Sustainable developments to improve energy consumption in buildings and energy storages are essential issues that can be solved by using green technologies. In this talk, we present electro-exploding wire and spray coating techniques for the synthesis of nanoparticulate films of WO3-MoO3 composite films. The nanoparticulate films are characterized in a three-electrode potentiostat and they are used to assemble electrochromic devices for the transmittance and energy storage measurements. The nanoparticulate WO3-MoO3 films exhibit high electrochromic performances with a diffusion coefficient of deintercalation of 3.39X10-10 cm2/s, a charge density of 28.5 mC/cm2, the coloration efficiency of 40.9 cm2/C at the light wavelength of 430 nm, and the transmittance variations of about 17% and 44% at wavelengths of 430 and 635 nm.

The nanoparticulate WO3-MoO3 films not only display good electrochromic performances but also energy storage capabilities. These films exhibit a high porosity that is beneficial for ion diffusions in electrolyte and for increasing the efficiency of oxidations and reductions. In particular, the porous nanoparticulate WO3-MoO3 films can be stacked to increase the thickness and to enhance the energy storage capability. Nanoparticulate WO3-MoO3 films with different thickness are prepared for charge and discharge measurements. Samples WMo-500, WMo-1000, WMo-1300, WMo-1600, and WMo-2000 are films with thicknesses of about 500, 1000, 1300, 1600, and 2000 nm, respectively. Figure 1a shows galvanostatic charge-discharge curves of all samples at a constant current density of 0.1 mA/cm2 in the voltage range between -1.2 and 0.5 V. The obtained area capacitances as a function of film thickness are displayed in Fig. 1b. We will discuss the particular energy storage feature of the nanoparticulate films.