The color of some transition metal oxides changes when they are exposed to an extrinsic excitation. The excitations are some physical effects including electric potential, UV light, H 2 gas, temperature or even ion bombardment. For example when the color changes with the exposure of hydrogen gas, the effect is called gasochromism or when electric potential is applied the effect is called electrochromism. In this project, we investigate and develop the gasochromism and introduce a new electrochromic system. In-liquid gasochromism has been attended in the recent years due to the special absorbing bands that has not been observed in thin film gasochromism. We tried to introduce simple and low cost methods in order to synthesize TMO nanostructures inside liquids. Hydrothermal, anodizing and pulsed laser ablation methods have been used in order to produce WO 3 or MoO 3 nanostructures in water. The gasochromic studies on these colloids was done with bubbling H 2 gas inside the corresponding liquids. A spectrophotometer showed the switching of color by determination of UV-visible-IR transmitted light during the bubbling. Thin films of WO 3 were the other case study of our project. WO 3 thin films were deposited epitaxially on SrTiO 3 substrates using pulsed laser deposition method. Reflection high-energy electron diffraction (RHEED) patterns during and after growth were used to determine the surface structure and morphology. Then it has been used to make a Field Effect Transistor (FET) by deposition of some electrodes on top. Ionic liquid gating on WO 3 thin film FETs was completely studied by measuring the resistivity of the film channel during gating. It is shown that another method to make coloration in TMO structure is to introduce ionic liquids as electrolyte in an electrochromic system. The characterization of colloidal nanostructures and thin films were determined by scanning electron microscopy, atomic force microscopy or transmission electron microscopy, X-ray photoelectron spectroscopy, furrier transform IR spectroscopy, X-ray diffraction and X-ray reflectivity.
