Helping catalysts breathe: Accelerating bubble release improves water electrolysis performance
Water electrolysis transforms water into hydrogen and oxygen gas. Now, ICFO researchers and collaborators have engineered the catalyst interface to tackle oxygen bubble accumulation, improving electrochemical performance. The strategy, published in ACS Catalysis, offers a path toward more efficient green hydrogen generation.
Hydrogen, if efficiently produced through water electrolysis, could become a major clean energy carrier for decarbonizing our society. One often overlooked challenge in water electrolysis, though, is the formation of oxygen bubbles at the anode, particularly under acidic conditions and at high current densities. Bubble build up blocks active sites, restricting water access to the catalyst surface and, consequently, degrading overall performance.
ICFO researchers, Aparna Das, Dr. Viktoria Golovanova, Dr. Anku Guha, Adrián Pinilla Sánchez, Tengyu Chen, Dr. Lu Xia, Ranit Ram, Andrea Rogolino, Dr. Kaiwen Wang, led by Prof. F. Pelayo García de Arquer at ICFO, have now developed a strategy that mitigates the problems associated with bubble accumulation. By engineering oxygen vacancies (a spot in the material where an oxygen atom is missing), interfacial water is better adsorbed at the catalyst surface. This promotes oxygen bubble detachment and suppresses the instabilities these bubbles induce, thereby improving electrochemical performance. The study, recently published in ACS Catalysis, was conducted in close collaboration with Prof. Jordi Arbiol at the Catalan Institute of Nanoscience and Nanotechnology (ICN2) and Prof. Núria López at the Institute of Chemical Research of Catalonia (ICIQ), as well as the University of Bayreuth and ALBA Synchrotron Light Source.
To achieve these results, the team engineered a ruthenium oxide-cerium oxide (RuOx-CeOx) catalyst as the anode in a water electrolyzer . Compared with a RuOx control catalyst, the bubbles that formed were four times smaller and the operating voltage was lower, which translates into energy savings. This is because CeOx acts as an oxygen buffer at the catalyst surface: it promotes the formation of oxygen vacancies, increases water availability and accumulation, and speeds up bubble detachment. “Although oxygen-vacancy formation is commonly regarded as a source of instability in ruthenium oxides, our results show that it can also be beneficial in terms of providing adequate water to the interface at high currents,” explains Aparna Das, first author of the article.
The team also observed improved performance when using iridium oxide–cerium oxide (IrOx-CeOx) systems, suggesting that the strategy could be extended to other catalysts combined with cerium oxide, a generalization the team plans to explore in the coming years.
Overall, this work highlights the importance of considering interconnected phenomena in electrocatalysis and underscores how fundamental surface properties can shape macroscale performance metrics. “By revealing a strong correlation between oxygen vacancies, water coverage, bubble dynamics, and catalytic activity, we offer a promising strategy for engineering more efficient catalyst–electrolyte interfaces,” says Prof. Pelayo García de Arquer, who led the study. “This, we believe, will be essential if we want to produce green hydrogen through water electrolysis under industrially relevant conditions.”
Reference:
Aparna M. Das, et. al.; Oxygen Management in Ruthenium–Cerium Anode Facilitates Water Adsorption and Bubble Desorption for Oxygen Evolution at High Current Densities. ACS Catal. 2026; https://doi.org/10.1021/acscatal.6c04063
Acknowledgements:
ICFO thanks the Fundació Cellex, Fundació Mir-Puig, CEX2024-001490-S, the European Union (NASCENT, 101077243), PID2022-138127NA-I00, and RED2024-154266-T projects funded by the MCIN/AEI/10.13039/501100011033/FEDER, UE; the European Union (NASCENT, 101077243) and ICONIC (101115204); Ignite (7th edition), Generalitat de Catalunya through CERCA (SGR 2021 01455); Fundación Ramón Areces (CIVP21S13318). ICN2 thanks the Generalitat de Catalunya 2021SGR00457; the Advanced Materials programme supported by MCIN and Next Generation EU (PRTR-C17.I1) and the Generalitat de Catalunya (In-CAEM Project); AMaDE (PID2023-149158OB-C43), funded by MCIN/AEI/10.13039/501100011033/ and by “ERDF A way of making Europe”, by the “European Union”; the Severo Ochoa program from Spanish MCIN/AEI (Grant No.: CEX2021-001214-S); the CERCA Programme/Generalitat de Catalunya. Part of the present work has been performed in the framework of the Universitat Autònoma de Barcelona Materials Science PhD program. D.L.R. acknowledges grant PRE2022-102638. A.G.M. has received funding from Grant RYC2021-033479-I, funded by MCIN/AEI/10.13039/501100011033, and by the European Union Next Generation EU/PRTR. The authors acknowledge the use of instrumentation as well as the technical advice provided by the Joint Electron Microscopy Center at ALBA (JEMCA). ICN2 further acknowledges funding from Grant IU16-014206 (METCAM-FIB) funded by the European Union through the European Regional Development Fund (ERDF), with the support of the Ministry of Research and Universities, Generalitat de Catalunya. ICN2 is a founding member of e-DREAM. (60) The authors also acknowledge the Federal Ministry of Education and Research (BMBF) under the funding codes Live XAS (Grant 05K22WC1) and HighHy (Grant 03SF0689B). The authors thank Bessy (Berlin, Germany) and DESY (Hamburg, Germany), members of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at the BAMline (Bessy) and PETRA III (DESY). The authors would like to thank Dr. Ana G. Buzanich (Bessy) and Dr. Wolfgang Caliebe (DESY) for assistance during the experiments. Beamtime was allocated for proposals 232-12335ST (Bessy) and I-20230896 (DESY). ICFO, ICIQ, and ICN2 acknowledge support from Generalitat de Catalunya and AGAUR (2023 CLIMA 00105). L.L., J.M.-V, and N.L. thank the Spanish Ministry of Science and Innovation (PID2024-157556OB-I00 funded by MICIU/AEI/10.13039/501100011033/ FEDER, UE), and Severo Ochoa Excellence Accreditation (CEX2024-001469-S funded by MCIU/AEI/10.13039/501100011033). L.L. also acknowledges funding from the European Union's Horizon Europe research and innovation programme through the Marie Skłodowska-Curie Actions (MSCA) grant (101149049-ADAMox). We thank the Barcelona Supercomputing Center MareNostrum (BSC-RES) for providing generous computiational resources.