Synthesis of single-phase Au nanorods in an anodic aluminum oxide template with an optimized process for a highly sensitive and non-enzyme methyl mercaptan gas detector

Single-phase Au nanorods were synthesized using an anodic alumina oxide (AAO) template for methyl mercaptan (CH₃SH) gas detection. The Au nanorods were fabricated by pulse electrodeposition on a H₂O₂ modified template. A Au precursor solution was modified with dimethyl sulfoxide to improve the synthesis of Au nanorods. The deposition parameters of the duty cycle were modulated in multiple groups to produce high-quality Au nanorods. Scanning electron microscopy images illustrated the high regularity of the Au nanorods. X-ray diffraction and transmission electron microscopy images revealed the high composition of the (111) lattice interface. A Au nanorod gas sensor was fabricated after removal of the AAO template. The sensor utilized the self-assembled monolayer property between Au and CH₃SH to alter the conductivity of the Au nanorod sensing layer. The sensor exhibited higher sensitivity and selectivity to CH₃SH than to N₂ and H₂S. The sensor had a 0.88% current response under a 0.5 ppm concentration of CH₃SH, which increased to 7.82% under 4 ppm CH₃SH. The Au nanorods possessed a response 13 times higher than that of a Au thin-film structure.