Multistage Coloring Electrochromic Device Based on TiO₂ Nanotube Arrays Modified with WO₃ Nanoparticles

Abstract

WO3 nanoparticles loaded in TiO2 nanotube arrays, fabricated by a chemical bath deposition (CBD) technique in combination with a pyrolysis process, is uniform and the diameter can be easily adjusted by the deposition times. The resultant hybrid nanotubes array shows a multistage coloring electrochromic response at different potential bias. The formation of a 3‐dimensional WO3/TiO2 junction promotes unidirectional charge transport due to the one‐dimensional features of the tubes, which leads to the significant positive‐shift onset potential of the cathodic reaction (ion insertion) and the highly increased proton storage capacity. Compared to non‐decorated nanotube arrays, the enhanced electrochromic properties of longer lifetime, higher contrast ratio (bleaching time/coloration time), and improved tailored electrochromic behavior could be achieved using the composite films.

WO3/TiO2 core–shell nanostructure for high performance energy-saving smart windows

“…4(a) show that the value of the peak current (cathodic current density and anodic current density) is the highest in the WT2 sample. These results suggest that the increase in current is due to the combined effect of the WO 3 core and the TiO 2 shell, which supports other recent findings [17,19]. These results were possibly caused by the WO 3 / TiO 2 core-shell nanostructure improving the kinetics of the mechanisms for intercalation and deintercalation among charges.…”

“…Cathode coloration occurs with the ion insertion, while anode coloration occurs with ion extraction. The coloration reaction equation oof the WO 3 /TiO 2 core-shell nanostructure can be expressed as follows [18,19]:…”

Self-organized Anodic TiO2 Nanotubes: Functionalities and Applications Due to a Secondary Material

“…They achieved complete decoration of comparably higher aspect ratio nanotubes, as shown in Fig. 3.11a [60]; c TEM image of WO 3 -decorated TiO 2 nanotube exteriors, d photocurrent density versus applied potential for the TiO 2 and WO 3 -decorated TiO 2 nanotubes prepared by soaking at different molarities of ammonium paratugnstate aqueous solution: a 0.3 mM, b 0.1 mM, c 0.5 mM, d pure TiO 2 nanotubes, e 1 mM, and f 5 mM, modified from [61] to non-decorated nanotube arrays, their nanotube arrays showed enhanced electrochromic properties of longer lifetime, higher contrast ratio (bleaching time/coloration time), and improved tailored electrochromic behavior compared to plane nanotubes.…”

“…In the follow up work by Song and coworkers, sodium tungstate was employed to decorate nanotubes with WO 3 nanoparticles of different size, depending on the number of repeated chemical batch deposition and annealing cycles [60]. They achieved complete decoration of comparably higher aspect ratio nanotubes, as shown in Fig.…”

Enhanced physical properties of the anodic TiO2 nanotubes via proper anodization time

“…In the past decades, TiO 2 nanotubes have been widely investigated due to their high interest in various applications like biomedical fields [1], photovoltaic cells [2], photocatalysts [3,4], solar cells [5][6][7] and electrochromic devices [8]. These possible applications are due to the advantages of not-toxicity, thermal and chemical stabilities, high photocatalytic activity [9][10][11][12][13] and high surface area of the TiO 2 nanotubes [14,15].…”