Au-decorated carbon nanopillar array for facile SERS substrate for the detection of R6G dye

Large area, vertically aligned one-dimensional, hexagonally patterned materials have been found to be efficient substrates for surface enhanced Raman spectroscopy (SERS). Here in this work, we have developed a facile substrate for SERS performance as vertically grown carbon nanopillars (CNPs) inside the porous hexagonally patterned anodic aluminum oxide (AAO). Nanoporous AAO was grown for the best pore ordering for optimum parameters. CNPs were synthesized in the AAO template inside a thermal chemical vapor deposition reactor. CNPs were exposed to mechanical polishing to remove excess overgrown amorphous carbon, followed by chemical etching. This facile SERS substrate was prepared by depositing Au to form SERS-active hot spots. This CNP-Au hybrid substrate for 30 nm Au deposition shows the uniform sub-10 nm gap between subsequent nanopillars. Based on UV-Vis spectroscopy, the plasmonic resonance of the CNP-Au substrate was observed at a wavelength of approximately 540 nm. Rhodamine (R6G) dye was investigated for its very low concentration up to 10^-9M due to its genotoxic and carcinogenic effects on human life. Thus, a low concentration of R6G analyte is strongly desired for sensitive detection. The electric field enhancement was validated with a 3D FDTD Lumerical simulation for CNP@Au-30 nm substrate for a 10 nm gap. This CNP@Au facile SERS substrate shows potential use for novel large-area electrode systems in next-generation optoelectronics, including photovoltaics, light-emitting diodes, ultralow molecule detection, and solar water splitting.