Two-Dimensional Conductive and Redox-Active Nanostructures Synthesized by Crystal-Controlled Polymerization for Electrochemical Applications

Two-dimensional nanomaterials have attracted much interest for their anisotropic structures and emergent properties. Whereas a variety of inorganic nanosheets are prepared by exfoliation, design and synthetic strategies of organic nanosheets are still developing. Here we report on crystal-controlled synthesis of conductive and redox-active organic polymer nanosheets with tunable thickness and lateral size. Although the nanosheets consist of classical conductive polymers, such as polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT), a new crystal-controlled polymerization approach provides 2D nanomaterials with enhanced and characteristic properties. Oxidative polymerization proceeds on the crystal surface of organic oxidants, such as quinone derivatives, with diffusion of the monomer vapor at low temperature under ambient pressure. The present method affords the control of lateral size and thickness of the nanosheets. The resultant nanosheets show the characteristic and enhanced properties originating from a 2D nature, such as the high structure anisotropy with aspect ratio around 10⁴, enhanced conductivity 287 S cm^-1, and specific charge-discharge capacitance 523 F g^-1 at the current density of 18 A g^-1. The organic nanosheets with conductivity and redox activity can be used as a building block for development of functional materials and devices. ©