Templated Synthesis of Ultrafine Polyaniline Fibers and Their Transfer to Carbon Substrates for Highly Rapid Redox Reactions

Polyaniline ultrafine fibers (PANI-UFs) prepared using commercial activated carbon (AC) as a template are transferred to conductive carbon substrates. This method starts with the adsorption of aniline in AC, followed by its subsequent electrochemical polymerization to produce PANI-UFs inside the AC pores. The resulting PANI-UFs can be transferred onto carbon substrates under an applied potential. In this study, two kinds of AC with different pore sizes (≈2 and ≈4 nm) are used, and carbon black, graphite rods, highly oriented pyrolytic graphite, and stainless steel are examined as conductive substrates. It is found that the transfer of PANI-UFs fails only in the case of stainless steel. The transfer of PANI-UFs cannot be confirmed by transmission electron microscopy observation because of their ultrafine structures. However, their existence is confirmed by energy dispersive X-ray spectroscopy, atomic force microscopy, and electrochemical analyses. The electrochemical analyses reveal that the electrochemical behavior of the PANI-UFs is not affected by the pore size of the AC template. In addition, the PANI-UFs are characterized by extremely rapid redox responses. This template method can be applied for the fabrication of PANI-UFs on versatile conductive carbon substrates for use in highly sensitive sensors and other electronic devices.