Mo_xW_1−xO₃·0.33H₂O Solid Solutions with Tunable Band Gaps

Abstract

A series of MoxW1−xO3·0.33H2O (x = 0, 0.25, 0.50, 0.75) micro/nanostructures and α-MoO3 nanobelts have been prepared by a facile hydrothermal treatment method starting from aqueous peroxo-polytungstic acid and peroxo-molybdic acid solutions. The WO3·0.33H2O lattice can be substituted with up to 75% Mo without structural alterations of the orthorhombic host structure. With the increase of the Mo content (x) from 0 to 0.75, the band gap of the as-prepared MoxW1−xO3·0.33H2O micro/nanostructures is narrowed from 3.25 to 2.77 eV. The increased M5+ (M = Mo and W) fraction and thus enhanced intervalency-transition are responsible for the narrowing of the band gap.