under visible light irradiation. The maximum degradation efficiency was observed for ZnO nanoflakes; the MB-related absorbance peak completely disappeared after 15 min of irradiation. Furthermore, the effect of various photocatalytic reaction parameters, such as pH (3-12) of the solution, the concentration of the dye (5, 10, 15, and 20 ppm), and the dosage of the photocatalyst (25, 50, 75, and 100 mg L(-1)), on the photodegradation of MB was investigated to determine the maximum degradation efficiency. The optimum values of solution pH, dye concentration, and photocatalyst dosage were 11, 10 ppm, and 75 mg L(-1), respectively.

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Molybdenum disulfide (MoS2) layered nanosheets were synthesized by the hydrothermal method.