Light-driven biohybrid systems for nitrogen removal: Insights into intimate coupling of photocatalysis with biodegradation systems and photocatalytic biohybrid systems

The increasing global nitrogen burden caused by intensive anthropogenic activities has underscored the need for efficient and sustainable nitrogen removal technologies. Light-driven biohybrid systems integrating photocatalysis and microbial metabolism have emerged as promising approaches for pollutant degradation and nitrogen transformation. This review systematically summarizes two representative strategies of light-driven biohybrid systems, intimate coupling of photocatalysis with biodegradation (ICPB) systems and photocatalytic/photosensitized biohybrid systems (PBS). The development trajectories, nitrogen removal mechanisms, and adaptability to target pollutants of both systems are systematically elucidated. While ICPB systems emphasize spatial separation and sequential synergy between photocatalysis and biofilm degradation, PBS rely on direct photogenerated electron transfer at the semiconductor-microbe interface. Differences in microbial requirements, light source utilization, and electron transfer mechanisms are discussed in detail. Moreover, critical factors affecting system performance, including photocatalyst properties, microbial community structure, carrier selection and operational conditions, are reviewed. Finally, current challenges and future outlook are proposed to provide theoretical support and practical guidance for the construction and engineering application of efficient light-driven biohybrid systems for nitrogen removal and pollution control. This review offers valuable insights into the design and application of photocatalysis-biodegradation coupling systems in the fields of environment and energy.