Synthesis and characterization of indium monoselenide nanosheets: A proposed pseudo top-down mechanism

• Colloidal synthesis of 2D-graphene like indium monoselenide nanosheets.
• New proposed growth mechanism.
• Controlled synthesis of 2D and 0D indium selenide nanostructures.

Rhombohedral InSe nanocrystals have been synthesized by the refluxing of InCl3 and Se in oleylamine (OLA) in one pot, at a temperature of 200 °C and a mole ratio of 1:1. The role of OLA in this method is to reduce the selenium while acting as both a solvent and a capping agent. The optical properties of the resulting nanoparticles have been studied by obtaining their absorption and photoluminescence spectra. The morphology and phase structure of the InSe nanoparticles have also been determined by X-ray diffraction and transmission electron microscopy (TEM). The TEM images show that the nanoparticles developed from large layered structures at the beginning of the synthesis, then later disintegrated to smaller particles as the time of synthesis is prolonged. This is confirmed by the UV–vis absorption spectra as they show that the nanoparticles obtained after 60 min are blueshifted compared to the ones obtained after 10 min. The formation mechanism of the nanoparticles resembles the top-down approach though the particles are first constructed chemically to form bulk InSe which then self-digest by breaking down chemically to form smaller particles; hence we call it the pseudo top-down approach.