Conjugated porous polymers regulated by thiophene and polycyclic aromatic hydrocarbons for photocatalytic water splitting toward hydrogen production

Abstract

Rational design of organic semiconductors with wide visible light absorption and quick charge separation is of great significance for photocatalytic hydrogen production form water. In this work, the chemical structure of a linear conjugated polymer composed of ethynyl-linked benzene (B) and 2,1,3-benzothiadiazole (BT) is regulated by thiophene (TP) and polycyclic aromatic hydrocarbons [naphthalene (N) and anthracene (A)], and series of polymers including B-BT-TP-x, N-BT-TP-x and A-BT-TP-x (x = 0.2, 0.4, 0.6, 0.8) are synthesized. After thiophene and polycyclic aromatic hydrocarbon regulation, the polymers exhibit strong absorption in the whole visible light region of 400->650 nm and quick internal charge separation and transfer. Visible-light-driven photocatalytic hydrogen production rates of the synthesized polymers follow the order of B-BT (170.0 μmol/h) < B-BT-TP-0.6 (735.3 μmol/h) < N-BT-TP-0.4 (841.5 μmol/h) < A-BT-TP-0.6 (969.2 μmol/h) using 30 mg catalyst with 1.0 wt% Pt as cocatalyst. In addition, high apparent quantum yield (AQY) values of 8.04%, 5.58% and 0.95% under 550 nm, 650 nm and 700 nm monochromatic lights are obtained using A-BT-TP-0.6 catalyst. The present work provides new insights into design of advanced organic semiconductors for highly efficient photocatalytic solar energy conversion.