Abstract: Superior photo-mineralization of pollutants, outstanding charge separation efficiency and exceptional photostability of catalysts constitute three pivotal factors for the effective photodegradation of organic pollutants. In this study, a dual S-scheme In₂O₃/Pedot/In₂S₃ (IO/Pedot/IS), inspired by natural photosynthesis, was successfully synthesized for the degradation of lignin and antibiotics. The resulting exceptional semiconductor contact creates a dual-interface electric field on Pedot, facilitating multi-channel charge transport and enhancing charge separation efficiency. The establishment of the dual S-scheme heterojunction raised the reduction-oxidation potential of the type-II In₂O₃/ In₂S₃. When subjected to 5 W LED irradiation for 60 min, IO/Pedot-2/IS demonstrated a remarkable mineralization rate of 85.8% for sodium lignosulfonate (SL), surpassing the 53.7% mineralization rate achieved by IO/IS. Furthermore, the degradation efficiency for tetracycline (TC) and ciprofloxacin (CIP) reached 91% and 88%, respectively. Crucially, the hole (h⁺) conductivity of Pedot efficiently alleviated the photocorrosion of sulfide, ensuring robust cyclic stability. Experimental simulations of natural photocatalysis showcased the exceptional versatility and applicability of IO/Pedot/IS. In-depth analysis led to the proposal of a potential photodegradation pathway for lignin, based on the intermediates detected through liquid chromatography-mass spectrometry (LC-MS). Overall, this study presents an effective strategy for the efficient photocatalytic treatment of organic pollutants.

Key words: Photodegradation, Lignin, Pedot, Photocorrosion, Double S-scheme