Oxygen Management in Ruthenium–Cerium Anode Facilitates Water Adsorption and Bubble Desorption for Oxygen Evolution at High Current Densities
Aparna M. Das, Viktoria Golovanova, Anku Guha, Bruna Ferreira Gomes, David Llorens Rauret, Alba Garzón Manjón, Adrián Pinilla-Sanchez, Lulu Li, Jordi Morales-Vidal, Tengyu Chen, Lu Xia, Ranit Ram, Andrea Rogolino, Carlos M. S. Lobo, Kaiwen Wang, Teresa Andreu, Christina Roth, Juan Jesús Velasco-Vélez, Jordi Arbiol, Núria López, F. Pelayo García de ArquerAbstract
The production of hydrogen via acidic water electrolysis requires efficient oxygen evolution reaction (OER) at high current densities. However, this is often limited by oxygen bubble accumulation, which blocks active sites and restricts water access. Although bubble release and water access are closely linked, these interfacial processes are rarely controlled together. We engineer a ruthenium oxide–cerium oxide (RuOx–CeOx) catalyst where CeOx is observed to modulate surface oxygen vacancies during operation, enhancing water availability and promoting bubble detachment in RuOx. In situ X-ray absorption studies show that CeOx dynamically facilitates the formation of surface oxygen vacancies, and Raman spectroscopy indicates improved electrolyte wetting under applied potentials. Simulations reveal that oxygen-depleted RuOx surfaces favor water accumulation, thereby facilitating the initiation of OER. This results in distinct bubble dynamics with a four-fold reduction in median bubble contact area and lower overpotentials at high current densities in RuOx–CeOx compared to RuOx. Implementation in a proton exchange membrane water electrolyzer achieves a 0.1 V reduction in full-cell potential at 1 A·cm–2, linking surface chemistry to device-level outcomes.