Preparation of porous TiO2/Ag heterostructure films with enhanced photocatalytic activity

TiO2/Ag nanostructured porous films were prepared by spin coating of P25 TiO2/colloidal silica on glass substrate and subsequent photochemical deposition of silver nanoparticles (AgNPs). The adhesion strength of the film on glass substrate was evaluated and the result indicated that porous films formed on the glass substrates were robust and durable. The porous structure of TiO2/SiO2 film facilitated the implantation of uniformly dispersed AgNPs having sizes generally less than 10 nm. By acting as electron scavengers, AgNPs effectively provided an alternative electron transfer route, thus enhancing the photocatalytic efficiency for degradation of methylene blue (MB). Compared with the bare TiO2 film derived from P25, TiO2/Ag porous films showed an improved photocatalytic activity. This conclusion was further supported by photocurrent density measurements on the films. The study also demonstrated experimentally that TiO2/Ag porous films had sustained stability with the photocatalysis maintaining its original activity after at least four consecutive reaction cycles.