Thermo- and photo-switchable electrodes consisting of carbon nanofiber/phase transition polymer/AuNP hybrid composite for improved electrochemical communication with dopamine.

内容摘要

We developed thermo- and photo-switchable electrodes based on a hybrid composite of carbon nanofibers (CNFs), thermo-responsive poly(N-isopropylacrylamide) (PNIPA), and gold nanoparticles (AuNPs). These electrodes were fabricated via electrochemical methods to achieve efficient electrochemical communication with dopamine. The electrochemically active surface area of AuNPs electrodeposited on the CNF electrode with extended PNIPA brushes at 25 °C (CNF/PNIPA/AuNP) was about (4.98 ± 0.64) × 10-2 cm2 and approximately four times larger than that with contracted PNIPA brushes at 45 °C (ca. (1.25 ± 0.03) × 10-2 cm2). The electron transfer rate for dopamine at the former electrode was higher than those at the latter electrode and an electrode modified in the reverse order AuNPs and PNIPA (CNF/AuNP/PNIPA). This enhancement is attributed to the surface-exposed AuNPs, which are not covered with PNIPA brushes. The CNF/PNIPA/AuNP electrode also exhibited switchable behavior based on the collapsed globule PNIPA induced by either high temperature (45 °C) or NIR light irradiation at 25 °C. This transition inhibited dopamine diffusion to the electrode surface due to steric hindrance, consequently decreasing the redox current. These findings provide a basis for developing novel hybrid functional nanomaterial composite electrodes with tunable electrochemical activity for smart device applications.