Advancing charge carriers separation and transformation by nitrogen self-doped hollow nanotubes g-C3N4 for enhancing photocatalytic degradation of organic pollutants

Abstract

The rapid recombination of photogenerated electrons and holes, low utilization of visible light and weak oxidation capacity significantly limit the photocatalytic activity for the degradation of organic pollutants. Doping is used as a conventional strategy for regulating the electronic structure of photocatalysts to obtain a wider light absorption, but also suffers from the problems of reduced charge mobility and oxidation capacity, which is not conducive to photocatalytic degradation of pollutants. To address this issue, a nitrogen self-doped hollow nanotubes g-C3N4 (N–PCN) was synthesized by synergistic self-doping and quantum confinement effects. The N–PCN exhibits excellent efficiency in photocatalytic degradation of TC compared to the pristine g-C3N4. The synthesized N–PCN has a more positive conduction band minimum and can generate more photogenerated electrons to reduce oxygen to superoxide radicals. In addition, experimental and theoretical evidence shows that N-self-doping not only suppresses the recombination of photogenerated charge carriers but also facilitates the adsorption of oxygen molecules. Consequently, more superoxide radicals and singlet oxygen are generated through oxygen activation process.