Boosted hydrogen evolution in conjugated polymer photocatalyst by noncovalent conformation-locked architecture

Abstract

A synergetic effect of noncovalent conformational locks (NCLs) and molecular framework engineering on the performance of polymeric photocatalysts is comprehensively investigated by tuning fluorination as well as framework structure with linear or planar backbone of conjugated polymers on the basis of the 2,2′-bithiophene and pyrene building blocks. Both fluorine-induced NCLs and molecular framework structure have beneficial influence on the electronic structure, photon absorption, nanomorphology and porosity, and charge migration/separation of conjugated polymers. As a result, the noncovalent conformation-locked conjugated polymer Py-2F2T achieves a significant high hydrogen evolution rate of 404.8 mmol h−1 under the conditions of being visible-light-driven and cocatalyst-free, which is 2.5- and 202.4-fold as those of the planar counterpart without NCLs and the linear counterpart with NCLs, respectively. Remarkably, Py-2F2T could show excellent apparent quantum yields of over 25.0 % at 450–600 nm irradiation with the highest value of 39.0 % at 575 nm. Overall, this work demonstrates the significance of the synergy of NCLs and molecular framework engineering for enhancing the photocatalytic activity, and the strategy of “noncovalent conformation-locked architecture” as a novel approach to the rational structure design of high-efficiency polymeric photocatalysts for visible-light-driven hydrogen evolution through water splitting.