Understanding charge transfer dynamics and carrier separation pathway is challenging due to the lack of appropriate characterization strategies. In this work, a crystalline triazine/heptazine carbon nitride homojunction is selected as a model system to demonstrate the interfacial electron-transfer mechanism. Surface bimetallic cocatalysts are used as sensitive probes during in situ photoemission for tracing the S-scheme transfer of interfacial photogenerated electrons from triazine phase to the heptazine phase. Variation of the sample surface potential under light on/off confirms dynamic S-scheme charge transfer. Further theoretical calculations demonstrate an interesting reversal of interfacial electron-transfer path under light/dark conditions, which also supports the experimental evidence of S-scheme transport. Benefiting from the unique merit of S-scheme electron transfer, homojunction shows significantly enhanced activity for CO₂ photoreduction. Our work thus provides a strategy to probe dynamic electron transfer mechanisms and to design delicate material structures towards efficient CO₂ photoreduction.

由于缺乏适当的表征策略，了解电荷转移动力学和载流子分离途径具有挑战性。在这项工作中，选择结晶三嗪/七嗪氮化碳同质结作为模型系统来演示界面电子转移机制。表面双金属助催化剂在原位光发射过程中用作敏感探针，用于追踪界面光生电子从三嗪相到七嗪相的 S 型转移。光开/关下样品表面电位的变化证实了动态 S 型电荷转移。进一步的理论计算证明了光/暗条件下界面电子转移路径的有趣逆转，这也支持了S型传输的实验证据。₂光还原。因此，我们的工作提供了一种探索动态电子转移机制并设计精细材料结构以实现高效CO ₂光还原的策略。