Current Progress in the Biosynthesis of Metal Sulfide Nanomaterials for the Degradation of Dyes: A Review

The contamination of water bodies by industrial dyes poses a significant environmental challenge on a global scale. Conventional wastewater treatment methods often suffer from limitations related to high cost, limited efficiency, and potential secondary environmental impacts. Recent advances in photocatalytic technologies have highlighted the potential of metal sulfide-based photocatalysts, particularly those synthesized through environmentally friendly, plant-mediated approaches, as promising alternatives for efficient and sustainable dye degradation. However, despite their promising potential, metal sulfide photocatalysts often suffer from limitations such as photocorrosion, low stability under irradiation, and rapid recombination of charge carriers, which restrict their long-term applicability. In light of these challenges, this review provides a comprehensive examination of the physicochemical characteristics, synthetic strategies, and photocatalytic applications of metal sulfides. Particular emphasis is placed on green synthesis routes employing plant-derived extracts, which offer environmentally benign and sustainable alternatives to conventional methods. Moreover, the review elucidates various modification approaches, most notably, the formation of heterostructures, as viable strategies to enhance photocatalytic efficiency and mitigate the aforementioned drawbacks. The green synthesis of metal sulfides, aligned with the principles of green chemistry, offers a promising route toward the development of sustainable and environmentally friendly water treatment technologies.