Characterization of the location and interfacial states of gallium in gallium/MCM-41 composites

A broad based approach, using nitrogen adsorption, X-ray diffraction, DSC, solid-state NMR and X-ray photoelectron spectroscopy, has been used to characterize a series of Ga/MCM-41 composite materials. Rather than filling the mesochannels of the MCM-41 it is found, through this combination of techniques, that most of the Ga is present in the spaces between the particles of MCM-41. High-angle XRD and 71Ga NMR indicate that at room temperature most of the Ga is in the liquid metal state. 29Si and 1H MAS NMR, and XPS reveal that at the Ga/MCM-41 interface the Ga reacts with silanol groups to form new Ga+ states like SiOGa, or bridging Si(OH)Ga hydroxyls.