Selective Electrochromic Regulation for Near-Infrared and Visible Light via Porous Tungsten Oxide Films with Core/Shell Architecture

Dual-band electrochromic smart windows have become a research hotspot owing to their unique ability to selectively control near-infrared (NIR) and visible (VIS) light. However, the design and exploitation of dual-band electrochromic films are still an extreme challenge due to the scarcity of relevant high-performance materials. To solve this issue, we here proposed a type of porous WO3 film with nanowires/nanoparticles core/ shell architecture as a promising candidate, endowing smart windows with a dual-band electrochromic feature. Moreover, the mechanism of the dual-band electrochromism is illustrated by the response of the transmittance spectra in Li+-based or TBA+-based electrolytes to distinguish the electrochemical behavior and the cyclic voltammetry to determine the degree of diffusion-limited kinetics. Our results indicate that the dual-band electrochromic performance is credited to the progressive electrochemical reduction procedure, in which the capacitive charging process gives rise to NIR regulation and the following ion intercalation contributes to VIS light modulation. Furthermore, we develop a dual-band electrochromic energy storage prototype device utilizing the porous WO3 film. This work describes a judicious strategy for designing dual-band electrochromic films, promoting the evolution of dual-band electrochromic technology.