Construction of an all-solid-state Z-scheme Ag@Ag3PO4/TiO2-(F2) heterostructure with enhanced photocatalytic activity, photocorrosion resistance and mechanism insight

Photocatalysis is still a promising technology to alleviate the antibiotic residual problem of wastewater in the ecological environment. Herein, an all-solid-state Z-scheme Ag@Ag3PO4/TiO2-(F2) (TFAP) heterojunction photocatalyst was constructed using the hydrothermal method for the first time. The photocatalytic performance of TFAP nanocomposites for tetracycline hydrochloride (TCH) degradation was evaluated under simulated sunlight. The prepared materials were characterized by XRD, FE-SEM, TEM, BET, FT-IR, UVevis DRS, XPS, PL, and ESR measurements. The TFAP nanocomposites showed high degradation efficiency and excellent repeatability to TCH destruction. Among them, the (TFAP 1-1) nanocomposite has a lower bandgap energy (1.80 eV), a larger specific surface area (53.48 m2/g), and a lower electron-hole re-combination rate. After 2.5 h of simulated sunlight irradiation, the degradation rate of the 200 mg/L (TFAP 1-1) nanocomposite (k = 0.0154 min-1) to 10 mg/L TCH reached 94.14%, which was much higher than that of the pure TiO2, TiOF2, and Ag3PO4 samples. The experimental results demonstrated that TiO2 was generated as an intermediate product during the chemical reaction process between Ag3PO4 and TiOF2. Additionally, Ag nanoparticles were formed in the Ag3PO4/TiO2/TiOF2 heterojunction system. An electric field was formed between Ag3PO4 and Ag, enhancing the visible light absorption ability. Because of the Schottky potential difference, the electrons accumulate in Ag nanoparticles, thus enhancing the photocorrosion resistance of Ag3PO4. Additionally, the localized surface plasmon resonance (LSPR) effect of Ag nanoparticles greatly promoted the separation of carriers at the interface of the heterojunction. The LSPR effect leads to the co -oscillation of free electrons, which leads to the strong absorption of electromagnetic energy and enhances the photocatalytic performance of the heterojunction. The Ag@Ag3PO4 nanocomposites acted as electron transport media for an all-solid-state Z-scheme TFAP heterojunction system. This study provides some in-depth insights into the structural design of Z-scheme heterojunctions, which have certain implications for other catalytic systems.(c) 2022 Elsevier B.V. All rights reserved.