Na + /K + -Intercalation Crystalline Carbon Nitride with High Charge Transfer Efficiency For Synergistically Enhanced Photocatalytic H 2 O 2 Production

g-C3N4-based photocatalysts have attracted considerable research attention for their applicability in green H2O2 production. However, the photocatalytic activity of these catalysts is limited by their low light-absorption efficiency and high carrier recombination rate. This study developed a highly crystalline carbon nitride (CDCN-X) through thermal polymerization using eutectic salt, which promoted the incorporation of cyano groups, created electron-transport "bridges", and guided directional material growth into a nanorod morphology. Enhanced crystallinity effectively minimized internal defects within the material, thus notably suppressing the recombination of photogenerated electron-hole pairs. Cyano groups and Na+/K+ ions were introduced to modulate the electronic band structure of CDCN-X and establish an internal built-in electric field, thus achieving a broader light absorption range and efficient transport channels for photogenerated charge carriers. Additionally, the cyano groups served as active sites, enhancing the adsorption capacity for O2 and promoting the reaction progress. As a result of these modifications, CDCN-550 enabled rapid two-step single electron oxygen reduction, thereby promoting rapid H2O2 generation. Furthermore, a CDCN-550-catalyzed H2O2 yield of 36.69 mmol g-1 h-1 was achieved, representing a 17.39-fold increase compared to conventional carbon nitride (DCN). Overall, the proposed approach is viable for the rational design and modification of carbon nitride materials to achieve excellent photocatalytic performance.