Hydrothermal deposition and the photochromic properties of molybdenum oxide hydrate (MoO3•(H2O)0.69) films induced by D, L-malic acid

Two kinds of molybdenum oxide hydrate films were successfully synthesized by a simple hydrothermal deposition method. The X-ray diffraction shows that all the samples can be indexed to hexagonal structure of MoO3 center dot(H2O)(0.69). Scanning electron microscopy images of the products revealed that hexagonal prismatic structures were revealed on the surface of the sample prepared without capping. While the surface of ones obtained with D, L-malic acid were covered by dandelion-like hierarchical structures, which may result from the effect of hydrogen bonds, and the dandelion-like hierarchical structures can be completed by increasing the amount of D, L-malic acid. The MoO3 center dot(H2O)(0.69) films prepared with D, L-malic acid possessed better photochromic properties compared with the one obtained without capping agents and the films prepared with the molar ratio of D, L-malic acid and sodium molybdate at 1: 5 performed best, which could be due to the changes in the morphologies that increased the amount of photogenerated electron-hole pairs and the proton diffusion rates. (C) 2013 Elsevier B. V. All rights reserved.