Abstract: Rare earth/g-C₃N₄-based composites hold significant promise for advancing the field of photocatalysis. The incorporation of rare earth elements effectively modulates the band structure of g-C₃N₄, thereby enhancing light absorption and promoting the separation and transport of photogenerated charge carriers, ultimately improving overall photocatalytic performance. However, their widespread application remains limited due to challenges such as high costs and insufficient long-term stability. Future research should focus on optimizing material design and fabrication processes to achieve efficient and stable photocatalytic activity. This review summarizes current strategies for improving rare earth/g-C₃N₄-based composite photocatalysts, particularly in enhancing charge separation efficiency, extending the light absorption range, and increasing both stability and catalytic activity. It also provides a comprehensive overview of advanced characterization techniques, including in-situ methods, theoretical modeling, and optimization approaches. In addition, emerging applications such as photocatalytic hydrogen evolution, CO₂ reduction, pollutant degradation, heavy metal remediation, and microbial inactivation are systematically discussed. Finally, future perspectives and strategies for improving the performance of rare earth/g-C₃N₄-based composite photocatalysts are proposed to guide subsequent material design. These insights aim to inform the rational design, fabrication, and modification of high-performance carbon-based photocatalysts, offering a theoretical foundation for scalable and controllable applications in this domain.

Key words: g-C₃N₄, Rare earth, Photocatalysis, In-situ characterization, Theoretical simulations