In the storage of renewable energy using water electrolysis, the structural dynamics of the electrified electrode–electrolyte interfaces, where electricity is converted into chemical energy, plays a significant role.
The hydrogen evolution reaction (HER) and the conversion efficiency of the oxygen evolution reaction are interfacial processes with extremely complex mechanisms. To accelerate these processes and make them more efficient, a comprehensive fundamental understanding of electrocatalysis is indispensable.
For decades it was considered that the electrocatalytic reactions can be accelerated by the reduction of activation energy. That was routinely attempted by optimization of adsorption energies of intermediates, in accordance to the Sabatier principle, the main paradigm of electrocatalysis.
In a recent publication in ACS Catalysis, Dr. Aleksandar R. Zeradjanin, Scientific Staff at MPI CEC (LINK TO PROFILE PAGE) and colleagues present new experimental findings on HER that can further deepen the general understanding of electrocatalysis.
Particularly noteworthy is the very surprising observation that the most active metals for HER (i.e. noble metals), which have the lowest overpotentials at a given current density, have the highest activation energies compared to the other metals of the d-block. This indicates a large, if not dominant, influence of the frequency factor on the activity trends and the need to think more deeply about the causes of electrocatalytic activity.
Obtained results received significant attention of audience during recent keynote lecture of Dr. Zeradjanin at Symposium 2022 at MAPEX Center for Materials and Processes, Bremen.
Detailed information can be found in the publication.
Original Publication:
Aleksandar R. Zeradjanin, Praveen Narangoda, Justus Masa, and Robert Schlögl (2022). What Controls Activity Trends of Electrocatalytic Hydrogen Evolution Reaction? - Activation Energy Versus Frequency Factor. ACS Catalysis 12 (19), 11597-11605 DOI: https://doi.org/10.1021/acscatal.2c02964