Fig. 6. Electrochemical characterization and OER performance of ligand-free cuboidal NPs. Inset: TEM micrograph of non-stabilized NPs (Cb13-2). The complete TEM micrograph is displayed in Fig. S15.† Cyclic voltammograms of synthetic NPs (black curve) in comparison to a commercial Co₃O₄ nanopowder (red curve). Both samples were cycled 10 times at a scan rate of 50 mV s⁻¹. The blue trace shows the electrochemical response of a bare glassy carbon RDE. The vertical dashed line indicates the position of E_H2O/O2⁰ and the horizontal dashed line marks the current density of J = 10 mA cm⁻² at which the overpotentials η_{i = 10 mA cm⁻²} were determined.