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.