Enhanced dual-band electrochromism in mesoporous WO3·H2O with high optical modulation and stability

The development of electrochromic materials with high optical modulation and good cycling stability is a key focus in dual-band electrochromism. Hydrated tungsten oxide exhibits dynamic and independent control over the near-infrared and visible transmittance within the solar spectrum, garnering widespread attention in electrochromic applications. However, its optical modulation and cycling stability need further enhancement due to limited ion diffusion kinetics. Herein, a simple photo-deposition method is developed for synthesizing mesoporous WO 3 ·H 2 O films, characterized by high porosity and large surface area, which facilitates ion and electron transport within the films. Experimental results show that mesoporous WO 3 ·H 2 O can achieve three functional modes under different voltages: “bright”, “cold”, and “dark”. Compared to WO 3 ·H 2 O nanoplates, mesoporous WO 3 ·H 2 O electrode enables a superior dual-band electrochromic performance, including high optical modulation (74.1 % at 700 nm and 65.9 % at 1150 nm), rapid response times (13.5 s for coloring and 11.5 s for bleaching), high coloring efficiencies (138.9 cm 2 /C), and excellent cycling stability (optical modulation retention rate of 88.2 % after 1000 cycles). This research provides a novel approach to enhancing dual-band electrochromic performance through the incorporation of mesoporosity in materials.