Abstract: The activity of photocatalysts can be significantly regulated by designing micro-scale interfacial heterojunctions. The present study demonstrates the skillful construction of a graphdiyne/Sr₂Co₂O₅ S-scheme heterojunction, exhibiting exceptional stability, excellent proton adsorption, and remarkable photocatalytic activity. On the basis of in-situ XPS and calculation of work function, it is proved that the electron migration path between the interface of graphdiyne and Sr₂Co₂O₅ conforms to the S-scheme heterojunction mechanism. The recombination rate of photogenerated carriers is significantly reduced by virtue of the synergistic effect of the internal electric field and band edge bending while preserving the inherent redox ability of the materials. The strong coupling between layered graphdiyne and hierarchical flower-like Sr₂Co₂O₅ effectively enhances the specific surface area of graphdiyne/Sr₂Co₂O₅ heterojunction, thereby facilitating H₂O pre-adsorption. Combined with experiments and DFT calculations, it was found that both graphdiyne and Sr₂Co₂O₅ have a direct band gap, which makes their electronic transitions without the assistance of phonons, thus improving the efficiency of solar energy conversion. This study offers insights into the potential application of graphdiyne and metal oxides in the field of photocatalytic hydrogen evolution.

Key words: Hydrogen evolution, Graphdiyne, In-situ XPS, S-scheme heterojunction, DFT