Electrochemical properties of ultrafine TiO2-doped MoO3 nanoplates prepared by one-pot flame spray pyrolysis

Abstract

Ultrafine TiO₂-doped α-MoO₃ nanoplates with a low thickness of 24 nm were prepared by one-pot flame spray pyrolysis, using water-soluble ammonium molybdate tetrahydrate as precursor. Pure MoO_x nanopowders had a mixed morphology of rod-like and cube-like crystals, and a complex crystal structure composed of α-MoO₃, β-MoO₃, and Mo₁₇O₄₇ phases. However, addition of TiO₂ influenced the morphology as well as the crystal structure of MoO_x. The TiO₂-doped MoO_x powders had a regular nanoplate-like morphology and single-crystalline α-MoO₃ structure. The initial discharge and charge capacities of the pure MoO_x powders were 1481 and 998 mA h g⁻¹ at a current density of 500 mA g⁻¹. In contrast, 5 wt% TiO₂-doped MoO₃ nanoplates had high initial discharge and charge capacities of 1728 and 1171 mA h g⁻¹, respectively. The discharge capacities of pure MoO_x, 5 wt% TiO₂-doped MoO₃, and 10 wt% TiO₂-doped MoO₃ nanopowders after 200 cycles were 676, 1022, and 831 mA h g⁻¹, respectively, and the corresponding capacity retentions measured from the second cycles were 68, 86, and 85%. The reversible discharge capacities of the TiO₂-doped MoO₃ nanoplates decreased from 1424 to 978 mA h g⁻¹ as the current density increased from 200 to 1000 mA g⁻¹, and the discharge capacity recovered to 1196 mA h g⁻¹ when the current density returned to 200 mA g⁻¹ after 50 cycles.