Interactions at the graphene/polyaniline interface: electron donation from graphene to polyaniline and stabilization of polarons
Michal Bláha, Martin Jindra, Oleksandr Volochanskyi, Jan Plšek, Martin Mergl, Otakar Frank, Martin Kalbáč
Abstract
Abstract This study aims to fill in the gaps in the experiment-based fundamental knowledge on the interaction of graphene and polyaniline at the “molecular” level, namely, charge redistribution and nature of charge carriers in polyaniline. We synthesized a two-dimensional graphene/polyaniline heterostructure and studied electronic structure and interactions of its components. The charge-transfer measurements showed that the formed polyaniline acts as a p -type dopant of graphene: the graphene electrons are accepted by polyaniline within the Fermi level alignment process. Raman and XPS spectroscopies and Raman spectroelectrochemistry on the ( 13 C–)graphene/polyaniline interface reveal that the majority of polyaniline is in the polaron lattice form and a minority in the bipolaronic form. The XPS data show that the number of polyaniline charged nitrogen atoms exceeds the number of counter-anions, indicating that the proton doping of polyaniline as the main mechanism of polaron formation/stabilization is accompanied by a second mechanism, in which polarons and bipolarons are stabilized by graphene electrons in a mutual interaction. The work provides essential knowledge needed for a rational design of graphene/polyaniline nanocomposites and their exploitation in various devices. Graphical Abstract