Investigation of selective chemisorption of fcc and hcp Ru nanoparticles using X-ray photoelectron spectroscopy analysis
2019
Gueye, Ibrahima | Kim, Jaemyung | Kumara, L.S.R. | Yang, Anli | Seo, Okkyun | Chen, Yanna | Song, Chulho | Hiroi, Satoshi | Kusada, Kohei | Kobayashi, Hirokazu | Kitagawa, Hiroshi | Sakata, Osami
We investigated the crucial relation between the intrinsic electronic structure and surface chemisorption behavior of prototypical Ruthenium nanoparticles (Ru NPs) by tuning the size (from 2.2 to 5.4 nm) and structure (face centered cubic (fcc) and hexagonal close packed (hcp)). Ru NPs covered with a polyvinylpyrrolidone (PVP) was analysed through the synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES). Core levels (O 1s and C 1s & Ru 3p3/2) and valence band results provide a valuable information about the selective surface interaction of the Ru NPs. Preferential adsorption of CO₂, CO and O₂ on the surface of fcc Ru 5.4 nm NP have been highlighted. This selective ability of fcc Ru 5.4 nm have been attributed to the existence of intermediate bond strength between the Ru 4d band and the O 2p in the case of the fcc Ru 5.4 nm. Overcrowding effects were introduced to explain surface adsorption depending to the sizes. Thorough analyses of the valence-band maximum (VBM) showed a size dependent for hcp 2.4 nm (−0.14 eV) and 5.4 nm (−0.12 eV) while VBM is fixed at −0.19 eV for all hcp NPs. Electronic and chemical results and explanations are consistent with the catalytic efficiencies recorded on the Ru NPs. The current work provides a new step towards a complete understanding on the catalytic behaviour of metallic alloy nanoparticles based on the Ru.
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