Recent advances in the development of polyoxometalates and their composites for the degradation of toxic chemical dyes

Polyoxometalates (POMs) and their composites have emerged as promising candidates for degrading toxic chemical dyes in wastewater remediation. POMs, with their tunable structures and redox properties, exhibit high catalytic activity towards various organic pollutants, including dyes. The integration of POMs into composite materials creates a synergistic effect that enhances endurance and efficiency during dye degradation. POMs are classified based on metal composition and structure, highlighting their roles in dye removal processes. Categories include molybdenum-based, tungsten-based, vanadium-based, and mixed metal-based POMs, each with distinct properties affecting dye elimination efficacy. The application of POMs and their composites in degrading specific chemical dyes, including cationic, anionic, and azo dyes, is elaborately described. Various mechanisms for dye removal from aqueous media, such as photocatalysis, adsorption, Fenton-like reactions, and electrochemical processes, underscore the crucial role of POMs and their composites in toxic chemical dye degradation. The factors influencing dye-POM interactions, such as pH, temperature, POM composition, and dye structure, are analyzed to understand their impact on removal efficiency. The review discusses the influence of metal type, POM structure, and solution conditions on dye removal efficacy, providing insights into how specific metal-based POMs interact with different dye molecules. Challenges and future perspectives for implementing POM-based materials in dye wastewater treatment are outlined, emphasizing the need for further research to optimize performance and ensure practical feasibility in large-scale applications.