Insights on the Performance of Nickel Foam and Stainless Steel Foam Electrodes for Alkaline Water Electrolysis

Abstract

Green hydrogen production seems to be the best route to achieve a sustainable alternative to fossil fuels, as hydrogen has the highest energy density on a mass basis and its combustion does not produce greenhouse gases. Water electrolysis is the method of choice for producing green hydrogen. Among commercially available water electrolysis systems, alkaline water electrolysis (AWE) is the most well-established technology, which, nevertheless, still needs to improve its efficiency. Since the electrodes’ performance is of utmost importance for electrolysis efficiency, nickel foam (NF) and stainless steel foam (SSF) electrodes were analyzed via voltammetry to validate their catalytic activity toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 30 wt.% NaOH electrolyte solution. Moreover, at a current density of 50 mA cm−2, the NF and the SSF exhibited good stability, with the potential for HER and OER stabilizing at −0.5 V and 1.6 V vs. reversible hydrogen electrode. A lab-scale electrolyzer attained current densities of 10, 20, and 50 mA cm−2 at small cell voltages of 1.70 V, 1.80 V, and 1.95 V. The results validated NF and SSF as electrodes for a high-performance AWE electrolyzer, especially at higher temperatures. They ensured the progress for the project’s next stage, i.e., constructing an electrolyzer at a pilot scale.

Bubbles in Porous Electrodes for Alkaline Water Electrolysis

“…Determination of C area is illustrated in Figure S5. Since the nickel catalysts are used here, the areal capacitance of the smooth nickel electrode is employed as C ref , which is equal to 19 μF /cm 2 . The ratios of the ECSA to projected area, ECSA/ A , for various porous electrodes are presented in Figure b.…”