On How Experimental Conditions Affect the Electrochemical Response of Disordered Nickel Oxyhydroxide Films

An electrochemical conditioning protocol was developed for studying amorphous phases of nickel hydroxide films (NiO<sub><i>x</i></sub>) that renders congruent and reproducible redox behavior that enables more standardized mechanistic studies. Dynamic oxidative behavior was measured for the conditioned films, where the initial peak associated with the oxidation of NiO<sub><i>x</i></sub> contains 1.3–2.0 times the charge for that measured in subsequent oxidative scans and the corresponding reductive peak. It is shown that charge trapping does not fully account for this excess charge. The magnitude of excess anodic charge is affected by pH, OH<sup>–</sup> diffusion through the film, and voltammetric scan rates.