In situ XAFS Study of Palladium Electrodeposition at the Liquid/Liquid Interface

Abstract

We report the use of XAFS (X-ray absorption fine structure) as an in situ method to follow the electrochemically driven deposition of palladium nanoparticles at a liquid/liquid interface.A novel glass/plastic hybrid electrochemical cell was used to enable control of the potential applied to the liquid/liquid interface. In situ measurements indicate that the nucleation of metallic nanoparticles can be triggered through chronoamperometry or cyclic voltammetry.Page 2 of 37 A c c e p t e d M a n u s c r i p tIn contrast to spontaneous nucleation at the liquid/liquid interface, whereby fluctuations in Pd oxidation state and concentration are observed, under a fixed interfacial potential the growth process occurs at a steady rate leading to a build-up of palladium at the interface. Raman spectroscopy of the deposit suggests that the organic electrolyte binds directly to the surface of the deposited nanoparticles. It was found that the introduction of citric acid results in the formation of spherical nanoparticles at the interface.

Decorating soft electrified interfaces: From molecular assemblies to nano-objects

“…Coupled in situ X-ray fluorescence (XRF) and X-ray absorption fine structure (XAFS) techniques monitored the gold nucleation and NPs growth at an electrified interface, which supported the formation of spherical gold NPs aggregates described by ex situ studies reported in earlier publications (see Figure 7B) [142]. Furthermore, in-situ XAFS was used to describe the growth and deposition of Pd NPs suggesting a direct two electron reduction of [PdCl4] 2to Pd 0 followed by the formation of stable Pd clusters [144]. Certainly, a better understanding of the NPs growth dynamics at a molecular scale during the interfacial electrodeposition is desirable.…”

Template-Free and Spontaneous Formation of Vertically Aligned Pd Nanofiber Arrays at the Liquid–Liquid Interface between Redox-Active Ionic Liquid and Water

“…42 Dryfe et al prepared Pd nanoparticles at the O|W interface by externally controlling the phase boundary potential across the O|W interface. 37,[43][44][45][46] Recently, growing interest has been drawn on replacing organic solvents by hydrophobic ionic liquids (ILs) in the L|L interfacial method. [47][48][49][50] ILs are liquid salts which are entirely composed of cations and anions.…”

“…prepared Pd particles by a heterogeneous redox reaction at the O|W interface and then applied the interfacial Pd nanoparticles as reductive photocatalysts for a photoinduced two-phase redox reaction . Dryfe et al prepared Pd nanoparticles at the O|W interface by externally controlling the phase boundary potential across the O|W interface. ,− …”

X-ray Raman scattering: a newin situprobe of molecular structure during nucleation and crystallization from liquid solutions

“…The technique has recently been shown to be able to detect the formation of prenucleation equilibrium during the reactive interfacial nucleation of metal nanoparticles. [13][14][15] The involvement of valence levels makes NEXAFS also highly sensitive to chemical and physical changes around organic molecules in solution and in the solid state. Differences due to crystal polymorphism, 16 solute-solvent interactions, [17][18][19] protonation and hydrogen bonding 18,20,21 have been reported.…”