Graphdiyne Nanosheets Integrated with Ni6MnO8 via In Situ Calcination: A Robust S-Scheme Heterojunction for Enhanced Eosin Y-Sensitized Photocatalytic Hydrogen Production

As a 2D semiconductor material, graphdiyne (GDY) is a promising photocatalyst with excellent carrier mobility, uniform pores, ideal light absorption, and appropriate bandgap structure. Herein, GDY nanosheets are prepared by mechanical ball milling and subsequently tightly bonded to Ni₆MnO₈ by the in situ calcination method. The constructed Ni₆MnO₈/GDY S-scheme heterojunction exhibits excellent photocatalytic performance. Under visible light, with eosin Y as the sensitizer, the hydrogen evolution of the optimized component reaches 1719.2 μmol (g h)⁻¹, representing 3.6 and 9.6 times enhancement in comparison with that of Ni₆MnO₈ and GDY, respectively. The in situ calcination method is thought to play a major role in improving the efficiency of hydrogen evolution, which can enhance the interactions between the materials without significantly reducing the specific surface area of the materials. The presence of an internal electric field in the composite catalyst facilitates the separation and migration of photogenerated carriers. Furthermore, an S-scheme heterojunction charge transfer model with Ni₆MnO₈ as the active site for hydrogen precipitation is rationally constructed by in situ X-ray photoelectron spectroscopy, thereby revealing the migration path of photogenerated carriers. The results provide a new strategy for the construction of GDY-based photocatalytic composite catalysts with exceptional potential for hydrogen generation.