Preferentially epitaxial growth of beta-FeOOH nanoflakes on SnO2 hollow spheres allows the synthesis of SnO2/alpha-Fe2O3 hetero-nanocomposites with enhanced gas sensing performance for dimethyl disulfide

Hetero-nanocomposites have shown extraordinary potential for improving the properties of nanomaterials originated from the interfacial interaction. Herein, we report the synthesis of the sea urchin-like SnO2/alpha-Fe2O3 hetero-nanocomposites, which was constituted of SnO2 hollow spheres and a-Fe2O3 needle-like nanoparticles, via integrating a two-step hydrothermal route with an annealing process. The detailed studies revealed that the preferentially epitaxial growth of two-dimensional beta-FeOOH nanonanoflakes on three-dimensional SnO2 hollow spheres in the second hydrothermal process is the main reason for the formation of such hetero-nanocomposites, which is also directly observed by the characterization on high resolution transmission electron microscopy. Significantly, such SnO2/alpha-Fe2O3 hetero-nanocomposites were demonstrated as a promising sensing material for dimethyl disulfide and showed excellent gas sensing performances, prominently superior to the gas sensor based on pristine SnO2 hollow spheres. More importantly, further H-2-TPR, CO-TPR and NH3-TPD measurements for such hetero-nanocomposites shows that the enhanced sensing performances probably arise from the improvement of oxidizability induced by change of surface basic property of nanocomposites, as well as the formation of electron accumulation layer driven by the heterojunctions between SnO2 and alpha-Fe2O3.