Interestingly, the partial oxidation of graphite, observed at large positive potentials in voltammograms of Fig. , left the consecutive [IrCl 6 ] 3-voltammograms unaffected, but had notable implications for the subsequent [Ru(NH 3 ) 6 ] 3+ voltammetry. The [Ru(NH 3 ) 6 ] 3+ reduction voltammograms shown in Fig. are qualitatively similar to those of [IrCl 6 ] 3-in that they exhibit the sigmoidal steady-state behavior and the hBN curves occur at increasingly more negative potentials as the hBN thickness increases. However, the k 0 values are much higher than expected.