Ikeda, S., Sugiyama, N., Pal, B., Marci, G., Palmisano, L., Noguchi, H., Uosaki, K. and Ohtani, B. (2001) Photocatalytic activity of transition-metal-loaded titanium (IV) oxide powders suspended in aqueous solutions: Correlation with electron–hole recombination kinetics. Physical Chemistry Chemical Physics, 3, 267-273.