Preparation of magnetic Fe3O4@PDA/CuS core-shell nanocomposite as a green photocatalyst

To solve the emerging aromatic organic pollutants in aqueous environment, in this study, the efficient recyclable core-shell structured photocatalyst Fe3O4@PDA/CuS was prepared by in situ reduction method. Firstly, Fe3O4 as cores were prepared to provide magnetic recovery. Through the self-polymerization of dopamine (DA), polydopamine (PDA) was coated on Fe3O4 as shells to protect Fe3O4 cores. Then, Cu2+ coordinated with PDA on the surface of Fe3O4@PDA and in situ reduced by Na2S to obtain core-shell structural Fe3O4@PDA/CuS with CuS uniformly growing on the PDA. CuS with a narrow band gap will endow Fe3O4 @PDA/CuS excellent photocatalytic performance for organic dyes degradation. The decomposition rate of methylene blue (MB) reached to 92.1 % within 180 min under visible light irradiation of Fe3O4@PDA/CuS as photocatalyst without any cocatalyst. When pH= 10, the decomposition rate of MB can reach to 92.7 % in 60 min, indicated Fe3O4@PDA/CuS was more suitable for use under alkaline conditions. The capture experiment determined that center dot OH was the main active substance. This also explained that under alkaline conditions, numerous OH- was conducive to the formation of center dot OH, thus accelerated the degradation rate. And the decomposition rate of MB by Fe3O4@PDA/CuS can still reach 83.95 % after reused three times.