Conductive Polyaniline–Indium Oxide Composite Films Prepared by Sequential Infiltration Synthesis for Electrochemical Energy Storage

[Image: see text] Composites of conductive polymers (CP) and metal oxides (MO) have attracted continued interest in the past decade for diverse application fields because the synergistic effects of CP and MO enable the realization of unusual electronic, electrochemical, catalytic, and mechanical properties of the composites. Herein, we present a novel method for the sequential infiltration synthesis of composite films of polyaniline (PANI) and indium oxide (InO(x)) with high electrical conductivities (4–9 S/cm). The synthesized composite films were composed of two phases of graded concentration: InO(x) with oxygen vacancies and PANI with partially protonated molecular units. The PANI–InO(x) composite films displayed enhanced electrochemical activity with a pair of well-defined redox peaks. The open interfacial regions between the InO(x) and PANI phases may provide efficient pathways for ion diffusion and active sites for improved charge transfer.