Impact of Zr precursor on the electrochemical properties of V2O5 sol-gel films.

Abstract In this work, we explore the impact of Zr precursor on the electrochemical and optical properties of V 2 O 5 thin films. These films were synthesized by the combination of the sol-gel route with dip-coating deposition on the electron conducting (fluorine tin oxide; FTO) substrate. We used vanadium oxytriisopropoxide (V) - [OV(OC 3 H 7) 3 ] and zirconium isopropoxide (IV) - [Zr(OCH 2 CH 2 CH 3) 4 ] as precursors, isopropanol as solvent, and glacial acetic acid as a catalyst. After the deposition, the thin films were subjected to densification at 350 °C for 30 min. We characterized these films by electrochemical techniques (cyclic voltammetry, chronoamperometry and chronocoulometry) and we obtained the best result of the load density of 109 mC·cm−2 for V 2 O 5 sample prepared with 5 mol% of Zr precursor; this sample also presented satisfactory responses of cyclic stability. We used atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) to obtain morphology and crystallinity of this film. Its optical properties, we studied by UV–vis spectroscopy and the transmittance results were of 82% for the discolored and 39% for colored states, both measured at 633 nm. In summary, we show that V 2 O 5 :ZrO 2 thin films have quite attractive properties for their application as a working electrode in electrochromic devices. Graphical abstract Unlabelled Image Highlights • Different V 2 O 5 :ZrO 2 thin films were synthesized and characterized. • V 2 O 5 doped with 5 mol% ZrO 2 had the best value of charge density of 109 mC/cm2. • The ΔT between colored and discolored states of this film was 43% at 633 nm. • This film had an orthorhombic structure with the preferential (001) orientation in the crystalline plane. • The AFM topography evidenced dense and compact structure and RMS roughness of 7.06 nm. [ABSTRACT FROM AUTHOR]