油水自组装制备Ag＠AgCl/K4Nb6 O17及其光催化降解有机污染物的研究∗

摘要

在高温固相法制备K4 Nb6 O17的基础上,采用油水自组装合成复合光催化剂 Ag ＠ AgCl/K4 Nb6 O17,利用 XRD、SEM、TEM、EDX、UV-Vis、PL、BET等多种手段对复合光催化剂的微观结构、形貌和性能进行了表征,并研究了可见光下降解亚甲基蓝(MB)的催化性能.研究表明,Ag＠AgCl 的粒径约为20 nm,均匀分散在二维层状结构K4 Nb6 O17的表面上；贵金属Ag纳米粒子的表面等离子体效应显著,对可见光的吸收范围从400 nm 拓展到800 nm；Ag＠AgCl(25％(质量分数))/K4Nb6O17在可见光照射60 min对亚甲基蓝的降解率为88．2％,远远高于单体Ag＠AgCl和K4 Nb6 O17的活性.循环实验证明催化剂具有较好的稳定性,同时对苯酚和罗丹明 B(RhB)也具有一定的催化降解活性.淬灭实验表明自由基和空穴均为活性物种,并在此基础上提出降解机理.%The composite photocatalyst of Ag@AgCl/K4 Nb6 O17 was composed of by the oil-water self-assembly method,on the basis that K4 Nb6 O17 was prepared in the high-temperature solid-state method.The microstruc-ture,morphology and properties of Ag@AgCl/K4 Nb6 O17 composite photocatalyst were characterized by means of XRD,SEM,TEM,EDX,UV-vis,PL,BET;and the photocatalytic performance was valued by the degra-dation of methylene blue (MB),phenol,and Rhodamine B (RhB)under visible light irradiation.The results shows that Ag@AgCl particles with the size of about 20 nm were dispersed in two-dimensional layer structure on the surface of K4 Nb6 O17 and the absorption of visible light of the composite photocatalyst ranged from 400 to 800 nm due to the surface plasmon resonance of Ag.The degradation rate of MB solution over Ag@AgCl (25wt%)/K4 Nb6 O17 under the visible light irradiation reaches 88.2% in an hour,which is more than two times compared with the sum of the Ag@AgCl and K4 Nb6 O17 degradation rate.The composite photocatalyst still ex-hibited high catalytic activity after recycled five times,and photocatalytic activities for the degradation of phenol and RhB were also observed.The degradation mechanism of Ag@AgCl/K4 Nb6 O17 composite photocatalyst was proposed.