High-Efficiency Visible Light Responsive Sulfide KSb5S8 Photocatalyst with a Layered Crystal Structure

Abstract

The development of efficient photocatalysts for degrading environmental pollutants in wastewater has drawn considerable attention due to their great potential in industrial applications. Herein, we used a solvothermal method to prepare KSb5S8 with a layered crystal structure. The crystal structure of the as-synthesized samples was characterized by powder X-ray diffraction and transmission electron microscope imaging. Our UV-vis diffuse reflectance spectroscopy results indicated that KSb5S8 could absorb visible light, and its optical band gap was 1.62 eV. The photocatalytic activity of KSb5S8 was evaluated in the degradation of methyl orange. A degradation of 73% within 180 min was achieved under visible light irradiation, which was considerably higher than that of commercial P25 and g-C3N4. Theoretical calculations demonstrated that KSb5S8 was an indirect band gap semiconductor. The estimated effective mass of holes ( m h * ) was approximately two times greater than that of electrons ( m e * ) . The large ratio of m h * / m e * might promote separation of photo-induced carriers during the photocatalytic process. On the basis of the layered crystal structure and large m h * / m e * value, KSb5S8 was a high-performance photocatalyst capable of harvesting visible light. This study provides valuable insight that will aid the design of improved sulfide photocatalytic materials with layered crystal structures.