Hydrothermal synthesis of Bi₂Se₃ nanosheets by using gallic acid as a reductant

In this work, a simple and reproducible hydrothermal synthesis was employed to synthesize two-dimensional Bi₂Se₃ nanosheets by using gallic acid as a reductant. Meanwhile, the effects of the amounts of gallic acid and sodium hydroxide and the surfactant Triton X-100 on phase composition and morphology of the obtained Bi₂Se₃ were also studied. The results reveal that gallic acid could effectively reduce Se⁴⁺ to Se^2- and gave rise to the formation of Bi₂Se₃. Additionally, keeping the reaction conditions of molar ratio of gallic acid to the precursor elements (Bi + Se) at 1 to 1 (or higher) and using strong alkaline solutions were the key factors to synthesize high purity crystalline Bi₂Se₃ nanosheets. Furthermore, flower-like Bi₂Se₃ composed of nanosheets with a dozen nanometer thickness could be easily fabricated by adding appropriate amounts of Triton X-100. This work provides a novel approach for synthesis of ultra-thin Bi₂Se₃ nanosheets in a controllable manner.