Terminal Group Effect of Conjugated Microporous Polymers for Photocatalytic Water-Splitting Hydrogen Evolution

Conjugated microporous polymers (CMPs) have attracted more and more attention as active materials for photocatalytic water-splitting hydrogen evolution, however, the correlation between terminal group and hydrogen evolution performance of CMPs is rarely studied. Herein, three triazine-based CMPs (Ta-CMPs) with the same polymer backbone and different terminal groups (Ta-CMP, Ta-CMP-N, and Ta-CMP-CN) are synthesized via Suzuki-Miyaura coupling reaction using different end-capping agents. Although the Ta-CMPs show similar porous structure and comparable band gaps, Ta-CMP-CN with electron-withdrawing terminal group exhibits the highest hydrogen evolution rate (HER) of 698 mu mol g(-1) h(-1) under visible light, while Ta-CMP-N with electron-donating terminal group exhibits the lowest HER of 99 mu mol g(-1) h(-1). It is found that the addition of electron-withdrawing terminal group can facilitate photoinduced charge separation, thus improving photocatalytic HER performance of the CMPs.