The MPI CEC is proud to be part of a groundbreaking research collaboration that has shed new light on the mechanism of cobalt-catalyzed acidic oxygen evolution reaction (OER). In a recent paper published in Nature Energy, an international collaboration of researchers from MPI-CEC, Monash University, Swinburne University of Technology, Los Alamos National Laboratory, Helmholtz-Zentrum Berlin for Materials and Energy, and Cambridge University, has made significant progress in understanding the behavior of cobalt-based catalysts in low-pH water electrolysis.

A Critical Step towards a Hydrogen Economy

The development of efficient and cost-effective catalysts for low-pH water electrolysis is crucial for the establishment of a hydrogen economy. Proton-exchange membrane water electrolysis (PEMWE) is a promising technology that relies on scarce and expensive iridium as a catalyst on the anode side. However, the limited availability of iridium poses a significant bottleneck for the widespread adoption of PEMWE. The team of researchers aimed to address this challenge by exploring an alternative catalyst based on the far more abundant elements cobalt, iron, and lead, which was developed from our Partners at Monash University.

Analysis of Catalytic and Degradation Mechanisms

By employing a multi-technique approach, including alternating current voltammetry, in situ hard and soft X-ray spectroscopy, electrochemical quartz crystal microbalance studies and first principle calculations, the researchers gained insights into the evolution of the [CoFePb]O_x catalysts active state when successively reaching relevant potentials to drive the reaction. The results show that the stabilization process of the catalyst occurs on a relatively slow timescale of minutes. The research also proposes a multi-site absorbate evolution reaction mechanism, which includes both Co and Pb sites, rather than taking place on Co-oxide-clusters. This finding is distinct from reaction mechanisms proposed for Co-based catalysts in neutral or alkaline conditions.

Key Findings and Implications

The study has revealed that the dissolution and reaction mechanisms of the studied cobalt-based catalysts occur independently of each other, rather than being linked. The discovery has important implications for the development of such catalysts for effective and stable low-pH water electrolysis and allows to address the optimization of the activity and stability of such systems as individual challenges. In this regards the findings represent important milestone in understanding such catalyst systems for future optimization.  

The team members of the MPI CEC played a crucial role in this research collaboration, contributing expertise in the fields of operando soft X-ray spectroscopy and electrochemical quartz crystal microbalance studies. Dr. Marc Tesch and Dr. Ioannis Spanos of the ‘Electrochemistry’ group at MPI CEC made significant contributions to the design and execution of the experiments, as well as the interpretation of the results. Their expertise in operando spectroscopy and electrochemical analysis was instrumental in gaining insights into the behavior of the studied catalysts.

Outlook and Future Directions

The study can guide future strategies in the development of iridium-free catalysts for PEMWE. The analysis of similar compounds can be undertaken to study the universality of the findings made on the [CoFePb]O_x catalyst. Finally, the studied system can be further enhanced and validated under industrial conditions to evaluate its potential as alternative to iridium-based catalysts for PEMWE.

The MPI CEC is committed to advancing the understanding of energy conversion processes and developing innovative solutions for a sustainable energy future. Our research collaboration has made significant progress in this direction, and we look forward to continuing our work in this exciting field.

Original Paper: Simondson, D., Tesch, M.F., Spanos, I. et al. Decoupling the catalytic and degradation mechanisms of cobalt active sites during acidic water oxidation. Nat Energy (2025). https://doi.org/10.1038/s41560-025-01812-x