Pharmaceutical contamination, particularly from methotrexate (MTX), poses a significant environmental and health challenge,

as conventional water treatment methods often fail to remove these persistent pollutants effectively. This study introduces a pioneering Ag-decorated oxygen-deficient TiO₂ (Vo-TiO2/Ag) photocatalyst that combines hydrothermal treatment to create oxygen vacancies and silver impregnation to enhance visible-light photocatalytic activity. The photocatalyst demonstrates remarkable performance, achieving both MTX degradation and detoxification under visible light. The Vo-TiO2/Ag catalyst showed complete MTX degradation (initial concentration: 10 mg/L) within 75 min at a catalyst dosage of 40 mg, accompanied by significant reductions in toxicity (91.31%) and mutagenicity (87.87% in TA98 and 89.68%in TA100), as evidenced by bioassays. The incorporation of oxygen vacancies and silver significantly enhanced photocatalytic efficiency by improving light absorption, charge separation, and the generation of reactive oxygen species (•OH, •O₂⁻, and h⁺). A radical scavenging experiment confirmed that •O₂⁻ and h⁺ were the primary active species responsible for the degradation of MTX. While the retained positive valence band potential permits •OH formation, its secondary role underscores a mechanistic shift where enhanced charge separation preferentially drives superoxide generation and direct hole oxidation. The dual functionality of degradation and detoxification, driven by these active species, offers a promising and sustainable solution for the remediation of pharmaceutical pollutants, particularly in hospital wastewater treatment. 

The Vo -TiO2/Ag has high stability across multiple cycles, further highlighting its potential for practical environmental 

applications.