Electrolyte cation types control electrochemical reactions on an electrode surface

March 07, 2024

The international research collaboration between NIMS and the Finnish University of Jyväskylä has uncovered significant insights into oxygen reduction reactions (ORRs) on electrode surfaces in electrochemical systems. They found that electron and proton transfer mechanisms during ORRs vary depending on the types of cations dissolved in the electrolyte solution. Specifically, they discovered two distinct ORR pathways—inner-sphere (IS) and outer-sphere (OS)—occurring on platinum electrode surfaces, each yielding different products. The choice between these pathways is influenced by the electrolyte composition: lithium ions favor the OS pathway, while potassium and sodium ions promote the IS pathway. These differences in ORR pathways may be attributed to the ways in which these electrolytic cations interact with the electrode surface, water molecules and ORR intermediates.
This discovery indicates that controlling ORR mechanisms can be achieved by adjusting the electrolyte composition, offering a novel approach to improving the energy conversion efficiency of electrocatalytic systems without relying on expensive electrode materials. By understanding how electrolytic ions interact with electrode surfaces and ORR intermediates, researchers aim to enhance the performance of both electrodes and electrolytes, potentially leading to even higher ORR efficiency and expanded pathway options.

From: EurekAlert!