Synthesis of niobium(iv) carbide nanoparticles via an alkali-molten-method at a spatially-limited surface of mesoporous carbon

One-pot synthesis of niobium carbabide (NbC) nanoparticles with ca. 30-50 nm was achieved via a rationally designed novel alkali-molten salt method using niobium oxide (Nb2O5), potassium carbonate (K2CO3), and mesoporous carbon (MPC). In this reaction, potassium niobate (KNbO3) was produced as an intermediate and carbonization of KNbO3 proceeds at a spatially limited external surface encompassed by the mesopores of MPC due to the repulsive characteristics of ionic KNbO3 toward hydrophobic MPC, which affords the size-controlled NbC nanoparticles with a narrow particle distribution. The particle sizes tended to become smaller as the pore sizes of MPCs or the temperature on the calcination under the nitrogen stream decreased. Elemental reactions along the one-pot synthesis of NbC nanoparticles were clarified by X-ray spectroscopic, thermogravimetric, and mass spectrometric measurements.