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

Abstract

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 Å, c = 10.353 Å, unit cell volume V = 333.3 Å 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.