Microscope images from the operando TEM experiments: Changes of the surface structure of the catalyst nanoparticles observed upon altering the temperature. Credit: FHI

In a study appearing in Nature Catalysis, researchers from the Inorganic Chemistry Department of the Fritz Haber Institute reveal how structural changes on the surface and in the bulk region of the cobalt oxide catalyst Co3O4 influence its selectivity in the production of industrially relevant chemicals like acetone.

They discovered that a metastable, structurally "trapped" state exhibits the highest catalytic activity—an important finding for catalyst design.

Heterogeneous catalysis, a cornerstone of the chemical industry

From ammonia synthesis to plastics production, heterogeneous catalysis is a fundamental process in the chemical industry. The catalyst is often in solid form, while other reagents are liquid or gaseous, which is ideal for separating the reaction products at the end. Therefore, a great deal of research is being invested in the development and refinement of heterogeneous catalysts.

This study emphasizes that findings regarding the processes on the catalyst surface must be taken into account.

The role of selectivity in catalysis

The ideal catalyst can preferentially promote a specific, desired reaction when multiple reactions are possible—it is selective. This property, which can be controlled through catalyst design, is crucial for industrial processes as it enhances product purity and saves energy, since it avoids cumbersome post-reaction product-separation processes.

However, it often remains unclear what exactly determines selectivity at the molecular level. To understand this, the research team uses operando methods that allow them to observe the catalysts "at work."

Gaining a new understanding of catalytic oxidation

In the study, the research team sheds light on a significant heterogeneously catalyzed industrial process in which selectivity plays an important role: the oxidation of isopropanol (2-propanol) to acetone using cobalt oxide (Co₃O₄) for thermal catalysis.

They combine operando X-ray spectroscopy and operando transmission electron microscopy to get a deeper insight into the catalyst performance, particularly how it is influenced by the processes taking place on the catalyst surface and within its interior (the bulk region).

How surface reactions influence catalyst performance

The comparison of catalyst activity measurements in a reactor and the operando information about the structural changes during catalyst operation yield two activity phases: one below and one above 200 °C. At lower temperature, a network of solid-state processes such as diffusion and defect formation distort the catalyst structure, which controls the catalytic properties of Co3O4, while at higher temperature, crystal ordering dominates.

Interestingly, the ideal combination of activity and selectivity is found at 200 °C, namely at the boundary between the two phases. Here, the catalyst can be conceived to be trapped in a transition between two energetically equivalent states, where small changes to the conditions can cause the system to flip between these states.

It is desirable to keep the catalyst in this state for optimized performance. This can be achieved by creating optimal working conditions, but might also be further enhanced by catalyst design and suitable pretreatment.

Significance of the findings

The findings of the study challenge conventional catalyst design. The study suggests that striving for a "perfect, stable" crystalline catalyst can sometimes be suboptimal. Rather, the authors show here that surface structural changes critically determine the activity and selectivity of oxidation catalysts.

Their methodology—combining operando spectroscopy, microscopy and activity measurements—sets a benchmark for how to study catalysts under realistic conditions, capturing dynamic behavior that is invisible in commonly used analysis.

Finally, the study even suggests a shift in how chemists should think about heterogeneous catalysis: catalyst surfaces should no longer be perceived as just static, but as dynamic materials where internal restructuring, defect chemistry, and metastable transitions strongly matter.

Publication details

Thomas Götsch et al, Local solid-state processes adjust the selectivity in catalytic oxidation reactions on cobalt oxides, Nature Catalysis (2025). DOI: 10.1038/s41929-025-01449-9

Citation: Catalyst selectivity as a balancing act: Co₃O₄ ‘trapped’ in transition shows peak activity (2026, January 19) retrieved 19 January 2026 from https://phys.org/news/2026-01-catalyst-coo-transition-peak.html

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