Direct observation of dynamic interfacial bonding and charge transfer in metal-free photocatalysts for efficient hydrogen evolution

Herein, we employed a simple approach for incorporating covalent triazine frameworks (CTF) with ultrathin black phosphorus (BP) nanosheets, resulting in one of the highest hydrogen evolution activities (17.1 mmol h−1 g−1) among all reported metal-free photocatalysts. More importantly, a detailed mechanistic study on dynamic charge transfer and interfacial bonding was conducted by an in-situ irradiation X-ray photoelectron spectroscopy (SI-XPS). The related results clearly reveal that the interfacial PC bonding between ultrathin BP and CTFs is crucial for promoting both photocatalytic activity and stability. More specifically, under light irradiation, the interfacial PC bonds were remarkably enhanced, which efficiently accelerate the photo-generated electron transfer from CTF to BP surfaces for hydrogen evolution reactions. Moreover, owing to the electron enrichments on BP for effectively restraining surface oxidation, the photocatalytic stability of BP/CTF has also been significantly improved. This work not only reported an effective way for fabricating highly efficient metal-free photocatalysts, but also provided the unique insights into the fundamental understanding of the intrinsic mechanisms during photocatalytic reactions.