Evidence by electrical conductivity for an excess of bismuth as Bi+ interstitials at the surface of gamma phase Bi2MoO6. Consequence for selectivity in propene catalytic oxidation

Abstract

Bismuth molybdate in the alpha phase Bi2Mo3O12 behaves as an intrinsic semiconductor, whereas the gamma phase (Bi2MoO6) appears as an n-type semiconductor, whose conduction electrons originate from the formation of Bi+ interstitials in the excess Bi2O3 layer, present at the surface. The elimination of the excess of Bi2O3 could account for the synergic effect observed in the mild catalytic oxidation of propene.