Enhanced visible-light photo-oxidation of nitric oxide using bismuth-coupled graphitic carbon nitride composite heterostructures

Pure bismuth (Bi) metal-modified graphitic carbon nitride (g-C₃N₄) composites (Bi-CN) with a pomegranate-like structure were prepared by an in situ method. The Bi-CN composites were used as photocatalysts for the oxidation of nitric oxide (NO) under visible-light irradiation. The inclusion of pure Bi metal in the g-C₃N₄ layers markedly improved the light absorption of the Bi-CN composites from the ultraviolet to the near-infrared region because of the typical surface plasmon resonance of Bi metal. The separation and transfer of photogenerated charge carriers were greatly accelerated by the presence of built-in Mott–Schottky effects at the interface between Bi metal and g-C₃N₄. As a result, the Bi-CN composite photocatalysts exhibited considerably enhanced efficiency in the photocatalytic removal of NO compared with that of Bi metal or g-C₃N₄alone. The pomegranate-like structure of the Bi-CN composites and an explanation for their improved photocatalytic activity were proposed. This work not only provides a design for highly efficient g-C₃N₄-based photocatalysts through modification with Bi metal, but also offers new insights into the mechanistic understanding of g-C₃N₄-based photocatalysis. Copyright © 2017 Dalian Institute of Chemical Physics, the Chinese Academy of Sciences.