Electrochemical Performance of Engineered NiCo₂O₄ in AEM Water Electrolyzers: Direct-Growth vs Spray-Coated Anode

This study investigates the synthesis and electrochemical performance of NiCo2O4 anodes for water electrolysis in both alkaline and anion exchange membrane (AEM) configurations. An engineered direct growth method using a urea-mediated sono-hydrothermal approach was used to synthesize NiCo2O4 on Ni felt, creating a binder-free electrode optimized for an alkaline environment. We evaluated the electrode's performance in AEM water electrolysis, comparing it with a spray-coated electrode incorporating ionomers and the same electrocatalyst. Our findings highlight that direct-grown binder-free electrodes, produced through varied synthesis routes, exhibit remarkable activity and stability in AEM cells operated in dry cathode mode (1.90 V @ 1 A cm-2), with seamless interaction between the catalyst layer and the membrane. Moreover, this binder-free NiCo2O4 on Ni felt is also an efficient anode under alkaline electrolysis configuration, exhibiting high stability and remarkable performance (1.78 V @ 1 A cm-2, 1.92 V @ 2 A cm-2), ascribable to the increased conductivity and improved charge transfer resistance of the catalyst layer.