Synthesis and photocatalysis performances of bismuth oxynitrate photocatalysts with layered structures

Abstract

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 Bi₂O₂²⁺ 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.