Main/side chain asymmetric molecular design enhances charge transfer of two-dimensional conjugated polymer/g-C3N4 heterojunctions for high-efficiency photocatalytic sterilization and degradation

Abstract

Heterojunctions based on conjugated polymers (PHJs) are of promise as photocatalysts. Here, we fabricate the two-dimensional benzodithiophene (BDT) and thieno[2,3-f]benzofuran (TBF) based conjugated polymers/g-C3N4 PHJs creatively using the symmetry-breaking strategy. PD1 and PD3 with the asymmetric backbone TBF have better crystallinity. Moreover, PD3 utilizing fluorinated benzotriazole as the electron acceptor unit possesses more compact π − π stacking and higher charge mobility. The conjugated polymer PD5 with asymmetric side chains in the donor unit BDT guarantees more efficient charge transfer in the corresponding PD5/g-C3N4 PHJ while maintaining comparable light utilization rate. Consequently, PD5/g-C3N4 shows the champion performance with photocatalytic sterilization rates reaching 99.1% and 97.3% for S. aureus and E. coli. Notably, the reaction rate constant for Rhodamine B degradation of PD5/g-C3N4 is 8 times that of g-C3N4, a record high among conjugated polymers/g-C3N4. This study aims to reveal the structure − property correlation of asymmetric conjugated polymers/g-C3N4 for potential photocatalysis applications.