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In this work, vanadium pentoxide (V2O5) and titanium-modified V2O5 thin films were synthesized using the sol-gel spin coating route. The effect of Ti-doping concentration on the electrochromic optical properties and atomic/electronic structures of V2O5 smart thin films is examined. As the doping concentration of Ti increases, the surface roughness of the films is reduced. The structure of the films is analyzed using X-ray diffraction (XRD) and Raman spectroscopy, while the electrochromic modulation of atomic and electronic structures is elucidated through Raman and X-ray absorption spectroscopy (XAS) conducted during lithiation and delithiation. The XRD patterns demonstrate that an increase in Ti concentration leads to a more amorphous structure of the films and a shift of the main diffraction peak to a lower angle, attributable to the enlarged spacing between the stacking layers resulting from the incorporation of Ti ions. Soft X-ray absorption spectroscopy (XAS) and in situ hard XAS of the V L-edge, the O K-edge, and the V K-edge revealed a reduction in the charge state of V and local atomic structural symmetry modification upon lithated coloration and delithiated bleaching process. The critical insights provided by in situ XAS provides reveal that a small amount of Ti has the ability to modify the interlayer distance and local atomic structure of V2O5, thereby improving its electrochromic switching rate and stability when utilized in smart windows.

The exploration of zinc oxide (ZnO) has seen rapid growth due to its wide bandgap, high thermal conductivity, and high electron mobility within its nanostructures, making it highly valuable for applications in electronic and optical devices. This study involves the deposition of ZnO nanostructures onto a quartz substrate using the thermal evaporation deposition technique. The research delves into the influence of various annealing environments on morphology and electronic/atomic structures. X-ray Diffraction (XRD) analysis reveals the development of the ZnO phase with a preferred orientation when annealed in a mixture of hydrogen and argon gases. It was observed that the films do not transform into complete ZnO for the as-prepared and for lower temperatures (< 400 °C). Annealing at lower temperatures or room temperature retains the metallic Zn. When subjected to higher annealing temperatures in the presence of oxygen and ambient conditions, formation of ZnO hexagonal wurtzite structures was evident. A wide variation in the morphology was observed for films annealed in different annealing environments, from petal-like structures to rods. Both the band edge and defect emissions using photoluminescence were observed to vary with varying annealing conditions. In-situ XANES uncovers the reduction of Zn and metallic nature noticed in the as-prepared sample and argon annealing at 400 °C. A higher charge transfer by Zn with a prominent delocalization of Zn 4p state was observed in oxygen annealing environment at 400 °C with an enhanced coordination of Zn–O and Zn–Zn. These distinct photoluminescence emissions from the films were correlated to the electronic structure and local atomic structure. Further, this investigation provides a path to develop next-generation optoelectronic devices. [ABSTRACT FROM AUTHOR]

• First report on strong hybridization of Fe-O in FeHAp for supercapacitor application. • High unoccupied density of states of Fe at 0.01FH compared with the other samples. • Reduction of coordination of Fe-O and its interatomic distance at 0.01FH. • The specific capacitance of asymmetric supercapacitor cell is 90 F/g at 30 mAg−1. Hydroxyapatite (HAp) is an interesting phosphate candidate with a weak electrical conductivity that can be tuned by doping metal ions to enhance the active sites for electrochemical charge storage. HAp and Fe-doped HAp were prepared by a wet chemical method. On doping, the crystallite size reduces to 9.56 nm. The surface area of 0.01FH (0.01% Fe) is 152.17 m2/g which is ∼3 times higher compared to PH. The 0.01FH sample shows the highest specific capacitance of 351.3 F/g at 30 mA/g. While X-ray photoemission spectroscopy shows the oxidation states of Fe in 2+ and 3+, X-ray absorption indicates (i) the enhancement of unoccupied density of states of Fe, and (ii) reduced interatomic distance of Fe-O in 0.01FH. These results show that the augmentation of surface properties and hybridization of Fe-O and the modification of its local atomic structures are responsible for high electrochemical charge storage in 0.01FH. [Display omitted] [ABSTRACT FROM AUTHOR]