Controllable synthesis of PbSe nanostructures and growth mechanisms

Octopod-like PbSe structures with eight symmetric arms of 1.0-3.0 mu m 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 mu m in-plane sizes can be formed. Similarly, by changing the molar ratio of NaOH/Pb(NO3)(2) from 40 to 5, the nanocubes of similar to 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.