One-step synthesis of silver nanoparticles exposed on the chitosan-covered polyamide 6 electrospinning nanofibers

A one-step method was developed for synthesizing Ag nanoparticles exposed on the chitosan-covered polyamide 6 (CS-Ag@PA6) nanofibers by the in-situ reduction of silver nitrate during the electrospinning process. The bioderived CS was employed as a stabilizer and chelating carrier of Ag-0/Ag+ through its functional groups. CS was also used as a tractive agent to promote the surface migration of Ag atoms owing to its polyelectrolytic properties and immiscibility with PA6. Formic acid was used as the co-solvent for PA6 and CS and the reducing agent for Ag+. It was verified that the Ag nanoparticles (AgNPs) with 31.7% Ag-0 were embedded inside the pure PA6 nanofibers. However, the incorporation of CS achieved the AgNPs with an improved reduction efficiency (i.e., 67.5% of Ag-0). In particular, the CS nanolayers were covered on the PA6 nanofiber skeleton, where the AgNPs migrated on the surface of the CS nanolayers. This surface migration of CS and AgNPS endowed a significantly enhanced catalytic activity to the reduction of 4-nitrophenol, where the reduction rate constant (k) and turnover frequency (TOF) were an order of magnitude higher than that of the CS-free nanofibers.