MoS2/BiOI复合光催化剂制备及其光催化氧化还原性能

通过两步法合成花状MoS_2/BiOI复合光催化剂,采用X射线衍射(XRD)、扫描电镜(SEM)、紫外可见漫反射(UVVis)、光电子能谱(XPS)等方法对合成的样品进行了表征,对其可能的形成机制进行探究,通过电化学表征计算出BiOI与MoS_2的价带与导带位置,显示复合材料形成了1型异质结.同时以罗丹明B(RhB)与含Cr6+溶液作为目标污染物测试光催化剂的氧化还原性能,相比于BiOI和MoS_2单体,MoS_2/BiOI复合光催化剂表现出更强的光催化氧化与还原能力,其中以质量分数为2%的MoS_2与BiOI复合光催化剂效果最佳,可见光照20 min后RhB降解率达到98.92%,80 min后Cr6+溶液光催化还原率可达到97.87%,较纯BiOI分别提高了1.79倍与3.85倍,且经过4次重复利用后仍具有较高的光催化活性.光催化降解Rh B过程中空穴(h+)与超氧自由基(·O-2)作为主要活性物种,其中空穴影响更为显著.

Fabrication of the Heterojunction Photocatalyst MoS2/BiOI and Its Investigation of Its Photocatalytic Reduction and Oxidation Activities

Based on a two-step approach, a flower-like MoS₂/BiOI composite with a heterojunction has been successfully fabricated. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared MoS₂/BiOI. The formation mechanism of this heterostructure was investigated. The valence band (VB) and conduction band (CB) of the MoS₂/BiOI heterojunction have been calculated based on electrochemical characterization, implying the formation of a type I band alignment. The photodegradation of Rhodamine B (RhB) and Cr⁶⁺ were used to assess photocatalytic reduction and oxidation activities. The results show that the MoS₂/BiOI composite structures perform much better than pristine MoS₂ and BiOI. Among the composites with various MoS₂ contents, 2% MoS₂/BiOI exhibits the best efficiency with respect to the degradation of RhB. After irradiation for 20 minutes, the degradation rate of RhB was 98.82%, which is 1.79 times higher than that using pure BiOI. After irradiation for 80 minutes, the removal of Cr⁶⁺ was 97.87%, which is 3.85 times higher than that using pure BiOI. Holes and·O₂^- are the main reactive species during the photocatalytic process of RhB degradation; holes play the leading role.