Pure CoO(OH), with intra particulate porosity up to 76%, was synthesized by an innovative aqueous precipitation method, starting either from nitrate or sulfate salts. Microstructural and chemical properties were characterized by powder X-ray diffraction (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The primary particles (10-15 nm) are self-organized in monolayer building hexagonal nano-platelets (50-200 nm) which are arranged randomly creating large pores. CoO(OH) was converted in Co 3 O 4 by heating in air at 250 • C. This treatment did not modify the porosity but increased the specific surface area, which became close to 100 m 2 /g. The catalytic activity for CO and C 3 H 8 total oxidation was better for Co 3 O 4 than for CoO(OH). Besides, at high conversion rate, catalysts prepared from sulfate precursor showed a superior activity for C 3 H 8 oxidation than those prepared from nitrate. This effect can be explained by the improved accessibility of reactants to the surface of the catalysts which exhibit a larger porosity. To our knowledge, the activity values presented here are the highest reported in literature for C 3 H 8 total oxidation.

WO3−x (oxygen deficient tungsten oxide) thin films and WO3−x/Ta2O5 (tantalum oxide) composite films exhibit a huge photochromic effect with 60% near-infrared transmission modulation.

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Herein, the successful synthesis of Ti-doped vanadium pentoxide from a polyol process is reported. A high Ti concentration (up to 8.5 mol % of the total metallic content) can be inserted in vanadium oxide thanks to the synthesis route leading to nanometric crystallites. X-ray diffraction patterns were refined showing the insertion of the titanium ions inside the free pentacoordinated sites in opposition to the vanadium square pyramidal sites. This crystal organization was shown in good agreement with the ab initio positioning performed from valence calculation. The nanoparticles, NPs, of Ti-doped VO compounds were characterized as electrochromic materials. Films elaborated from a dip-coating process from oxide particle suspensions exhibited three distinct colorations during the redox cycling in lithium-based electrolyte. These colors were associated with three distinct oxidation states for the vanadium ions: +III (blue), +IV (green), and +V (orange). The morphology of the films was shown to drastically impact the electrochromic performances in terms of electrochemical capacity and stability.

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Oxide thin solid films were prepared by dip-coating into colloidal dispersions of oxide nanoparticles stabilized at room temperature without the use of chelating or complex organic dispersing agents. Crystalline oxide nanoparticles were obtained by inorganic polycondensation and characterized by X-ray diffraction and field emission gun scanning electron microscopy. Water and ethanol synthesis and solution stabilization of oxide nanoparticle method was optimized to prepare two different structural and compositional materials, namely Cu 2 O and ZnO. The influence of hydrodynamic parameters over the particle shape and size is discussed. Spherical and rod shape nanoparticles were formed for Cu 2 O and ZnO, respectively. Isoelectric point values of 7.5 and 8.2 were determined for cuprous and zinc oxides, respectively, after zeta potential measurements. A shear thinning and thixotropic behavior was observed in both colloidal sols after peptization at pH~6 with dilute nitric acid. Every colloidal dispersion stabilized in a low cost and environmentally friendly azeotrope solution composed of 96 vol.% of ethanol with water was used for the thin film preparation by the dip-coating technique. Optical properties of the light absorber cuprous oxide and transparent zinc oxide thin solid films were characterized by means of transmittance and reflectance measurements (300-1100 nm).

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