Abstract
<title>Abstract</title> <p> With the increasing presence of pharmaceutical contaminants in aquatic ecosystems, there is need for the development of a sustainable method of wastewater treatment through photocatalytic oxidation. In this study, an effective cerium-doped indium sulfide (Ce-InS) hydrogel photocatalyst was developed that could concurrently degrade sulfamethoxazole (SMX) and produce photocatalytic hydrogen peroxide. For this purpose, Ce-doped In₂S₃ was loaded onto a hydrogel to enhance the performance of the material in terms of charge separation, light absorption and stability. Characterization studies on the physical, structural, morphological, and optical properties of the synthesized materials confirmed the successful synthesis of the Ce-InS hydrogel with a porous structure, uniform elemental composition, reduced electron–hole pair recombination and lowered optical band gap from 1.90 eV (powder form) to 1.44 eV (hydrogel). The photocatalytic degradation experiments showed good degradation efficiency with a value of about 91% achieved at the degradation of 10 ppm SMX under the visible-light condition. It is important to note that the degradation efficiency was enhanced from 73% to 91% by increasing the catalyst concentration (5–15 beads). At the same time, the increasing SMX concentration from 10 to 30 ppm resulted in the degradation efficiency decrease from 91% to 56%. The radical scavenging experiment confirmed that the hydroxyl radicals(•OH) were the main species responsible for the degradation process. Moreover, it was found that the Ce-InS hydrogel (90%) provided better results than the Ce-InS powder (77%) and pristine In₂S₃ (60%). In addition to achieving 91% SMX degradation, the Ce-InS hydrogel generated a maximum H₂O₂ concentration of <bold>190 µM</bold> , highlighting its dual-functionality as an efficient photocatalyst for simultaneous pollutant degradation and sustainable oxidant production under visible-light irradiation. </p>