油水自组装制备Ag＠AgCl/K4Nb6O17及其光催化降解有机污染物的研究

Oil-water self-assembly synthesis of Ag@AgCl/K_4Nb_6O_(17) and enhanced photocatalytic degradation of organic pollutants

在高温固相法制备K4Nb6O17的基础上,采用油水自组装合成复合光催化剂Ag@Ag Cl/K4Nb6O17,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@Ag Cl的粒径约为20 nm,均匀分散在二维层状结构K4Nb6O17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@Ag Cl(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@Ag Cl和K4Nb6O17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(Rh B)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/K4Nb6O17 was composed of by the oil-water self-assembly method,on the basis that K4Nb6O17 was prepared in the high-temperature solid-state method. The microstructure,morphology and properties of Ag @ Ag Cl / K4Nb6O17 composite photocatalyst were characterized by means of XRD,SEM,TEM,EDX,UV-vis,PL,BET; and the photocatalytic performance was valued by the degradation of methylene blue( MB),phenol,and Rhodamine B( Rh B) under visible light irradiation. The results shows that Ag@ Ag Cl particles with the size of about20 nm were dispersed in two-dimensional layer structure on the surface of K4Nb6O17 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@ Ag Cl(25wt%) / K4Nb6O17 under the visible light irradiation reaches 88. 2% in an hour,which is more than two times compared with the sum of the Ag@ Ag Cl and K4Nb6O17 degradation rate. The composite photocatalyst still exhibited high catalytic activity after recycled five times,and photocatalytic activities for the degradation of phenol and Rh B were also observed. The degradation mechanism of Ag@AgCl/K4Nb6O17 composite photocatalyst was proposed.