Mimicking High-Silica Zeolites: Highly Stable Germanium- and Tin-Rich Zeolite-Type Chalcogenides

High-silica zeolites,
as exemplified by ZSM-5, with excellent chemical
and thermal stability, have generated a revolution in industrial catalysis.
In contrast, prior to this work, high-silica-zeolite-like chalcogenides
based on germanium/tin remained unknown, even after decades of research.
Here six crystalline high-germanium or high-tin zeolite-type sulfides
and selenides with four different topologies are reported. Their unprecedented
framework compositions give these materials much improved thermal
and chemical stability with high surface area (Langmuir surface area
of 782 m2/g–1) comparable to or better
than zeolites. Among them, highly stable CPM-120-ZnGeS allows for
ion exchange with diverse metal or complex cations, resulting in fine-tuning
in porosity, fast ion conductivity, and photoelectric response. Being
among the most porous crystalline chalcogenides, CPM-120-ZnGeS (exchanged
with Cs+ ions) also shows reversible adsorption with high
capacity and affinity for CO2 (98 and 73 cm3 g–1 at 273 and 298 K, respectively, isosteric
heat of adsorption = 40.05 kJ mol–1). Moreover,
CPM-120-ZnGeS could also function as a robust photocatalyst for water
reduction to generate H2. The overall activity of H2 production from water, in the presence of Na2S–Na2SO3 as a hole scavenger, was 200 μmol h–1/(0.10 g). Such catalytic activity remained undiminished
under illumination by UV light for as long as measured (200 h), demonstrating
excellent resistance to photocorrosion even under intense UV radiation.