For the first time, InTaO 4 photocatalysts with different morphologies and structures were facilely prepared using a versatile sol precursor. SEM, TEM and HRTEM were used to characterize their structures and morphologies. The as-synthesized materials exhibit different physicochemical properties. Compared to InTaO 4 nanoparticles and SiO 2 @InTaO 4 core-shell nanospheres, InTaO 4 nanofibers have higher light absorption ability, larger specific surface area, and better photocatalytic activity for hydrogen evolution.We proposed mechanisms for the formation and photocatalytic activity of the three catalysts. The present work not only provides a new approach for the synthesis of tantalates that are different in morphology and structure but also offers new insights into the controllable preparation of photocatalysts through a versatile precursor for environmental and energy applications.Scheme 1 Schematic illustration of the formation of InTaO 4 nanoparticles, SiO 2 @InTaO 4 core-shell nanospheres, and InTaO 4 nanofibers.
A series of heterostructured CdS/Sr2(Nb17/18Zn1/18)2O7-δ composites with excellent photocatalytic ability for simultaneous hydrogen evolution and As(III) oxidation under simulated sunlight were synthesized and characterized. Among them, 30% CdS/Sr2(Nb17/18Zn1/18)2O7-δ (30CSNZO) has the highest in activity, exhibiting a H2 production rate of 1669.1 μmol·h(-1)·g(-1) that is higher than that of many photocatalysts recently reported in the literature. At pH 9, As(III) is completely oxidized to As(V) over 30CSNZO in 30 min of irradiation of simulated sunlight. In the photocatalytic system, H2 production rate decreases with the increase of As(III) concentration, and the recycle experiments show that 30CSNZO exhibits excellent stability, durability, and recyclability for photocatalytic hydrogen evolution and As(III) oxidation. We propose a mechanism in which superoxide radical (·O2(-)) is the active species for As(III) oxidation and the oxidation of As(III) has an effect on hydrogen evolution. For the first time, it is demonstrated that simultaneous hydrogen evolution and arsenite oxidation is possible in a photocatalytic system.
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