Electronic conductivity of films of electroflocculated 2 nm iridium oxide nanoparticles

The electronic conductivity of films of iridium oxide (IrO(x)) composed of ca. 2 nm nanoparticles (NPs) is strongly dependent on the film oxidation state. The Ir(IV)O(x) NPs can be electrochemically converted to several oxidation states, ranging from Ir(III) to Ir(V) oxides. The NP films exhibit a very high apparent conductivity, e.g., 10(-2) S cm(-1), when the NPs are in the oxidized +4/+5 state. When the film is fully reduced to its Ir(III) state, the apparent conductivity falls to 10(-6) S cm(-1).