and acetic acid as an internal standard in acidic conditions (pH = 1). The Faradaic Efficiency (FE) was calculated with: FE = (8 × F × C(NH3) × V)/Q, where F is the Faraday Constant (96485 C/mol), C is the ammonia concentration, V is the electrolyte volume in the working electrode compartment and Q is the charge passed during a chronoamperometric measurement (typically 1 h).