| Hydrogenated ?a-Fe2O3 nanoparticles,sea urchin-like nanostructures and naonocubes with exposed {012},{102} and {112} facets as well as InOOH hexagrams with exposed clean {020} facets were prepared by hydrogenation,heat treatment in air and hydrothermal methods.The morphology,crystal phase and surface structure were characterized by using powder X-ray diffraction(XRD),SU-8020 field emission scanning electron microscopy(FESEM),field emission transmission electron microscopy(FETEM),Fourier transform infrared(FTIR)spectroscopy and X-ray photoelectron spectra(XPS).The gas-sensing properties of non-hydrogenated and hydrogenated a-Fe203 nanostructures and photocatalytic activities of the InOOH hexagram before and after heat treatment in air were studied.The relation between surface structures and gas-sensing as well as photocatalytic activities were discussed.The specific research results are as follows:(1)The hydrogenated ?-Fe2O3 nanostructures were obtained by heating ?-Fe2O3 nanoparticles and sea urchin-like nanostructures under a H2 flow,the gas-sensing performances of them were measured.The results showed that hydrogenated ?-Fe2O3 nanostructures show higher response towards ethanol,formaldehyde,acetone and n-Butylamine compared to the non-hydrogenated one,and.it increased further with the hydrogenation time.The effects of hydrogenation on its surface structure were studied,and discussed the relation between surface structures and gas-sensing,then the unsaturated Fe atom with dangling bonds may function as a sensing reaction active site were proposed,by which can explain the excellent sensing mechanism at molecular level.(2)The ?-Fe2O3 nanocubes with exposed clean {012},{102} and {112} facets were obtained by hydrothermal reaction at 140 ? and soaking in AgNO3 and NH3 H2O solutions in turn.Then the nanocubes were hydrogenated.And the gas-sensing performances of were measured.The results showed that the response of the a-Fe2O3 towards ethanol,acetone and n-Butylamine were enhanced obviously by hydrogenation and in-site reduction AgCl.The relation between hydrogenation and surface structures as well as gas-sensing was discussed.We considered that 3-coordinated Fe atoms at Fe-a-Fe2O3(012)and(102)surface function as the active sites.And the enhanced gas-sensing of ?-Fe2O3 is described in detail.(3)The InOOH hexagrams with exposed {020} facets were pepared by hydrothermal reaction at 220 ?,the InOOH hexagram were heated at different temperature in air.And the photocatalytic activities of them were measured.The results showed that InOOH hexagrams after heat treatment show higher photocatalytic activities on the degradation of RhB and MO,and it increased further with the heat treatment temperature.The relation between heat treatment and surface structures as well as photocatalytic activities was discussed.A charge separation modle of polar {020}facets of InOOH was proposed.And the enhanced photocatalytic activities mechanism of InOOH is described in detail. |
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