Inexpensive and Efficient Alkaline Water Electrolyzer with Robust Steel-Based Electrodes

Abstract

Electrolysis of aqueous solutions of alkali is a promising approach for the production of pure hydrogen. For this approach to be economical on a large scale, the overpotentials for the electrode reactions and the high-cost of nickel-based electrode substrates must be reduced. We report here on the performance of an “all-iron” electrolyzer cell that uses inexpensive steel-based electrodes. This alkaline water electrolyzer uses a steel mesh coated with a thin catalytic coating of alpha-nickel hydroxide for the oxygen evolution electrode, and another steel mesh sputter-coated with nickel and molybdenum for the hydrogen electrode. An alkaline electrolyzer with these steel-based electrodes, a commercial Zirfon® separator, and a solution of 30% potassium hydroxide exhibited an electrolysis cell voltage of 1.83 V and 1.71 V at 100 mA cm −2 when operating at 23 °C and 70 °C, respectively. We show that the performance of the steel-based electrodes is comparable to commercial electrodes based on nickel substrates. When the cell was operated continuously for 100 h at 1 A cm −2 at 23 °C, there was no measurable loss in performance, providing a preliminary confirmation of the robustness of these iron-based electrodes and electrocatalysts. We conclude that cost-effective iron-based electrolyzers could be a promising route to low-cost hydrogen production.