Controlled photocatalytic activity of TiO2 inverse opal structures with atomic layer deposited (ALD) metal oxide thin films
Khai Pham, Ségolène Pélisset, Niko Kinnunen, Petri Karvinen, Tommi K. Hakala, Jarkko J. Saarinen
Abstract
Atomic layer deposited (ALD) thin films of Al2O3, SiO2, and TiO2 with thicknesses ranging from 0.25 nm to 10 nm were studied on TiO2 inverse opal (IO) structures for their effect on photocatalytic activity under ultraviolet A (UVA) excitation. 1 nm coating of Al2O3 suppressed the photocatalytic activity significantly by more than 90% removing all water molecules from the surface. On the contrary, 0.25 nm SiO2 layer enhanced the photocatalytic activity by 112% by increasing the number of water molecules on the surface whereas 3 nm SiO2 layer reduced the activity by 87% as the thicker layer prevented electron and hole diffusion onto the surface. The highest photocatalytic activity enhancement up to 226% was observed with 10 nm ALD TiO2 layer.