Exploiting Cu(II) Amphoterism for the Epitaxial Electrodeposition of Cuprous Oxide and Copper on Gold(111) from an Alkaline Bath Free of Organic Complexing Agents
Year: 2026
Type: article
Abstract: Epitaxial Cu2O and epitaxial Cu are usually accessed from chemically distinct electrodeposition baths. Here, we show that both can be obtained from a single alkaline Cu(II) electrolyte without added organic complexing ligands by exploiting Cu(II) amphoterism in 3 M NaOH. Speciation and solubility calculations show that a 5 mM Cu(II)/3 M NaOH bath can support dissolved Cu(II) and that Cu(OH)42– is the dominant dissolved mononuclear Cu(II) species. Voltammetry identifies distinct cathodic regimes for Cu2O deposition, Cu deposition, and reduction of pre-existing Cu2O films: deposition at −0.35 V vs Ag/AgCl yields Cu2O, whereas deposition at −0.80 V vs Ag/AgCl yields Cu, and film reduction occurs at −1.1 V vs Ag/AgCl. Hydrodynamic voltammetry shows that Cu deposition is strongly mass-transport dependent, whereas Cu2O deposition is only weakly dependent on rotation rate, indicating different transport and interfacial constraints in the two regimes. X-ray diffraction shows that the Cu2O regime yields single-domain epitaxial Cu2O(111) on Au(111), whereas the Cu regime yields epitaxial Cu(111) with twin in-plane domains. Switching the applied potential further enables sequential epitaxial Cu/Cu2O bilayer growth while retaining the Cu2O underlayer. These results establish a chemically simple route to potential-programmed epitaxial oxide/metal growth from a single alkaline Cu(II) electrolyte.
Source: ACS Materials Au
Authors: John Z. Tubbesing, Jay A. Switzer
Institution: Missouri University of Science and Technology
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,500
OpenAlex ID: W7225652631