Topochemical synthesis of holey 2D molybdenum nitrides nanosheets via lime-assisted nitridation of layered MoS2

Abstract

In this study, we introduced a facile and efficient method for the large-scale synthesis of porous 2D molybdenum nitrides nanosheets via the topochemical nitridation of MoS2 by NH3 with the assistance of CaO at 750 °C–820 °C. The presence of CaO can noticeably promote the reduction rate of MoS2 by generating CaS. After acidic leaching, porous 2D MoN, a mixture of 2D MoN and Mo2N, as well as Mo2N nanosheets with the thickness of about 7 nm and pore size of about 10.5 nm were successfully prepared at different temperatures. When the temperature increased from 750 °C to 820 °C, the product gradually changed from MoN to Mo2N. Due to the weak Van der Waals forces between the layers of MoS2, the topochemical substitution of S in MoS2 by N led to the exfoliating of layers. The large difference of crystal structures and volume between precursor and product, as well as the high reaction rate led to the formation of porous structure of molybdenum nitrides.