Two-Step Bipolar Electrochemistry: Generation of Composition Gradient and Visual Screening of Electrocatalytic Activity.

Bipolar electrochemistry (BE) is employed for both creating electrocatalysts composition gradient and visual screening of the prepared composition on a single substrate in just two experiment runs. In a series of proof-of-principle experiments, we demonstrate gradient electrodeposition of Ni-Cu using BE; then the electrocatalytic activity of the prepared composition gradient toward the hydrogen evolution reaction (HER) is visually screened in the BE system using array of BPEs. Moreover, the morphology and the chemical composition of the Ni-Cu gradient are screened along the length of the bipolar electrode (BPE). By measuring the potential gradient over the BPE, it is also demonstrated that by controlling the concentration of the metals precursor and the supporting electrolyte, the length of the bipolar electrodeposited gradient can be controlled.