Nanoplasmonic sensing to study CO and oxygen adsorption and CO oxidation on size-selected Pt10 clusters.

Abstract

The adsorption of CO, oxygen and CO oxidation on size-selected Pt10 clusters was studied by indirect nanoplasmonic sensing (INPS) in the pressure range 1 – 100 Pa at T = 418 K. CO adsorption was reversible, inducing a blue-shift in the localised surface plasmon resonance (LSPR) response, regardless of the initial CO pressure. We observe a plateau at approximately nm at PCO > 2.7 Pa, indicating saturation of CO adsorption on Pt10 clusters. Oxygen induces both chemisorption and oxidation of Pt10 clusters until a regime is reached where max remains positive and constant, showing that the Pt10 clusters are completely oxidised. CO oxidation at different molar fractions is also followed by INPS. All results are discussed in relation to our previous works on 3 nm Pt nanocubes [ACS Omega 6, 20 (2021)]. The study demonstrates the suitability of INPS towards the understanding of the nature and function of matter in the largely unexplored subnanometer size regime where properties can often dramatically change when altering particle size by a single atom.