Direct Evidence of Black Phosphorus Formation in Carbon Nanospaces by Quasi-high Pressure Effect

Black phosphorus (BP) has attracted attention as an anode material for lithium or sodium ion batteries due to its high electrical conductivity and theoretical specific capacity (2596 mAh/g). However, the synthesis of BP requires high-pressure conditions at >1 GPa. We directly demonstrated that carbon nanospaces with the pore size around 4 nm are effective to synthesize BP without an external high-pressure apparatus. Red phosphorus was introduced in CNT with average diameter of 4 nm. From the STEM image, the crystalized phosphorus in the CNT pores was observed. And the layer on the (020) plane of black phosphorus was observed in the STEM image of the composite, and it was found that black phosphorus was formed.