Solute Capture and Doping of Al in Cu2O: Corrosion, Tarnish Resistance, and Cation Release of High-Purity Cu-Al Alloys in Artificial Perspiration

Frequently-touched surfaces are a common transmission source for hospital and community acquired infections. Cu alloys have shown promise as antimicrobial surfaces, able to kill even antibiotic-resistant bacteria within minutes. However, the most efficacious alloy systems readily tarnish making them unsuitable for hospital applications and tarnish-resistant (e.g., passive) systems often cannot maintain sufficient Cu ion release to maintain antimicrobial function. An ideal alloy would have optimal corrosion, tarnishing, and Cu release tuned through alloying elements. Cu-Al alloys are tarnish-resistant, yet the precise role of Al remains unclear. Highpurity binary alloys of Cu-Al were fully immersed in artificial perspiration at open circuit to evaluate soluble cation release, quantity and identity of corrosion products, as well as interrogate the role of Al on the chemical, structural, and electronic defect structure of oxides formed. Al became captured in Cu2O as a substitutional cation defect which in turn caused structural, and electronic modifications. This doped film did not inhibit soluble Cu cation release for antimicrobial function even after 144 h. Al-doped cuprous oxide had fewer electronic charge carriers (holes) due to Al-doping and subsequent increased electronic resistance. These results are promising regarding the aim of generating a tunable tarnish-resistant layer for an antimicrobial Cu-based alloy. (C) The Author(s) 2018. Published by ECS.