Fluorenone-Based Covalent Triazine Frameworks/Twinned Zn0.5Cd0.5S S-scheme Heterojunction for Efficient Photocatalytic H2 Evolution

Photocatalytic hydrogen evolution reaction (HER) is a very promising and sustainable technology, yet precisely exploring effective HER photocatalysts remains a critical challenge due to the rapid charge recombination. In this work, a brand-new S-scheme heterojunction is successfully designed and constructed by in situ growth of twinned Zn0.5Cd0.5S Solid Solution (CZS) on a novel fluorenone-based covalent triazine framework (FOCTF). The S-scheme heterojunctions is identified via in situ irradiation XPS, and electron spin resonance, which can greatly improve the photocatalytic HER rate and stability. Under illumination, the highest photocatalytic HER rate of well-designed CZS-FOCTF is 247.62 mmolg(-1)h(-1), 3.83 times as high as that of pure CZS. Experimental and theoretical investigations corroborate that the new FOCTF has a well-matched staggered band alignment and work function difference with CZS. The as-fabricated CZS-FOCTF S-scheme heterojunction can establish a favorable internal electric field, which accelerates the directional S-scheme charge migration, thereby enhancing the separation and utilization efficiency of carriers. This finding precisely achieves the spatially oriented powerful electron transport and separation at the interfaces of inorganic-organic hybrid heterojunctions. It is thus desirable that this work can furnish an alternative strategy to rationally design new CZS-based S-scheme heterojunction photocatalysts based on novel organic oxidation semiconductors for diversified photocatalytic reactions.