Rational Design of Conjugated Microporous Polymer Photocatalysts with Definite D-π-A Structures for Ultrahigh Photocatalytic Hydrogen Evolution Activity under Natural Sunlight

Organic polymers with conjugated architectures have been widely exploited as photocatalyst materials for hydrogen generation. However, it is still an enormous challenge to develop photocatalysts with high hydrogen generation activity under natural sunlight, which is pretty significant for practical applications. Herein, two conjugated microporous polymer photocatalysts with definite D-K-A structures are designed and prepared using dibenzo[g,p]chrysene or pyrene with planar conjugated architecture as electron donors, thiophene as a K-spacer, and dibenzo[b,d]thiophene-S,S-dioxide as an electron acceptor. Benefiting from the efficient separation of light-generated electrons/ holes due to the definite D-K-A structure and the broad light absorption range, the bare polymer Py-TP-BTDO could deliver a high photocatalytic hydrogen evolution rate (HER) of 115.03 mmol h-1 g-1 upon exposure to visible light (A > 420 nm). Impressively, the outdoor photocatalytic experiment reveals that abundant and continuous hydrogen bubbles could be produced fast and visually observed under natural sunlight by the Py-TP-BTDO polymer film with a large active area of 120 cm2. A water-drainage experiment further demonstrates that 1224 mL of hydrogen gas could be produced by 25 mg of a polymer photocatalyst with 3 wt % Pt cocatalyst under natural sunlight in 7 h, corresponding to a high HER of 312.24 mmol h-1 g-1, which represents the state of the art of organic photocatalyst materials to date. The high photocatalytic activity under natural sunlight suggests the potential of the developed PyTP-BTDO polymer photocatalyst in the practical applications for photocatalytic hydrogen production.