Ag2SO4 decorated with fluorescent Agn nanoclusters

Microstructured fluorescent Ag2SO4 is synthesized via anodization of Ag foil in a HF-H2SO4 electrolyte. The residual Ag2O is embedded in the Ag2SO4 deposit and photo-decomposed to fluorescent nanoclusters (Agn). [Display omitted] ► Ag foil was anodized in a HF-H2SO4 electrolyte to produce an Ag2SO4/Ag2O mixed-grain powder. ► The photo-decomposed powder exhibited strong fluorescence. ► We proposed fluorescence arises from silver nanoclusters embedded with the Ag2SO4. Here we report on the production of an Ag2SO4/Ag2O mixed-grain powder during the anodization of Ag foil in a HF-H2SO4 electrolyte. We propose that there are three competing reactions during the anodization process: (i) the production of Ag2O at the Ag foil anode surface from the presence of water in the electrolyte, (ii) the dissolution of the Ag2O in the presence of HF releasing Ag+ ions, (iii) the precipitation of Ag+ and SO42− ions, as Ag2SO4 on the Ag foil anode surface. This co-precipitation/dissolution process ultimately results in a mixed-grain powder. We then show that the Ag2O embedded within the mixed-grain is photo-decomposed to produce highly fluorescent silver nanoclusters (Agn) which decorate the Ag2SO4 crystals. The Ag2SO4 salt offers a stable matrix for the photo-decomposed Agn nanoclusters to emit their strong fluorescence.