g-C3N4/Metal–Organic Framework Nanosheet/CuO Heterostructure for the Visible Photocatalytic Degradation of Tetracycline

Developing highly efficient photocatalysts for the degradation of pharmaceutical and personal care product residues is of significance and challenge. Herein, a graphitic carbon nitride (g-C3N4)/metal–organic framework (MOF) nanosheet/CuO heterostructure was successfully constructed via electrostatic self-assembly and in situ growth strategies. The heterostructure at ultralow doses (6 mg) displayed the highest tetracycline (TC, 20 mg/L) degradation efficiency of 78.8% under visible light within 27 min. Moreover, this heterostructure maintained a good TC degradation efficiency after four cycles. Experimental data and density functional theory calculations demonstrate that the good photocatalytic performance of the as-prepared heterostructure is attributed to the positively charged MOF sheet interlayer and the coupling effect between the g-C3N4, MOF nanosheet and CuO, which can enrich electrons, ions, molecules, and block holes to greatly improve the rapid separation of photogenerated carriers from g-C3N4 or CuO and the adsorption of reactants. The types of reactive oxygen species and effects of inorganic ions on photocatalytic performance were further studied. This work presented a novel strategy to construct a self-assembled heterostructure for visible photocatalytic applications.