Se-vacancy engineered CoSe2/MoS2 heterojunction with DFT revealed dual charge transfer pathways for accelerated antibiotic photocatalytic degradation

To address the challenge of antibiotic-contaminated water remediation, we designed a defect-engineered CoSe2@MoS2 photocatalyst by integrating selenium-deficient CoSe2 dodecahedra (derived from ZIF-67) with vertically aligned MoS2 nanosheets. The catalyst achieved 90.4% visible-light-driven tetracycline (TC) degradation within 60 minutes, demonstrating a 3.1-fold performance enhancement over pristine MoS2 due to the synergistic effects of atomic-scale defect engineering and heterostructure design. Density functional theory (DFT) calculations revealed a dual enhancement mechanism: selenium vacancies introduced localized mid-gap states, increasing the photogenerated electron density by 2.8-fold, while the CoSe2/MoS2 heterojunction formed a type II band alignment, facilitating interfacial electron transfer via a built-in electric field. In situ spectroscopic analysis confirmed the vacancy-mediated enhancement of reactive oxygen species (·OH/·O2−) generation, showing a 2.8-fold increase in yield. DFT-guided quantitative analysis further demonstrated that the improved activity resulted from the synergistic interaction between heterojunction formation and vacancy modulation. The catalyst exhibited excellent environmental stability, maintaining >88% efficiency over 10 cycles with minimal metal leaching (<0.2 ppm). These findings advance the development of photocatalysts for visible-light-driven wastewater treatment, addressing the critical trade-offs between catalytic efficiency, operational stability, and ecological compatibility.