Shedding Synchrotron Light on Model Transition Metal Electrocatalysts

Licentiatavhandling, 2026

Green hydrogen is key in transforming various industrial sectors towards decarbonization. Non-noble metal electrode materials like Ni, Co and Fe are preferred in alkaline water electrolysis due to their low cost and availability. A major challenge in achieving efficiencies close to the thermodynamic optimum is to overcome the slow kinetics of the oxygen evolution reaction (OER). Moreover, the impact of Fe incorporation into the catalyst on the catalytic properties is not fully understood. An increase in the fundamental understanding of the structural and dynamic processes at the electrode surfaces will contribute to the rational design of new and more efficient electrocatalysts. In this thesis, surface-sensitive operando techniques are used to gather atomic-scale insights on the dynamic surface structures of model Co and Ni (oxy)hydroxide electrodes and the influence of Fe on their structure and activity.

High-energy surface X-ray diffraction (HESXRD) is used to monitor the Ni and Co oxide and (oxy)hydroxide surface structures in model single crystal electrodes on an atomic scale under operando conditions. HESXRD is combined with Surface Optical Reflectance (SOR), which gives additional information on surface roughness or surface optical parameters.

The correlation of HESXRD, SOR and electrochemical data identified potential-dependent surface structure transformation processes between Ni and Co (oxy)hydroxides in the transition to OER. Fe doping of the Ni electrode lowered the overpotential required for OER and could be linked to changes in the surface structure. Following the Fe-electrodeposition on Co revealed changes in the complex Co surface structure and its catalytic activity depending on the amount of deposited Fe.