Confined Growth of WO<sub>3 </sub>for High-Performance Electrochromic Device

Abstract

Nanoscale material world attracted researchers because of their outstanding properties and prospective novel applications. Tungsten trioxide semiconductor is one of the fundamental functional materials due to its versatile application as gas sensors, solar cells, and smart windows. Confined growth of the metal oxide nanostructures can tune the electrical and optical properties for modern device application. The management of morphology is a challenge to investigate the ultimate performance. In this paper, self-assembled growth of four different tungsten trioxide nanostructures were carried using a different structure directing agents through either co-precipitation or hydrothermal techniques. The monoclinic spherical and rod-like WO3 nanostructures were obtained by acid precipitation method. WO3 nanocuboids and nanofibers were synthesized hydrothermally using HBF4 and NaCl as structure directing reagents to attain monoclinic and hexagonal crystal phases, respectively. Analytical techniques like XRD, TEM, and FESEM imaging methods were used to confirm the phase and morphology. All the nanopowders were calculated to have similar band gap energy at visible wavelength. A simple dip coated WO3/ITO fabricated electrode was used as a reference electrode to carry out the electrochemical measurements for all nanopowders. The evaluated properties suggested the plausible use of WO3 nanofibers for high efficient electrochromic device.