Thiazolo[5,4-d]thiazole-Based Donor-Acceptor Covalent Organic Framework
for Sunlight-Driven Hydrogen Evolution

Wenqian Li,# Xiaofeng Huang,# Tengwu Zeng, Yahu A. Liu, Weibo Hu, Hui Yang,* Yue-Biao Zhang,* and Ke Wen,*
Angew. Chem. Int. Ed. 2020, DOI: 10.1002/anie.202014408. (VIP paper, Highlighted as Front Cover)
2D covalent organic frameworks (COFs) could have well‐defined arrangements of photo‐ and electro‐active units that serve as electron or hole transport channels for solar energy harvesting and conversion, but their insufficient charge transfer and rapid charge recombination impede the sunlight‐driven photocatalytic performance. We report a new donor–acceptor (D–A) system, PyTz‐COF that was constructed from the electron‐rich pyrene (Py) and electron‐deficient thiazolo[5,4‐d]thiazole (Tz). With its bicontinuous heterojunction, PyTz‐COF demonstrated exceptional optoelectronic properties, photocatalytic ability in superoxide anion radical‐mediated coupling of (arylmethyl)amines and photoelectrochemical activity in sunlight‐driven hydrogen evolution. Remarkably, PyTz‐COF exhibited a photocurrent up to 100 μA cm−2 at 0.2 V vs. RHE and could reach a hydrogen evolution rate of 2072.4 μmol g−1 h−1. This work is paving the way for reticular design of highly efficient and highly active D–A systems for solar energy harvesting and conversion.