FTIR experiments were conducted similar to previously established studies on nitrate reduction mechanisms. The experiments were performed on a Bruker Invenio-S infrared spectrometer. A custom-made electrochemical cell was mounted on top of a 60 0 -face angled Ge crystal was setup on a ATR VeeMax-III variable angle accessory (Pike Tech.). To enhance the metal wettability of the Ge crystal and the conductivity of the substrate, an IR transparent indium tin-oxide (ITO) layer of 100 nm was sputter coated over which using an EMS Quorum 150TS plus sputter coater. Silver (Ag) was sputter coated on top of this ITO layer with a thickness of 2 nm. After subtracting the background of the base electrolyte, a potential of -0.1 vs RHE was applied and the spectra were acquired at different time stamps with a resolution of 2 cm -1 averaged over 10 scans. A liquid N2 cooled mid-band mercury cadmium telluride (MCT) detector was used while conducting these measurements. The schematic of the setup used is provided in the supporting information (Figure ).