Synergistic Effect of Cobalt and Iron in Layered Double Hydroxide Catalysts for the Oxygen Evolution Reaction

Co-based layered double hydroxide (LDH) catalysts with Fe and Al contents in the range of 15 to 45 at% were synthesized by an efficient coprecipitation method. In these catalysts, Fe3+ or Al3+ ions play an essential role as trivalent species to stabilize the LDH structure. The obtained catalysts were characterized by a comprehensive combination of surface-and bulksensitive techniques and were evaluated for the oxygen evolution reaction (OER) on rotating disk electrodes. The OER activity decreased upon increasing the Al content for the Co-and Al-based LDH catalysts, whereas a synergistic effect in Co-and Fe-based LDHs was observed, which resulted in an optimal Fe content of 35 at %. This catalyst was spray-coated on Ni foam electrodes and showed very good stability in a flow-through cell with a potential of approximately 1.53 V at 10 mAcm(-2) in 1m KOH for at least 48 h.