Confirmatory Synthesis of Donor‐Acceptor Thiophene‐Based Covalent Organic Framework for Bifunctional Photocatalytic Water Splitting

Covalent organic frameworks (COFs) are highly efficient platforms for solar energy conversion, featuring tunable structures, exceptional light‐harvesting capabilities, large surface areas, and well‐defined porous architectures. These properties enable remarkable photocatalytic water splitting. While most COFs are used for hydrogen production, only a few can simultaneously produce both hydrogen and oxygen. We developed a covalent organic framework with a robust donor‐acceptor (D‐A) structure, TFTC‐TAPT‐COF, which exhibits dual functionality for both hydrogen and oxygen evolution reactions. Under visible light, TFTC‐TAPT‐COF achieved a hydrogen evolution rate of 16.5 mmol·g‐1·h‐1 using 3 wt% Pt as a cocatalyst and an oxygen evolution rate of 1.4 mmol·g‐1·h‐1 using 1 wt% Co as a cocatalyst. The favorable energy band structure, high crystallinity, and sufficient surface area of TFTC‐TAPT‐COF provide the necessary driving force and active sites for efficient photocatalytic water splitting. Compared to TFPB‐TAPT‐COF with a weaker D‐A structure, TFTC‐TAPT‐COF exhibits significantly enhanced light absorption and charge separation efficiencies. Density functional theory (DFT) calculations further confirm its enhanced electron‐hole separation and superior light‐harvesting capabilities. This work highlights the potential of COFs as photocatalysts for achieving overall water splitting.