Unearthing\nAtomic Dynamics in Nanocatalysts

Being able to access\nthe rich atomic-scale phenomenology, which\noccurs during the reactions pathways, is a pressing need toward the\npursued knowledge-based design of more efficient nanocatalysts, precisely\ntailored atom by atom for each reaction. However, to reach this goal\nof achieving maximum optimization, it is mandatory, first, to address\nhow exposure to the experimental conditions, which will be needed\nto activate the processes, affects the internal configuration of the\nnanoparticles at the atomic level. In particular, the most critical\nexperimental parameter is probably the temperature, which among other\nunwanted effects can induce nanocatalyst aggregation. This work highlights\nthe high potential of experimental techniques such as the scanning\nprobe microscopies, which are able to investigate matter in real space\nwith atomic resolution, to reach the key challenge in heterogeneous\ncatalysis of achieving access to the atomic-scale processes taking\nplace in the nanocatalysts. Specifically, the phenomenology occurring\nin a nanoparticle system during annealing is studied with atomic precision\nby scanning tunneling microscopy. As a result, the existence of an\ninternal atomic restructuring, occurring already at relatively low\ntemperatures, within Ir nanoparticles grown over h-BN/Ru(0001) surfaces\nis demonstrated. Such restructuration, which reduces the undercoordination\nof the outer Ir atoms, is expected to have a significant effect on\nthe reactivity of the nanoparticles. Going a step further, an internal\nrestructuring of the nanoparticles during their involvement as catalysts\nhas also been also identified.