A comprehensive review on recent advances in bismuth chalcogenide-based heterostructured photocatalysts for pesticide degradation

The extensive use of pesticides in modern agriculture has led to persistent contamination of water and soil, posing severe risks to ecosystems and human health due to their chemical stability and low biodegradability. This critical review highlights recent advancements in bismuth chalcogenide-based visible-light-active photocatalysts and their heterostructure composites for the degradation of recalcitrant herbicidal and pesticidal residues. The structural, optical, and electronic properties enabling enhanced light absorption, charge separation, and redox activity under solar irradiation are discussed. Recent progress in band-structure engineering, defect modulation, and the design of Z -scheme, S-scheme, and p-n heterojunctions is shown to significantly improve photocatalytic efficiency. Photocatalytic degradation mechanisms, including reactive oxygen species generation and molecular breakdown pathways, are also examined. Despite these advances, major challenges remain, such as rapid charge carrier recombination, photo corrosion and interfacial instability, limited redox potential leading to incomplete mineralization, slow degradation kinetics, and the formation of toxic intermediate by-products in complex aqueous systems. • Reviews recent advances in Bi-chalcogenide photocatalysts for pesticide degradation. • Summarises key structural, optical, and electronic features enhancing photocatalysis. • Evaluates Z-scheme, S-scheme, and p–n heterojunction strategies. • Discusses ROS generation and degradation pathways of persistent pollutants. • Provides design insights for efficient photocatalysts for environmental remediation.