Probing the Hydrogen Interaction with Supported Pt and Pd Catalysts by Inelastic Neutron Scattering

Pt and Pd nanoparticles on carbonaceous supports are widely employed as heterogeneous catalysts for hydrogenation reactions, and find application in fundamental industrial sectors such as fine chemistry or as fuel cell electrocatalysts. Carbonaceous materials are also largely investigated as hydrogen storage materials, and the introduction of metal nanoparticles was demonstrated to be able to increase the hydrogen uptake of the material. Albeit their routine use, many details about their interaction with H₂, and hence on their hydrogenation catalytic activity, are still not completely understood.<br/>In this presentation, I will make a journey into the recent advances we made on the understanding of several key aspects of these catalysts: the influence of the carbon activation method and possible post-treatment on the catalytic activity [1,2]; the morphology of the H-terminated graphenic domains [3]; identification and quantification of functional groups [4]; the active hydrogen species in the catalytic process [5]; the dynamical nature of the active species [6,7,8]; the catalysts support interaction including spillover effects [5,8]; the differences in behavior between gas and liquid phase [7,9]. All such effects are those that together finally shape catalytic activity and selectivity.<br/>In this respect, Inelastic Neutron Scattering played a major role thanks to its high sensitivity to hydrogen. INS spectra display an unprecedented quality, allowing the detection of extremely small changes on real catalysts. The data obtained for this same set of carbons and catalysts from other laboratory techniques, offered us the possibility to critically compare the results without the issue of sample reproducibility. When necessary, measurements were made on the same catalysts supported on alumina, to be able separate effects due to active phase or support.<br/>Overall, our findings provide important insights for better understanding the complex nature of the support-catalysts system and the interaction between hydrogen and Pt and Pd-loaded catalysts.<br/><br/><b>References</b>:<br/>[1] <i>Catal. Sci. Technol.</i> <b>2016</b>, 6, 4910; [2] <i>Catal. Sci. Technol.</i> <b>2017</b>, 7, 4162; [3] <i>Carbon</i> <b>2020,</b> 169, 357-369; [4] <i>Catal. Sci. Technol.</i> <b>2022</b>, 12, 1271; [5] <i>Faraday Discuss.</i> <b>2018</b>, 208, 227; [6] <i>ACS Catal.</i> <b>2019</b>, 9, 7124−7136; [7] <i>ChemCatChem</i> <b>2021</b>,13, 900; [8] <i>ACS Catal.</i> <b>2022</b>, 12, 5979−5989; [9] <i>Catal. Sci. Technol.</i> <b>2022</b>, 12, 1359