Here is a selection of recent scientific papers I (co-)authored. A complete list can be found on my Google Scholar. All code that led to published works can be found on my GitHub.
On the crystal structure of nanoparticles
Modern electrocatalysts for the oxygen reduction reaction in a hydrogen fuel cell are commonly composed of platinum-alloy nanoparticles on a carbon support. Understanding what does or doesn’t influence activity or stability helps us focus on what truly improves them.
At the atomic scale, platinum and copper atoms may be randomly mixed or arranged in an ordered structure. We found that ordered sites near the particle surface, where the reaction occurs, are more stable when preparing the catalyst for long-term use. This was possible by combining identical-location 4D-STEM with unsupervised learning.
Structure–Stability Relationships in Pt-Alloy Nanoparticles Using Identical-Location Four-Dimensional Scanning Transmission Electron Microscopy and Unsupervised Machine Learning.
A.R. Kamšek et al, ACS Nano, 19 (2), 2334–2344, 2025.
Within the ordered phase, defects known as anti-phase boundaries can form, as previously seen in bulk alloys. In this work, we confirmed they also appear in nanoparticles, but found no effect on the catalytic activity.
Periodic anti-phase boundaries and crystal superstructures in PtCu₃ nanoparticles as fuel cell electrocatalysts.
A.R. Kamšek et al, Materials Today Nano, 23, 100377, 2023.
Microscopy in focus
We showed how identical-location microscopy tracks the local history of platinum-cobalt nanoparticles, which complements the bulk information from other methods like electrochemical measurements.
The first paper compares commercial electrocatalysts for the oxygen reduction reaction in acidic media, and the second is a detailed STEM investigation of platinum-cobalt nanoparticles at the atomic scale.
Resolving the nanoparticles’ structure–property relationships at the atomic level: a study of Pt-based electrocatalysts.
L.J. Moriau et al, iScience, 24 (2), 102102, 2021.
Observing, tracking and analysing electrochemically induced atomic-scale structural changes of an individual Pt–Co nanoparticle as a fuel cell electrocatalyst by combining complementary electron microscopy techniques.
A. Hrnjić et al, Electrochimica Acta, 388, 138513, 2021.
Scanning electron microscopy was used here to image more realistic catalyst layers, including very small nanoparticles. The presence of a membrane resulted in more moderate catalyst degradation.
Realistic fuel cell catalyst degradation via automated identical location SEM-PSD analysis with the GDE half-cell setup.
M. Kostelec et al, ACS Catalysis, 16 (12), 11207-11218, 2026.
Atomically resolved images hold more detail than the human eye can process. This review explains how algorithms can unlock that hidden information, enabling the objective image analysis of datasets too large or too tricky for manual work.
Bringing into play automated electron microscopy data processing for understanding nanoparticulate electrocatalysts’ structure–property relationships.
A.R. Kamšek et al, Current Opinion in Electrochemistry, 35, 101052, 2022.
What about the support?
The performance of electrocatalysts with supported nanoparticles can be improved not only by optimizing the noble-metal-based nanoparticles, but also by tailoring the support. Certain supports, such as ceramics, can interact with nanoparticles in ways that improve the catalytic performance.
These two papers are examples of how using a titanium oxynitride support created beneficial metal–support interactions for reactions in hydrogen fuel cells and water electrolyzers.
Metal–support interaction between titanium oxynitride and Pt nanoparticles enables efficient low-Pt-loaded high-performance electrodes at relevant oxygen reduction reaction conditions.
A. Hrnjić et al, ACS Catalysis, 14 (4), 2473–2486, 2024.
Titanium oxynitride-supported Ru nanoparticles as exceptional electrocatalysts for alkaline hydrogen evolution reaction.
M. Smiljanić et al, Chemical Engineering Journal, 164204, 2025.
Carbon capture
This paper explores electrocatalytic CO₂ reduction, a carbon capture and utilization technology. Copper catalysts speed up the reaction, but their structural changes during operation affect long-term performance.
Deactivation of copper electrocatalysts during CO₂ reduction occurs via dissolution and selective redeposition mechanism.
B. Tomc et al, Journal of Materials Chemistry A, 13 (6), 4119–4128, 2025.
