Triazine-Based Covalent Organic Framework for Photocatalytic Water Oxidation: The Role of Bipyridine Ligand and Cobalt Coordination

Covalent organic frameworks (COFs) are crystalline porous conjugated polymers that have been widely used for photocatalytic hydrogen evolution and CO2 reduction. However, only few COFs showed photocatalytic oxygen evolution, which is a more challenging half-reaction of photocatalytic water splitting. Here, we presented visible-light-driven photocatalytic water oxidation of a triazine-based COF (TAPT-Bpy-COF) coordinated with cobalt as cocatalysts. The highest oxygen evolution rate (OER) was achieved at 483 μmol g–1 h–1 (≥420 nm) with an efficient apparent quantum efficiency (AQE) of 7.6% (420 ± 20 nm). The highly photocatalytic oxygen evolution activity of TAPT-Bpy-COF could be attributed to its highly ordered structures, high surface area, good wettability as well as enhanced charge separation. This work demonstrates the potential of COFs for photocatalytic oxygen evolution half-reaction and overall water splitting.