Carbazolyl-based metal organic framework for photocatalytic antibiotic degradation and H2O2 green generation assisted by silver nanoparticles

Tetracycline, a widely used antibiotic that persists in the environment, is a significant pollutant, making its efficient degradation crucial for ecosystem and human health. Meanwhile, green production of hydrogen peroxide, an important chemical raw material and green oxidant, is significant in various fields. In this study, a novel visible-light-responsive photocatalyst, the ACM-X series material, was successfully synthesized through post-synthetic modification of Cz-MOF-2, with the deposition of Ag nanoparticles on the surface significantly enhancing the photocatalytic performance, enabling efficient degradation of tetracycline (TC) and high-yield production of hydrogen peroxide (H₂O₂) under simulated solar light irradiation. The Ag surface plasmon resonance (SPR) effect played a crucial role in improving charge separation efficiency, as confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. The ACM-1 catalyst demonstrated exceptional photocatalytic activity, achieving over 95 % TC degradation within 60 min and a H₂O₂ production rate of 50 μmol/h. The free radical scavenging experiments and electron paramagnetic resonance (EPR) technique confirmed that reactive oxygen species (ROS), including superoxide anion radicals (·O₂⁻), hydroxyl radicals (·OH) and singlet oxygen (¹O₂), were identified as key intermediates in the photocatalytic process. Density functional theory (DFT) calculations revealed that Ag modification reduced the band gap of Cz-MOF-2, enhancing light absorption and promoting electron transfer. The 2e⁻ oxygen reduction reaction (ORR) for H₂O₂ production was found to be spontaneous, with Ag acting as an electron and proton transfer mediator. Additionally, the degradation pathway of tetracycline (TC) was elucidated by using a mass spectrometer. The ACM − 1 catalyst exhibited excellent stability and reusability during multiple cycles of use, highlighting its potential in environmental remediation and sustainable chemical synthesis. This work provides a promising strategy for the design of advanced photocatalysts for solar energy conversion and pollutant degradation.