Unraveling Rigidified Superexchange Couplings in Organic Donor-Acceptor Polymers for Boosting the Photocatalytic Reduction of Nitrate

Regulating the spatial twist angle of flexible geometry is an effective strategy to enhance the spatial overlap in organic semiconductors and provide transfer channels for electron transfer. However, the internal migration rates of macromolecular polymers with flexible geometries and complex compositions are severely restricted, making them elusive and easily overlooked. Here, different configurations of donor-acceptor (D-A)-based perylene diimide (PDI) polymers have been elaborately designed and prepared. In fact, the high crystallinity and molecular polarity of coplanar semiconductors lead to a differentiated charge distribution and carrier transfer site, which opens the prelude for charge transfer and exciton dissociation. More importantly, the unique pi-conjugated D-A configuration not only provides a smooth carrier transfer channel for promoting intermolecular electron transfer rates but is also conducive to the adsorption, diffusion, and charge exchange and activation of nitric acid as well as reduces the hydrogenation energy barrier. Ultimately, the coplanar configuration of PDI-connected 3,3-diaminobenzidine polymers (D-PDI) exhibited efficient photocatalytic nitrate reduction activity without the use of a cocatalyst and sacrificial agent. Our work provides fresh insights into molecular structure regulation to develop efficient photocatalysts for solving environmental problems.