Periodic Reporting for period 2 - 123STABLE (Towards Nanostructured Electrocatalysts with Superior Stability)
Periodo di rendicontazione: 2021-07-01 al 2022-12-31
ERC Starting Grant 123STABLE is addressing the problem of unstable energy conversion fuel cells and electrolyzers. Especially, in their core component, namely electrocatalyst, the fundamental understanding of its long-term performance stability is not yet sufficient. Due to the scarcity and limited access to platinum and iridium, which are essential for these applications and at the same time also critical raw materials, we need to optimally utilize them to enable hydrogen economy technologies to become effective and economically viable. This is important for society as hydrogen economy provides the solution to completely replace fossil fuels and thus resolve global warming and eliminate the pollution it is causing. Fuel cells and electrolyzers possess enormous potential for converting and storing the harvested energy from the sun (wind) in a completely sustainable way. Although the technology is well known and already commercialized in some applications like cars, it still possesses a lot of space for improvement and further development. The aim of the 1234STABLE project is to obtain new insights into noble metals' atomic-scale corrosion and use this knowledge to design and produce new and improved metallic nanostructures with superior stability.
In the first half of the project, most of the work was done on the establishment of the methodology (schematically represented in the attached image) and on the use of this advanced characterization approach to study Pt- and Ir-based electrocatalysts. More specifically, methodology for the preparation of different kinds of electrocatalysts was established, ranging from different Pt- and Ir-alloy nanoparticles, with different dopants and decoration, sizes and on different supports (Pavko et al, ACS Appl. Energy Mater. 2021). Secondly, an identical location transmission electron microscopy approach was upgraded to enable high current densities and atomic resolutions (Hrnjić et al, Electrochim. Acta 2021). Furthermore, experimental methods and protocols to enable measuring online dissolution and volatile species detection via mass spectroscopy were established. Still, further upgrades are planned that will enable our experimental setup to be even more versatile.
Among others, in the recent paper by Đukič et al, ACS Catalysis 2021 online dissolution setup was upgraded to enable temperature control. Interestingly, upon raising the temperature in electrochemical testing of our PtCo/C catalyst, we revealed that while less noble metal (Co) dissolution was increasing Pt dissolution was decreasing.
Progress was also made on electron microscopy data processing and simulations, which is part of work package 2 (Koderman Podboršek et al, Electrochim. Acta 2022). We demonstrated the ability to automatically process atomically resolved STEM images with in-house developed computer algorithms where different unprecedented information can be extracted, for instance, surface roughening was increasing through the electrochemical treatment of Ir nanoparticles larger than 2 nm Ir nanoparticles, whereas for smaller ones it remained constant. We believe this approach will also reveal new atomically-resolved catalysts stability insights in other electrocatalytic systems.
First results were achieved for work package 3 where perspective Pt-based electrocatalysts with enhanced stability were already produced on a large scale (Pavko et al, ACS Catalysis 2022). We are now developing methods to prepare even more stable Pt catalysts and different methods to produce Ir-based catalysts on a larger scale.
Among others, in the recent paper by Đukič et al, ACS Catalysis 2021 online dissolution setup was upgraded to enable temperature control. Interestingly, upon raising the temperature in electrochemical testing of our PtCo/C catalyst, we revealed that while less noble metal (Co) dissolution was increasing Pt dissolution was decreasing.
Progress was also made on electron microscopy data processing and simulations, which is part of work package 2 (Koderman Podboršek et al, Electrochim. Acta 2022). We demonstrated the ability to automatically process atomically resolved STEM images with in-house developed computer algorithms where different unprecedented information can be extracted, for instance, surface roughening was increasing through the electrochemical treatment of Ir nanoparticles larger than 2 nm Ir nanoparticles, whereas for smaller ones it remained constant. We believe this approach will also reveal new atomically-resolved catalysts stability insights in other electrocatalytic systems.
First results were achieved for work package 3 where perspective Pt-based electrocatalysts with enhanced stability were already produced on a large scale (Pavko et al, ACS Catalysis 2022). We are now developing methods to prepare even more stable Pt catalysts and different methods to produce Ir-based catalysts on a larger scale.
Our new advanced characterization methodology platform has enabled us to go beyond the state-of-the-art in an understanding of Pt- and Ir-based electrocatalysts. We are now in the process of utilizing our unique approach to reveal new unprecedented insights into nanoparticulate electrocatalysts' degradation mechanisms. We have prepared various new variations of catalyst that we are now testing. Our ability to prepare multi-gram batches enables us to conduct also tests in real fuel cells and electrolyzers. Following the success in establishing the new methodology, new synthesis procedure and our in-house data processing computer algorithms we expect several high-impact publications in the next 12 months.