摘要： In this research, we rationally designed and synthesized quantum dots self-decorated SnIn4S8/g-C3N4 (QDs-SISCN) nanocomposites by in situ anchoring quantum dot (QDs) self-decorated SnIn4S8 (SIS) nanosheets onto the surface of mesoporous graphite carbon nitride (CN) nanosheets in a mixed solvothermal environment. The photoreduction of 4-nitroaniline (4-NA) was used to assess their photocatalytic activity. In this framework, the construction of CN nanosheets-supported QDs-decorated SIS homojunctions can integrate the advantages of both homojunctions and heterojunctions. Benefiting from those favourable properties, the QDs-SISCN nanocomposites exhibit superior photocatalytic activity towards 4-NA reduction under visible-light irradiation (l > 400) as a result of the optimizied amount of CN nanosheets added. The recycling experiments also reveal high stability of the QDs-SISCN nanocomposites during photocatalytic reactions for 4-NA reduction. Moreover, the investigation of the photocatalytic mechanism from systematic characterizations, including measurements of the photocurrent response, electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) indicate that the improved separation efficiency of charge carriers is a critical parameter for the enhanced photocatalytic activity for 4-NA reduction. We expect this research to provide a promising path to the design and synthesis of highly efficient hybrid photocatalysts for functional-group transformations.