Synthesis of β-Ag2Se from organo-selenium precursor and silver nitrate in DMF via simultaneous reduction of selenium and silver salt

Reaction of selenium powder and silver nitrate in aqueous N, N′-dimethylformamide (aq. DMF) leads to formation of silver selenide. Similar reaction with cycloalkeno-1,2,3-selenadiazole, an organic compound of selenium upon thermolysis, also produces silver selenide. It is believed that DMF activates selenium and reduces silver salt via in-situ generated hydrogen ion simultaneously. Slightly broadened X-ray diffraction pattern for pure beta silver selenide (β-Ag2Se) was observed. Scanning electron microscopy (SEM) indicated that the agglomerated particles could be in the range of about 100 to 200 nm in dimension. EDAX analysis showed non-stoichiometric elemental ratio between silver and selenium. It is found that the weight percent of Ag is slightly higher than Se. However, free amorphous selenium is also detected by XPS analysis when the product is made by use of elemental selenium. Thermal analysis (TGA) revealed a small (4%) weight loss due to the presence of organics or the solvent from the reaction medium.