Cu-doped Bi/Bi2WO6 catalysts for efficient N2 fixation by photocatalysis

In this paper, Cu-doped Bi2WO6 was synthesized via a solvothermal method and applied it in photocatalytic N2 immobilization. Characterization results showed the presence of a small amount of metallic Bi in the photocatalyst, indicating that the synthesized photocatalyst is actually Bi/Cu-Bi2WO6 composite. The doped Cu had a valence state of +2 and most likely substituted the position of Bi3+. The introduced Cu did not affect the metallic Bi content, but mainly influenced the energy band structure of Bi2WO6. The band gap was slightly narrowed, the conduction band was elevated, and the work function was reduced. The reduced work function improved the transfer and separation of charge carriers, which mainly caused the increased photoactivity. The optimized NH3 generation rates of Bi/Cu-Bi2WO6 reached 624 and 243 (µmol·L−1·g−1·h−1 under simulated solar and visible light, and these values were approximately 2.8 and 5.9 times higher those of Bi/Bi2WO6, respectively. This research provides a method for improving the photocatalytic N2 fixation and may provide more information on the design and preparation of heteroatom-doped semiconductor photocatalysts for N2-to-NH3 conversion. [graphic not available: see fulltext]