Polymer Interfacial Self-Assembly Guided Two-Dimensional Engineering of Hierarchically Porous Carbon Nanosheets

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).

Universal Access to Two‐Dimensional Mesoporous Heterostructures by Micelle‐Directed Interfacial Assembly

“…Scanning electron microscopy (SEM) image reveals that the MXene@F127/MF heterostructured nanosheets are finely dispersed with relatively rough surface (Figure 2a). Closer observation of aM Xene@F127/MF nanosheet at ah igher magnification ( Figure 2b)s hows uniform mesopores on its surface.F rom the transmission electron microscopy (TEM) images ( Figure 2c and Figure S2, Supporting Information), single-layered composite micelles with the pore size and thickness of % 12 nm and % 20 nm, respectively,are uniformly coated on both surfaces of the MXene nanosheets,d emonstrating the sandwichlike heterostructure.T he low-angle Xray diffraction (XRD) pattern of the sample shows ab road diffraction peak at 0.448 8 ( Figure S3, Supporting Information), indicating the presence of ashort-range ordered mesoporous structure, [8] which is in agreement with the electron microscopy observation. Moreover,the surface density of F127/MF composite micelles coated on MXene nanosheets can be controlled by tuning the amount of block copolymer F127 and mass ratio of MXene to composite micelles added in the .…”

Polymer blend directed anisotropic self-assembly toward mesoporous inorganic bowls and nanosheets

“…Anisotropic mesoporous inorganic materials are an emerging class of porous materials, which have attracted notable attention in recent years because the shape anisotropy and high complexity break the symmetry of particles, thereby creating remarkable physical properties that cannot be attained by conventional isotropic materials (1,2). Of particular importance are (i) bowl-like morphologies with fascinating new functions, e.g., superhydrophobicity of array film (3,4), special optical properties (5), and stacking phase behavior (6,7); and (ii) two-dimensional (2D) nanosheets with unique optical, chemical, and electronic properties and a high packing density and an improved mass/ionic transport capability (8)(9)(10)(11)(12). These intriguing features of anisotropic morphologies could add a new dimension to the range of potential applications for mesoporous inorganic materials.…”

Universal Access to Two‐Dimensional Mesoporous Heterostructures by Micelle‐Directed Interfacial Assembly

“…From the transmission electron microscopy (TEM) images (Figure c and Figure S2, Supporting Information), single‐layered composite micelles with the pore size and thickness of ≈12 nm and ≈20 nm, respectively, are uniformly coated on both surfaces of the MXene nanosheets, demonstrating the sandwichlike heterostructure. The low‐angle X‐ray diffraction (XRD) pattern of the sample shows a broad diffraction peak at 0.44° (Figure S3, Supporting Information), indicating the presence of a short‐range ordered mesoporous structure, which is in agreement with the electron microscopy observation. Moreover, the surface density of F127/MF composite micelles coated on MXene nanosheets can be controlled by tuning the amount of block copolymer F127 and mass ratio of MXene to composite micelles added in the reaction system (Figure S4,S5, Supporting Information).…”