Fluorination-mediated polarization engineering in block copolymers for enhanced photocatalytic hydrogen evolution.

Abstract

Porous polymers have emerged as promising candidates for photocatalytic hydrogen evolution, but their structural rigidity and crosslinking pose significant challenges, often leading to charge recombination and inadequate water/polymer interfaces. This study introduces novel block copolymers (BCPs) comprising a rigid pyrene core and various fluorinated benzene structures coupled with flexible diethyl ether-based hydrophilic units. By computationally predicting monomer structures and dipoles, the relationship between structure and function in these BCPs is examined, particularly focusing on local charge delocalization. Four fluorinated block copolymers (F-BCPs), sharing identical π-conjugated skeletons but differing in the positions and quantities of fluorine atoms on the benzene rings, are explored. Experimental and theoretical analyses reveal that fine-tuning fluorination induces local charge polarization and delocalization. Notably, Py-DE-2F, with fluorination at two ortho positions on benzene, exhibits a remarkable hydrogen evolution rate of 77.68 μmol/h under visible light (λ > 420 nm) without any co-catalyst, surpassing other F-BCPs by an order of magnitude. These results underscore the potential of utilizing fluorination-mediated polarization engineering for developing advanced metal-free polymer photocatalysts.