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).
