Local electrochemistry of nickel (oxy)hydroxide material gradients prepared using bipolar electrodeposition

Abstract

Nickel (oxy)hydroxide materials gradients were prepared using bipolar electrochemistry. A correlated microscopy approach, using scanning electron microscopy and scanning electrochemical cell microscopy, was used to study the local morphology and electrocatalytic activity of the nickel (oxy)hydroxide materials gradient. It was found that bipolar electrodeposition led to the formation of discrete nickel (oxy)hydroxide particles, while energy dispersive X-ray spectroscopy and local electrochemical surface area measurements showed that the amount of nickel on the surface increased with increasing deposition overpotential. An apparent turnover frequency was calculated for the oxygen evolution reaction as a function of electrode position enabling local electrocatalytic activity to be quantified. This new approach, combining bipolar electrochemistry with local electrochemical measurements, enables the screening of electrocatalytic materials gradients generated across the surface of heterogeneous bipolar electrode substrates.