Dual-Mode Porous Polymeric Films with Coral-like Hierarchical Structure for All-Day Radiative Cooling and Heating

Abstract

Passive radiative cooling (PRC) and passive radiative heating (PRH) have drawn increasing attention as green and sustainable cooling and heating approaches, respectively. Existing material designs for PRC/PRH are usually static and unsuitable for dynamic seasonal and weather changes. Herein, we demonstrate an all-day dual-mode film fabricated by decorating MXene nanosheets on porous poly(vinylidene fluoride) with abundant coral-like hierarchical structures obtained via phase inversion. The cooling side of the dualmode film exhibits high solar reflectivity (96.7%) and high infrared emissivity (96.1%). Consequently, daytime subambient radiative cooling of 9.8 °C is achieved with a theoretical cooling power of 107.5 W/m 2 and nighttime subambient cooling of 11.7 °C is achieved with a theoretical cooling power of 140.7 W/m 2 . Meanwhile, the heating side of the dual-mode film exhibits low infrared emissivity (11.6%) and high solar absorptivity (75.7%), contributing to a PRH capability of 8.1 °C, and excellent active solar and Joule heating as effective compensation for PRH. The dual-mode film could be easily switched between cooling and heating modes by flipping it to adapt to dynamic cooling and heating scenarios, which is important for alleviating the energy crisis and reducing greenhouse emissions.

A Hierarchically Nanofibrous Self-Cleaning Textile for Efficient Personal Thermal Management in Severe Hot and Cold Environments

“…Obviously, the temperature difference between the PAN-CNT side and black cotton is much greater than that of black cotton/PAN-CNT and black cotton, indicating that the synergistic effect of thermal insulation and radiative heating is better than single radiative heating in low temperature environments. Also, the heating performance of the HNF textile improved significantly, which outperforms the reported radiative heating textiles (Figure e). ,,,,− Additionally, the infrared thermal images of the HNF textile covered on the human arm with the PAN-CNT surface exposed to the outside are displayed in Figure S22. It is clear that surface color of the PAN-CNT side is cooler than that of black cotton, probably because most of the heat cannot be transferred to the upper surface through the HNF textile.…”

“…In recent years, radiative thermal management technology, which has the advantages of no energy consumption and zero emissions, has sparked immense attention in many different fields. − Radiative thermal management focuses on the regulation of two types of radiative heat fluxes involving solar radiation from the sun and infrared radiation into the outer space. , Specifically, radiative cooling can be achieved via enhancing the reflectivity in the solar spectrum and increasing the emissivity in the atmospheric window. , Similarly, radiative heating is achieved under the opposite optical conditions . There have been some attempts to investigate the potential of functionalized textiles for personal thermal management, and most research has focused on localized temperature regulation through advanced textiles with single or dual-mode capabilities. − For instance, by adjusting the optical properties based on the surface of the textiles, single temperature-controlled textiles are prepared that can effectively achieve personal radiative cooling or radiative heating performances. − Additionally, dynamic temperature control textiles, such as Janus textiles, and temperature or humidity responsive textiles can meet personal thermal regulation. Nonetheless, these textiles are usually not appropriate for use in severely hot and cold environments owing to their limited temperature regulation capabilities, which could cause heat/cold stress and serious medical emergencies .…”

One-Step Method for Fabricating Janus Aramid Nanofiber/MXene Nanocomposite Films with Improved Joule Heating and Thermal Camouflage Properties

“…44 Figure 3d shows the XPS spectra obtained from pure ANF, MXene, and Janus ANF/MXene films. The MXene, obtained through a selective etching process, has introduced abundant 45 After combining ANF and MXene, the corresponding characteristic peaks of MXene and ANF are present in the XPS spectra of the ANF/MXene film. In agreement with the findings from Raman spectroscopy, the XPS spectra of ANF/MXene-A demonstrate a concordance with that of the pure ANF film, while the XPS spectra of ANF/ MXene-M exhibit a parallel resemblance to that of MXene.…”

Mechanically Switchable Multifunctional Device for Regulating Passive Radiative Cooling and Solar Heating

“…Another way to fabricate thermal regulation materials for dynamic windows was using dual-mode materials. Some works about dual-mode materials combining RC and SH for thermal management have been reported previously, ,− mainly concerning personal thermal regulation. Li et al proposed a dual-mode device for energy saving in buildings.…”