Interfacial Redox Properties of Gold/Gold Oxide in the Presence and Absence of Applied Potential

Abstract

Although gold does not form a native oxide under ordinary conditions, its surface can be oxidized electrochemically and the resulting oxide film studied. We have used this approach to examine the effects of anodization potential, anodization time, pH, and presence or absence of dissolved oxygen on the open-circuit decomposition of anodic gold oxide using a combination of in situ ellipsometric, potentiometric, coulometric, and microgravimetric measurements. As expected, increasing the anodization time or potential resulted in more inert films that persisted for longer times in the absence of an applied potential. We also found that this decomposition was faster at low and high pH, but slow at neutral pH. Decomposition of the oxide film was also inhibited by the presence of dissolved oxygen in the contacting electrolyte solution.

Controlling Atomic-Scale Restructuring and Cleaning of Gold Nanogap Multilayers for Surface-Enhanced Raman Scattering Sensing

“…At pH 7, several days are required for the CB [5] to penetrate all nanogaps because the Au oxide layer still fills the nanogap. However, at acidic conditions (pH < 3 using HCl or H 2 SO 4 ), the Au oxide layer rapidly decomposes, 37 allowing CB [5] to bind within seconds to the AuNP surfaces. All three films now show pristine CB [5] SERS spectra (Figure 2e), exhibiting only a small relative variance (hundred-fold smaller than before replacement).…”

Multi-spectroscopic study of electrochemically-formed oxide-derived gold electrodes

“…The following chemical compositions have been suggested: AuO, AuOH, AuOOH, Au 2 O 3 , and Au(OH) 3 . [10][11][12][13][14][15][16][17][18][19] The lack of consensus about the chemical composition of the electrochemically-formed (hydr-)oxides, as well as in situ changes of oxide compositions, prevents the fundamental understanding of the catalytic properties of gold. 20,21 Here, to investigate the electronic and chemical properties of the OD-Au, operando non-resonant sum frequency generation (SFG) 22,23 was used to follow the electronic changes in gold surfaces formed under different OD-Au preparation conditions, and ex situ high-pressure X-ray photoelectron spectroscopy (HP-XPS) 24,25 was used to gain chemical insight into the nature of the observed electronic changes.…”

“…The following chemical compositions have been suggested: AuO, AuOH, AuOOH, Au 2 O 3 , and Au(OH) 3 . 10–19 The lack of consensus about the chemical composition of the electrochemically-formed (hydr-)oxides, as well as in situ changes of oxide compositions, prevents the fundamental understanding of the catalytic properties of gold. 20,21…”

A Microscopic View on the Electrochemical Deposition and Dissolution of AU with Scanning Electrochemical Cell Microscopy – Part Ii: Potentiostatic Dissolution and Correlation with In-Situ Ec-Tem

“…[10,15] Experimental factors such as the composition and concentration of the electrolyte, the applied potential and the ageing time have an impact on the composition, structure, and thickness of the oxide films. [16,17] Complexing ions like Cl -, [13,[18][19][20] that adsorb strongly on the gold surface and trigger dissolution, affect the formation of the oxide film. In addition, the formation of stable gold complexes with Clfavors the anodic dissolution of gold.…”