Uniform silver shell formation for air-stable Cu@Ag NW coatings with enhanced conductivity

Abstract

Copper@silver (Cu@Ag) core–shell nanowires (NWs) were synthesized using a controlled galvanic displacement approach designed to suppress the oxidation typically observed in copper nanostructures. The procedure included a Diethylhydroxylamine (DEHA) based pretreatment to remove native surface oxides from the Cu NWs, improving the uniformity of subsequent silver deposition. Addition of Ascorbic Acid at a delayed rate enhanced homogenous shell formation was the enabling even surface adsorption of silver ions prior to reduction. This timing minimized premature nucleation and facilitated the growth of smooth, continuous Ag shells. Inks formulated from these Cu@Ag NWs displayed low percolation thresholds (∼0.14 vol%) and high conductivity at only 1 vol% loading. The resulting films retained more than 90% of their initial conductivity after 28 days and very low Oxygen presence in EDX mapping spectrum peaks after 90 days ambient exposure, demonstrating enhanced environmental stability compared to uncoated Cu NW systems. This synthesis protocol offers a reproducible, solution processable route for preparing conductive inks suited to applications in flexible and large area printed electronics.