Direct Observation of Morphological and Chemical Changes during the Oxidation of Model Inorganic Ligand-Capped Particles.

Autor:	Jaugstetter M; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Qi X; Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Chan EM; Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Salmeron M; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Wilson KR; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Nemšák S; Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.; Department of Physics and Astronomy, University of California, Davis, California 95616, United States., Bluhm H; Fritz Haber Institute of the Max Planck Society, Berlin D-14195, Germany.
Jazyk:	angličtina
Zdroj:	ACS nano [ACS Nano] 2024 Dec 19. Date of Electronic Publication: 2024 Dec 19.
DOI:	10.1021/acsnano.4c08846
Abstrakt:	Functionalization and volatilization are competing reactions during the oxidation of carbonaceous materials and are important processes in many different areas of science and technology. Here, we present a combined ambient pressure X-ray photoelectron spectroscopy (APXPS) and grazing incidence X-ray scattering (GIXS) investigation of the oxidation of oleic acid ligands surrounding NaYF 4 nanoparticles (NPs) deposited onto SiO x /Si substrates. While APXPS monitors the evolution of the oxidation products, GIXS provides insight into the morphology of the ligands and particles before and after the oxidation. Our investigation shows that the oxidation of the oleic acid ligands proceeds at O 2 partial pressures of below 1 mbar in the presence of X-rays, with the oxidation eventually reaching a steady state in which mainly CH x and -COOH functional groups are observed. The scattering data reveal that the oxidation and volatilization reaction proceeds preferentially on the side of the particle facing the gas phase, leading to the formation of a chemically and morphologically asymmetric ligand layer. This comprehensive picture of the oxidation process could be obtained only by combining the X-ray scattering and APXPS data. The investigation presented here lays the foundation for further studies of the stability of NP layers in the presence of reactive trace gases and ionizing radiation and for other nanoscale systems where chemical and morphological changes happen simultaneously and cannot be understood in isolation.
Databáze:	MEDLINE
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