GCMS with labeled 15 NH3 solution (0.5 M in H2O) did not show any conversion to 30 N2 (Figures and), which led us to the assumption that different products must be formed in water. Inspired by the work of Liu et al. we tested our systems with the Griess test (Figures ) after electrocatalysis to determine the formation of NO2 -and NO3 -in water. Selective conversion of NH3 to NO3 -was achieved when applying 0.98 V vs NHE for 90 min in 200 mM NH3 in aqueous phosphate buffer (pH= 10.86) (Figure ). Guest 1, showed high stability at pH 10.86 and a FE of 96%. Guest 2, showed varying values, with an average FE of 69%, which could be due to the high pH conditions and therefore faster desorption from the binding pocket. Thereby, the catalyst loading on the surface is limiting the charge flow and the FE. Proton decoupled N NMR studies of the anolyte solution exhibited the presence of a single peak at 371 ppm (Figure ), which can be assigned to NO3 -in basic conditions (pH 11) as referenced by a standard KNO3 sample.