Enhanced photocatalytic degradation of sulfamethoxazole using MIL-101 (Fe) supported Mo single-atom with oxygen vacancies under visible light activation of peroxymonosulfate

This study investigates the degradation of sulfamethoxazole (SMX), a widely detected and persistent antibiotic in the environment, using a novel photocatalytic system based on MIL-101(Fe) supported Mo single-atom with oxygen vacancies (Mo/Ov-MOF). Anchoring Mo single-atoms into the MOF structure enhances catalytic activity by effectively improving charge separation and reducing electron-hole recombination. The Mo/Ov-MOF efficiently activates peroxymonosulfate (PMS) under visible light, generating singlet oxygen (1O2) as a primary reactive species responsible for SMX degradation. Degradation experiments demonstrated that the degradation efficiency reached 96.8 % in the presence of PMS and visible light. Through quenching and trapping experiments on active species, an in-depth investigation into the source of 1O2 was performed, demonstrating the crucial role of holes in the rapid and selective generation of 1O2 under visible light. Additionally, the reusability of the Mo/ Ov-MOF catalyst was confirmed, maintaining over 70 % degradation efficiency after five cycles. Toxicity assessments indicated that the degradation by-products exhibited significantly lower toxicity than the parent compound SMX, thus mitigating potential ecological risks. The mechanistic insights reveal that oxygen vacancies and Mo single-atom enhance electron transport and facilitate efficient PMS activation, ultimately leading to effective pollutant degradation. The findings underscore the potential of the Mo/Ov-MOF photocatalytic system for practical applications in wastewater treatment, particularly for removing persistent organic pollutants from aquatic environments.