Nanoplates of α-SnWO4 and SnW3O9 prepared via a facile hydrothermal method and their gas-sensing property

Nanoplates of α-SnWO4 and SnW3O9 were selectively synthesized in large scale via a facile hydrothermal reaction method. The final products obtained were dependent on the reaction pH and the molar ratio of W6+ to Sn2+ in the precursors. The as-prepared nanoplates of α-SnWO4 and SnW3O9 were characterized by X-ray powder diffraction (XRD), N2-sorption BET surface area, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The XPS results showed that Sn exists in divalent form (Sn2+) in SnW3O9 as well as in α-SnWO4. The gas-sensing performances of the as-prepared α-SnWO4 and SnW3O9 toward H2S and H2 were investigated. The hydrothermal prepared α-SnWO4 showed higher response toward H2 than that prepared via a solid-state reaction due to the high specific surface area. The gas-sensing property toward H2S as well as H2 over SnW3O9 was for the first time reported. As compared to α-SnWO4, SnW3O9 exhibits higher response toward H2S and its higher response can be well explained by the existence of the multivalent W (W6+/W4+) in SnW3O9.