Pronounced Surface Sensitivity of Hydroxylamine Oxidation on Gold Single-Crystal Electrodes in Acidic and Neutral Aqueous Solutions

Abstract

The oxidation of hydroxylamine on the three low index faces of Au single crystal has been investigated by cyclic voltammetry in buffered aqueous solutions in the pH range 1–7 under quiescent conditions. The results obtained have shown that the onset potential for the reaction on Au(100) is more negative, and the current in the region of small overpotentials is higher than for Au(110) and Au(111) regardless of the pH of the solution. Measurements performed in phosphate buffer (pH 7) with single crystal rotating disk electrodes in the hanging meniscus configuration yielded rather linear Tafel slopes in the small overpotential region for Au(111) and Au(110), which were higher than those found for Au(100). This affords clear evidence that the mechanism for this latter surface is different that for the other two faces involving in all likelihood one or more yet to be identified adsorbed intermediates.

Voltammetric and in situ infrared spectroscopy studies of hydroxyurea electrooxidation at Au(111) electrodes in HClO4 solutions

“…Note that this band corresponds to a dissolved species, as DFT calculations have shown that isocyanic acid interacts very weakly with gold surfaces [27]. Regarding hydroxylamine, recent results by Scherson's group show that this species readily oxidizes above 0.50 V SCE on gold electrodes in HClO4 solutions [35]. In situ infrared by the same group proved the formation of N2O as witnessed by a band at 2230 cm -1 [28], similar to that in Figure 2.…”

Hydroxylamine Oxidation on Polycrystalline Gold Electrodes in Aqueous Electrolytes: Quantitative On‐Line Mass Spectrometry under Forced Convection

“…[3] Further evidence of an adsorbed species was obtained from differences in the rates constants for the reaction for the low index faces of Au single crystal as measured with rotating disk electrodes. [13] As the Au oxide is reduced, the presumably bare Au surface acquires very high activity toward NH 2 OH oxidation yielding, within the time scale of the measurements, currents which exceed those found during the scan toward positive potentials, as clearly seen in Figure 5 above.…”

“…rotating disk electrode techniques for the low index faces of Au single crystal. [13] As mentioned in the Introduction the most likely species based on the in situ SERS data reported in a previous communication is NO 2 (ads). [3] Further evidence of an adsorbed species was obtained from differences in the rates constants for the reaction for the low index faces of Au single crystal as measured with rotating disk electrodes.…”

“…A possible explanation for this effect may be found in the formation of an adsorbed species derived from the oxidation of NH 2 OH, which blocks the electrode surface from further reaction for E≤1.1 V, and either desorbs and/or oxidizes at higher potentials to yield one or more species that have no affinity for the oxidized Au surface. rotating disk electrode techniques for the low index faces of Au single crystal . As mentioned in the Introduction the most likely species based on the in situ SERS data reported in a previous communication is NO 2 (ads) .…”

Low-Temperature Vapor-Phase Synthesis of Single-Crystalline Gold Nanostructures: Toward Exceptional Electrocatalytic Activity for Methanol Oxidation Reaction

“…To the best of our knowledge, the oxidation current density of 14.65 mA/cm 2 obtained in this experiment is the highest value among those measured in the same media using Au-based electrodes, including self-supported nanoporous Au film electrodes [11], polycrystalline Au electrodes [13], and nanoporous Au electrodes prepared by dealloying Au-Ag [10]. The excellent catalytic activity of the Au NPs can be attributed to the combination of their clean surfaces [21,728, facets well-arranged by the Au (111) plane [69,70], and intimate contact with the FTO substrate. Consequently, we expect that this Au NS-based electrode can be a versatile tool for various catalytic and electrochemical applications.…”