Stable self-assembly Cu2O/ZIF-8 heterojunction as efficient visible light responsive photocatalyst for tetracycline degradation and mechanism insight

Currently, the occurrence of tetracycline (TC) in the water environment has raised serious concerns. For utilizing the sunlight for degradation of TC is important to develop visible light semiconductor photocatalysts with high catalytic activity. In this paper, Cu2O/ZIF-8 particles were prepared by in situ growth method. The effects of the structures and performances of ZIF-8-doped Cu2O were examined via XRD, XPS, FTIR, SEM, TEM, BET, PL, EIS, ESR and UV–vis techniques. As result, Cu2O/ZIF-8 exhibited a better TC degradation rate constant (k ​= ​0.0102 ​min−1), 1.9 times higher than that of Cu2O (k ​= ​0.0053 ​min−1). The TC removal rate of Cu2O/ZIF-8 (84.1%) was higher than that of Cu2O (67.1%). Cu2O/ZIF-8 could still degrade TC effectively after four cycles, which proved that it had good stability. Also, the composite material showed superior removal efficacy in oxytetracycline (52%) and tetracycline hydrochloride (73%). The investigations on active species revealed that synergetic effects of Cu2O/ZIF-8 facilitated the production of oxygen radicals (•O2−) and hole (h+) for boosting TC degradation. The photoelectrochemical results also confirmed the improved separation and transfer of electron-hole pairs at the interface of Cu2O and ZIF-8. The photocatalytic mechanism and the factors responsible for the enhanced photocatalytic performance of the Cu2O/ZIF-8 were investigated. This visible light-driven system will ultimately reduce resource consumption, providing a sustainable and energy-saving environmental decontamination strategy.