Alkali and donor–acceptor bridged three-dimensional interpenetrating polymer networks boost photocatalytic performance by efficient electron delocalization and charge transfer

[Display omitted] •A 3D polymer network interpenetrated with donor–acceptor and alkali linkages was assembled.•Multiscale pore structure improved light harvesting and exposed more active edges.•Intense charge delocalization of linkages narrowed band gaps and accelerate charge transfer.•The synergy endows polymer photocatalyst with remarkable enhancement in H2 evolution and Cr(VI) reduction. In this work, the synthesis of a three-dimensional interpenetrating porous polymer network (K/Na-DA-PPN) was accomplished via the intramolecular linkage of cyano/hydroxyl donor–acceptor motifs and interlayer linkage of alkalis. In addition to the improved light harvesting and more exposed active edges arising from the multiscale pore structure, narrowed band gaps and fast charge transfer induced by intense charge delocalization were observed after introducing alkalis and DA motifs in the K/Na-DA-PPN polymer, as confirmed by experimental and theoretical studies. The synergy endows the obtained polymer photocatalyst with remarkable enhancement in H2 evolution and Cr(VI) reduction performance and an optimized reaction rate that is 6 times and 4.3 times that of pristine CTF. The molecular design of specific linkages combined with structural control of polymer networks provides a novel strategy to synthesize polymer-based organic photocatalysts.