Synthesis And Properties Exploration Of BiOI-based Photocatalysts

As a promising photocatalytic material,BiOI has attracted more and more attention due to its high photocatalytic efficiency,low toxicity and good response to visible light.Its molecular internal by anion I^-and cation[Bi_xO_y]ⁿ⁺interlacing composition,so in the direction perpendicular to the layer structure,the generation of built-in electric field,is conducive to hinder photogenerated electrons and hole recombine efficiency.The purpose of this paper is to improve the photocatalytic performance of BiOI,through regulating the factors in preparation technology of BiOI,building the heterojunction between Sm（OH）₃and BiOI,then depositing the Ag nanoparticles on the surface of Sm（OH）₃ and forming a new type of high efficient photocatalyst,three-phase compound-Ag/Sm（OH）₃/BiOI.（1）BiOI photocatalyst was prepared from bismuth nitrate pentahydrate（Bi（NO₃）₃·5H₂O）and potassium iodide（KI）by simple hydrothermal method.The influences of pH value,different mediums and different reaction temperatures of the precursor on the structure,morphology and photocatalytic performance of BiOI were studied.Results show that when the precursor solution pH=3,reaction solvent elected EG+H₂O（1:1）,the reaction temperature is 80℃,the degradation efficiency of the as-prepared BiOI is about 90%under visible light in 120 min.（2）In order to reduce the recombination efficiency of carriers in BiOI,we have built the heterojunction between Sm（OH）₃ and BiOI with excellent structure and morphology.The effects of temperature,solvent and reaction time on the heterostructure were studied.The photocatalytic properties of Sm（OH）₃/BiOI heterojunction were characterized by using methyl orange（MO）as the target degradant.Test results reveal that when the reaction temperature is80℃,the medium is EG+H₂O（1:1）,preparation of sample preparation time is 3h,the phase of Sm（OH）₃ and BiOI are explicit,the morphologies are neat,the degradation efficiency is more than 85%under visible light in 80 min,is the best photocataysts compared to other samples.（3）In order to further promote the photocatalytic activity of Sm（OH）₃/BiOI,different sizes of Sm（OH）₃ were prepared:the nano-level（nano-Sm（OH）₃）and micron-level（micr-Sm（OH）₃）,then Ag nanoparticles were deposited on the surface of two Sm（OH）₃ structures by oil bath method,and the modified Ag/Sm（OH）₃ was compounded with BiOI to obtain the three-phase complex:Ag/micr-Sm（OH）₃/BiOI、Ag/nano-Sm（OH）₃/BiOI.The results showed that Ag/nano-Sm（OH）₃/BiOI exhibited excellent photocatalytic activity,and the degradation efficiency of MO was up to 90%when exposed to visible light for60min.Compared with the pure phase BiOI,the efficiency of Sm（OH）₃/BiOI sample was about twice as high.