Construction of a hybrid MoS2@polythiophene heterojunction photocatalyst for enhanced degradation of pharmaceutical pollutants and dyes

Abstract

In this study, a hybrid molybdenum disulfide anchored polythiophene (MoS₂@PTh) heterojunction photocatalyst has been synthesized via an in-situ chemical oxidative polymerization method. The structural, morphological, and optical properties have been studied. The photocatalytic activity of MoS₂@PTh was systematically evaluated for the degradation of different organic pollutants, including Tetracycline (TC), Ciprofloxacin (CIP), Rhodamine B (RhB), and Brilliant Blue (BB), under visible-light irradiation. The synthesized MoS₂@PTh composite exhibited significantly enhanced photocatalytic performance for pharmaceutical pollutants achieving 90% degradation of TC and 88% of CIP within 240 min. The corresponding rate constants (0.00861 min⁻¹ for TC and 0.00640 min⁻¹ for CIP) were markedly higher than those of pristine MoS₂ and PTh. Additionally, the composite efficiently degraded organic dyes, achieving degradation of 95% for RhB and 91% for BB within 240 min. Kinetic analysis confirmed that the degradation followed pseudo-first-order kinetics (R² = 0.997). A direct Z-scheme charge transfer pathway was identified, where hydroxyl (˙OH) and superoxide (˙O₂⁻) radicals served as the primary reactive species, supported by the participation of photogenerated electrons and holes. Stability assessment demonstrated excellent durability and reusability of the MoS₂@PTh photocatalyst, retaining high degradation efficiency over four consecutive cycles.