Preparation and photocatalytic performance of Bi2MoO6/Bi7O9I3 heterojunction
Bismuth oxide bismuth molybdate(Bi2MoO6)is a typical Bi(Ⅲ)based semiconductor with visible light driving characteristics,which has advantages such as good ion conductivity,narrow bandgap,and environmental friendliness.However,the practical application of Bi2MoO6 monomer is severely limited due to its poor intrinsic photo-generated carrier separation,high recombination rate,and narrow light response range.Constructing heterojunctions is an effective method to improve their photocatalytic performance,which not only expands the light absorption range but also promotes the separation of photo-generated charge carriers.However,the construction of heterojunctions has the drawback of lattice mismatch at the interface of two substances,which hinders charge transfer between the interfaces.The one-step synthesis of composite catalysts can effectively reduce the lattice mismatch at the interface,promote the spatial separation of photo-generated electrons and holes,and expand the light absorption range of catalytic materials.In this study,Bi2MoO6/Bi7O9I3 heterojunction materials were synthesized by one-step method.The morphology,chemical composition and photoelectric properties of the heterojunction materials were characterized by instrumental analysis.The effect of material adsorption and photocatalytic degradation of ciprofloxacin(CIP)was studied.The results showed that compared with the single component,Bi2MoO6/Bi7O9I3 composite improved the visible light absorption capacity of Bi2MoO6 monomer,reduced its band gap width,and improved the activity of CIP adsorption and photocatalytic degradation.When the molar ratio of Bi2MoO6 to Bi7O9I3 was 7∶3,the best removal rate of CIP was obtained.The absorption removal and photocatalytic degradation rates of CIP were 82.6％and 94.7％.Under the same conditions,the adsorption and degradation rates of monomer Bi2MoO6 and Bi7O9I3 were only 57.4％and 66.4％,35.2％and 43.6％,respectively.Free radical capture experiments showed that the main active species of Bi2MoO6/Bi7O9I3 photocatalytic degradation of ciprofloxacin were h+and·O2-.
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