A Janus Textile Capable of Radiative Subambient Cooling and Warming for Multi‐Scenario Personal Thermal Management

Abstract Textiles with radiative cooling/warming capabilities provide a green and effective solution to personal thermal comfort in different climate scenarios. However, developing multiple‐mode textiles for wearing in changing climates with large temperature variation remains a challenge. Here a Janus textile is reported, comprising a polyethersulfone (PES)‐Al 2 O 3 cooling layer optically coupled with a Ti 3 C 2 T x warming layer, which can realize sub‐ambient radiative cooling, solar warming, and active Joule heating. Owing to the intrinsically high refractive index of PES and the rational design of the fiber topology, the nanocomposite PES textile features a record high solar reflectance of 0.97. Accompanied by an infrared (IR) emittance of 0.91 in the atmospheric window, sub‐ambient cooling of 0.5–2.5 °C is achieved near noontime in humid summer under ≈1000 W m −2 solar irradiation in Hong Kong. The simulated skin covered with the textile is ≈10 °C cooler than that with white cotton. The Ti 3 C 2 T x layer provides a high solar‐thermal efficiency of ≈80% and a Joule heating flux of 66 W m −2 at 2 V and 15 °C due to its excellent spectral selectivity and electrical conductivity. The switchable multiple working modes enable effective and adaptive personal thermal management in changing environments.