Redox-mediated proton transport of two-dimensional polyaniline-based nanochannels for fast capacitive performance

Two-dimensional (2D) materials are being increasingly exploited for ion transport and storage under nanoconfinement. Here we demonstrate distinct ion transport behavior upon potential-induced redox reaction in 2D tungstate anion cross-linked polyaniline (TALP) electrode. It is found that, in the neutral electrolyte, SO42- ion serves as the main charge carrier in 2D polyaniline backbone when the electrical double layer charging dominates. While in an acidic electrolyte, proton transport in TALP turns to be the dominant ion behavior that is associated with the proton-promoting surface redox processes. Moreover, higher capacitance along with better capacitive retention at a high rate is also demonstrated for TALP electrode in acidic electrolyte compared with that in the neutral environment. The results show that 2D nanoionics can be manipulated by applying redox-active materials to build the nanochannels that allow the regulation of surface charge and chemistry with potential-specific redox reactions.