In Situ Scanning Tunneling Microscopy Study of the Anodic Oxidation of Cu(111) in 0.1 M NaOH

Abstract

In situ electrochemical scanning tunneling microscopy (STM) measurements of the anodic oxidation of Cu(111) in 0.1 M NaOH are reported. Anodic oxidation is preceded, in the underpotential range, by adsorption of an ordered layer assigned to OH species. This ordered adlayer is a precursor of the oxide growing at higher potential with the copper surface reordering to mimic the structural arrangement of a (111) oriented Cu2O oxide. In the potential range of Cu(I) oxidation, a Cu2O(111) oxide film is formed with a faceted, and most likely hydroxylated, surface. The nucleation, growth, and crystallization of this Cu(I) oxide depend on the overpotential of oxidation. At low overpotential, poorly crystallized and one-monolayer-thick islands partially covering the substrate are formed after preferential nucleation at step edges. At higher overpotential, well crystallized and several-monolayer-thick films are formed, and the step edges are not preferential sites of nucleation. In the potential range of Cu(II) oxidation, a crystalline Cu2O/CuO,Cu(OH)2 duplex film is formed. The cathodic reduction of these anodic oxides rebuilds the original extended and flat terraces of the substrate for oxides of monolayer thickness but produces a faceted Cu surface when a thicker oxide film is reduced.

Facile electrochemical preparation of three-dimensional porous Cu films by potential perturbation

“…1, which is similar to previous results [26][27][28][29][30]. Two well-defined anodic peaks (A1, A2) and one ill-defined one (A3) during the positive scan were assigned to the oxidation of Cu at the electrode surface to the corresponding oxides of Cu(I), Cu(II) and Cu(III), respectively.…”

“…When the potential shifted to −2.5 V, Cu(II) oxides were quickly reduced to Cu atoms, which were removable due to the reconstruction of Cu surface lattice structure by the incorporation and removal of O species and H 2 bubbles releasing. The interaction between O species (OH − in the alkaline solution) and Cu surface and the formation of Cu oxide film have been studies elsewhere [26,27]. The cycle repeated and 3D porous structure was finally formed.…”

“…Considering the effect of NaOH concentration, when the concentration was lower than 0.2 M, the electrochemical reaction (surface oxidation-reduction and H 2 releasing) became very weak at the potential of 0.4 (anodic) and −2.5 V (cathodic). When a higher concentration of NaOH (4 M) was used, it was observed that the dissolution of Cu became severe during the electrochemical treatment, which should be due to the strong interaction between OHand Cu(II) at the Cu surface [26,27]. This was unfavourable for the surface rebuilding.…”

State of the Surface of Antibacterial Copper in Phosphate Buffered Saline

“…The related anodic peak (A 1 ) is in alkaline electrolyte typically associated with oxidation of copper to Cu 2 O. 14,15,18,49,50 The current density increased continuously after the electrode potential reached ≈−0.1 V, indicating a high metal dissolution rate. A more detailed CV peak assignment was obtained by in situ Raman spectroscopy, and will be discussed later in this section.…”

Detection of phase transients in two-dimensional adlayers of adenosine at the solid amalgam electrode surfaces

“…2(B)). It was shown that, on the CuE substrate, protective anodic oxides in solutions of pH > 5 are formed [49]. Due to this fact, the CV of the CuE in alkaline solution (0.1 M NaOH) shows characteristic anodic and cathodic peaks that are related to the formation and reduction of these anodic oxides ( Fig.…”