Used as a catalyst in the Deacon process for the production of chlorine from hydrogen chloride. Employed as a catalyst in organic synthesis, particularly in coupling reactions such as Ullmann-type reactions. Used in the production of printed circuit boards as an etching agent for copper due to its ability to oxidize metallic copper. Utilized in industrial dyeing processes as a mordant to fix dyes on fabrics. Applied in wood preservation to protect against fungal decay and insect damage. Also used in the preparation of other copper-based chemicals, in some electroplating solutions, and in wastewater treatment to remove sulfides and control odors.