Study on the reduction of commercial MoO3 with carbon black to prepare MoO2 and Mo2C nanoparticles

Abstract

AbstractA simple method was developed to synthesize MoO2 and Mo2C nanoparticles via controlling nucleation and growth in carbothermic reduction of commercial MoO3 with carbon black. It was found that the appropriate C/MoO3 molar ratio for preparation of Mo2C was 2.8, and the carbothermic reduction process followed the sequence: MoO3 → transport phase (TP) → MoO2 → Mo2C. It was revealed that the most crucial issues for controlling number of produced particles of product were migration of Mo source and aid of nucleating agent, which can be achieved by using MoO3 and carbon black as starting materials. MoO2 nanosheets with the thickness of 12 nm and lateral size of 60 nm, as well as Mo2C nanoparticles with particle size of 30 nm were prepared via reduction of MoO3 with carbon black. However, MoO2 and Mo2C produced via reducing MoO3 by other kinds of carbon sources (activated carbon, graphite) or gas reductants (10% CH4/H2, CO) had much larger particle sizes of a few micrometers, which were tens of times than those using MoO3 and carbon black, due to the too small amount of formed nuclei. The effects of C/MoO3 molar ratio (0.5‐2.8), molybdenum sources and carbon sources on the reaction mechanisms were investigated in detail.