Dual-functional Polyindole/MXene composite for superior proton storage and corrosion protection

Although Polyindole (Pind) with a π-conjugated polymeric structure has been regarded as a promising organic material, the loosely packed and brittle backbones still hinder its long-term usage stability for various applications. Herein, a novel Pind/MXene composite with a 3D robust architecture has been developed by confining Pind nanoparticles in layered MXene through a simple and mild polymerization approach, which shows unique dual functionality for energy storage and corrosion protection for tcorrosion protection for the first time. On the one hand, the Pind/MXene composite as an electrode material exhibits a rapid, reversible, and stable energy storage behavior with a large proton-storage capacity of 118 mAh g−1 and excellent cycle stability (∼98.2 % after 2000 cycles) in aqueous electrolyte. On the other hand, the Pind/MXene composite as an anti-corrosion additive is introduced into the epoxy resin to achieve a coating, which shows a long-term anti-corrosion performance with a low corrosion rate of 9.17×10−6 mm a−1 and a high corrosion inhibition efficiency of 99.72 %. Furthermore, theoretical calculations prove the obvious electron transfer between Pind and MXene, endowing the Pind/MXene composite with enhanced redox capability, high electrochemical activity and robust structural stability, suggesting its great potential as the bi-functional material for high-performance energy storage and corrosion protection.