Heterogeneous structural defects to prompt charge shuttle in g-C3N4 plane for boosting visible-light photocatalytic activity

Structural defect engineering toward g-C3N4 plane usually has great benefit on modulating electron structure and photocatalytic performance. Here, we report a porous g-C3N4 material with heterogeneous structural defects, oxygen atom replacing edge nitrogen and cyano group, obtained via a facile treatment method. The reconstructed material shows narrowing band gap, high light absorption and fast charge separation. Theoretical calculation discloses that the doped oxygen atom and the nearby atoms accept electrons as reduction site to produce hydrogen, while the undoped fraction and cyano group take the duty to oxidize water. The delocalization of reactive sites drives charge shuttle on the plane, limiting recombination of charge carriers. Consequently, the modified g-C3N4 shows excellent photocatalytic activity with apparent quantum efficiency of 8.41% under 420 nm wavelength, surpassing pure g-C3N4 and other reported materials with defect compilation. We think that this work provides a new avenue to understand the function of structural defect on prompt charge separation.