Controllable synthesis and structure analysis of VCxO1-x solid solution by experiment and first-principles calculation

Abstract

Vanadium oxycarbide (i.e. VCxO1-x) solid solution was expected to be a novel and promising ceramic materials in energy storage, catalysis and the preparation of metallic vanadium. The controllable synthesis and structure analysis of VCxO1-x solid solution are still rare. Here, VCxO1-x solid solution with different C/O molar ratio are successfully synthesized through a convenient carbothermal reduction of V2O3. The influences of reaction temperature, time, and C/V2O3 molar ratio in raw material are studied. It is found that carbothermal reduction must be carried out at higher temperature than 1500 °C in order to prepare single-phase VCxO1-x solid solution. C/O molar ratio in VCxO1-x solid solution can be well controlled by C/V2O3 molar ratio in raw material. Based on structure examination, it is confirmed that VCxO1-x is a continuous solid solution. Compared to VC, VCxO1-x solid solution exhibits better thermal stability and oxidation resistance. The lattice constant of VCxO1-x solid solution will increase with the increase of C content due to larger radius of C atom. Electronic properties of VCxO1-x solid solution were evaluated by first-principles calculations and experiments. The results demonstrated that VCxO1-x solid solution possesses high conductivity. The work is beneficial to controllable synthesis of VCxO1-x solid solution and promising applications in energy storage, catalysis and the preparation of metallic vanadium.