Superior Performance and Stability of Anion Exchange Membrane Water Electrolysis—Non-Precious Electrocatalysts for the Oxygen Evolution Reaction

The application of electrocatalysts with high activity to a practical water electrolysis cell is a crucial challenge for the production of pure hydrogen and commercialization of the water electrolyzer. Herein, the Cu–Co oxide electrocatalysts were synthesized for the OER through pH-controlled co-precipitation to apply as the anode electrode of AEMWE. We developed nano-sized Cu_0.5Co_2.5O₄ with abundant oxygen vacancies very easily and creatively by using the difference in precipitation rate with the pH of Cu and Co. It was confirmed that Cu_0.5Co_2.5O₄, which has been optimized by pH control, has many oxygen vacancies and a large amount of Co3+, which is an active site for the OER. Because of this, it exhibits superior catalytic activity and long-term stability in the half-cell tests. Recent reports on electrocatalysts for water electrolysis have only focused on catalytic activity in half-cell tests. An important point for the commercialization of water electrolysis is that they should show excellent performance even when the catalyst is applied to an electrolyzer. This study not only compared the catalytic activity of the synthesized Cu_0.5Co_2.5O₄ catalyst but it also directly applied a full cell for the AEMWE system to confirm the performance of practical hydrogen production. The performance of the AEMWE cell was higher than that of any AEMWE cells reported in the literature, even compared to the AEMWE using IrO₂ as an anode.