Investigation of the Ligand–Nanoparticle Interface: A Cryogenic Approach for Preserving Surface Chemistry
[1];
[2];
- School of Engineering and Applied Science, Ahmedabad University, Ahmedabad, Gujarat 380009, India; Division of Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Ahmedabad, Gujarat 380009 India
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an, Shaanxi China 710062
- Division of Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Ahmedabad, Gujarat 380009 India
- EMSL, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Nanoscience and Technology Centre, University of Central Florida, Orlando, Florida 32826, United States
Ligand functionalized nanoparticles have replaced bare nanoparticles from most biological applications. These applications require tight control over size and stability of nanoparticles in aqueous medium. Understanding the mechanism of interaction of nanoparticle surfaces with functional groups of different organic ligands such as carboxylic acids is confounding despite the two decades of research on nanoparticles because of the inability to characterize their surfaces in their immediate environment. Often the surface interaction is understood by correlating the information available, in a piecemeal approach, from surface sensitive spectroscopic information of ligands and the bulk and surface information of nanoparticles. In present study we report the direct interaction of 5-7 nm cerium oxide nanoparticles surface with acetic acid. In-situ XPS study was carried out by freezing the aqueous solution of nanoparticles to liquid nitrogen temperatures. Analysis of data collected concurrently from the ligands as well as functionalized frozen cerium oxide nanoparticles show that the acetic acid binds to the ceria surface in both dissociated and molecular state with equal population over the surface. The cerium oxide surface was populated predominantly with Ce4+ ions consistent with the thermal hydrolysis synthesis. DFT calculations reveal that the acetate ions bind more strongly to the cerium oxide nanoparticles as compared to the water and can replace the hydration sphere of nanoparticles resulting in high acetate/acetic surface coverage. These findings reveal molecular level interaction between the nanoparticle surfaces and ligands giving a better understanding of how materials behave in their immediate aqueous environment. This study also proposes a simple and elegant methodology to directly study the surface functional groups attached to nanoparticles in their immediate aqueous environment.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1438993
- Report Number(s):
- PNNL-SA-131439; 39891; KP1704020
- Journal Information:
- Journal of Physical Chemistry. C, Vol. 122, Issue 6; ISSN 1932-7447
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
Similar Records
Catalytic Deprotection of Acetals In Strongly Basic Solution Usinga Self-Assembled Supramolecular 'Nanozyme'
Contaminant Organic Complexes: Their Structure and Energetics in Surface Decontamination Processes