We report the synthesis of metal-chalcogenide aerogels from Pt2+ and polysulfide clusters ([S-x](2-), x = 3-6). The cross-linking reaction of these ionic building blocks in formamide solution results in spontaneous gelation and eventually forms a monolithic dark brown gel. The wet gel is transformed into a highly porous aerogel by solvent exchanging and subsequent supercritical drying with CO2. The resulting platinum polysulfide aerogels possess a highly porous and amorphous structure with an intact polysulfide backbone. These chalcogels feature an anionic network that is charged balanced with potassium cations, and hosts highly accessible S-S bonding sites, which allows for reversible cation exchange and mercury vapor capture that is superior to any known material.