Water Solvation of Charged and Neutral Gold Nanoparticles

Abstract

Gold nanoparticles are unique electrocatalysts for oxygen reduction, carbon dioxide reduction, and alcohol oxidation. Electrocatalytic processes are influenced by the interaction with the solvent, yet the direct investigation of the solvation of nanoparticles is scarce. Here we select gold nanoparticles as 10 nm sized solutes of which we can control the charge. We perform mid-infrared and terahertz spectroscopy to compare the behavior of the water in solution with micelles loaded with neutral and positive gold nanoparticles. We find indications that the hydration water around the gold-loaded micelles is characterized by weaker hydrogen bonds than bulk water. A positive nanoparticle charge is observed to result in a larger blue shift of the OH stretch, quenches the intensity of the collective translational mode, and increases the absorption by librating water molecules. Water at the interface of a positive gold nanoparticle could experience a stiffer potential energy surface which, in turn, might unveil local thermodynamic properties.

References in corpus (3)

• The Interplay of Structure and Dynamics in the Raman Spectrum of Liquid Water over the Full Frequency and Temperature Range
• Evidence Of Protein Collective Motions On The Picosecond Time Scale
• Experimentally Probing the Libration of Interfacial Water: the Rotational Potential of Water is Stiffer at the Air/Water Interface than in Bulk Liquid

Cited by in corpus (2)

• Ion-specific Adsorption on Bare Gold (Au) Nanoparticles in Aqueous Solution: Double-Layer Structure and Surface Potentials
• Highly Heterogeneous Polarization and Solvation of Gold Nanoparticles in Aqueous Electrolytes