Bridges Engineering Manipulated Exciton Dissociation and Charge Separation in Small Acceptors of Pdi Supramolecular for Boosting Photocatalytic Nitrogen Fixation

Constructing acceptor–donor units (D/A) of polymer is an efficient method for promoting carrier separation to optimize photoreactivity. However, the carriers across the D/A interface of micromolecule was relatively hindered by the Coulomb potential. In this work, the polarity-bridged acceptor–donor units of PDI composite (BOPDI) has been constructed using a simple strategy. The improved BOPDI achieves excellent photocatalytic nitrogen fixation rate (74.0 μmol g-1 h-1) as well as stability without using any co-catalyst and sacrificial agent, which is 11 times that of the original PDI group. DFT calculations and experimental results show that the polarity-bridges reasonably adjusts the HOMO and LOMO bands and absorption characteristics, ensuring the BOPDI absorbed near-infrared light and activated N2 molecules. In addition, the polarity bridged units strengthens the construction of the built-in electric field for overcoming the Coulomb potential, resulting in a higher carrier separation and exciton dissociation efficiency. This work not only provides an tactics for enhancing the electronic transmission of D/A units, but also expanding the application research of PDI composite materials in the photocatalytic reduction of nitrogen