BiOCl_(0.5)Br_(0.5)/BiPO_(4)双层异质结薄膜光催化剂的一步电化学法制备及性能

One⁃Pot Electrochemical Preparation and Performance of BiOCl_(0.5)Br_(0.5)/BiPO_(4) Double⁃Layer Heterojunction Thin Film Photocatalyst

采用一步电化学法在金属Bi板上成功制备了BiOCl_(0.5)Br_(0.5)/BiPO_(4)双层异质结薄膜,并通过多种表征手段对薄膜的晶型结构、元素组成及化合价、形貌和尺寸特征、吸光性能和荧光强度进行了表征。结果表明,制备得到的复合薄膜呈现出上层为梭子状的BiPO_(4)颗粒层分散在下层为BiOCl_(0.5)Br_(0.5)固溶体层的双层结构。这样的双层膜排列顺序使得光生电子和空穴在不同组分之间的界面电场作用下分别向薄膜两侧流动,促进光致载流子的分离,提高了BiOCl_(0.5)Br_(0.5)/BiPO_(4)复合薄膜的光催化活性。活性测试结果表明,在模拟太阳光照射120 min后,BiOCl_(0.5)Br_(0.5)/BiPO_(4)复合薄膜对苯酚的降解率达到了99.97%,是相同条件下制备的BiOCl/BiPO_(4)和BiOBr/BiPO_(4)复合薄膜对苯酚降解率的1.69倍和1.20倍。在苯酚的降解过程中,主要参与的活性物种是空穴(h^(+))和羟基自由基(·OH)。其光催化活性增强的原因归功于BiOCl_(0.5)Br_(0.5)/BiPO_(4)复合薄膜拓宽的光谱吸收范围和增强的载流子分离率。

BiOCl_(0.5)Br_(0.5)/BiPO_(4) double-layer heterojunction thin film photocatalyst was successfully prepared on Bi plate by one-pot electrochemical method.The crystal structure,elemental composition and valence,morphology and optical property were characterized.The as-obtained double-layer film consisted of BiOCl_(0.5)Br_(0.5) solid solution layer at the bottom and BiPO_(4) nanoparticles layer at the top.The interface internal electric field of BiOCl_(0.5)Br_(0.5)/BiPO_(4) composite film led the photo-induced electrons and holes to shift in the opposite direction,thus improving the photocatalytic performance of BiOCl_(0.5)Br_(0.5)/BiPO_(4) composite film.The results displayed that the photodegradation efficiency of phenol reached 99.97%after 120 min under simulated sunlight irradiation,which was nearly 1.69 times and 1.20 times more than that of BiOCl/BiPO_(4) and BiOBr/BiPO_(4) composite films,respectively.Besides,the hole(h^(+))and hydroxyl radical(·OH)played a crucial role in the photodegradation process of phenol.The improved photocatalytic performance of BiOCl_(0.5)Br_(0.5)/BiPO_(4) composite film can be ascribed to the broadened absorbance spectra range and efficient separation of photo-induced charge carriers.