Vanadium doping to increase the production batch size of Carbon-Free Ti4O7: A new strategy for its mass production

The most conductive Magnèli phase titanium suboxide, Ti4O7, has attracted increasing attention as a carbon-free conductive material due to its high electrical conductivity and electrochemical stability. However, this material has not been widely used in applications as a result of the difficulty of its mass production to limit the number of suppliers. In this study, a new and inexpensive route to increase the production batch size, i.e., the mass of carbon-free Ti4O7 synthesized in a single reaction, was developed. By simply doping vanadium into Ti4O7 via a conventional high-temperature synthesis route, the production batch size was successfully increased to 2 g. Vanadium (V) cations were found to not exist in the V5+ form, instead being reduced to V4+/V3+ in the Ti4O7 lattice without segregating to form other phases, and the production batch size increased with an increase in the vanadium-to-titanium atomic ratio up to 0.10. The optimized (Ti0.91V0.09)4O7 material can be used in polymer electrolyte fuel cell cathodes and is promising for use in many other applications.