Triazine Ring-Enhanced Transient-State Self-Bipolarized Organic Frameworks for Natural Sunlight-Driven H2O2 Photosynthesis

Organic photocatalysts offer exciting opportunities for the conversion of solar energy to storable chemical products. Their intricate spatial architecture, tailored with precision, affords a sophisticated level of control over the light absorption characteristics and the efficacious transport of charge carriers. Nonetheless, the state-of-the-art advancements in catalytic performance have predominantly stemmed from the strategic disruption and subsequent reconfiguration of the pre-existing conjugated matrix structures. In this work, we develop a molecular cocatalyst strategy based on our recently reported transient-state self-bipolarized frameworks to improve photocatalytic performance. It was demonstrated that introducing a triazine ring through covalent bonding or mechanic mixing could significantly enhance the performance of photocatalysts without disturbing the original frameworks. Under natural sunlight irradiation and using only water and air as raw materials, the generation rate of H2O2 can be increased by approximately 4.3 times. Comprehensive experimental characterizations, including surface photovoltage and in situ electron paramagnetic resonance, along with theoretical calculations demonstrated the cocatalytic nature of triazine rings. These rings effectively delocalize photoexcited electrons, promoting the reduction of adsorbed O2 and enhancing the production of H2O2. Notably, the strategic incorporation of a triazine ring within the catalyst matrix while leaving the underlying framework intact underscores the potential for this approach to be extrapolated to a broader spectrum of organic photocatalysts. This innovative tactic not only paves the way for enhanced catalytic performance but also exemplifies the versatility and adaptability of molecular design in the field of catalysis.