KCl-mediated dual electronic channels in layered g-C3N4 for enhanced visible light photocatalytic NO removal

Abstract

Limited by relatively fast charge carrier recombination, the performance of g-C₃N₄ photocatalysts is still far below what is expected. Herein, we tackle this challenge by introducing K and Cl ions into the interlayer of graphitic carbon nitride (KCl-doped g-C₃N₄). It is found that K and Cl ions coexisting in g-C₃N₄ could function as a dual channel for electron and hole transfer, respectively. As-prepared KCl-doped g-C₃N₄ shows a narrow bandgap, positive-shifted valence band edge and lower barriers for charge transfer between layers. Under visible light irradiation, the electrons created in the g-C₃N₄ layer are transferred by K ions, while the holes are transferred via Cl ions to induce photocatalysis. As expected, the enhanced visible light absorption, strong oxidization ability of the valence band holes and the prolonged lifetime of the charge carriers benefiting from the dual electronic channel endow KCl-doped g-C₃N₄ with a superior photocatalytic performance for NO_x removal, exceeding the performances of both bare g-C₃N₄ and K doped g-C₃N₄. An in situ DRIFTS investigation reveals the reaction mechanism of the photocatalytic NO oxidation. The perspective of the dual channel for charge transfer could present a new design concept to effectively steer the efficiency of photocatalysts.