Spatially resolved electrochemical reversibility of a conducting polymer thin film imaged by oblique-incidence reflectivity difference

Abstract

The spatially resolved electrochemical reversibility of a polyaniline (PANI) thin film is successfully imaged by an oblique-incidence reflectivity difference (OIRD) technique.

Reusable OIRD Microarray Chips Based on a Bienzyme-Immobilized Polyaniline Nanowire Forest for Multiplexed Detection of Biological Small Molecules

“…Meanwhile, all of the peak currents increase with the scanning cycle, indicating the increased electrochemical capacity and thickness of the PANI film. The simultaneous OIRD signal during the PANI growth shows fluctuation during each potential cycle, and the amplitude of the fluctuation increases with the growth of the PANI film, as shown in Figure S1b, indicating that the change of the redox state of the PANI film can cause an OIRD response in a thickness-dependent manner, which is in line with our previous work …”

“…The simultaneous OIRD signal during the PANI growth shows fluctuation during each potential cycle, and the amplitude of the fluctuation increases with the growth of the PANI film, as shown in Figure S1b, indicating that the change of the redox state of the PANI film can cause an OIRD response in a thickness-dependent manner, which is in line with our previous work. 38 The SEM image of electrochemically polymerized PANI nanowires on FTO is shown in Figure 1a. The nanowires exhibit a curving morphology with an average diameter of ∼100 nm and entangle with each other to form a porous network.…”

“…0.5 V, indicating that the OIRD is able to sensitively monitor the redox state change of PANI, which is in good agreement with our previous investigation. 38 H 2 O 2 is a moderate oxidant able to oxidize PANI nanowires under the catalysis of HRP enzyme via generation of oxidative hydroxyl radicals. 47 We thus further studied the OIRD response of HRP-PANI/FTO to H 2 O 2 .…”

“…During detection, the small-molecule target is oxidized under the catalysis of its attached oxidase to produce hydrogen peroxide, which further oxidizes the neighboring PANI nanowires in the presence of immobilized HRP, causing the oxidation of local PANI from a reductive leucoemeraldine to an emeraldine state. As an electrochromic polymer, the redox state change of PANI nanowires is accompanied by a dielectric constant change and thus arouses an OIRD response. − As such, all of the targets are quantified in the OIRD scanning mode with high sensitivities, excellent specificities, and broad dynamic ranges. Meanwhile, this microarray chip can be regenerated by simply electrochemically reducing the partially oxidized PANI nanowires and exhibits reliable detection performance even after eight detection-regeneration cycles.…”

Enhanced Chemical and Electrochemical Stability of Polyaniline-Based Layer-by-Layer Films

“…In addition, PANI can lose its electroactivity by diffusion of dopants and irreversible oxidation, resulting in performance degradation [ 7 , 8 , 9 ]. The low chemical and electrochemical stability of PANI is disadvantageous in many cases, which hinders its more practical applications [ 11 , 12 ]. Therefore, it is essential to improve PANI’s chemical and electrochemical stability, which remains a challenge.…”