Polarized electric field-mediated graphitic carbon nitride-based S-scheme heterostructure for efficient photocatalytic removal of bisphenol A

Abstract

Tuning interface charge transfer is considered as a feasible way to promote electron migration and separation in heterojunction system, but the role of in-plane electron behavior in single phase has received little attention. Here, a carboxyl functionalized graphitic carbon nitride (CCN) coupled PbBiO2Br (PBOB) S-scheme heterostructure is elaborately designed for investigation. Compared with pristine CN/PBOB, although the existence of carboxyl group weakens the built-in electric field strength of CCN/PBOB (ΔΦ = 0.44 eV), the formed polarized electric field (µ = 3.18 Debye) is conducive to the pre-separation of photogenerated electrons and holes in CCN, thereby improving interface charge transfer. In addition, the introduced carboxyl group can also serve as an O2 adsorption site to enhance its activation, and generate reactive oxygen species (ROS) through a two-step single-electron O2 reduction route. Thus, the optimized CCN/PBOB exhibits excellent photocatalytic ROS generation ability, which can remove 88.7 % of bisphenol A and significantly reduce the acute toxicity of the formed intermediates. This work provides a new perspective for the development of advanced heterojunction photocatalyst by regulating in-plane/interface charge dynamics, and helps to fully understand the pollutant detoxification/degradation process initiated by molecular oxygen activation.