C3N4 as a precursor for the synthesis of NbC, TaC and WC nanoparticles

While there already exit some routes to prepare carbides, highly efficient and facile routes are still desired to meet the increasing demand on carbides. By a facile solid-state reaction process using graphite-like phase of C3N4 (g-C3N4) as the carbonizing reagent, we synthesized three technologically important carbides including cubic NbC and TaC, and hexagonal WC nanoparticles at relatively low temperature (1150 °C). The products were characterized by power X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The results show that g-C3N4 is a highly efficient carbonizing reagent and the oxides Nb2O5, Ta2O5 and WO3 are completely converted into the corresponding carbides at 1150 °C, which is significantly lower than that reported for the commercial preparation of the carbides, typically >1600 °C. The NbC, TaC and WC nanoparticles are found to have an average particle size of 4, 35 and 60 nm, respectively. An important feature of this solid-state reaction process is that g-C3N4 plays double roles as both efficiently reducing and carbonizing reagent.