Thermo-oxidative stability of SnO crystals and obtained few layer crystals by mechanical exfoliation

Stannous oxide (SnO) is prepared by a sol–gel reaction, and the intermediate product is a white gel material, Sn6O4(OH)4, which is decomposed by a constant temperature heat treatment to form a regular black crystal, and the size reach 300 μm approximately. TG-DSC analysis shows that under air atmospheric conditions, SnO undergoes an oxidation and thermal decomposition reactions at 350 °C, which to form SnO2, Sn, and Sn3O4. With the temperature increasing, the reaction will continue and the final product will be SnO2. X-ray photoelectron spectroscopy (XPS) analysis shows that SnO is sensitive to oxygen. It is placed in air for about 2 months, and 81.8% of the crystal surface is oxidized to SnO2, but the inside of the crystal remains as SnO. Few layer crystal sheets was prepared by mechanical exfoliation with a thickness of 85 nm and a surface roughness of 1.02 nm, which provides a possibility for the application of few layers of SnO crystals to transparent and flexible electronic devices.