Ultrasound-assisted synthesis of hyper-dispersed type-II tubular Fe3O4@SiO2@ZnO/ZnS core/shell heterostructure for improved visible-light photocatalysis

Abstract

Abstract Novel Datura inoxia-like Fe3O4@SiO2@ZnO/ZnS (FSZZ) core/shell nanocomposites were prepared via a simple ultrasound-assisted in situ surface sulfidation method. The samples displayed excellent uniformity and were highly dispersed. The effects of the sulfidation concentration on the morphological, structural, optical, photoelectrochemical and photocatalytic properties of the nanocomposites were systematically studied. Regulating the sulfidation concentration introduced abundant zinc defects into the nanocomposites, so the light absorption was successfully extended to the visible light region. The intrinsic tubular core/shell heterostructures and number of zinc defects at the heterointerface were the key elements for synergistically promoting the transfer and separation efficiency of photogenerated charge carriers and then improving the degradation efficiency. When the concentration of thioacetamide was 9 mM (FSZZ0.3), the prepared sample exhibited superior photocatalytic efficiency of up to 99% under ultraviolet light irradiation and higher than 80% within 180 min under visible light irradiation for antibiotics and organic dyes degradation. Type-II staggered band alignment formed in FSZZ0.3, and the probable photocatalytic mechanism was proposed and discussed in detail. This novel 3D tubular core/shell heterostructure is an effective and promising photocatalyst for the wastewater purification, and our synthesis process provides a new simple and rapid strategy for designing other hyper-dispersed materials for different practical applications.