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

Abstract 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.