g-C_(3)N_(4)/Pd/Bi_(2)WO_(6)光催化剂协同降解苯扎贝特机理研究

Study on g-C_(3)N_(4)/Pd/Bi_(2)WO_(6) heterostructure and its synergistic degradation mechanism of bezafibrate

利用贵金属Pd的等离子体共振效应和形貌可控Bi2WO6的光催化协同作用,通过低温水热法设计合成具有高效可见光活性的花状g-C_(3)N_(4)/Pd/Bi_(2)WO_(6)异质结复合催化剂.在可见光照射下,异质结复合催化剂光催化降解BZF的去除率均高于g-C_(3)N_(4),g-C_(3)N_(4)/Bi_(2)WO_(6),Pd/g-C_(3)N_(4)和Bi_(2)WO_(6),其中,50%g-C_(3)N_(4)/Pd/Bi_(2)WO_(6)对BZF的去除率为96%,是Pd/g-C_(3)N_(4)的1.8倍,g-C_(3)N_(4)和Bi_(2)WO_(6)的2.7倍.基于表征分析可知,g-C_(3)N_(4)/Pd/Bi_(2)WO_(6)复合催化剂中Bi_(2)WO_(6)呈现中心辐射花状纳米结构,并与层状Pd/g-C_(3)N_(4)连接;贵金属Pd可作为电子传输的介质,促进g-C_(3)N_(4)和Bi_(2)WO_(6)Z型异质结构的形成,有利于协同提升可见光催化活性.淬灭实验和EPR表征证实了·OH是g-C_(3)N_(4)/Pd/Bi_(2)WO_(6)催化降解BZF的主要活性物质,LC-MS/MS分结果表明羟基化作用取代贝特链是BZF降解的主要路径.

A flower-like g-C_(3)N_(4)/Pd/Bi_(2)WO_(6) heterostructure with high visible light activity was designed and synthesized by low temperature hydrothermal method utilizing the plasmon resonance effect of noble metal Pd and the photocatalytic synergism of shape-controlled Bi_(2)WO_(6).It was found that the composite of Pd/g-C_(3)N_(4) and Bi_(2)WO_(6) significantly enhanced removal efficiency of BZF under visible light irradiation.Further analysis of characterization showed that Bi_(2)WO_(6) in g-C_(3)N_(4)/Pd/Bi_(2)WO_(6) exhibited a central radiated flower-like nanostructure,which is connected with layered Pd/g-C_(3)N_(4).The noble metal Pd could be used as the medium for electron transport to promote the formation of Z-type heterostructures between g-C_(3)N_(4) and Bi_(2)WO_(6),which is beneficial to cooperatively enhance the photocatalytic activity.It was confirmed that·OH was the main active species in degradation of BZF with g-C_(3)N_(4)/Pd/Bi_(2)WO_(6) heterostructures by quenching experiments and EPR analysis.Moreover,the LC-MS/MS analysis indicated that hydroxylation with fibrate chain substituent was the main route of BZF degradation.