Mesoporous germanium-rich chalcogenido frameworks with highly polarizable surfaces and relevance to gas separation

Abstract

Mesoporous materials with tunable non-oxidic framework compositions can exhibit new kinds of functionality including internal surfaces with high polarizability. As the chemical and physical characteristics of the framework components can induce useful catalytic, absorption and optoelectronic features, the mesoporous structure can promote fast mass diffusion kinetics and size-selective transport of guest molecules. So far, synthetic efforts have resulted in mesoporous metal chalcogenides on using structure-directing moulds of soft or hard templates. These include ordered mesoporous II-VI semiconductors (such as CdS (refs 2,3), ZnS (ref. 4) and CdTe (ref. 5)). Recently, template-free synthetic routes for high-surface-area chalcogenide aerogels have been reported. Here, we describe a novel kind of porous materials based on germanium-rich chalcogenide networks and 'soft' highly polarizable surfaces. We demonstrate that these materials can exhibit excellent selectivity for separating hydrogen from carbon dioxide and methane. These highly polarizable mesoporous structures have important implications for membrane-based gas separation process technologies including hydrogen purification.