Preparation And Properties Of The Silver-based Solid Solution Heterostructure

Semiconductor heterojunctions had the potential applications in optoelectronic functional materials and received extensive attention.Considering the drawbacks of traditional photocatalysts,such as large band gap,narrow response to visible light,and low photocatalytic efficiency,how to effectively solve the above problems had become a focus in this research field.Semiconductor heterojunctions provided an effective way for the development of visible light-responsive photocatalytic materials.Constructing effective heterojunctions to form the built-in electric fields could accelerat the separation efficiency of photogenerated electrons and holes and improve the photoelectric conversion efficiency such as photocatalytic efficiency.In this article,BiOI/α–AgAl_0.4Ga_0.6O₂ heterostructures were synthesized by a precipitation route.The SEM results showed that flower–like BiOI microspheres grow on platelet–likeα–AgAl_0.4Ga_0.6O₂.With regard to the heterojunctions,the visible–light absorption edges expanded from 470 to 650 nm by controlling the molar ratio ofα–AgAl_0.4Ga_0.6O₂ to BiOI.Photoluminescence spectra demonstrated that the BiOI/α–AgAl_0.4Ga_0.6O₂ exhibited lower emission intensity than the BiOI andα–AgAl_0.4Ga_0.6O₂,indicating the enhancement of carrier separation efficiency of the the BiOI/α–AgAl_0.4Ga_0.6O₂ which was also verified by electrochemical impedance spectroscopy.Thus,the BiOI/α–AgAl_0.4Ga_0.6O₂ heterostructures could efficiently utilize visible light and facilitate carrier separation.Theα/β–AgAl_0.4Ga_0.6O₂ heterojunction was synthesized by in situ hydrothermal synthesis.The morphology was regulated by controlling the hydrothermal time and the temperatures.The X–ray diffraction and Raman spectra showed the phase transformation behavior of the sample.SEM and TEM illustrated that the samples with high crystallinity had the mixed morphology of near–sphericalβphase and plateletαphase and the formation of phase heterojunctions.The UV–vis absorption edges of the heterostructure were adjusted from 450 to 520 nm by controlling the ratio of two phases under different hydrothermal time or temperatures.The heterostructure displayed the enhanced photocatalysis activity compared with singleαorβphase by monitoring the degradation of the dye model methyl orange.This might be attributed to the absorption behavior for efficiently utilizing visible light and the phase heterojunction for promoting the separation of photogenerated carriers.The survey of photocatalytic mechanism indicated that reactive h⁺and·O₂^-were the oxygen active species.In addition,electrochemical performance tests showed that the EIS and the photocurrent spectroscopy of the mixed–phase samples had the smallest diameter of the arc radius and the maximum photocurrent electrochemical performance,respectively.This indicated high separation and fast transfer of the photoinduced carriers.This work demonstrated that the design of mixed–phase heterojunction which enhanced the utilization of visible light and efficient carrier separation was an efficient approach to enhance photocatalytic activity.