Polymer Interfacial Self-Assembly Guided Two-Dimensional Engineering of Hierarchically Porous Carbon Nanosheets
Seongseop Kim, Mieun Ju, Jisung Lee, Jisung Lee, Jongkook Hwang, Jinwoo Lee, Jinwoo Lee
Abstract
Two-dimensional (2D) carbon nanosheets with micro- and/or mesopores have attracted great attention due to unique physical and chemical properties, but well-defined nanoporous carbon nanosheets with tunable thickness and pore size have been rarely realized. Here, we develop a polymer–polymer interfacial self-assembly strategy to achieve hierarchically porous carbon nanosheets (HNCNSs) by integrating the migration behaviors of immiscible ternary polymers with block copolymer (BCP)-directed self-assembly. The balanced interfacial compatibility of BCP allows the migration of a BCP-rich phase to the interface between two immiscible homopolymer major phases (i.e., homopoly(methyl methacrylate) and homopolystyrene), where the BCP-rich phase spreads thinly to a thickness of a few nanometers to decrease the interfacial tension. BCP-directed coassembly with organic–inorganic precursors constructs an ordered mesostructure. Carbonization and chemical etching yield ultrathin HNCNSs with hierarchical micropores and mesopores. This approach enables facile control over the thickness (5.6–75 nm) and mesopore size (25–46 nm). As an anode material in a potassium ion battery, HNCNSs show high specific capacity (178 mA h g–1 at a current density of 1 A g–1) with excellent long-term stability (2000 cycles), by exploiting the advantages of the hierarchical pores and 2D nanosheet morphology (efficient ion/electron diffusion) and of the large interlayer spacing (stable ion insertion).