Reduction of colloidal Ag2S to binary Ag2–XS/Ag nanoparticles under UV and visible irradiation

The formation of Ag_{2 – x}S /Ag binary nanoparticles in an aqueous colloid dispersion of Ag₂S under irradiation leads to an asymmetry in the optical absorption spectrum as a consequence of the Fano resonance due to the interaction between the excitons of semiconductor nanoparticles and the plasmons of metallic nanoparticles. Aqueous dispersions from different stability regions containing Ag₂S nanoparticles have been studied. Sunlight, UV and laser irradiation leads to the partial reduction of silver in the dispersion and the formation of the Ag_{2 – x}S /Ag particles depending on the initial state of the dispersion and the conditions of irradiation.