AgCu NP Formation by the Ag NP Catalysis of Cu Ions at Room Temperature and Their Antibacterial Efficacy: A Kinetic Study.

Although a facile route to prepare AgCu nanoalloys (NAs) with enhanced antibacterial efficacy using Ag NP catalysis of Cu ions at elevated temperatures was previously developed, its detailed reaction process is still unclear due to the fast reaction process at higher temperatures. This work found that AgCu NAs can also be synthesized by the same process but at room temperature. AgCu NAs formation kinetics have been studied using UV-Visible spectra and Transmission Electron Microscopy (TEM), where formation includes Cu deposition onto the Ag NP surface and Ag release, reduction, and agglomeration to form new Ag NPs; this is followed by a redistribution of the NA components and coalescence to form larger AgCu NPs. It is found that SPR absorption is linear with time early in the reaction, as expected for both pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetics; neither model is followed subsequently due to contributions from newly formed Ag NPs and AgCu NAs. The antibacterial efficacy of the AgCu NAs thus formed was estimated, with a continuous increase over the whole alloying process, demonstrating the correlation of antibacterial efficacy with the extent of AgCu NA formation and Ag release.