热处理改性天然闪锌矿的可见光催化性能研究

A study of the photocatalytic capability of hea-ttreated sphalerite in visible light

天然闪锌矿是一种具有良好可见光催化性能的半导体光催化剂,然而其结构缺陷会成为光生电子的捕获阱,导致其光催化反应效率降低。为了进一步提高其可见光催化效率,本文在空气气氛下对天然闪锌矿进行了500～1 200℃的热处理改性实验研究,并利用X射线衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis DRS)对热改性后样品的半导体物理化学性质进行了初步的表征分析;然后以甲基橙为目标降解物进行了热处理样品的光催化实验研究。研究结果显示,空气气氛下的热处理随着温度的逐渐升高,闪锌矿物相先转变为氧化硫酸锌,再转变为红锌矿和锌铁尖晶石,到1 100～1 200℃时样品完全转变为红锌矿-锌铁尖晶石二元复合半导体光催化剂,此时样品在可见光下对甲基橙的降解率从原样的54.2%提高到99.7%,1 100～1 200℃改性后样品的可见光催化性能最好。

As a kind of photocatalytic semiconductor material,natural sphalerite has a considerable photocatalytic capability in visible light.However,its structural defects could be the capture trap of photo-generated electrons,which results in the decrease of its photocatalytic reaction efficiency.To further improve its photocatalytic efficiency in visible light,the authors conducted the heat-treating experimental study of natural sphalerite at 500～1 200℃ in static air.The physical and chemical semiconductor properties of the original and modified samples were analyzed and characterized by using testing means of X-ray Diffraction （XRD） and UV-Vis Diffuse Reflectance Spectra （UV-Vis DRS）.Then the photocatalytic experimental study which utilized the original and modified samples to degrade methyl orange was performed.The X-ray diffraction results showed that sphalerite was converted into Zn3O（SO4）2 and then into zincite and franklinite with the increasing heat-treating temperature.Samples were totally converted into ZnO-ZnFe2O4 binary compound semiconductor at 1 100 ～ 1 200℃.The UV-Vis Diffuse Reflectance Spectra results show that the response of modified samples to visible light is stronger than that of the original sample,and the absorption range of visible light of 900 ～ 1 200℃ modified samples is larger than that of 500～800℃ modified samples.The degradation experimental results show that the 1 100～1 200℃ heat-modification of natural sphalerite significantly improved its degradation rate of methyl orange from 54.2 ％ to 99.7 ％,which indicates that the photocatalytic capability in visible light of 1 100～1 200℃ modified samples is the best.Based on these test and experimental results,the authors infer that the photoeatalytic capability in visible light of ZnO-ZnFe2O4 binary compound semiconductor is higher than that of the single ZnS semiconductor and other types of compound semiconductor.