Influence of morphology on the photocatalytic and fiber optic ammonia gas sensing performance of tin oxide nanostructures by a novel microwave irradiation method

摘要

Tin oxide hexagonal-shaped nanodisks (NDs) and nanowires (NWs) were successfully prepared by one-step microwave irradiation method using cetyltrimethylammonium bromide (CTABr) and polyethylene glycol (PEG) as surfactants. The XRD pattern indicates that SnO2 is crystalline with tetragonal rutile structure. TEM micrographs confirm SnO2 nanodisks, approximately 100 nm in width and 20 nm in thickness, and a straight single SnO2 nanowire with a diameter of about 30 nm and length up to several micrometers for CTAB- and PEG-assisted samples, respectively. The elemental composition and oxidation state were also confirmed through EDS and XPS analyses. Effect of morphology on the photocatalytic performance of SnO2 nanostructures was studied toward degradation of methylene blue (MB) and rhodamine B (RhB) under visible light irradiation. For SnO2 NDs, it was observed that 99% and 97% of MB and RhB dyes were degraded in 100 min of irradiation time. In contrary, the SnO2 NWs showed high sensitivity (71.4 counts/ppm), fast response (35 min) and recovery time (25 min) toward ammonia gas compared to SnO2 NDs. This could be attributed to large surface area and high adsorption of ammonia molecules on the SnO2 surface.