Z-scheme FeOOH/g-C3N4 nanosheets promoted PDS activation for efficient tetracycline degradation under visible light

Recently, photocatalysis combined peroxydisulfate (PDS) activation as a novel advanced oxidation processes (AOPs) was applied to remove pharmaceuticals and personal care products (PPCPs) in waterbody. Under visible light irradiation, photocatalysts, such as graphitic carbon nitride (g-C3N4, CN), could generated holes and electrons for both organic oxidation and PDS activation. However, it exhibits the drawbacks of low organics removal rate, high electron-hole recombination rate and low activation efficiency of PDS. In this study, amorphous iron oxyhydroxide (FeOOH) was intercalated into the surface of the g-C3N4 nanosheets (CNNS) to form a Z-scheme heterojunction to solve these problems. Electrochemical impedance spectroscopy (EIS) and photoluminescence spectrum (PL) tests proved the enhancement of the charge separation and migration capability of FeOOH/CNNS. The density functional theory (DFT) supported the constructive role of the Z-type heterojunction between FeOOH and CNNS in promoting photocarrier transfer and facilitating more effective PDS activation reactions. The removal rate of tetracycline (TC) achieved 98.8 % within 80 min by FeOOH/CNNS coupled PDS under visible light (FeOOH/CNNS-PDS/Vis) system. Finally, electron spin resonance (ESR) approved the pivotal role of •OH, SO4•-, and •O2- during the process. [Display omitted] •FeOOH/CNNS achieves 98.8 % TC removal in 80 minutes under visible light irradiation.•Z-scheme heterojunction enhances charge separation and improves photocatalytic performance.•FeOOH/CNNS maintains over 95 % efficiency after five cycles, demonstrating excellent stability.•Reactive species analysis offers insights into the TC degradation mechanism.