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

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. The modification of thiophene and PAHs enhanced the absorption of the linear conjugated polymer in the visible region of 400–650 nm and accelerated the separation and transfer of internal charge. [Display omitted] • The prepared conjugated polymer exhibits strong absorption in the visible light range of 400∼>650 nm. • A high rate of photocatalytic H 2 evolution of 969.2 μmol/h was achieved with 30 mg of catalyst. • The polymer exhibits high quantum yields at wavelengths of 550 and 700 nm, with values of 8.04% and 0.95%, respectively. • The introduction of polycyclic aromatic hydrocarbons enhance photo-induced charge separation efficiency. • Exploring the Impact of Polymers on Hydrogen Production Efficiency from the Perspective of Electronic Density. [ABSTRACT FROM AUTHOR]