Controllable synthesis of In2O3 octodecahedra exposing {110} facets with enhanced gas sensing performance

In2O3 octodecahedra have been successfully prepared by annealing the 18-facet In(OH)(3) precursor. The as-prepared In2O3 polyhedra inherit the morphology of the In(OH)(3) precursor and expose twelve {110} and six {100} facets. Gas sensing tests show that octodecahedron-based In2O3 sensor exhibits a sensitivity of 610 to 1000 ppm ethanol, which is 2.3-fold and 5.5-fold enhancement compared with cube-and particle-based sensor, respectively. The XPS results demonstrate that the {110} and {100} facets of In2O3 octodecahedra provided more oxygen vacancies than either the cubes exposing only {100} facets or the irregular particles. More oxygen vacancies would contribute to the enhancement of gas sensing performance. The crystal facet analysis of In2O3 octodecahedra show that high energy {110} facets could be easier to form oxygen vacancy than that of {100} facets, which could be the main reason for high gas sensing property. This finding will open a door to the design of high performance gas sensor, and the results are also beneficial to other fields such as energy conversion, environmental protection.