Activation of stable molecules with nanostructured oxide photocatalysts: shading light on the molecule-matter interaction with advanced characterization techniques

One of the biggest challenges of today’s society, and probably of all humankind history, is changing the paradigm of a linear and consumerist economy towards a sustainable and circular way of exploiting, transforming, and use resources and products. Shifting from a fossil fuel-based foundations to a carbon-neutral, and lately a carbon-negative economy, is crucial to ensure the future of next generations, giving them the chance to develop and progress; thus, new strategies have to be developed to successfully achieve decarbonization and CO2 concentrations abatement. This work will focus on both two pathways, exploiting photo-assisted catalysis both to upcycle carbon dioxide and convert it into high added-value and to find an alternative way to produce ammonia from sustainable resources and using milder conditions with respect to the Haber-Bosch process. An innovative procedure to prepare nanostructured materials through nanoparticles surface decoration was studied to gain knowledge about the correlation between the synthetic conditions and the final result, with the aim to further optimize the material properties. Extensive and thorough characterization of the catalysts developed allowed the correlation between the activity of each material and its properties, allowing a better understanding of the mechanisms involved and thus making room for future optimizations and further performance enhancements. In-situ and operando techniques were often exploited to gain deep insights on the catalyst role during the reaction, allowing an enhanced understanding of the interactions between the material surface and the reactants. In the present work, both material design and process optimization have been tackled to improve the catalytic performances, allowing a better understanding of the reaction mechanisms and shading light on the role of the catalyst in the process; reactor design and engineering were employed to understand better the effect of different conditions on the reaction, developing new strategies to critically assess the role of different parameters in the process.