Selective Surfaces: High-Surface-Area Zinc Tin Sulfide Chalcogels

Porous zinc tin sulfide aerogel materials were constructed by metathesis reactions between Zn(acac)₂·H₂O and tetrahedral thiostannate cluster salts containing discrete [SnS₄]^4-, [Sn₂S₆]^4-, and [Sn₄S₁₀]^4- units. Self-assembly reactions of the Zn²⁺ linker and anionic thiostannate clusters yielded polymeric random Zn/Sn/S networks with gelation properties. Supercritical drying of the gels and solvent/counterion removal resulted in a metal sulfur framework. Zn₂Sn_xS_2x+2 (x = 1, 2, 4) aerogels showed high surface areas (363−520 m²/g) and pore volumes (1.1−1.5 cm³/g), and wide bandgap energies (2.8−3.2 eV). Scanning and transmission electron microscopy studies show the pores are micro- (d < 2 nm), meso- (2 nm < d < 50 nm), and macro- (d > 50 nm) regions. The zinc chalcogenide aerogels also possess high affinities toward soft heavy metals and reversible absorption of strong electron-accepting molecules.