Fabrication of a novel Z-scheme p-n heterojunction photocatalyst 0D/3D CeVO4/MIL-88(A): enhanced photocatalytic performance and mechanism insight

This article aims to synthesize an efficient catalyst for the photocatalytic degradation of antibiotics in an aqueous environment. To this end,zero-dimensional (0D) CeVO₄ nanoparticles were encapsulated on the spindle shaped (3D) MIL-88 (A) surface to fabricate a CeVO₄/MIL-88 (A) p-n heterojunction photocatalyst by using solvothermal method, aiming at increasing the active sites of the composite photocatalyst. The prepared photocatalysts were characterized using SEM, FT-IR, XRD, XPS and UV–vis spectra. The photocatalytic degradation efficiency of tetracycline hydrochloride (TC) under visible light irradiation were used to assess the photocatalytic activity of the prepared composites. The results indicated that the CVM2 heterojunction photocatalyst fabricated under the optimized conditions (with a CeVO₄ mass ratio of 20 %) had the strongest photocatalytic activity. Under the irradiation of visible light for 120 min, the photocatalytic degradation efficiency of CVM2 to TC (10 mg/L) in water reached 81 %, which was marked higher than that of MIL-88 (A) and CeVO₄. Superoxide radicals were the main active species in the reaction system, and hydroxyl radicals and holes also contribute to the degradation of TC. Cations such as Ca²⁺, Na⁺, K⁺, Mn²⁺, and anions such as Cl⁻, CO₃²⁻, and natural organic compound FA did not have an obvious impact on TC degradation. The reason for the improvement of the photocatalytic performance of composite material CVM2 was due to the formation of a p-n internal electric field at the interface between CeVO₄ and MIL-88 (A), which enhances the separation and transfer ability of photogenerated charges on the surface of the composite material.