CoO_x@NiMoN/Ti₃C₂T_x Interface for Stable High‐Performance Electrochemical Energy Storage Devices

Abstract Transition metal nitrides (TMNs) are promising electrode materials for use in high‐performance electrochemical energy storage devices due to their unique properties, which include a high conductivity, pseudocapacitance, and energy density. However, structural instability during electrochemical reactions has limited their practical deployment for energy storage devices. In this context, the present study fabricated a CoO_x@NiMoN/Ti₃C₂T_x electrode via in situ growth on Ni foam using hydrothermal treatment with post‐nitrogenization. The effect of atomic layer deposition (ALD) of CoO_x on the TMN/Ti₃C₂T_x interface and the consequent electrochemical charge storage mechanisms are investigated in detail. The proposed CoO_x@NiMoN/Ti₃C₂T_x electrode delivers an impressive specific capacity in a 2 m potassium hydroxide (KOH) electrolyte and is then employed in both a hybrid solid‐state supercapacitor (HSSC) with reduced graphene oxide and a symmetric SC in a 2 m KOH + polyvinyl alcohol (PVA) gel electrolyte. Outstanding charge storage and high capacity retention during cyclic testing are observed for both energy storage devices. The exceptional electrochemical performance of the fabricated electrode is a result of its high conductivity and high number of active sites. Here a feasible new strategy is demonstrated for the fabrication of stable energy storage devices with a high energy density using TMNs and MXenes.