Synthesis and photocatalysis performances of bismuth oxynitrate photocatalysts with layered structures.

A new type of layered oxy-acid salt of bismuth oxynitrate was synthesized by a simple hydrothermal method. The obtained bismuth oxy-nitrates consist of a Bi2O2(2+) layered module inserted into the interlamellar anion modules of NO3(-) and OH(-). Varying amounts of NO3(-) and OH(-) complexes on the surface of the bismuth oxynitrate were also obtained by adjusting the precursor pH before hydrothermal treatment. It was found that the sample prepared with the precursor pH = 5.00 presented the highest photocatalytic activity, with a rate constant of 0.05 min(-1), which is 2 and 6.7 times higher than those presented by the samples with the precursor pH = 7.00 and 1.22, respectively. The largest cathodic to anodic photocurrent switching was also presented by the sample with the precursor pH = 5.00, which can be reasonably attributed to NO3(-) complexes on the surface of the bismuth oxynitrate. The NO3(-) complexes could efficiently migrate the photo-induced holes to the surface of the semiconductor.