Carbon-doped titania nanoplates with exposed {001} facets: facile synthesis, characterization and visible-light photocatalytic performance

Abstract

C-doped TiO₂ nanoplates (CTNP) with exposed {001} facets were successfully synthesized by hydrothermal treatment of TiC powder in a HF–HNO₃ mixed aqueous solution for the first time. The effects of hydrothermal temperature (140, 160, 180 and 200 °C) on the crystal phase, morphology, specific surface area and porous properties, surface element composition, optical response properties of the resultant samples were investigated in detail, and the photocatalytic activities of these obtained CTNP samples for the degradation of methylene blue (MB) were evaluated under visible light irradiation. The results showed that precursor cubic TiC was transformed into anatase TiO₂ with the morphology of well-defined nanoplate completely after hydrothermal treatment for 30 h. The specific surface area of CTNP was significantly improved in comparison with that of micrometer sized C-doped TiO₂ plates (CTP) due to smaller particle size. Due to C-doping, CTNP presented red-shift absorption edge, which supported it with strong visible-light response. All these factors led to as-prepared CTNP having more excellent visible-light photocatalytic activity in comparison with micrometer sized CTP. The CTNP synthesized at 180 °C presented the optimal visible-light photocatalytic activity with a high reaction rate constant (0.03692 min⁻¹) among the four CTNP samples. Based on the results of the present study, a reasonable mechanism of photocatalysis on CTNP under visible light was proposed.