Making sense out of sulfated tin dioxide mesostructures

Abstract

An in-depth investigation into the synthesis, characterization and sensor response of mesoporous SnO₂ materials formed utilizing tin(IV) chloride, sodium dodecylsulfonate, and urea is described. The structures have been stabilized towards calcination by increasing the condensation of the tin oxide network utilizing urea as a slow-release base. PXRD, FT-Raman, N₂ gas adsorption, thermal gravimetric analysis, and pyrolysis mass spectroscopy were used to monitor the two-step surfactant decomposition in which a sulfated tin oxide surface is formed followed by removal of the sulfate groups at elevated calcination temperatures. In situ a.c. impedance measurements of the materials in dry air and 2000 ppm carbon monoxide showed that the sensitivity of these materials towards carbon monoxide was inhibited by the presence of sulfate groups on the surface, whereas after the sulfate groups were removed the materials became much more sensitive towards carbon monoxide. These materials could find promising applications as gas-selective chemical sensors, super-acid catalysts, and anode materials for lithium battery applications.