Preparation and mechanism investigation of Bi2WO6/UiO-66-NH2 Z-scheme heterojunction with enhanced visible light catalytic activity

Bi2WO6/UiO-66-NH2 Z-scheme heterojunction photocatalyst was successfully synthesized by a simple two-step solvothermal method. The structure and composition of the composite were studied by means of XRD, FT-IR, XPS, etc. The morphology of the composite was characterized by SEM and TEM. The photoelectrochemical properties of the composite were analyzed by transient photocurrent response, EIS and PL spectra. Compared with the single material, the construction of heterojunction composite materials was more conducive to the separation of photo-generated electron hole pairs, and the purpose of improving photocatalytic activity was achieved. When n(Zr):n(Bi) = 1:2, Bi2WO6/UiO-66-NH2 had the best catalytic activity for rhodamine B (RhB, 20 mg/L) and tetracycline (TC, 30 mg/L). The results of the four-cycle experiment verified that the composite material had better stability and reusability. Free radical trapping experiments showed that superoxide radicals (center dot O-2(-)) and holes (h(+)) were the main active substances in the photocatalytic degradation process, and the possible photocatalytic mechanism was speculated.