Carbon Species Doping Overcomes the Limitation of Graphitic Carbon Nitride Toward Frontier Photocatalysis: Precise Division, Synergistic Strategy and Improvement Mechanism

ABSTRACT Photocatalytic technology, as a representative example of chemical reactions driven by solar energy, paves a transformative path toward a sustainable energy future. However, graphitic carbon nitride (g‐C 3 N 4 , CN), a highly promising metal‐free photocatalyst, currently faces practical limitations due to inherent deficiencies in light harvesting, charge transfer, and surface reactivity. Doping modification with carbon species has been demonstrated as an effective strategy to overcome these bottlenecks. This review systematically organizes and precisely classifies carbon species doping strategies into three categories: carbon atom substitution, carbon ring embedding, and external carbon species. Building upon this foundation, this review highlights the synergistic strategies combining carbon species with other modification techniques, such as heteroatom doping, defect engineering, morphology regulation, and heterostructure construction, which elucidate the advantages in overcoming the limitations of single‐mode carbon doping and enhancing photocatalytic performance. From an application perspective, we further discuss the critical improvements brought about by carbon‐species doping in light absorption, charge transfer, and surface reaction kinetics. Finally, the challenges and future directions for precisely controlling carbon species doping are outlined, which will facilitate the large‐scale implementation of g‐C 3 N 4 ‐catalyzed energy conversion processes and promote revolutionary and diversified advancements in solar energy utilization.