Anchoring single Co sites on bipyridine-based covalent triazine framework for efficient photocatalytic oxygen evolution

The photocatalytic oxygen evolution reaction (OER) is a half-reaction of water splitting for oxygen evolution, faces the drawback of sluggish kinetics. Developing highly efficient photocatalysts for OER represents a significant challenge in the field of water splitting advancement. Herein we report the bipyridine-based covalent triazine framework (CTF-Bpy) with the periodic metal coordination sites and suitable band gap position for efficient photocatalytic oxygen evolution. Single Co sites are introduced into CTF-Bpy as cocatalyst through a facile immersion treatment. The obtained CTF-Bpy-Co exhibited remarkable photocatalytic oxygen evolution performance, achieving an initial rate of up to 3359 μmol g–1 h–1 within the first hour and an average rate of 1503 μmol g–1 h–1 over 5 h under visible light irradiation (λ ≥ 420 nm), which exceeds most of the reported porous organic polymers. Moreover, CTF-Bpy-Co can achieve continuous oxygen evolution for a duration of 40 h and the total oxygen production amount of up to 180 μmol. Charge density difference using density functional theory calculations confirm that the Co single site is the reaction site that drives the photooxidation of water to generate oxygen.