Scalable manufacture of nearly pure-phase metallic MoS2 nanosheets

Abstract Metallic, two-dimensional molybdenum disulfide (MoS ₂ ) nanosheets show promise for energy storage and catalysis applications. However, current chemical exfoliation methods require more than 48 h to produce milligrams of material, and result in an impure mixture of metallic (1T/1T′, approximately 50%–70%) and semiconducting (2H) phases. Here we demonstrate large-scale and rapid (>600 g h ⁻¹ ) production of nearly pure-phase metallic two-dimensional MoS ₂ nanosheets using microwave irradiation. Atomic-resolution imaging and X-ray photoelectron spectroscopy show nearly 100% metallic phase in the basal plane. This high purity leads to a large exchange current density (0.175 ± 0.030 mA cm ⁻² ) and low Tafel slopes (39–47 mV dec ⁻¹ ) for hydrogen evolution reaction. In supercapacitors and lithium–sulfur pouch-cell batteries, the resulting nanosheets enable a high volumetric capacitance of 753.0 ± 3.6 F cm ⁻³ and a specific capacity of 1,245 ± 16 mAh g ⁻¹ (electrolyte-to-sulfur ratio, 2 µl mg ⁻¹ ), respectively. Our method provides a practical pathway for producing high-quality metallic two-dimensional materials for high-performance energy devices.