nanosheets can also be prepared at room temperature. for instance, hexagonal pbo (lead oxide)) nanosheets were synthesized using gold nanoparticles as seeds under room temperature. the size of the pbo nanosheet can be tuned by gold nps and concentration in the growth solution. no organic surfactants were employed in the synthesis process. oriented attachment, in which the sheets form by aggregation of small nanoparticles that each has a net dipole moment, and ostwald ripening are the two main reasons for the formation of the pbo nanosheets. the same process was observed for iron sulfide nanoparticles.