Depositing Ag2S quantum dots as electron mediators in SnS2/g-C3N4 nanosheet composites for constructing Z-scheme heterojunction with enhanced photocatalytic performance

•A novel Z-scheme system of g-C3N4/Ag2S/SnS2 with Ag2S quantum dots as electron mediators•Synthesis the photocatalyst by in-situ ion exchange and self-peeling•Photodegradation of methyl orange and phenol under visible light irradiation•Superoxide radicals and holes were the main photocatalytic active species•The probable photocatalytic mechanism was proposed combined various tests