In Situ XPS Proved Efficient Charge Transfer of S-Scheme Heterjunction Based on Graphdiyne (g-C_nH_2n-2) Nanosheets Coupling with Semi-Crystalline NiCo₂S₄ for Efficient Photocatalytic H₂ Evolution

The excessive utilization of fossil fuels has resulted in an energy crisis. The implementation of a heterojunction for photocatalytic hydrogen evolution represents a promising solution to the current energy predicament. In this work, a 0D/2D S-scheme graphdiyne/NiCo2S4 (GDY/NiCo2S4) heterojunction is constructed by semi-crystalline NiCo2S4 nanoparticles (NPs) immobilized on the surface of GDY nanosheets through hydrothermal method. Atomic force microscopy (AFM) demonstrated the thickness of GDY nanosheets is 2.8 nm. The unique 2D laminar structure and porous structure of GDY ensures a tight bond with NiCo2S4 NPs. The maximum rate of photocatalytic hydrogen production is 6682.6 mu mol h(-1) g(-1) over 15% GDY/NiCo2S4, which is much higher than GDY and NiCo2S4. The outstanding photocatalytic hydrogen production performance can be attributed to the S-scheme GDY/NiCo2S4 heterostructure. The fluorescence results demonstrated that the incorporation of GDY significantly enhanced the efficiency of photoelectron-hole transfer and prolonged the electron lifetime. The S-scheme photogenerated charge transfer mechanism is verified through in situ irradiated X-ray photoelectron spectroscopy. The present study introduces innovative concepts for the design of an S-scheme heterojunction based on graphdiyne, aiming to enhance photocatalytic hydrogen production.