Peroxo sol-gel preparation: photochromic/electrochromic properties of Mo-Ti oxide gels and thin films

Metallic Mo powder and Ti(OBun)(4) were separately dissolved in H2O2 soluti on and the solutions obtained mixed in different Mo/Ti atomic ratios to pre pare precursor solutions. Fresh gels obtained from the precursor solutions with > 40% Mo became blue upon exposure to ambient light. X-Ray photoelectr on spectroscopy (XPS) was used to examine the chemical states and compositi ons of the resultant blue-tinged xerogel powders. Based on the XPS results, it is proposed that TiO2 particles and surface species, including adsorbed water and organic residue, all contribute to the photochromic effect of Mo O3. Mo-Ti oxide films were spin-coated on ITO-coated glass substrates using a precursor solution containing 70% Mo. The cycling behaviours of the film s annealed at 150 degrees C for 1 h were studied using cyclic voltammetry ( CV) in propylene carbonate solution containing 1 mol L-1 LiClO4. The electr ochromic properties of the films upon lithium intercalation were investigat ed by in situ monochromatic transmittance measurements during the CV proces s, as well as ex situ in the UV/Vis region. The Mo-Ti oxide films were foun d to possess excellent electrochromic properties upon Li+ ion insertion/ext raction.