Ion- and surface-sensitive interactions during oxygen evolution reaction in alkaline media

Abstract

Clean and sustainable energy has turned towards electrochemical water splitting as a viable solution in minimizing carbon emissions. Electrolysis of water converts electrical energy to chemical energy, through the production of hydrogen and oxygen gases, which can be harnessed for potential applications without contributing to greenhouse emissions. While this energy storage process shows great potential, its efficiency is hindered by the sluggish kinetics of the oxygen evolution reaction (OER). As a result, its widespread application in green electrolytic technologies is limited hence investigations on improving OER kinetics are of utmost importance. Recent research breakthroughs indicate that alkali metal cations are more than passive observers. They play complex roles in the electric double layer (EDL), which positively influences the OER kinetics. The presence of numerous ions and their combinations presents a challenge of complexity. This study aims to delve into the impact of alkali metal cations on OER activity due to the variance in their hydration energies. Specific investigations focusing on different alkali metal cations in solution, such as Li+, Na+, and K+, was conducted on RuO2 to gain a deeper understanding of how these ions interact with both reactants and intermediate species in the reaction kinetics. Traditional electrochemical tests, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and accelerated degradation test (ADT) measurements were employed to elucidate critical aspects such as surface activation, electric double layer interactions, catalytic activity and stability, ohmic resistance, and mass and charge transport.