Molecular-level regulation strategies for charge separation in conjugated polymer/polymeric carbon nitride heterojunction enabling efficient uranium photoreduction

Abstract

Construction of metal free conjugated polymer/polymeric carbon nitride heterojunction has been closely monitored as alternatives to traditional inorganic heterojunction photocatalysis, due to their molecular-level tunable electronic structure. Nevertheless, the realization of efficient photocatalytic is severely hindered by insufficient separation of photogenerated electrons and holes. To address the challenge, we report a general strategy for inserting thiophene units into electron acceptors to form novel donor-acceptor conjugated polymers/polymeric carbon nitride heterojunction (named YSS-2/CN). Combining experiments and theory calculations, it can be concluded that YSS-2/CN exhibits strong charge spatial separation, which is crucial for the photocatalytic process. As expected, the YSS-2/CN shows better photocatalytic reduction activity towards uranium (k = 0.043 min⁻¹), which is 1.16 and 2.87 times higher than those of YSS-1/CN and bulk carbon nitride (CN). This rational molecular design strategy provides a good platform for the development of efficient polymeric heterojunction photocatalysts for the removal and extraction of uranium.