Considering Ferrocene

The article on South Korea’s research on the photochemical activity of TiO₂ nanotubes coated with iron oxide suggests that the reduction in activity with the addition of iron oxide was unexpected (C&EN, April 11, page 39). In the pigments and coatings industries, these results would not be surprising at all, since iron oxides are well-known to be relatively inert under photochemical conditions, and their coating of TiO₂ will decrease its composite reactivity.

If the researchers want an increase in activity, they should consider a much more reactive form of iron, such as ferrocene. Previously published research clearly demonstrates that as little as 1% vinyl ferrocene in an acrylic backbone causes the otherwise stable polymer to degrade rapidly to a black form, and then drop off the substrate, within months of exterior exposure and within a few hundred hours of accelerated ultraviolet exposure.

Lou Floyd
Independence, Ohio