Next, a series of control experiments were performed to confirm the C and N sources and shed light into the reaction pathway (Table ). As expected, the reaction in absence of electrolysis or cyclohexanone or NO3 -did not yield any oxime product (entries 2, 3 and 4). Experiments using a bare Cu foil as cathode (entry 5) were also inactive towards oxime formation, highlighting the catalytic role of the Zn93Cu7 alloy. To confirm the N source, an isotopic labelling experiment with K 15 NO3 was carried out (entry 6), and the formation of Nlabelled cyclohexanone oxime was corroborated by mass spectroscopy (Figure ). The recorded 1 H-NMR spectrum (Figure ) also revealed the duplet splitting behaviour of the 15 NH4 + peak generated from 15 NO3 -reduction, while 14 NH4 + produced by normal 14 NO3 - reduction features a triplet peak. A series of possible NO3R intermediates, including NO2 -, NO and NH2OH, was each used as the starting N source (entries 7-9) and resulted in the formation of cyclohexanone oxime, indicating a NO3R reaction pathway via those species that is consistent with previous studies. Finally, using NH3 as the N source (entry 10) failed to produce any cyclohexanone oxime, further confirming that the oxime product was generated from an intermediate of NO3R instead of the final product of NO3R (NH3).