Morphology-dependent impedance and electrocatalytic activity of Ni-Co nanocoatings

In this work, it was shown that by varying the pH of the electrolyte for electrodeposition of the bimetallic NiCo system on carbon felt, it is possible to obtain thin coatings of different morphologies. The chemical composition of the synthesized coatings and the distribution of metals in them were determined by the PXRD and EDX methods. The morphology of the coatings was studied using SEM: rough for NiCo(r) synthesized from an electrolyte with pH = 4 and smooth for NiCo(s) obtained at pH = 6. A set of electrochemical techniques (CVA, ChP, ECSA measurement, EIS) demonstrated that a smooth NiCo(s) coating has a smaller surface area (200 cm2), but is more effective as an electrocatalyst for the hydrogen evolution reaction (110 = -130 mV) than a rough NiCo(r) (110 = - 226 mV) with a surface area of 338 cm2. Based on the EIS results, equivalent circuits of the NiCo system on carbon felt are calculated and modeled.

Automated summary

This study demonstrates the production of thin coatings with different morphologies of bimetallic NiCo system on carbon felt by adjusting the pH of the electrolyte. The electrochemical performance of the coatings was evaluated using various techniques, showing that a smooth NiCo(s) coating is more effective as an electrocatalyst for the hydrogen evolution reaction compared to a rough NiCo(r). Equivalent circuits of the NiCo system on carbon felt were calculated and modeled based on the EIS results.