In the presence of ammonia (0.2 M, phosphate buffer at pH 10.8), catalytic onset is evident at approximately 0.6 V vs. NHE, coinciding with the Ru III /Ru IV oxidation (Figure ). Ru IV has been previously identified as the active species for ammonia oxidation in aqueous media. Furthermore, a weak Ru II /Ru III transition can be observed at approximately 0.25 V vs. NHE for 1 (Figure ). We note that little catalytic activity is observed for CA measurements at 0.5 V vs. NHE (Ru III ) with the amount of charge passed similar to blank mITO (3 mC). Ammonia oxidation was also observed on bare mITO, albeit with an increased overpotential. Electrocatalysis was carried out for 90 min at 0.9 V vs. NHE (Ru IV ), a potential where background oxidation by the electrode material is minimal (Figure and c, black line). Nitrate formation was identified as the main product with FE of up to 100 ± 4%, as determined by the Griess test (Figure , Table -10). Subsequent reabsorption of the guest molecules demonstrated decent stability of the surface-bound PA [6]. However, based on the charge accumulation during the experiment, a decrease in catalytic activity of approximately 30-40% was observed (Figure ). This suggests the presence of fewer host-guest complexes, indicating partial desorption of PA [6].