Sincrotrón ALBA
Energy conversion chemical reactions: from the nanoscale properties to the catalytic activity and reactivity, by Rui Maia (University of Pennsylvania, USA) within the ALBA-FCT joint collaboration.
The search for sustainable energy sources and decentralized energy conversion has become the most important technological need of our time due to fossil fuel depletion and global climate change. I combine atomic-scale characterization through Transmission Electron Microscopy with X-ray diffraction and spectroscopy, and multivariate reaction kinetic analysis to address key scientific questions in methane oxidation to methanol over gold-palladium nanocatalysts, electrochemical CO2 reduction to hydrocarbons, CO2 fixation on alkaline minerals and degradation of platinum nanocatalysts during the oxygen evolution reaction.
This year, we developed the first approach for obtaining atomic-scale chemical and oxidation state analysis during liquid-phase TEM experiments, which was key for obtaining time-resolved chemical insights of CO2 electroreduction and battery reactions in real-world conditions. For example, our results show that large copper nanocatalysts are surprisingly more susceptible to degradation during CO2 electroreduction than the smaller ones due to greater local pH changes. Likewise, we showed that contrary to previous reports, AuAg de-alloying occurs through two sequential stages, and that the pore size is entirely dictated by the first stage where only phase separation occurs. Combining multi-faceted nanoscale characterization with reactivity studies we proposed new reaction mechanisms for the platinum catalyzed H2O2 decomposition and for the CH4àCH3OH catalyzed by AuPd, and we are unveiling the pathway and kinetics of CO2 mineralization on alkaline Mg and Ca bearing minerals.
The techniques and results obtained in these studies are contributing for the development of more efficient energy conversion and storage solutions and provide a platform for countless future studies that can help revolutionize the world energy landscape.