This is the new beacon of research that for the first time brings to light dwell times present in the intricate choreography between ions and electrocatalyst surfaces underpinning energy and chemical conversion technology.
Navigating the Ionic Hike
Picture this: the ions are intrepid hikers, navigating the ups and downs of electro catalyst surfaces. Through new research, we now know that this path is not nearly as straight forward.
To comprehend this process, it is imperative to undergo the structural reorganization that occurs in the solvation shell surrounding the metallic ions. The solvation shell of ions before intercalation into battery cathodes, entering ion channels across biochemical membranes, or adsorption and conversion on to valuable chemicals on electrocatalyst surfaces. While it may seem like a pretty simple step, this is one of the most important parts in the mechanism — and one that until now has mystified clues for the past fifty years.
A group of researchers from the Fritz-Haber Institute — for example, have finally unraveled the connection between activation entropy and enthalpy which vests control on solvation kinetics at electrocatalyst surfaces. Interpreting the kinetics through the theories of statistical physics and Eyring-Evans-Polanyi equation, they achieved for the first time an insight into this fundamental process.
Uncovering the Mysteries of Solvation Kinetics
Armed with this new knowledge, the researchers say their breakthrough has wide-reaching ramifications for fields involving electro catalysis and energy conversion technologies.
The team developed a millisecond-resolution method to directly access the electrosorption kinetics of hydroxide ions on structural features like step-edges or defects (see figure). The researchers could not measure these kinetics in detail until now, leading to them having a finer resolution of how these kinetics correlate with the overall electrocatalyst performance.
These were not the only revelations that the team made. Additionally, they explored the poisoning dynamics of the platinum surface during NH3 oxidation and how it influences the solvation kinetics. Uncovering changes at even finer scales could revolutionize how we perceive electrocatalyst activity and stability, leading to the creation of faster and more durable catalysts.
By far the most provocative of these results has been the realization that changes in pH can directly affect activation entropy, causing non-Nernstian activity trends with cell potential. This contradicts the conventional wisdom that it is activation energy which fundamentally drives the bias dependence of these reactions.
Conclusion
The work of the team at the Fritz-Haber Institute opens a new chapter in our understanding of kinetics of solvation on electrocatalyst surfaces. Through statistical physics and cutting-edge experimental methods, they have provided new insight into this complex puzzle that plays out as ions tango with their solvation shells– a fundamental interaction that could hold the key to the development of energy or chemical conversion technology in the future. Exploring these insights in more detail could have a transformative impact on fields from battery design to hydrogen production.
