(27f) Understanding the Effect of Surface Deposited Pt On the Photoactivity of TiO2
It is well know that Pt can be utilized to enhance the photoactivity of TiO2. We have produced Pt coated TiO2 via Atomic Layer Deposition (ALD) and tested its ability to degrade methylblue. At low Pt loadings Pt increases the photodegredation rate by three times at a 1% Pt loading, but the photoactivity decreases at higher Pt loadings. We have additionally used density functional theory to develop an understanding of the processes that cause the initial increase and subsequent decrease in photoactivity as the Pt coverage increases. We study O2’s interaction with a pure TiO2 surface and a Pt cluster on a TiO2 surface, as well as interactions of both simulated holes and excited electrons. Pt allows O2 to interact with the TiO2 surface by providing adsorption sites, which are rare on pure TiO2 surfaces. However, Pt clusters always act as electron hole recombination centers. The initial rise and subsequent fall in TiO2’s photoactivity with Pt loading results from the competition between enhanced electron scavenging due to increased O2 adsorption and increased electron-hole recombination.