A comprehensive review on synthesis methods, photodegradation mechanisms, and diverse applications of tin oxide (SnO2) nanoparticles

The persistent release of synthetic dyes from textile, printing, and related industries poses severe environmental and health hazards due to their toxicity, stability and resistance to biodegradation. Among various semiconductor-based photocatalysts, tin oxide (SnO₂) has emerged as a promising candidate for dye degradation owing to high stability, strong oxidation potential and wide band gap. This review provides a comprehensive overview of recent advances in the photodegradation of dyes using SnO₂. Various synthesis methods including precipitation, hydrothermal, sol-gel, ultrasonication, ball milling and microwave methods are discussed with emphasis on how synthesis routes influence particle morphology, crystallinity and photocatalytic activity. The fundamental photocatalysis mechanism of SnO₂ is elucidated, highlighting charge generation, separation and reactive oxygen species (ROS) formation. Special attention is given to the development of SnO₂-based composites, such as coupling with metals, metal oxides, and carbonaceous materials, which enhance visible light response, reduce electron-hole recombination and improve degradation efficiency. Furthermore, the review addresses practical applications of SnO₂ photocatalysts in dye wastewater treatment, sensors, solar cells, antimicrobial activity and environmental remediation, while also outlining existing challenges and future prospects. By critically analysing the structure property performance relationships, this article aims to guide the design of next-generation SnO₂-based photocatalysts for sustainable environmental cleanup.