Chromium Effect Over the Hydrogen Evolution Reaction and Corrosion Behavior on Ni-Cr Porous Electrodes

This work aimed to evaluate the hydrogen evolution reaction and the corrosion behavior of the Ni and Ni-Cr porous electrodes as a function of the chromium content. Porous electrodes were fabricated by powder metallurgy, and the chromium content was varied from Ni-5Cr, Ni-10Cr, Ni-15Cr, and Ni-20Cr. The electrocatalytic activity of the Ni-Cr systems was determined by overpotential at 100 mA cm^-2, analyzing the cathodic branch of potentiodynamic tests. Otherwise, the corrosion behavior was determined by polarization curves and linear polarization resistance using an electrolyte of 1.5 M NaOH. The Ni-Cr electrodes showed a segregation of chromium on the Ni particle boundary after the sintering process for the Ni-5Cr, Ni-10Cr, and Ni-15Cr; however, the Ni-20Cr sample showed a better distribution of nickel and chromium according to de EDS analysis obtained which influence significantly on HER and corrosion behavior which showed a higher catalytic activity due to present the lower overpotential calculated. Otherwise, the polarization curves and linear polarization resistance showed a better performance in the Ni porous sample caused by a lower corrosion rate and higher polarization resistance. As chromium content increases, the corrosion resistance is reduced. The chromium solubility in the nickel matrix increases the HER and reduces the corrosion resistance.