Donor-acceptor porous conjugated polymers for photocatalytic hydrogen production: The importance of acceptor comonomer

Porous conjugated polymer (PCP) is a new kind of photocatalyst for photocatalytic hydrogen production (PHP). Here, we report the importance of the electronic properties of acceptor comonomer in determining the reactivity of 4,8-di(thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene (DBD)-based PCP photocatalyst for PHP application. It was found that the incorporation of nitrogen-containing ligand acceptor monomers into PCP network is an effective strategy to enhance the PHP activity. These moderately electron-deficient comonomers enhanced the dipole polarization effect. These PCPs exhibit appropriate solid-state morphology for charge transport. Powder X-ray diffraction (XRD) studies demonstrate that these PCP materials are semicrystalline materials. A strong correlation between the crystalline property and PHP activity is observed. The replacement of nitrogen-containing ligand acceptors with ligand-free strong acceptors is proved to be detrimental to the PHP process, indicating the proper choice in the electronic properties of monomer pair is important for achieving high photoactivity.