Formation of BiOCl/Bi2O3 and Related Materials for Efficient Visible-Light Photocatalysis

초록

Novel heterojunction structures of BiOCl/Bi2O3 exhibit remarkable photocatalytic activities in decomposing organic compounds in gas or aqueous phase under visible-light irradiation, even though individual BiOCl and Bi2O3 show negligible catalytic efficiency. In this BiOCl/Bi2O3 system, the BiOCl with a band gap of 3.7 eV works as a main photocatalyst, while the Bi2O3 with a band gap of 2.6 eV plays a role as a sensitizer absorbing visible light. It is deduced that its photocatalytic activity is caused by the inter-semiconductor hole transfer between the valence band (VB) of Bi2O3 and BiOCl. Moreover, visible-light photocatalytic efficiency of BiOCl/Bi2O3 nanocomposite can be further enhanced by covering their surfaces with molecular WO3 species. It is found that monolayer coverage of WO3 maximizes the photocatalytic activity of WO3/BiOCl/Bi2O3 system, whereas further increase of WO3 concentration sharply decreases its activity, suggesting that the role of molecular WO3 on the surface of BiOCl/Bi2O3 is to improve the adsorption of organic species as well as OH− or H2O. Furthermore, the surface coverage of WO3 protects BiOCl/Bi2O3 system, thus notably extending its chemical- and photostability during photocatalytic reactions. BiOCl/Bi3O4Cl nanocomposites also exhibit considerable visible light photocatalytic efficiency. Herein the Bi3O4Cl plays a role as a sensitizer absorbing visible-light, and the significant visible-light photocatalytic activity of the BiOCl/Bi3O4Cl system originates from the hole (h+) transfer between the VB of Bi3O4Cl and BiOCl. © Springer International Publishing Switzerland 2016.

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