Effects of Mo-doping on microstructure and near-infrared shielding performance of hydrothermally prepared tungsten bronzes

Abstract

Both Mo and W belong to VIB-sub-group, and possess similar ionic radii, electronegativity and oxide lattice configuration. Herein, Mo-doped (0–80at.%) tungsten bronzes, MxWO3, were hydrothermally prepared to systematically explore the influence of Mo-doping on their micro-structure and optical performance. The products adopted a hexagonal structure within 6at.% Mo-doping, and transformed into a monoclinic phase with higher Mo-doping content. Further tests suggested that 1.5at.% Mo-doping is beneficial for the formation of pure hexagonal phase and uniform nano-rod morphology. Optical measures showed that all samples exhibited high and comparable visible transmittance (70–80%), but a very different near infrared (NIR) shielding ability. The sample doped with 1.5at.% Mo demonstrated the best NIR shielding ability with a transmittance minimum of 20% at 1300nm. Further increase of Mo-doping dosage remarkably deteriorated NIR shielding ability by depressing the absorption of localized surface plasmon resonance (LSPR). However, the optical absorption from small-polaron was less influenced by the introduction of Mo. As a result, Mo-doping caused an evident blue shift of the infrared absorption peaks from 1350 to 750nm.