Charge separation in a niobate nanosheet photocatalyst studied with photochemical labeling. 
Photolabeling was employed to probe charge separation and the distribution of redox-active sites on the surface of nanosheets derived from the layered photocatalysts KCa(2)Nb(3)O(10).  Electron microscopy reveals 1-50 nm particles of silver, gold, iridium oxide, and manganese dioxide particles and small atomically sized clusters of platinum and IrO(x) on the nanosheet surfaces and along the edges.  The sizes, shapes, and particle densities vary with the deposition conditions, i.e., the precursor concentration and the presence of sacrificial agents.  Overall, the study shows that photogenerated electrons and holes are accessible throughout the nanosheets, without evidence for spatial charge separation across the sheet.