The intermittent nature of renewable energy sources requires a clean, scalable means of converting and storing energy. One Earth-abundant storage option is water electrolysis: storing energy in the bonds of O2 and H2, and later extracting electricity by the electrochemical reaction of gasses in a fuel cell. Nickel oxides are notably active for oxygen electrocatalysis in alkaline solutions, and the perovskite structure (ANiO3) in particular. We will present studies of model oxide electrodes grown by pulsed laser deposition (PLD) and molecular beam epitaxy (MBE) on single crystal substrates that display a known crystallographic orientation, strain, surface area, and path for charge transport. Electrochemical measurements on these heterostructures can establish the intrinsic activity of oxide catalysts in a way that cannot be realized with polydisperse nanoparticle systems, and we use these findings to rationally design the nickelate composition and structure to maximize activity. Additional insight into the mechanism of the oxygen evolution reaction (OER) is obtained from spectroscopic probing of adsorbates with ambient pressure X-ray photoelectron spectroscopy (AP-XPS), pH dependence of activity, and measurements of oxygen isotope exchange. This fundamental understanding aids in the design of active, earth-abundant electrocatalysts for efficient conversion of renewable energy into chemical fuels.

Tuning the activity of nickelates for oxygen electrocatalysis

ACS Spring Meeting 2021

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