Understanding the mechanism of interfacial interaction enhancing photodegradation rate of pollutants at molecular level: Intermolecular π-π interactions favor electrons delivery.

Uncovering the interaction between photocatalyst and reaction substrate as well as subsequent electron transfer process is critical to achieve high-performance photodegradation of pollutants. Herein, based on the reduced density gradient (RDG) method, we visualize the simulation of the π-π interactions between photocatalyst (g-C 3 N 4) and pollutant molecule (flumequine, FLU). Results revealed that π-π interactions between g-C 3 N 4 and FLU favor electrons delivery, resulting in enhanced charge separation efficiency and direct hole oxidation of FLU. Moreover, it is found that the charge transfer rate is determined by the valence band (VB) level of g-C 3 N 4 and E HOMO of FLU, of which the deeper VB position of g-C 3 N 4 favors faster charge transfer, leading to further enhancement in photocatalytic degradation rate of FLU. Additionally, the possible degradation pathways of FLU were proposed by theoretical calculation and the determined intermediates. Our work afforded a new insight into pollutants degradation and the rational design of highly efficient photocatalysts. [Display omitted] • π-π interactions between g-C 3 N 4 and flumequine were established based on the reduced density gradient (RDG) method. • Interface relationship and electrons transfer mode were investigated at the molecular level experimentally and theoretically. • Intermolecular π-π interactions formed channels for electron delivery which induced to enhanced FLU degradation efficiency. • A positive correlation between the rate constant and the difference value of E VB (g-C 3 N 4) and E HOMO (FLU vs. NHE) was found. • The possible degradation pathways of pollutants were proposed by theoretical calculation and the determined intermediates. [ABSTRACT FROM AUTHOR]