Superior performance of an anion exchange membrane water electrolyzer: Sequential electrodeposited Co-based oxygen evolution catalyst

Green hydrogen production in the anion exchange membrane water electrolysis (AEMWE) field requires catalysts for the oxygen evolution reaction (OER) with high performance, low cost, and ease of fabrication. Here, we report a sequential electrodeposited Co-based electrode supported on FeOxHy (Fe@Co) as a superior anode in alkaline media. The Fe@Co electrode exhibited an overpotential of 184 mV at 10 mA cm−2 with a Tafel slope of 44 mV per decade in 1 M KOH solution. In an AEMWE single-cell, it showed a current density of 1,780 mA cm−2 at 1.8 V at 50 °C, outperforming the state-of-the-art OER catalysts. This notable OER performance was attributed to the Fe-based support, which not only increased the active sites and oxidation state of Co but also formed Fe active sites. By comparing with other support materials and adjusting the method for synthesizing Fe, it was confirmed that Fe@Co has the highest OER activity. Our discovery and analysis of the sequential electroplating strategy provide an innovative perspective in the field of non-noble-metal AEMWE, which is a step forward toward cost-effective green hydrogen generation for the oncoming hydrogen economy.