Mapping the photocatalytic activity or potential free radical toxicity of nanoscale titania

The design of optimal nanoparticle photocatalysts requires a detailed understanding of how materials parameters relate to photoactivity. To make these devices safe the same information is needed to assess the potential for nanotoxicity from free radicals. In this study a structure-property map for predicting the efficiency for free radical production of titania nanoparticles as a function of particle size and the thermal/chemical environment is presented. The results, which account for the size- and temperature-dependent anatase-to-rutile phase transition and changes in shape, show an increase in activity/toxicity at around 33 nm, in agreement with previously reported experimental results.