Atomic-scale insights into surface reconstruction and transformation in Co-Cr spinel oxides during the oxygen evolution reaction

During the oxygen evolution reaction (OER), electrocatalysts undergo surface transformation. We found that Cr dissolution in Co-Cr spinel oxide triggers reversible hydroxide-to-oxyhydroxide transformation that enhances OER activity and stability.

B. He, P. Hosseini, T. Priamushko, O. Trost, E. Budiyanto, C. Bondue, J. Schulwitz, A. Kostka, H. Tüysüz, M. Muhler, S. Cherevko, K. Tschulik, T. Li, Nature Communications (2025) 9895.

Chelation-Driven Electrolyte Design for Enhanced Interface and Electrochemical Window in Aqueous Aluminum Batteries

This study addresses key challenges in aqueous aluminum-ion batteries by introducing the chelating agent Bis(2-methoxyethyl)amine (BMEA) to restructure the solvation environment and suppress detrimental side reactions. By forming a stable solid-electrolyte interphase and expanding the electrochemical window, the BMEA-based electrolyte enables a high-capacity (218.0 mAh g⁻¹) Al||TCB battery with excellent cycling stability over 300 cycles.

D.Y. Wang, E. Hu, G. Wu, H. Choo, C. Franke, B.E. Jia, J. Song, A. Sumboja, I.T. Anggraningrum, A.Z. Syahrial, Q. Zhu, M.F. Ng, T. Li, Q. Yan, Angewandte Chemie (2025) e202508641.

Unveiling Surface Species Formed on Ni-Fe Spinel Oxides During the Oxygen Evolution Reaction at the Atomic Scale

This study investigates how surface state changes in Ni-Fe spinel electrocatalysts impact their oxygen evolution reaction (OER) performance using advanced characterization techniques. It finds that NiFe₂O₄ and P-doped NiFe₂O₄ develop a defective, oxygen-rich surface layer that enhances charge transfer and lowers the Tafel slope, whereas Ni₁.₅Fe₁.₅O₄ lacks this feature, leading to inferior catalytic performance.

W. Xiang, S. Hernandez, P. Hosseini, F. Bai, U. Hagemann, M. Heidelmann, T. Li, Advanced Science (2025) 2501967.

A Review of Surface Reconstruction and Transformation of 3d Transition-Metal (oxy)Hydroxides and Spinel-Type Oxides during the Oxygen Evolution Reaction

This review explores the dynamic transformations of 3d transition-metal (oxy)hydroxides and spinel-type oxides during the oxygen evolution reaction (OER), highlighting key elementary processes that impact their performance. By critically assessing oxidation, surface reconstruction, cation dissolution, and other factors, it provides insights for designing next-generation OER electrocatalysts for sustainable energy applications.

B. He, F. Bai, P. Jain, T. Li , Small, (2025) 2411479.

Effects of Dynamic Surface Transformation on the Activity and Stability of Mixed Co-Mn Cubic Spinel Oxides in the Oxygen Evolution Reaction in Alkaline Media

This study uses a multimodal approach to investigate how Co₂MnO₄ and CoMn₂O₄ electrocatalyst surfaces dynamically reconstruct and transform during the oxygen evolution reaction (OER). The findings reveal that Co₂MnO₄ forms Co-Mn oxyhydroxides with an optimal Co/Mn ratio, which enhances OER stability through Mn dissolution and redeposition, while CoMn₂O₄ forms less active Mn-rich oxides during the process. Read more...

B. He, P. Hosseini, D. Escalera-López, J. Schulwitz, O. Rüdiger, U. Hagemann, M. Heidelmann, S. DeBeer, M. Muhler, S. Cherevko, K. Tschulik, T. Li, Advanced Energy Materials, (2024) 2403096.

Revealing Dynamic Surface and Subsurface Reconstruction of High-Entropy Alloy Electrocatalysts during the Oxygen Evolution Reaction at the Atomic Scale

High-entropy alloys (HEAs) are promising for oxygen evolution reaction (OER) electrocatalysts, but understanding their surface and subsurface changes during OER is key to improving performance. Our study reveals that the CrMnFeCoNi Cantor alloy undergoes dissolution and complex layer formation during OER, leading to activity deterioration, highlighting the importance of structure–activity–stability relationships in HEAs. Read more...

C. Luan, D. Escalera-López, U. Hagemann, A. Kostka, G. Laplanche, D. Wu, S. Cherevko, T. Li, ACS Catalysis, 14 (2024) 12704–12716.

Correlating atomic-scale structural and compositional details of perovskite nanoparticles with activity and stability towards the oxygen evolution reaction

To develop efficient oxygen evolution reaction (OER) electrocatalysts, we used atom probe tomography and transmission electron microscopy to analyze LaCoO₃ and Ca-doped LaCoO₃ surfaces. Our findings reveal that while LaCoO₃ surfaces deteriorate after OER due to the formation of amorphous La(OH)₃, Ca-doped LaCoO₃ shows enhanced OER activity and stability due to increased hydroxide ion intercalation and the appearance of a Co ^3+/4+ redox couple. Read more...

F. Bai, J. Schulwitz, T. Priamushko, U. Hagemann, A. Kostka, M. Heidelmann, S. Cherevko, M. Muhler, T. Li, Journal of Catalysis, 438 (2024) 115697.

Linking Composition, Structure and Thickness of CoOOH to Oxygen Evolution Reaction Activity by Correlative Microscopy,

Our correlative multimodal approach can link local activity with atomic-scale details of structure, morphology and composition of surface species formed during the oxygen evolution reaction (OER). We found that 6 nm β-CoOOH(01-10) layer, grown on [-12-10]-oriented Co, contains more hydroxyl ions and easily reducible CoIII-O sites, exhibiting a higher OER activity than 3 nm thick β-CoOOH(10-13) formed on [02-21]-oriented Co. Read more..

C. Luan, J. Angona, A. BalaKrishnan, M. Corva, P. Hosseini, M. Heidelmann, U. Hagemann, E.B. Tetteh, W. Schuhmann, K. Tschulik, T. Li, Angewandte Chemie International Edition, 62 (2023).

Atomic-scale Insights to Morphological, Structural and Compositional Evolution of CoOOH during Oxygen Evoltuion Reaction

We unveil that in situ generated thin ß-CoOOh(0001) layer undergoes dynamic morphological and elemental changes along with (de)incorporation of water molecules and hydroxyl groups during OER, which in turn alters OER perfomance.

C. Luan, M. Corva, U. Hagemann, H. Wang, M. Heidelmann, K. Tschulik, T. Li;  ACS Catalysis 12 (2023) 1400-1411.

Atomic-scale Characterisation of (electro-)catalysts and battery materials by atom probe tomography

This perspective provides an overview of recent developments in experimental setups, sample preparation methods and data analysis algorithms for APT.

T. Li, A. Devaraj, N. Kruse; Cell Reports Physical Science 3 (2022) 101188.

3D atomic-scale imaging of mixed Co-Fe spinel oxide nanoparticles during oxygen evolution reaction

We use atom probe tomography to elucidate the 3D structure of 10 nm sized Co₂ FeO₄ and CoFe₂O₄ nanoparticles during oxygen evolution reaction (OER). We reveal nanoscale spinodal decomposition in pristine Co₂FeO₄.

W. Xiang, N. Yang, X. Li, J. Linnemann, U. Hagemann, O. Ruediger, M. Heidelmann, T. Falk, M. Aramini, S. DeBeer, M. Muhler, K. Tschulik, T. Li;  Nature Communications 13 (2022) 179.