In situ grown monolayer N–Doped graphene and ZnO on ZnFe2O4 hollow spheres for efficient photocatalytic tetracycline degradation

Herein, ZnFe2O4/ZnO hollow porous spheres (HPS) of the dual–template and self–dissolution design, on which monolayer nitrogen–doped graphene (NG) is in situ grown by chemical vapor deposition, are applied for realizing effective photocatalytic degradation of antibiotics. The constructed photocatalyst possesses a hollow interior for strengthening visible–light absorption ability and offering large surface area, a porous for facilitating rapidly mass transfer capability, a thin shell for shortening the migration distance of photo–generated electrons (e⎺), tight adhesion for expediting charge separation and mobility, and a monolayer NG cage surface for adsorbing and stimulating activating antibiotics molecules. Benefiting from the novel HPS structure, the prepared ZnFe2O4/NG/ZnO HPS photocatalyst exhibits high activity under visible–light irradiation, currently the largest to the best of our knowledge, which is much enhanced compared with those of the ZnFe2O4/NG/ZnO solid spheres and ZnFe2O4/NG hollow spheres.