Constructing Large-Area Oriented Covalent Organic Framework Based PN Heterostructure Films to Enhance Artificial Photosynthesis of H2O2.

Two-dimensional conjugated covalent organic framework (COF) films exhibit enormous application potential in the photosynthesis of hydrogen peroxide (H2O2), however, they suffer from various photogenerated electron-hole recombination. Herein, we first report a new strategy of in situ constructing oriented COF-based PN heterostructure film through single-layer MoS2 induced growth, significantly enhancing the photogenerated carrier separation efficiency, which promotes the photocatalytic H2O2 synthesis. Experimental results reveal that the as-made oriented TAPB-DMTA COF/MoS2 (TAPB: 1,3,5-tris(4-aminophenyl) benzene, DMTA: 2,5-Dimethoxyterephthalaldehyde) film exhibits a high photocatalytic H2O2 yield of 8154 µmol g-1 h-1, which is ∼2.5 times and ∼4 times higher than that of non-oriented TAPB-DMTA COF films and powder. The mechanism reveals that the oriented structure of the TAPB-DMTA COF can significantly promote the generation and the transmission of photogenerated electron-hole pairs along the skeleton and layer-by-layer stacking direction, thus enhancing the photocatalytic H2O2 performance. The new strategy of in situ constructing oriented COFs-based PN heterostructure film for enhancing the photosynthesis of H2O2 will open the door to rational design of molecular films towards high photogenerated carrier separation efficiency.