Cluster #2 represents the application and performance of POM-based photocatalyst, and "degradation" is the most frequent terminology. Humans emit many pollutants in industrial production, especially dyes in wastewater. Currently, researchers are searching for efficient and stable photocatalysts that can be activated by visible light. In addition, the energy crisis has also promoted the search for new clean fuels, and HER has also attracted attention. POM-based materials are potential materials to solve the above problems due to their excellent photocatalytic performance in homogeneous or heterogeneous systems. However, some defects prevent POM-based materials from becoming efficient photocatalysts. Firstly, most polyanions are unstable in water and polar solvents. Secondly, they have room for improvement in photocatalytic performance under visible light or sunlight irradiation.