Optimized repeated impregnation-drying co-precipitation method for roll-to-roll industrial production: A case study on FeCo(OOH)x catalysts for the oxygen evolution reaction

The oxygen evolution reaction (OER) plays a crucial role in hydrogen production, but its potential is limited by the lack of scalable and stable electrocatalysts for industrial applications. In this study, we developed a repeated impregnation-drying co-precipitation (RIP) method to prepare CoFe-based OER electrocatalysts. We found that the optimized FeCo(OOH) x -5/NF catalyst achieves an overpotential of 340 mV at 500 mA cm −2 , significantly outperforming catalysts prepared via hydrothermal or chemical bath deposition methods. The RIP method accelerates the co-precipitation rate of metal ions and helps repair defects between the catalytic layer and the nickel foam substrate, promoting the three-dimensional growth of the catalyst layer. Notably, the entire reaction occurs in air, and the solution can be reused, ensuring the optimal utilization of all ions. Additionally, the FeCo(OOH) x -5/NF catalyst was scaled up to 6000 cm 2 to assess the feasibility of roll-to-roll industrial production. In practical alkaline water electrolysis, electrolyzers equipped with FeCo(OOH) x -5&RANEY Nickel catalysts demonstrated excellent performance, achieving 500 mA cm −2 at 1.75 V in 6.0 M KOH. This work provides valuable insights into the design of efficient alkaline OER electrocatalysts, such as FeCo(OOH) x /NF, for promising industrial applications.