煅烧对纳米TiO_2/蛋白土复合材料光催化性能的影响及机理

Effects of Calcination Condition on Photocatalytic Properties of Nano-TiO_2/Opal Composite and Its Mechanism

纳米TiO2/蛋白土复合材料是一种采用钛盐水解沉淀法在蛋白土表面负载纳米TiO2的新型光催化剂。本文结合晶型与晶粒度、比表面积和孔结构等性质,讨论了煅烧工艺对其光催化性能的影响机理。结果表明,复合材料升温到800℃时仍无金红石相出现,说明载体蛋白土对TiO2的晶型转变起到抑制作用。以染料罗丹明B溶液为目标降解物,250 W汞灯为光源,评价纳米TiO2/蛋白土复合材料的光催化性能,其中600℃煅烧2 h得到的样品具有较优的光催化性能,照射4 h后,对罗丹明B的去除率达到97.24%。

Nanocrystalline TiO2 particles immobilized on opal by a hydrolysis precipitation method are used as a novel catalyst in photocatalysis. Effects of crystalline and size, BET specific surface area and porous properties on the photoactivity were investigated by characterizing samples obtained under various calcination temperatures and periods. Results reveal that there is still no evidence of rutile phase in XRD patterns when the calcination temperature increases to 800℃. This indicates that the opal support impedes the phase transformation. The photocatalytic reactivity of this nano-TiO2/opal composite catalyst was evaluated by degrading Rhodamine B（RhB） under ultraviolet light. The sample calcined at 600℃ for 2 h exhibits the smaller crystalline size and larger specific surface area with a concomitant higher activity of 97.24% for RhB degradation by 4 h irradiation under 250 W Hg lamp.