Co-doping MoS₂ nanosheets with Fe and Co atoms induces electronic and structural modifications that enhance the sluggish OER activity of the MoS₂ catalyst.

Ethanol–water etched Prussian blue analog nanocages decorated with molybdenum disulfide nanoflowers exhibit remarkable electrocatalytic activity toward the OER. The catalyst delivers an excellent OER activity with an overpotential of only 260 mV to obtain a current density of 10 mA cm⁻².

Supercapacitors (SCs) coupled with redox materials have been extensively investigated to maximize the energy density of SCs. Common metal–organic frameworks explicitly used for this purpose are Prussian blue analogs (PBAs). However, their low conductivity and number of external electroactive sites hinder their capacitance and reaction rate. Our work focuses on a material-level optimization strategy, including morphology modification and superstructure fabrication of PBA. We report the synthesis of Co–Co@Ni–Fe trimetallic core–shell PBA nanocubes containing an Fe^II/III redox couple in the Ni–Fe PBA shell over the conductive Co–Co PBA core. This complex underwent a reversible redox reaction and was further encapsulated in a polypyrrole (PPy) network as a redox additive to prepare a novel polymer-encapsulated double-PBA nanocube composite (Co–Co@Ni–Fe PBA–PPy). The composite exhibited a faradaic non-capacitive diffusion-dominated charge storage ability. It yielded an improved specific capacity of 318.1 C g⁻¹ at 1 A g⁻¹ with a capacity retention of 90% over 2000 cycles @15 A g⁻¹. Furthermore, an asymmetric supercapacitor based on Co–Co@Ni–Fe PBA–PPy and activated carbon electrodes delivered a maximum energy density of 20 W h kg⁻¹ at a power density of 808.9 W kg⁻¹ within a 1.6 V voltage window. The electrochemical analysis demonstrated a considerable improvement in the charge-storage performance due to an increase in electron transfer, electrolyte diffusion, and electroactive area via strong electronic coupling between the Co–Co@Ni–Fe core–shell PBA and the PPy. Furthermore, this work helps to differentiate the composite's current contributions from the PBA and PPy. The detailed electrochemical characterization steps of these methods concerning redox additives integrated into conducting polymers are provided in this work.