Annealing temperature on photocatalytic activity of (hollow Au-Ag nanoparticles)/TiO2 composites prepared from block copolymer-stabilized bimetallic nanoparticles

摘要

Composite containing a TiO2 and hollow Au-Ag nanoparticles (H-AuAg-NPs) have been prepared by using H-AuAg-NPs with block copolymer shells as templates, and the influence of annealing temperature on structure, surface property, and the photocatalytic activity has been investigated. The structures of H-AuAg-NPs/TiO2 Composites were examined by X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The carbon content was measured by thermogravimetric analyses (TGA). The specific surface areas and pore volumes of the H-AuAg-NPs/TiO2 composites after annealing at different temperature were characterized using the nitrogen gas sorption technique. The photocatalytic activities of the H-AuAg-NPs/TiO2 composite were investigated by the photodecomposition of methylene blue (MB). The results show that the TiO2 in H-AuAg-NPs/TiO2 composite is amorphous upon annealing at 400 degrees C. Anatase phase appears as annealing temperature is increased to 450 degrees C, and the crystallinity is further increased if the annealing temperature is raised to 500 degrees C. The specific surface area decreases with annealing temperature from 400 degrees C to 500 degrees C. It is found that the H-AuAg-NPs/TiO2 composite annealed at 450 degrees C shows the highest photocatalytic activity.