Isotope-driven hydrogel smart windows for self-adaptive thermoregulation.

Tu, Hongyi; Wang, Tong; Chen, Min; Wu, Limin · Nat Commun · 2025

basic_science · Level V

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Abstract

As a cutting-edge and environmentally friendly approach, thermochromic hydrogel smart windows show great potential in combating climate change and achieving carbon neutrality. However, the substantial absorption of near-infrared (NIR) energy by H<sub>2</sub>O poses an enormous challenge in enhancing the spectral responsiveness. Herein, we propose an ingenious concept of isotope-driven D<sub>2</sub>O-hydrogel smart windows, which can effectively resolve the inherent issue of NIR energy absorption associated with H<sub>2</sub>O, without compromising versatility. It facilitates near-optimal transmittance modulation across the entire solar spectrum (ΔΓ<sub>Sol</sub> = 91.97%), demonstrating a marked enhancement in NIR modulation of transmittance (ΔΓ<sub>NIR</sub>) and reflectance (ΔR<sub>NIR</sub>) by ~16% and ~31%, respectively, in comparison to conventional H<sub>2</sub>O-hydrogel. Moreover, the integration of Ag-nanowires into D<sub>2</sub>O-hydrogel further substantially augments the regulation of longwave infrared emissivity ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>Δ</mi> <msub><mrow><mi>ε</mi></mrow> <mrow><mi>L</mi> <mi>W</mi> <mi>I</mi> <mi>R</mi></mrow> </msub> </math>  = 31.89%) while preserving a comprehensive modulation ratio (ΔΓ<sub>Sol</sub> = 66.02%, ΔR<sub>Sol</sub> = 48.41%) that is not achieved by the existing thermochromic devices. This isotope-driven D<sub>2</sub>O-hydrogel smart window provides another design strategy for future energy-efficient windows.