Periodic Reporting for period 4 - 123STABLE (Towards Nanostructured Electrocatalysts with Superior Stability)
Période du rapport: 2024-07-01 au 2025-10-31
ERC Starting Grant 123STABLE addresses the problem of limited long-term stability in fuel cells and water electrolysers, two key technologies for the emerging hydrogen economy. Their core components, called electrocatalysts, are made of tiny nanoparticles of precious metals such as platinum and iridium. These metals are scarce, expensive and classified as critical raw materials in Europe, and we still do not fully understand how and why they slowly degrade during operation. This lack of understanding limits our ability to use them efficiently and to make hydrogen technologies truly cost-effective. This challenge is highly relevant for society. A hydrogen-based energy system can help us move away from fossil fuels, reduce greenhouse gas emissions and improve air quality. Fuel cells can convert hydrogen into electricity for cars, buses and industry, while electrolysers can use renewable electricity from the sun and wind to produce green hydrogen from water. Although these technologies are already entering the market, their cost and durability still need significant improvement to enable large-scale deployment. The overall objective of 123STABLE was to gain new insight into how precious-metal nanoparticles corrode and change at the atomic scale, and to use this knowledge to design nanostructured catalysts with much better stability. The project followed a simple logic: first observe individual nanoparticles during operation with advanced microscopes and electrochemical methods, then understand the mechanisms behind their degradation, and finally design new catalyst structures that are more resistant to these processes.
By the end of the project, we had developed new platinum- and iridium-based electrocatalysts that show clearly improved stability under relevant conditions, outperforming current benchmark materials. We achieved this by optimising their composition, internal structure, interaction with the support and activation procedures. In parallel, we created a new experimental “NanoLab” approach that allows us to follow nanoscale structural changes during synthesis and operation. The knowledge and tools developed in 123STABLE have started to influence both academic research and industrial development. Our institute has transferred know-how and granted an exclusive licence for catalyst production and characterisation to the start-up company ReCatalyst, which was also supported by an ERC Proof of Concept grant.
By the end of the project, we had developed new platinum- and iridium-based electrocatalysts that show clearly improved stability under relevant conditions, outperforming current benchmark materials. We achieved this by optimising their composition, internal structure, interaction with the support and activation procedures. In parallel, we created a new experimental “NanoLab” approach that allows us to follow nanoscale structural changes during synthesis and operation. The knowledge and tools developed in 123STABLE have started to influence both academic research and industrial development. Our institute has transferred know-how and granted an exclusive licence for catalyst production and characterisation to the start-up company ReCatalyst, which was also supported by an ERC Proof of Concept grant.
In the first half of the project, most effort focused on establishing the methodological platform (schematically shown in the attached figure) and applying advanced characterisation tools to Pt- and Ir-based electrocatalysts. We developed robust synthesis routes for a wide range of Pt- and Ir-alloy nanoparticles with different dopants, decorations, sizes and supports (Pavko et al., ACS Appl. Energy Mater. 2021). In parallel, we significantly enhanced the identical-location TEM approach to operate at high current densities and (near) atomic resolution for both Pt-based (Hrnjić et al., Electrochim. Acta 2021) and Ir-based systems (Bele et al., ACS Appl. Nano Mater. 2023). We established experimental methods and protocols to measure online metal dissolution and detect volatile species (Moriau et al., Electrochim. Acta 2024; Pavko et al., Carbon 2023), creating the core NanoLab platform.
Using this platform, we then gained new mechanistic insight into degradation and structure–stability relationships. In Đukić et al., ACS Catalysis 2021 and 2024, temperature-controlled online dissolution experiments showed that higher temperature increases Co dissolution but reduces Pt dissolution in PtCo/C, and that Pt loss can be strongly minimised by optimising the potential window. In parallel, we developed in-house algorithms to automatically analyse atomically resolved STEM images and quantify effects such as size-dependent surface roughening of Ir nanoparticles (Koderman Podboršek et al., Electrochim. Acta 2022). Towards the end of the project, we integrated 4D-STEM into the identical-location concept and created a machine-learning-based “IL-TEM scale-up” workflow (Hrnjić et al., ACS Catalysis 2024; Kamšek et al., ACS Nano 2025; Research Square preprint, 2025), turning IL-TEM into a high-throughput, statistically robust tool that, together with NanoLab and temperature-controlled online ICP-MS, uniquely correlates structure, composition, dissolution and performance across large nanoparticle populations.
For work package 3, our initial results demonstrated Pt-based intermetallic alloy electrocatalysts with enhanced stability that can already be produced on a larger scale (Pavko et al., ACS Appl. Energy Mater. 2021). We then showed that stability can be further improved by tailoring the support, in particular by moving from conventional carbon to reduced graphene oxide (Pavko et al., Carbon 2023) and to titanium oxynitride (Hrnjić et al., ACS Catalysis 2024). In the final phase, we broadened testing to multiple electrochemical configurations (RDE, MFE, GDE) for Pt catalysts and developed synthesis and scale-up procedures for Ir-based catalysts, which were subsequently evaluated in different electrochemical cell setups.
The work has resulted in a series of high-impact publications (e.g. in ACS Nano, ACS Catalysis, Carbon), numerous conference presentations and invited talks. Methodologically, we documented the experimental workflows in a dedicated paper and released software and analysis scripts as open-source tools on GitHub. Industrially, our institute transferred know-how and granted an exclusive licence for catalyst production to the spin-off company ReCatalyst (ERC PoC), enabling exploitation of the results in commercial fuel-cell and electrolyser catalysts. Finally, the methodologies developed in 123STABLE are now being extended beyond Pt and Ir to other important systems, such as copper catalysts for CO2 reduction (Tomc et al., J. Mater. Chem. A 2025).
Using this platform, we then gained new mechanistic insight into degradation and structure–stability relationships. In Đukić et al., ACS Catalysis 2021 and 2024, temperature-controlled online dissolution experiments showed that higher temperature increases Co dissolution but reduces Pt dissolution in PtCo/C, and that Pt loss can be strongly minimised by optimising the potential window. In parallel, we developed in-house algorithms to automatically analyse atomically resolved STEM images and quantify effects such as size-dependent surface roughening of Ir nanoparticles (Koderman Podboršek et al., Electrochim. Acta 2022). Towards the end of the project, we integrated 4D-STEM into the identical-location concept and created a machine-learning-based “IL-TEM scale-up” workflow (Hrnjić et al., ACS Catalysis 2024; Kamšek et al., ACS Nano 2025; Research Square preprint, 2025), turning IL-TEM into a high-throughput, statistically robust tool that, together with NanoLab and temperature-controlled online ICP-MS, uniquely correlates structure, composition, dissolution and performance across large nanoparticle populations.
For work package 3, our initial results demonstrated Pt-based intermetallic alloy electrocatalysts with enhanced stability that can already be produced on a larger scale (Pavko et al., ACS Appl. Energy Mater. 2021). We then showed that stability can be further improved by tailoring the support, in particular by moving from conventional carbon to reduced graphene oxide (Pavko et al., Carbon 2023) and to titanium oxynitride (Hrnjić et al., ACS Catalysis 2024). In the final phase, we broadened testing to multiple electrochemical configurations (RDE, MFE, GDE) for Pt catalysts and developed synthesis and scale-up procedures for Ir-based catalysts, which were subsequently evaluated in different electrochemical cell setups.
The work has resulted in a series of high-impact publications (e.g. in ACS Nano, ACS Catalysis, Carbon), numerous conference presentations and invited talks. Methodologically, we documented the experimental workflows in a dedicated paper and released software and analysis scripts as open-source tools on GitHub. Industrially, our institute transferred know-how and granted an exclusive licence for catalyst production to the spin-off company ReCatalyst (ERC PoC), enabling exploitation of the results in commercial fuel-cell and electrolyser catalysts. Finally, the methodologies developed in 123STABLE are now being extended beyond Pt and Ir to other important systems, such as copper catalysts for CO2 reduction (Tomc et al., J. Mater. Chem. A 2025).
Our new advanced characterization methodology platform, which combines electrochemical methods (e.g. modified floating-electrode setup) with identical-location electron microscopy and advanced data treatment, has enabled us to go beyond the state-of-the-art in an understanding of Pt- and Ir-based electrocatalysts. Utilizing our unique approach, we are uncovering unprecedented insights into nanoparticulate electrocatalyst degradation mechanisms, namely structure-stability relationships. Based on these insights, we prepared and tested various new catalyst variations. Our capability to produce multi-gram batches enables validation in real fuel cells and electrolysers under relevant operating conditions. For Pt-based electrocatalysts, these activities have also been translated towards commercialization through the ERC PoC project (Grant Agreement ID: 966654) and the spin-off company ReCatalyst, further supported by the EIC Transition Grant (Grant Agreement ID: 101112991). Building on our new methodology, synthesis procedures and in-house data-processing algorithms, we have published several high-impact papers in the past year, with additional publications and some optimized catalyst concepts expected even after the end of the project.