2022 Annual Meeting
Understanding the Impact of Residual Stress on the Activity and Selectivity of Electroreductions on Ni
Nickel is an abundant material of interest for the hydrogen evolution reaction (HER) in alkaline electrolyzers. However, Ni can form hydrides under the conditions of HER with implications on electrocatalytic activity. Nickel metal hydrides are also the basis for many battery technologies. The goal of this project is to see how changing the residual stress of an electrodeposited Nickel cathode influences its selectivity towards hydride formation, as well as change the ability of the near surface to be oxidized/reduced, where corresponding changes in electronic structure also influence electrocatalytic activity. Here, we present the HER activity and hydride formation on electrodeposited Nickel foils with low, medium and high residual stresses in comparison to Nickel foil. Along with changes in HER activity, we also consider the ability of stressed Ni to electroreduce nitrate at comparable potentials. We consider changes in activity and selectivity via shifts in metal d-states relative to the Fermi level and corresponding changes in adsorption and competition of species at the surface. The trends indicate that residual stress is a promising approach to increase activity and selectivity towards electroreduction reactions for earth abundant transition metals.