Rapid preparation and properties investigation on TinO2n-1@C core-shell nanoparticles

Abstract

Magnéli phase materials offer attractive physical and electrochemical properties-high electrical conductivity similar to metals and excellent acid-base chemical stability, while core-shell nanostructures can protect the core from aggregating into large particles and often possess remarkable physicochemical properties compared with single-component structures. Herein, TinO2n-1 (n = 2–6, 8 and 9) particles with core-shell nanostructure were rapid-prepared by an extraordinary carbothermal reduction process of P25 powders using polyvinyl alcohol (PVA) reductant. The products synthesized at different temperatures were investigated by XRD, TEM, XPS, TG-DSC and UV–Vis. The results showed that carbon-coated TinO2n-1 powders were obtained within a few seconds in argon atmosphere, while the resistivity and BET surface area of TinO2n-1@C are 0.02–0.206 Ω cm and 4.62–14.6 m2 g−1, respectively. Notably, the carbon shell thickness varied from 2 nm to 11 nm and the average particle size of the Magnéli phase core ranged from 30 nm to 100 nm with an increase in reduction temperature. The residual carbon in the typical Magnéli phases of Ti5O9 and Ti4O7 was between 4.92 wt% to 5.91 wt%. In addition, the UV–visible absorptivity showed that samples had favourable optical absorption properties in the visible range. This work is expected to be helpful in developing a rapid, simple and practical approach to fabricate different core-shell TinO2n-1 powders.