Effect of D/A Ratio on Photocatalytic Hydrogen Evolution Performance of Conjugated Polymer Photocatalysts

Abstract

Although excellent photocatalytic activity of donor–acceptor (D–A) polymers has been widely proved, different D/A ratios in the polymer skeleton affect their electronic properties and microstructure, which may limit their photocatalytic activity. To understand the relationship between the D/A ratio and photocatalytic activity, in this paper, a series of random conjugated polymers were synthesized by adjusting the molar ratio of D/A using pyrene as the electron D unit and dibenzothiophene sulfone as the electron A unit and applied to the study of photocatalytic hydrogen evolution from water reduction. When the molar ratio of D/A was 1:20, the PySO-2 polymer showed the highest photocatalytic hydrogen production activity of 23.3 mmol g–1 h–1, which was probably caused by the increase of the photo-induced carrier separation efficiency, indicating that the photocatalytic performance depended on the molar ratio of D/A in the skeleton. In addition, the hydrogen evolution rate (HER) of PySO-2 was nearly two times higher than that of PySO-6 under the same reaction conditions, suggesting that the photocatalytic performance relies on the molar ratio of D/A in the skeleton. All results indicate that adjusting the molar ratio of D/A in the polymer skeleton can influence the separation and migration efficiency of photogenerated charge carriers, which in turn accelerates the performance of photocatalytic hydrogen production.