Graphene nano-mesh-Ag-ZnO hybrid paper for sensitive SERS sensing and self-cleaning of organic pollutants

Abstract

Rationally designed self-assemble, functional 3D architecture of graphene nano-meshes with unique plasmonic resonance metal nanoparticles can be excellent nanohybrid Raman scattering (SERS) substrate in spotting the low levels of environmental organic pollutants. In this study, graphene nano-mesh-Ag-ZnO metal (GNMM) nanohybrid was prepared by self-assembled hydrothermal reduction of graphene oxide (GO) followed by thermal annealing of site-localized metal-salts as a highly sensitive surface-enhanced Raman scattering (SERS) substrate. The crumpled graphene nano-meshes decorated with Ag-ZnO nanoparticles created SERS hot spots (holes) that manifested high SERS sensitivity to model organic pollutants such as methyl orange (MO), rhodamine 6G (Rh-6G) and paraquat (PQ) with detection limit as low as 10−11, 10−13 and 10−14 M, respectively. A maximum enhancement factor (EF) of 1.97 × 1011 was obtained with PQ molecules on synthesized GNMM substrate. The enhancement in signal can be supported through charge transfer mechanism that induced strong enhancement of the local electric field on free available graphene nano-mesh edges abundant with hotspots. This novel nanohybrid SERS substrate realized self-cleaning by photocatalytic degradation of model organic Rh-6G molecules adsorbed on the nanohybrid paper and shows reusability during the detection process. Meanwhile, GNMM nanohybrid also possesses highly effective antimicrobial activities for Escherichia coli. The detection of organic pollutants by GNMM nanohybrid SERS substrate has several advantages such as low cost, easy and simple preparation method, sensitive detection and reusability that can be potentially applied for detection of variety of environmental pollutants and antimicrobial agent applications.