Polyoxometallates act as electon relays in a photocatalytic process that involves POM/S/Mn+ (POM = polyoxometallates PW12O403−, SiW12O404− and P2Mo18O626−; S = organic substrate and Mn+ = metal ions Ag+, Cu2+, Pd2+ and Ni2+). By a suitable choice of POM and, to a lesser extent, organic substrate, selective photocatalytic reduction of metal ions in aqueous solutions can be achieved.
