Porous α-Fe2O3/SnO2 nanoflower with enhanced sulfur selectivity and stability for H2S selective oxidation

Branched SnO(2)/alpha-Fe(2)O(3) semiconductor nanoheterostructures (SNHs) of high purity were synthesized by a low-cost and environmentally friendly hydrothermal strategy, through crystallographic-oriented epitaxial growth of the SnO(2) nanorods onto the alpha-Fe(2)O(3) nanospindles and nanocubes, respectively. It was demonstrated that the SnO(2) nanorods would change their preferential growth direction on the varied alpha-Fe(2)O(3) precursors with distinct crystallographic surface, driven by decrease in the distortion energy induced by lattice mismatch at the interfaces. All of the prepared SNHs were of high purity, ascribing to the successful preinhibition of the SnO(2) homonucleation in the reaction system. Significantly, some of the SnO(2)/alpha-Fe(2)O(3) SNHs exhibited excellent visible light or UV photocatalytic abilities, remarkably superior to their alpha-Fe(2)O(3) precursors, mainly owing to the effective electron-hole separation at the SnO(2)/alpha-Fe(2)O(3) interfaces.

CeO2 decorated SnO2 hollow spheres were successfully synthesized via a two-step hydrothermal strategy. The morphology and structures of as-obtained CeO2/SnO2 composites were analyzed by various kinds of techniques. The SnO2 hollow spheres with uniform size around 300 nm were self-assembled with SnO2 nanoparticles and were hollow with a diameter of about 100 nm. The CeO2 nanoparticles on the surface of SnO2 hollow spheres could be clearly observed. X-ray photoelectron spectroscopy results confirmed the existence of Ce(3+) and the increased amount of both chemisorbed oxygen and oxygen vacancy after the CeO2 decorated. Compared with pure SnO2 hollow spheres, such composites revealed excellent enhanced sensing properties to ethanol. When the ethanol concentration was 100 ppm, the sensitivity of the CeO2/SnO2 composites was 37, which was 2.65-times higher than that of the primary SnO2 hollow spheres. The sensing mechanism of the enhanced gas sensing properties was also discussed.