Preparation and formation mechanism of few-layer black phosphorene through liquid pulsed discharge

Black phosphorene has received great attention owing to its outstanding properties, such as unique layer-dependent properties in the band gap. In this study, a unique mechanical exfoliation route, the liquid-electric effect, is applied to prepare a few-layer black phosphorene using black phosphorus powders through liquid pulsed discharge. The discharge current and voltage data were recorded to analyze pulsed discharge processes. The discharge-treated suspensions were recovered, dried, and characterized by XRD, Raman, SEM, TEM, and AFM techniques. The characterization results confirm the existence of the few-layer black phosphorene with a lateral size in micro-scale under proper discharge conditions. The results also imply that the charging voltage is the key factor to adjust the formation of black phosphorene. At a charging voltage of 6.0 kV, the recovered black phosphorene nanosheets are with lateral size in micro-scale. An increase in the charging voltage (7.5 kV) leads to the formation of black phosphorene nanosheets with lateral size in nanoscale. Our investigation further reveals the corresponding formation mechanism that the transient liquid-electric effect induces the exfoliation of black phosphorus layers by tensile stress, wedge effect, and shear effect to form the few-layer black phosphorene. This study provides a novel route to prepare black phosphorene materials.