ZnO nanoplate-induced phase transformation synthesis of the composite ZnS/In(OH)3/In2S3 with enhanced visible-light photodegradation activity of pollutants

Abstract

The composite ZnS–In(OH)₃–In₂S₃ (ZnO-ZIIS) was synthesized via a facile hydrothermal method using ZnO nanoplates as the zinc source. As a comparison, the composite ZnIn₂S₄–ZnS was obtained by applying zinc chloride as zinc raw material and ZnS–In₂S₃, In(OH)₃–In₂S₃ and In₂S₃ were prepared via a hydrothermal process. The products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) measurement, photoluminescence spectrometry (PL) and UV–vis absorption spectrometry. In the hydrothermal process, ZnO nanoplates change the hydrolysis and sulfuration rate of indium salt, which leads to products with different compositions and microstructures compared to the obtained composite using zinc chloride as zinc raw material instead of ZnO. Photocatalytic activity was evaluated by degradation of Rhodamine B (RhB) under visible light (λ ≥ 420 nm) irradiation. The degradation activity of the product obtained by applying ZnO nanoplates as zinc raw material is superior to those of the other products and is nearly 5 times as high as that of the product synthesized using zinc chloride as zinc raw material. The enhanced photodegradation activity can be attributed to the extended visible light absorption range, the larger specific surface area, wider pore size distribution and the effective photogenerated electron–hole separation due to the suitable energy-band structure. A possible mechanism is discussed.