Hydrazone-linked COFs have shown promising potential in photocatalysis, but still face problems of limited visible-light absorption and inefficient photocarrier separation/transportation. Herein, electron-rich and conjugated benzotrithiophene (BTT) is introduced into the aldehyde monomer to get two novel BTT-based hydrazone-linked COFs (BTT-Hz-1, −2). Systematical experiments and theoretical calculations show that comparing with the benzene aldehyde-based COFs (TFB-Hz-1, −2), conjugated structure of BTT broadens the visible-light absorption range and improves the transfer efficiency of the photocarriers; electron-rich structure of BTT constructs strong built-in electric field within the COFs, therefore promotes the separation of photocarriers. As a result, BTT-Hz-1 shows a recorded photocatalytic H₂ evolution rate for hydrazone-linked COFs of 17.27 mmol g^-1h⁻¹, 22 times than that of TFB-Hz-1, and also reveals noble metal-free CO₂ photoreduction property with CO evolution rate of 774.3 μmol g^-1h⁻¹. This work presents the importance of electronic structure modulation to the COF-based photocatalysis, and opens a new avenue to improve the photocatalysis performance of hydrazone-linked COFs.

腙连接的COF在光催化方面显示出广阔的潜力，但仍然面临可见光 吸收有限和光载流子分离/传输效率低下的问题。在此，将富电子的共轭苯并三噻吩（BTT）引入到醛单体中，得到两种新型的基于BTT的腙连接的COF（BTT-Hz-1，-2）。系统实验和理论计算表明，与苯醛基COF（TFB-Hz-1，-2）相比，BTT的共轭结构拓宽了可见光吸收范围，提高了光载流子的传输效率；BTT的富电子结构在COF内构建了强大的内建电场，从而促进了COF的 分离  光载体。结果，BTT-Hz-1记录的腙连接COF的光催化H ₂析出速率为17.27 mmol g ^-1 h ^-1，是TFB-Hz-1的22倍，并且还显示出不含贵金属CO ₂光还原性能，CO释放速率为774.3 μmol g ^-1 h ^-1。这项工作展示了电子结构调制对基于COF的光催化的重要性，并为提高腙连接的COF的光催化性能开辟了一条新途径。