Semiconductor photocatalysis is currently attracting increasing interest in both scientific and engineering areas [1]. In view of the better utilization of the solar light and the indoor illumination, it is appealing to develop visible light-sensitive photocatalysts. Thus, some new photocatalysts with visible light-responsive characteristics have been developed in the recent years [2]. Solid acids are among the most important compounds in materials science, and have a large number of applications like catalysts, ion conductors, and electrode materials. Ti- and Nb-based lamellar solid acids are more attractive because of some particular properties like the layered structure, favorable electron-transfer character, and the protonic acidity. In the present study, a lamellar solid acid, viz. HNb3O8, had been successfully doped with nitrogen for visible light photocatalysis. It was found that the nitrogen-doped HNb3O8 photocatalyst shows superior activity for Rhodamine B photodegradation than the nitrogen-doped KNb3O8, Nb2O5, and TiO2 samples under visible light irradiation. The sample preparation methodology was studied with detail. The physico-chemical properties of the photocatalysts were investigated by using a variety technique such as XRD, BET, SEM, TG-DTA, and UV-visible diffuse reflectance spectroscopy. It turned out that the unique properties like the layered structure and the protonic acidity of HNb3O8 could have profound impacts on both nitrogen doping and the resultant visible light photocatalysis.

References
[1] M.R. Hoffmann, S.T. Martin, W. Choi, D.W. Bahnemann, Chem. Rev. 95 (1995) 69.
[2] X. Li, J. Ye, J. Phys. Chem. C 111 (2007) 13109.