Electrodeposited NiFe-succinate for the oxygen evolution reaction in anion exchange membrane water electrolysis

This study proposes Platinum Group Metal-free (PGM-free) electrocatalysts for the Oxygen Evolution Reaction (OER) to be used in Anion Exchange Membrane Water Electrolyzers (AEMWEs). NiFe-based electrodes were synthesized via an optimized electrodeposition process in the presence of succinic acid onto a low-cost 304 stainless steel (SS) mesh, resulting in an active and durable inorganic–organic complex. Morphological characterization confirmed the formation of high-surface-area electrodes, with a catalyst layer composed of Ni and Fe ions coordinated by organic carboxylic groups. X-ray Photoemission Spectroscopy (XPS) proved the formation of NiFe 2 O 4 as the active species for OER, showing improved electrochemical performance compared to Ni-based and Fe-based electrodes. Notably, 240 mV and 306 mV were recorded as onset overpotential and overpotential at 10 mA cm −2 , respectively, with a low Tafel slope of approximately 50 mV dec −1 , using electrodes with total catalyst layer mass loading lower than 1 mg cm −2 . Density Functional Theory (DFT) calculations were performed to gain more insight into the OER mechanism on NiFe 2 O 4 species, obtaining simulated polarization curves in very good agreement with experimental data. Finally, the best-performing electrode was tested in a single-cell AEMWE, achieving a maximum current density of 1.86 A cm −2 at 2.2 V and 60 °C, and demonstrating good stability after a 40-h chronoamperometric test conducted at 2 V.