Novel Anode Materials for Oxygen Evolution during Seawater Electrolysis for Green Hydrogen Fuel Production

Mn1-x-yMoxWyO2+x+y triple oxide electrocatalysts for the anode producing oxygen without forming chlorine in seawater electrolysis were prepared by anodic deposition. The performance of the anode for oxygen evolution in 0.5 M NaCl solutions was examined. The tungsten addition was effective in extending the life of the anode by decreasing the density of pores in electrocatalysts responsible for partial detachment of electrocatalysts, which occurs by high pressure of oxygen formed preferentially at the bottom of pores during electrolysis. Repeated anodic deposition of the electrocatalyst significantly extended the life of the anode, because repeated deposition was able to cover the pores in the underlying electrocatalysts. The potential observed in anodic polarization of an oxide electrode was the sum of the overpotential of the electrochemical reaction and the potential drop as a result of passage of current through the oxide. The potential difference of the two anodes at individual current, Ei, versus the current, i, should show the straight line: The gradient, Ei/i, is the difference of the electrical resistances of the two electrodes, and the activity of the two anodes can be compared from the current, i, at Ei= 0 volt. The tungsten addition enhanced the activity for oxygen evolution.