OH/Na co-functionalized carbon nitride: directional charge transfer and enhanced photocatalytic oxidation ability
The graphitic carbon nitride (g-C3N4, CN for short) is a compelling visible-light response photocatalyst. However, the photocatalytic efficiency is not efficient due to the random carriers transfer in planes and insufficient redox potential. Herein, we build oxygen functional groups modified sodium-doped carbon nitride (OH/Na co-functionalized carbon nitride) to promote charge carriers directed transfer for the acceleration of separation efficiency, and enhance redox potential for the efficient oxidation of NO in air. Specifically, the function of sodium atoms could control the directional transfer of random carriers from intralayer to surface-modified oxygen functional groups for the purpose of effectively reducing photogenerated electron-hole recombination. Meanwhile, the modification of oxygen-containing functional group could adjust the band structure of CN, thereby increasing the oxidation-reduction potential of NO in the photocatalyst. The transform pathways and reaction mechanism of photocatalytic NO oxidation on CN and OH/Na co-functionalized carbon nitride also have been explicated, by the ESR spectra and in situ DRIFTS spectra, and compared. This work provides a new method for simultaneously controlling the random transfer of carriers and adjusting the energy band structure of CN to optimize photocatalytic efficiency. It is also possible to extend this strategy to improve other 2D layered catalysts performance to photocatalytic oxidation.