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

In this study, a reusable double Z-scheme In2S3/Bi2WO6/CdS (ICB) photocatalytic hydrogels were developed for efficient reclamation of sulfamethoxazole (SMX) using peroxymonosulfate (PMS) activation and H2O2 production. The ternary In2S3/Bi2WO6/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 In2S3, Bi2WO6, 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 SO4*–, O2*–, OH*–, and electrons. Additionally, photocatalytic studies revealed a maximum H2O2 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.