Reduced graphene oxide supporting Ag meso-flowers and phenyl-modified graphitic carbon nitride as self-cleaning flexible SERS membrane for molecular trace-detection

There is an imperious demand on developing of self-cleaning surface enhanced Raman scattering (SERS) substrates, for eliminating traditional single-use substrates. Herein, ternary flexible membranes of reduced graphene oxide (r-GO) supporting Ag meso-flowers (Ag-MFs) and phenyl-modified graphitic carbon nitride nanosheets (PCNs) were fabricated for photocatalysis-driven self-cleaning SERS detection. In-situ growth of Ag-MFs with tunable morphology (such as coral-like, urchin-like, highly-branched, etc.) on r-GO surfaces provide abundant options for optimizing SERS detection limit, and thus, these PCNs/Ag-MFs@r-GO membranes exhibited strong SERS activity attributed to high density of intraparticle hotspot in Ag-MFs and preconcentration ability to probe molecules via pi-pi stacking. Among these membranes, the optimum PCNs/Ag-MFs@r-GO membrane shown a detection limit of 10(-15) M for rhodamine 6G (R6G) molecules, and this membrane could effectively remove probe molecules due to the excellent photocatalytic activity. We used R6G or methylene blue (MB) molecules for investigating the self-cleaning repeatability and stability of this PCNs/Ag-MFs@r-GO membrane, and the signal intensity for SERS detection maintained a high degree of 95% after five cycle-runs. Besides, this PCNs/Ag-MFs@r-GO membrane can be used as a high-efficiency filter membrane for simultaneous detection and purification in wastewater treatment (10 mg/mL imidacloprid solution as the example).