RESUMO
The structural engineering of active materials at the nanoscale level is crucial to improving the performance of electrochromic devices. However, an insufficient structural design inevitably results in limited electron/ion transportation and inadequate electrochromic performance. Herein, a new type of layer-stacked nanowire/nanosheet homostructure is proposed for enhancing the electrochromic properties of transition metal oxide films. Benefiting from the one-pot feature integration of nanowire and nanosheet structures, the NiO film with a unique homostructure delivers ultra-large optical modulation up to 93.4% at 550 nm and a high coloration efficiency of 72.1 cm2 C-1 in comparison with NiO-based materials. In addition, the film maintains 91% of its optical modulation over 1000 cycles of coloration and bleaching processes. Furthermore, the high performance of the device was verified by integrating the NiO film with the TiO2 ion storage layer in assembled smart windows with a dual function of electrochromic and energy storage. As a proof of concept, the integration of solar cells with electrochromic devices demonstrates the great significance of self-powered smart windows for energy-saving. To this end, such a strategy of structural design for electrochromic films would offer a distinctive pathway toward studying high-performance electrochromic systems.
RESUMO
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.
RESUMO
Exploring materials with high electrochemical activity is of keen interest for electrochemistry-controlled optical and energy storage devices. However, it remains a great challenge for transition metal oxides to meet this feature due to their low electron conductivity and insufficient reaction sites. Here, we propose a type of transition metal phosphate (NiHPO4·3H2O, NHP) by a facile and scalable electrodeposition method, which can achieve the capability of efficient ion accommodation and injection/extraction for electrochromic energy storage applications. Specifically, the NHP film with an ultra-high transmittance (approach to 100%) achieves a large optical modulation (90.8% at 500 nm), high coloration efficiency (75.4 cm2 C-1 at 500 nm), and a high specific capacity of 47.8 mAh g-1 at 0.4 A g-1. Furthermore, the transformation mechanism of NHP upon electrochemical reaction is systematically elucidated using in situ and ex situ techniques. Ultimately, a large-area electrochromic smart window with 100 cm2 is constructed based on the NHP electrode, displaying superior electrochromic energy storage performance in regulating natural light and storing electrical charges. Our findings may open up new strategies for developing advanced electrochromic energy storage materials and smart windows.
