Direct Dissolution of Silver Halides to a Super Highly Concentrated Solution for Antimicrobial and Photocatalytic Materials

The successful dissolution of silver halide AgX (X = Cl, Br, I) in an efficient and eco-friendly way would greatly promote the application of AgX in broad applications. In this work, a sustainable new strategy to directly dissolve AgX (including AgCl, AgBr, and AgI) using imidazolium chloride ionic liquids, such as 1-allyl-3-methylimidazolium chloride (AmimCl), is presented. The dissolution process was carried out under mild conditions with heating (80 °C) and mild stirring. AgX/AmimCl solutions with a high concentration were successfully obtained, which were 1020 g/L for AgCl/AmimCl, 667 g/L for AgBr/AmimCl, and 834 g/L for AgI/AmimCl. The combination of AgX and chloride ions (Cl^–) in AmimCl facilitated the formation of complex anion [AgXCl]⁻, which acted as the “driving force” to enable the effective dissolution of AgX. The addition of water or reductants into the AgX/AmimCl solutions could lead to the formation of AgX or silver nanoparticles (Ag NPs), respectively. Furthermore, cellulose/AgCl composites were prepared using this dissolving strategy and showed superior antimicrobial property and photocatalytic activity under visible light. More importantly, the solvent AmimCl could be efficiently recycled and reused. This work provides a sustainable new strategy for efficient processing and utilization of chlorargyrite and silver-containing materials.