Graphene Grown On Ni Foam: Molecular Sensing, Graphene-Enhanced Raman Scattering, And Galvanic Exchange For Surface-Enhanced Raman Scattering Applications

The growth of graphene on an irregular three-dimensional (3D) Ni structure is demonstrated to be an interesting platform for molecular sensing, graphene-enhanced Raman scattering, and surface-enhanced Raman scattering (SERS) applications after galvanic exchange of Ag+ ions. Raman, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), optical images, and diffuse reflectance demonstrate that graphene grows in a multilayer fashion with different stacking configurations. Statistics performed employing Raman show that the as -grown graphene can be classified into two main stacking configurations: AB (or Bernal stacking) and rotated graphene, which are separated by a full width at half-maximum (fwhm) threshold of similar to 30 cm(-1) corresponding to the 2D Raman band. The rotated stacking senses low concentrations of methylene blue (MB), whereas the AB stacking seems to be much less sensitive upon molecular adsorption. The galvanic exchange of Ag leads to agglomerates preferentially formed on top of graphene wrinkles, which ultimately became the target spots for performing SERS. Our experiments demonstrate that the as-grown graphene, composed of different stacking configurations, can be used as a molecular sensor to detect 10(-6) M concentration of MB as well as nanomolar concentrations of MB and thiram (by SERS applications), after the galvanic exchange with Ag.