Study on the reduction of commercial MoO 3 with carbon black to prepare MoO 2 and Mo 2 C nanoparticles

Abstract A simple method was developed to synthesize MoO 2 and Mo 2 C nanoparticles via controlling nucleation and growth in carbothermic reduction of commercial MoO 3 with carbon black. It was found that the appropriate C/MoO 3 molar ratio for preparation of Mo 2 C was 2.8, and the carbothermic reduction process followed the sequence: MoO 3 → transport phase (TP) → MoO 2 → Mo 2 C. 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 MoO 3 and carbon black as starting materials. MoO 2 nanosheets with the thickness of 12 nm and lateral size of 60 nm, as well as Mo 2 C nanoparticles with particle size of 30 nm were prepared via reduction of MoO 3 with carbon black. However, MoO 2 and Mo 2 C produced via reducing MoO 3 by other kinds of carbon sources (activated carbon, graphite) or gas reductants (10% CH 4 /H 2 , CO) had much larger particle sizes of a few micrometers, which were tens of times than those using MoO 3 and carbon black, due to the too small amount of formed nuclei. The effects of C/MoO 3 molar ratio (0.5‐2.8), molybdenum sources and carbon sources on the reaction mechanisms were investigated in detail.