Electrocatalytic activity and corrosion behavior of FeMo and FeMoP coatings employed as cathode material for alkaline water electrolysis

The electrocatalytic activity and corrosion performance of binary Fe53Mo47 and ternary Fe54Mo30P16 coated alloys were compared to Ni and mild steel electrodes. The electrochemical efficiency of the electrodes was studied based on steady-state polarization, electrochemical impedance and long-term stability tests in KOH 1 M solution at 25 °C at a current density of 250 mA cm−2. The corrosion performance of these electrodes was determined via potentiodynamic measurements. The Fe54Mo30P16 electrode showed the best catalytic activity towards hydrogen evolution reaction (HER) and reduced the overpotential close to 350 mV equal to 47% as compared to mild steel and Ni. However, the results of corrosion performance revealed poor resistance of FeMo and FeMoP electrodes in comparison to Ni and mild steel. Although phosphorous addition to Fe53Mo47 enhanced the catalytic activity to HER, it deteriorated the corrosion performance of coated alloy. However, the corrosion of electrodes could be avoided by applying a protective voltage in order to create a cathodic protection or by avoiding the immersion of the electrodes in alkaline solution and their water washing during shut-down period.