Sunlight‐Driven Photocatalytic Degradation of Methylene Blue and Metanil Yellow Using WSe 2 /PEDOT Nanocomposites: Synergistic Charge‐Transfer Dynamics and Sustainable Textile Wastewater Remediation

ABSTRACT Textile effluents rich in azo and thiazine dyes pose a persistent water pollution problem, and widely used TiO 2 photocatalysts are limited by their UV‐only activity. Here we compare WSe 2 /PANI and WSe 2 /PEDOT, prepared by a one‐step hydrothermal in situ polymerization, for the simultaneous degradation of a cationic dye (methylene blue, MB) and an anionic azo dye (metanil yellow, MY) under natural sunlight. To our knowledge, this is the first side‐by‐side evaluation of these two composites for such a dual‐dye system. Using 10 µM dye solutions and a catalyst loading of 0.4 g/L over 180 min, WSe 2 /PEDOT removed ∼94.7% of MB and ∼89.5% of MY, ahead of WSe 2 /PANI (81.5% and 78.5%) and the bare components, following pseudo‐first‐order kinetics (k = 0.0185 and 0.0127 min −1 for MB and MY). TOC analysis showed that this corresponds to partial mineralization (∼62% for MB and ∼56% for MY), indicating that color removal outpaces mineralization. The higher activity of WSe 2 /PEDOT is consistent with its larger BET surface area (82.5 m 2 /g) and lower interfacial charge‐transfer resistance (94.87 Ω), indicating a type‐II heterojunction that improves charge separation. Radical‐trapping experiments identify as the dominant reactive species, with smaller contributions from h + and •OH. Tested here on model dye solutions, WSe 2 /PEDOT is a promising sunlight‐driven photocatalyst, with performance under real textile effluents warranting further study.