Part <scp>III</scp> : <scp> NiMoO ₄ </scp> nanostructures synthesized by the solution combustion method: The influence of material synthesis parameters on the electrocatalytic activity toward the oxygen evolution reaction in an alkaline me

Abstract The oxygen evolution reaction (OER) is a critical step in water electrolysis and has long been recognized as the primary bottleneck of the process, owing to its inherently sluggish kinetics and significant energy demands when compared to the hydrogen evolution reaction (HER). Transition metal oxides have been identified as promising electrocatalytic materials for the OER, attributed to their low cost, high catalytic activity, thermodynamic stability, and ease of synthesis and scalability. Among these, NiMo‐oxide‐based materials exhibit particularly advantageous electrochemical and structural properties, making them strong candidates for OER electrocatalysis. In our previously published study (Part I of the series), NiMo‐oxide nanostructures with varying physicochemical properties and microstructures were synthesized via the solution combustion method by systematically modifying key experimental parameters and subsequently tested as HER electrocatalysts. In the current study, the electrocatalytic performance of these materials was thoroughly investigated in the context of the OER in an alkaline medium. The results demonstrated that the β‐NiMoO 4 phase exhibited superior OER activity compared to the α‐phase. Notably, the in‐house catalyst outperformed the benchmark IrO 2 , achieving a lower overpotential at 10 mA cm −2 (289 mV vs. 429 mV for IrO 2 ) and a Tafel slope of 47 mV dec −1 . Furthermore, the catalyst demonstrated exceptional stability during the 24 h polarization test. The observed enhancement in long‐term performance was attributed to the formation of NiOOH and the increased surface area of the electrocatalytic layer.