Ternary Indium Sulfide Based 3D Hydrogels as Versatile Photocatalysts: Unraveling Peroxymonosulfate Activation for Sulfamethoxazole Degradation and H₂O₂ Production

Abstract

In this study, a reusable double Z-scheme In 2 S 3 /Bi 2 WO 6 /CdS (ICB) photocatalytic hydrogels were developed for efficient reclamation of sulfamethoxazole (SMX) using peroxymonosulfate (PMS) activation and H 2 O 2 production. The ternary In 2 S 3 /Bi 2 WO 6 /CdS nanocomposites were prepared using the hydrothermal method and formulated into hydrogels via an immobilization strategy using sodium alginate as base substrate. The morphological, optical, structural, and electrochemical characterization of ICB hydrogels confirmed the formation of a ternary heterojunction. The ICB hydrogels displayed 99% sulfamethoxazole (10 mg/L) degradation (Rate constant = 0.191 min –1 ) in 20 min of visible light irradiation via peroxymonosulfate (PMS) activation (400 mg/L) with a reusability of 15 cycles. Also, the ICB hydrogels/PMS/Visible system demonstrated higher mineralization efficiency (56%) and ensured practicability by reclaiming the real wastewater. Higher catalytic efficacy is ascribed to the construction of double Z-scheme heterojunctions between In 2 S 3, Bi 2 WO 6, and CdS, which resulted in enhanced separation efficiency and suppressed recombination ratio of charge carriers. The synergistic interaction between the photocatalyst and PMS activation boosted the production of reactive oxygen species like SO 4 *–, O 2 *–, OH *–, and electrons. Additionally, photocatalytic studies revealed a maximum H 2 O 2 production of 302 μM in 60 min. The advantages of ternary photocatalytic hydrogels include higher reusability, easiness in catalyst recovery, higher utilization of visible light (1.34 eV), and sustainability. This research provides perspectives on the successful fabrication of a reusable double Z-scheme photocatalyst for peroxymonosulfate activation in the redemption of noxious contaminants.

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