Area-Step Cyclic Voltammetry for Assessing Local Electrocatalytic Activity of Gradient Materials

This work presents a voltammetric method for measuring the electrocatalytic activity of gradient materials as a function of position across the material surface. The Ni-Cu-Fe gradient alloys are deposited on nickel substrates by bipolar electrochemistry and tested as an electrocatalyst for oxygen evolution reaction (OER). We attempt "area-step" cyclic voltammetry to continuously measure the local electrocatalytic activity of the gradient alloys, by serially increasing the contact area between the electrolyte and the gradient surface. The local surface roughness can also be characterized using the same procedure. The parallel experiments consistently point to the same position where presents the highest intrinsic OER activity. Both the Fe content in the alloys and the surface roughness play important roles in the OER.