Promoting exciton dissociation in crystalline carbon nitride via cation-anion synergy for hydrogen peroxide photosynthesis

Enhancing the carrier separation efficiency and charge transport properties of polymeric carbon nitride (PCN) has been a major focus of research. Extensive interest has been directed toward its modification and functionalization. In this study, a molten-salt approach was employed to simultaneously introduce cationic (K + ) and anionic (–C≡N) species, enabling the one-step synthesis of highly crystalline PCN with significantly improved carrier separation and charge transport efficiencies. Comprehensive experimental characterization and theoretical calculations reveal that the coupling interaction between the cations and anions substantially increased the localized charge distribution, thereby facilitating exciton dissociation. Moreover, the incorporation of –C≡N and K + ion pairs enhanced the adsorption and activation of O 2 , driving the two-electron oxygen reduction reaction (2e – ORR) to produce H 2 O 2 , exhibiting a remarkable 46.6-fold increase over unmodified PCN. This work provided valuable insights into the critical role of cation-anion pairs in enhancing exciton dissociation, paving the cost-effective way for photocatalysts toward efficient solar energy conversion and high-value-added chemicals artificial photosynthesis.