Verifying the Unique Charge Migration Pathway in Polymeric Homojunctions for Artificial Photosynthesis of Hydrogen Peroxide

Artificial photosynthesis for producing high-value hydrogen peroxide (H₂O₂) using carbon nitride-based systems holds immense potential. However, understanding the charge transfer dynamics in homojunction photocatalysts remains a significant challenge owing to the limitations of current characterization techniques. Here, a polymeric C₃N₅/C₃N₄ homojunction (CNHJ) is employed as a model system to probe interfacial electron transfer. Bimetallic cocatalysts serve as sensitive probes, enabling in situ tracking of the S-scheme electron transfer between C₃N₅ and C₃N₄ via X-ray photoelectron spectroscopy. Leveraging the unique advantages of this S-scheme, the CNHJ demonstrates substantially enhanced performance in the two-electron oxygen reduction reaction, achieving an impressive H₂O₂ production rate of 8.78 mmol g^-1 h^-1 under visible light irradiation. Furthermore, the system demonstrates robust performance in continuous-flow setups, under natural sunlight, and in photocatalytic disinfection tests, highlighting its practical potential. This approach offers new insights into dynamic electron transfer mechanisms and paves the way for advancing artificial photosynthesis technologies.