Promoting energy transfer pathway in porphyrin-based sp2 carbon-conjugated covalent organic frameworks for selective photocatalytic oxidation of sulfide

The sp2 carbon-conjugated covalent organic frameworks (COFs) with fully π-conjugated lattice and high chemical stability are promising but challenging to achieve heterogeneous photocatalysts. Herein, we report the design and synthesis of a novel palladium porphyrin-based sp2 carbon-conjugated COF (PdPor-sp2c-COF) with an eclipsed AA stacking 2D structure. Interestingly, PdPor-sp2c-COF showed high crystallinity, good chemical stability, and a broad absorption of visible light. Moreover, compared to our previously reported metal-free Por-sp2c-COF, PdPor-sp2c-COF displayed an improved photocatalytic performance in the selective aerobic oxidation of sulfides under green light irradiation. The systematic mechanism studies testified that the enhanced photocatalytic performance can be ascribed to the promoted energy transfer pathway by PdPor-sp2c-COF during photocatalytic process. Our study clearly demonstrated that it is favorable to promote the energy transfer pathway in sp2 carbon-conjugated COFs to enhance the photocatalytic property by using metalloporphyrin-based molecular building blocks, which will inspire us to design and synthesize novel photocatalyst based on COFs for the selective aerobic oxidation.