Triptycene-based discontinuously-conjugated covalent organic polymer photocatalysts for visible-light-driven hydrogen evolution from water

• Published in: Applied catalysis. B, Environmental Environmental, 2021-05, Vol.285, p.119802, Article 119802
• Main Authors: Elewa, Ahmed M., Elsayed, Mohamed Hammad, EL-Mahdy, Ahmed F.M., Chang, Chih-Li, Ting, Li-Yu, Lin, Wei-Cheng, Lu, Chia-Yeh, Chou, Ho-Hsiu
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Chemical fuels; Conjugation; Covalent organic polymers (COPs); Electron microscopy; Evolution; Hydrogen; Hydrogen evolution; Microscopy; Photocatalysis; Photocatalysts; Polymers; Scanning electron microscopy; Solar energy; Solar energy conversion; System effectiveness; Transmission electron microscopy; Triptycene; Visible-light
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119802

A series of new triptycene-based discontinuously conjugated covalent organic polymer photocatalysts is developed for visible-light-driven hydrogen evolution. Although triptycene interrupts the continuous conjugation length, the absorption of the short-conjugated segment is sufficient to harvest the visible light irradiation. DPBT-TP with rod-like shape affords a high hydrogen evolution rate of 17,806 μmol g−1 h−1. [Display omitted] •A series of Triptycene-Based Discontinuously-Conjugated Polymer is constructed for photocatalytic H2 evolution.•Based on our design, the absorption of the short-conjugated is sufficient to harvest the visible light to produce hydrogen.•DPBT-TP COP affords an excellent HER of 17,806 μmol g−1 h−1, which is a significant enhancement in comparison to others.•Interestingly, by tuning the short-conjugated linker, the COP photocatalysts exhibited various shape. Effective photocatalytic systems that are capable of converting solar energy into chemical fuels have recently attracted significant attention. Covalent organic polymers (COPs) have been explored as promising photocatalysts for visible-light-driven hydrogen evolution from water. Herein, a series of triptycene (TP)-based discontinuously conjugated COP photocatalysts are described for the first-time using TP with monothiophene (MT), trithiophene (TT), dithiophene benzothiadiazole (DTBT), and diphenyl benzothiadiazole (DPBT), denoted as MT-TP, TT-TP, DTBT-TP, and DPBT-TP, respectively. Difference photophysical, morphological, and photocatalytic properties can be tuned by introducing different types of linkers of the TP-based COPs. DPBT-TP shows a significant enhancement of the hydrogen evolution rate (HER) in comparison to those using other polymer photocatalysts at identical conditions. The transmission electron microscopy/scanning electron microscopy data show that the tube-like polymer photocatalysts afford higher HERs than those observed with the particle-like polymer photocatalysts. This report describes the first demonstration that the polymer photocatalysts constructed by the disconuiously conjugated system (conjugation length: less than 5 aromatic rings) is sufficient for an efficient visible-light-driven hydrogen evolution. It provides an alternative material design strategy for polymer photocatalysts to achieve efficient visible light hydrogen evolution.