New efficient visible light photocatalyst based on heterojunction of BiOCl-bismuth oxyhydrate

A novel active photocatalyst, which is a heteroconjuction of a bismuth oxyhydrate and BiOCl, has been synthesized by a simple hydrothermal method. The photocatalytic activity of the new material was measured in the degradation of Rhodamine B (RhB) and Acetophenone (AP) and in the photocatalytic oxidation of iodide in water under UV-vis and visible light irradiations respectively. The heterojunction between bismuth oxyhydrate and BiOCl provided exceptional photocatalytic activity, whereas both the individual bismuth oxyhydrate and BiOCl showed a negligible efficiency. Compared to Degussa P25, the new composite material demonstrated 5 times higher activity in removing aqueous RhB under visible light (λ ≥ 420 nm) irradiation. The chemical composition and crystal structure were investigated using powder X-ray diffraction, scanning and transmission electron microscopy, and thermal methods. The preliminary study has revealed the bismuth oxyhydrate has tetragonal crystal structure with unit cell parameters a = b = 5.674 , c = 10.353 , unit cell volume V = 333.3 ³ and possible P4/mmm (No. 123) space group. Temperature behavior of new photocatalyst has been investigated. It was found that at heating to 550 °C for 45 min the new phase transforms into well-known monoclinic Bi ₂O ₃.