One-step synthesis of monodisperse polydopamine-coated silver core–shell nanostructures for enhanced photocatalysis

Abstract

Nanosized silver (Ag) and polydopamine (PDA) composite was prepared via one-step polymerization of dopamine, using Ag⁺ ion as an oxidant. The oxidization of dopamine and the reduction of Ag⁺ ion occurred simultaneously in one-step, which resulted in a well-defined core–shell structure of PDA coating around the Ag nanoparticles (AgNPs). Its morphology, structure, and composition were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray power diffraction (XRD), UV-vis, Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS), respectively. The composite showed good performance toward the photo-catalytic degradation of neutral red under UV irradiation. The possible mechanism regarding the plasmon-induced photocatalysis was discussed in some detail, where the main active species of O₂˙⁻ on the surface of the AgNPs were involved in this photoreaction system. The PDA shells greatly improve the photocatalysis due to the existence of the π–π* electron transition under UV light.