Polydopamine-Mediated Ag and ZnO as an Active and Recyclable SERS Substrate for Rhodamine B with Significantly Improved Enhancement Factor and Efficient Photocatalytic Degradation

Abstract

We demonstrate the development of an active multicomponent Ag/PDA/ZnO@GMF surface-enhanced Raman scattering (SERS) substrate via introducing bio-inspired polydopamine (PDA) in between a noble metal (AgNPs) and ZnO nanorods. The insertion of PDA enabled efficient charge redistribution between metal and semiconductor through their aromatic cores. The substrate exhibited a high enhancement factor (EF) of 1010 for the organic pollutant dye Rhodamine B (RhB). Subsequent exposure of a RhB-loaded substrate to an external UV light source developed an efficient pathway for RhB degradation and replenished the substrate for multiple usage cycles with remarkable photostability. Thus, enhanced performance of the substrate in terms of light-harvesting capability and high charge-separation efficiency was observed. In addition, the much larger surface area of the branched ZnO nanostructures served as a template for PDA assisted synthesis and controlled deposition of AgNPs, which further improved the SERS effect. Our work seeks to understand the contributions of the noble metal and semiconductor components and the synergistic effects of combining them with a facile charge transport medium to enable the fabrication of highly efficient SERS substrates for use in industrial and environmental applications.