Elucidation of the discharge mechanism of CuO cathode material in alkaline electrolyte

Two CuO materials were synthesized having vastly different physico-chemical properties – one being amorphous with a high BET surface area, while the other is a low-area crystalline material. Linear sweep voltammetry characterization in a 9.0 M KOH electrolyte revealed markedly different discharge behavior in terms of reaction pathway, with the amorphous material undergoing a two-step process and the crystalline material a single step process. Investigation into the mechanism of the discharge of the amorphous CuO suggests a possible dissolution/re-precipitation route. This was confirmed by direct electrochemical detection of the soluble reduced intermediate. Confirmation of this mechanism explained the different reaction pathway followed by the crystalline sample, as the material is kinetically inert to the solubilization step in the mechanism, forcing it to discharge via an altogether different two-electron pathway.