Decoupling the contributions of industrially relevant conditions to the stability of binary and ternary FeNi-based catalysts for alkaline water oxidation

As a crucial half-reaction in electrochemical water splitting, advancing the stability performance of the oxygen evolution reaction (OER) under industrial conditions is of great importance for practical water electrolysis. Nonprecious FeNi-based binary and ternary catalysts have been developed with improved activity toward the OER in alkaline media. However, these catalysts often exhibit degradation under industrial water electrolysis operation conditions. Here, we demonstrate the impact of industrially relevant conditions on the long-term stability performance of binary NiFe and ternary FeNiCr hydroxide as a showcase of highly active catalysts. Under the simulation of industrial operating conditions in alkaline water electrolysers (AWEs), the ternary FeNiCr catalyst exhibits a faster decline in the OER stability compared to the binary FeNi catalyst. Decoupling of industrial conditions revealed that the concentration of alkaline electrolyte has the biggest effect on stability decline followed by temperature and current density. Results show a different metal dissolution pattern during the OER compared to the binary FeNi catalyst, entailing changes in surface morphology and overpotential increase. The findings in this study reveal the significance of testing conditions in developing high-performance and durable catalysts for practical water electrolysis. Decoupling the industrially relevant conditions simulating the electrolytic conditions in alkaline water electrolysers reveals a larger stability decay for ternary FeNiCr hydroxides as a promoted catalyst for water oxidation compared to binary FeNi.