For the catalyst screening, the effect of applied potential, and stability studies, a solution of 0.1 M KNO3 and 0.1 M KHCO3 was used. For the effect of concentration of NO3 -, the following solution concentrations were used: 1 M KNO3 + 0.1 M KHCO3, 0.5 M KNO3 + 0.1 M KHCO3, 0.1 M KNO3 + 0.1 M KHCO3, 0.01 M KNO3 + 0.1 M KHCO3, and 0.001 M KNO3 + 0.1 M KHCO3. The solution was sparged with CO2 by using a sparger for 15 mins such that the solution is equilibrated with CO2. The pH of the solution was measured before and after electrolysis by using a pH probe. Gas products were collected during the experiment using a gas bag by flowing Ar at a rate of 30 sccm for a period of 30 mins. Liquid products remain in the catholyte and hence the catholyte was collected in a vial post-electrolysis. The possible gas products are CO, CH4, H2, and N2. The gas products were quantified by using Gas Chromatography (GC) (SRI Multiple Gas Analyzer). The possible liquid products are NH3, urea, NO2 -, and HCOOH. NH3 and urea were quantified by using colorimetric techniques, NO2 -was quantified by using Ion exchange chromatography (IC) (Metrohm), and the rest of the products were quantified by using high-performance liquid chromatography (HPLC) (Agilent 1200 HPLC).