The oxygen molecule (pink) binds to potassium ions (green) at the platinum-water interface. **marko melander
Electrochemical reactions are at the heart of the green transition. These reactions use electric current and potential difference to carry out chemical reactions, which enable the electrical energy of chemical bonding to be combined and realized. This chemistry is the basis for a variety of applications, such as hydrogen technology, batteries, and aspects of the circular economy.
The development and improvement of these techniques requires a detailed understanding of electrochemical reactions and the different factors that affect them. Recent studies have shown that, in addition to the electrode material, the solvent used, its acidity, and the electrolyte ions used have a crucial impact on the efficiency of the electrochemical reaction.
Therefore, the recent focus has shifted to studying how the reaction environment at the electrochemical interface, such as the electrode and electrolyte interface, affects the outcome of an electrochemical reaction.
Understanding interfacial chemistry using only experimental methods is very difficult because they are very thin, only a fraction of a nanometer. Therefore, computational and theoretical are crucial because they provide an accurate way to study electrochemical interfaces at the atomic level and as a function of time.
The long-term development of methods and theories in the Department of Chemistry at Jyväskylä University (Finland) has provided a new understanding of the chemistry of the electrochemical interface, especially the electrolyte ion effect.
Two of our recent research articles focus on the electrolyte ion effect in the reduction reaction of oxygen and carbon dioxide, which determines the efficiency of fuel cells, hydrogen peroxide synthesis, and the conversion of carbon dioxide into carbon-neutral chemicals and fuels," says Marco Melander, a researcher at the Finnish Academy of Sciences at Jyväskylä University's Department of Chemistry.
The electrochemical interface is a very complex reaction environment in which multiple interactions and processes contribute to chemical reactions. **marko melander
Combine experimental and calculated results.
Researchers at Jyväskylä University collaborated with experimental and computational groups to understand electrolyte effects. The findings were recently published in journals such as Nature Communications and Angewandte Chemie International Edition.
In both studies, we focus on the fundamental properties and research, which requires the use of highly accurate and demanding experiments combined with the latest simulation methods. For example, for the first time, we were able to combine experiments and simulations of the quantum-mechanical kinetic isotopic effects of hydrogen to understand oxygen reduction reactions. We have also developed and applied advanced computational methods to simulate the recombination of aqueous electrolyte solutions to understand in detail their combined effects on the reaction mechanism," explains Melander.
This study provides an atomic diagram of how electrolytes affect electrochemical reactions. One definite mechanism is bond formation between ions and reactive molecules.
We were able to demonstrate that ions control the structure and dynamics of electrode surface and interfacial water through non-covalent interactions. These rather weak interactions determine the reaction pathway, rate, and selectivity, which control the activity and outcome of the electrochemical reaction," Melander explains.
While this research focuses on fundamental aspects of electrochemical systems, it can lead to the development of improved electrochemical techniques.
The use of ionic and solvent effects can provide a way to adjust the reactivity and selectivity of electrochemical reactions. For example, electrolytes can be used to direct oxygen reduction reactions into fuel cells or hydrogen peroxide synthesis applications. Electrolyte chemistry is also an effective way to direct CO2 reductions to needed, valuable products," says Melander.
More information: Xueping Qin et al., Changes in the mechanism of cation-induced electrocatalytic CO2 reduction of inner and outer spheres, Nature Communications (2023). doi： 10.1038/s41467-023-43300-4