Construction of dual Z-scheme UNiMOF/BiVO4/S-C3N4 photocatalyst for visible-light photocatalytic tetracycline degradation and Cr(VI) reduction

Rapid recombination of the photogenerated carrier, a limited range of photoexcitation, and unsatisfactory photocatalytic activity are the limiting factors in photocatalytic applications. Accelerating photogenerated carrier transfer and constructing surface active sites have become critical tasks. In this study, a dual Z-scheme UNiMOF/BiVO4/S-C3N4 (NBSCN) photocatalyst with a 2D/3D/2D structure was successfully constructed. Under visible-light irradiation, NBSCN outperforms single and binary composites in photocatalytic tetracycline photodegradation and Cr(VI) photoreduction due to the synergistic effect of adsorption and photocatalysis. The maximum photocatalytic efficiency of tetracycline (90.1 %) and Cr(VI) (93.6 %) in 120 min was achieved by NBSCN-20 %. The exceptional photocatalytic activity of NBSCN-20 % can be attributed to the large specific surface area, increased active sites, improved visible-light absorption ranges, and the construction of heterojunctions. The fabricated dual Z-scheme heterojunction at the interface of NBSCN reduces the recombination rate of photogenerated carriers and widens the range of light absorption. NBSCN-20 % exhibits excellent stability in the process of cyclic experiments. On the basis of the results, the feasibility of the dual Z-scheme mechanism is proposed. This work demonstrates that NBSCN-20 % photocatalyst has promising application prospects in removing heavy-metal ions and organic pollutants from aqueous environments.