| Summary: | 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 KSb<sub>5</sub>S<sub>8</sub> 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 KSb<sub>5</sub>S<sub>8</sub> could absorb visible light, and its optical band gap was 1.62 eV. The photocatalytic activity of KSb<sub>5</sub>S<sub>8</sub> 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-C<sub>3</sub>N<sub>4</sub>. Theoretical calculations demonstrated that KSb<sub>5</sub>S<sub>8</sub> was an indirect band gap semiconductor. The estimated effective mass of holes (<inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>m</mi> <mi>h</mi> <mo>*</mo> </msubsup> </mrow> </semantics> </math> </inline-formula>) was approximately two times greater than that of electrons <inline-formula> <math display="inline"> <semantics> <mrow> <mrow> <mo>(</mo> <mrow> <msubsup> <mi>m</mi> <mi>e</mi> <mo>*</mo> </msubsup> </mrow> <mo>)</mo> </mrow> </mrow> </semantics> </math> </inline-formula>. The large ratio of <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>m</mi> <mi>h</mi> <mo>*</mo> </msubsup> <mo>/</mo> <msubsup> <mi>m</mi> <mi>e</mi> <mo>*</mo> </msubsup> </mrow> </semantics> </math> </inline-formula> might promote separation of photo-induced carriers during the photocatalytic process. On the basis of the layered crystal structure and large <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>m</mi> <mi>h</mi> <mo>*</mo> </msubsup> <mo>/</mo> <msubsup> <mi>m</mi> <mi>e</mi> <mo>*</mo> </msubsup> </mrow> </semantics> </math> </inline-formula> value, KSb<sub>5</sub>S<sub>8</sub> 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.
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