Controllable Synthesis of PbSe Nanostructures and Growth Mechanisms

Octopod-like PbSe structures with eight symmetric arms of 1.0−3.0 µm in length have been hydrothermally synthesized without any surfactant. Keeping the other conditions the same, only by changing the molar ratio of NaOH/Pb(NO3)2 from 40 to 5, quasi-spherical nanoparticles were obtained. As poly(vinyl pyrrolidone) (PVP) was added, single-crystal PbSe nanosheets of 20−60 nm in thickness and 0.5−5.0 µm in-plane sizes can be formed. Similarly, by changing the molar ratio of NaOH/Pb(NO3)2 from 40 to 5, the nanocubes of ∼70 nm in edge length were formed. The possible growth mechanisms for the nanosheets and octopod-like structures of PbSe are discussed on the basis of transmission electron microscopy and scanning electron microscopy analysis from the time-dependent experiments.