SPR effect of bismuth enhanced visible photoreactivity of Bi2WO6 for NO abatement

Bi2WO6 is a typical visible-light-responsive semiconductor photocatalyst with a layered structure. However, the relatively large bandgap (2.6–2.8 eV) and quick recombination of photo-generated carriers result in its low quantum efficiency. In this paper, Bi-nanospheres-modified flower-like Bi2WO6 was successfully prepared by solvothermal treatment of Bi2WO6 powders in Bi(NO3)3 solution using ethylene glycol as reductant. The photoreactivity of this photocatalyst was evaluated by the oxidation of NO in a continuous-flow reactor under irradiation by a visible LED lamp (λ > 400 nm). It was found that both Bi nanospheres and flower-like Bi2WO6 precursor exhibit very poor photocatalytic activity with NO removal rates of only 7.7% and 8.6%, respectively. The photoreactivity of Bi/Bi2WO6 was found to steadily increase from 12.3% to 53.1% with increase in the amount of Bi nanospheres from 0 to 10 wt%. However, with further increase in the loading amount of Bi nanospheres, the photoreactivity of Bi/Bi2WO6 hybridized photocatalyst begins to decrease, possibly due to the light filtering by the Bi nanospheres. The enhanced visible photoreactivity of Bi/Bi2WO6 towards NO abatement was attributed to surface plasmon resonance driven interfacial charge separation. The excellent stability of Bi/Bi2WO6 hybridized photocatalyst towards NO oxidation demonstrates its potential for applications such as air purification.