High-performance gas-sensing properties of octahedral NiO crystals prepared via one-step controllable synthesis route

Octahedrally shaped NiO powders have been synthesized via a one-step composite-hydroxide-mediated method without any surfactant. The synthesized materials are characterized by XRD, EDS, TEM and FESEM techniques. Each particle exhibited a nearly perfect octahedron shape with sharp edges and corners as well as smooth surfaces. The octahedral NiO particles performed better gas-sensitivity toward ethanol than that of NiO nanopowders, which was attributed to the exposed ｛111｝ facets of octahedron. The result was confirmed by the first-principle calculation which indicated that the (111) facet was more active than (100) and (110) facet.