Robust production of 2D quantum sheets from bulk layered materials

Abstract

The production of two-dimensional quantum sheets (2D QSs) from bulk layered materials is highly desired but far from satisfactory. Herein, we report a unified top-down method capable of producing a range of 2D QSs in high yields. The method combines silica-assisted ball-milling and sonication-assisted solvent exfoliation and thus enables production of graphene QSs (GQSs), boron nitride QSs (BNQSs), molybdenum disulfide QSs (MoS₂ QSs), and tungsten disulfide QSs (WS₂ QSs) in exceedingly high yields of 35.5, 33.6, 30.2, and 28.2 wt%, respectively. The as-produced 2D QSs are confirmed as intrinsic and defect-free by multiple characterization techniques. Such 2D QSs can be collected as powders and then redispersed in a wide range of solvents with high concentration up to 5 mg mL⁻¹. Both (re)dispersions and solid thin films of the 2D QSs exhibit extraordinarily high performance in linear and nonlinear optics. Specifically, the QS (re)dispersions show prominent exciton-, solvent-, and concentration-dependent photoluminescence, while the QS solid thin films demonstrate exciting solid-state fluorescence (with lifetimes up to 3.0 ns) and remarkable nonlinear absorption saturation (with absolute modulation depths up to 59% and saturation intensities down to 6.70 kW cm⁻² (0.67 nJ cm⁻²)). Our method could be applicable to any bulk layered materials and therefore paves the way for mass production and full exploration of 2D QSs.