Smart windows are an important strategy to reduce the energy consumption in buildings, which accounts for as much as 30%e40% of the society's energy consumption. VO₂-based thermochromic materials can intelligently regulate the solar heat gains of building interiors. However, the unmatched thermal emissivity (ε) modulation of traditional VO₂/glass systems, i.e., high emissivity at low temperatures and low emissivity at high temperatures, leads to additional heating and cooling energy loads in winter and summer, respectively. In this study, we propose a novel VO₂/polyacrylonitrile (PAN)/AgNW multilayer possessing flexible Ag nanowire supported Fabry–Pérot cavities, which synchronously ach-ieves high modulation abilities in both solar spectrum (ΔT_sol of 13.6%) and middle infrared region (Δ_ε of 0.50 at 8–13 μm). These achievements are the best among reports for pure VO₂ smart windows. This study provides a flexible and effective protocol to dynamically enhance the light and heat utilization for practical building windows.

As a typical strongly correlated transition oxide, vanadium dioxide (VO₂) based nanomaterials have drawn many research attentions these years due to the giant metal-to-insulator phase transition (MIPT) at around 68 °C. However, due to the complexities of the V–O system and interplays between various vanadium oxide phases, the synthesis of high-quality VO₂ nanopowders is still fraught with many challenges, especially in air atmosphere. In this paper, we report a novel air atmosphere available liquid-shielding synthesis method for thermochromic VO₂ nanoparticles, by using low-eutectic molten-salt (LiCl–KCl) as the liquid-state air-insulation medium at elevated temperature and high-pressure pressed VOSO₄–KCl pillars immersed in these liquid salts as the precursor. Small amounts of glucose are added to introduce a slight reductive environment, and well dispersed VO₂ nanoparticles with excellent thermochromic properties can be directly synthesized at an ultra-low temperature of 375 °C. This feasible and atmosphere-available mass-production method is rarely reported in the related fields, which may provide a novel protocol strategy for the synthesis of high performance thermochromic VO₂ and other functional oxide powders.

Low-frequency microwave absorbing materials have been challenging for many years. Three-dimensional dielectric/magnetic porous materials are beneficial for improving the low-frequency microwave absorbing performance because of natural resonance and improved impedance matching. In this study, Fe₃O₄@C 3D foam was prepared by carbothermal reduction method and the microwave attenuation performances and mechanisms were studied. By adjusting the content of Fe₃O₄@C 3D foam in paraffin composites, the low-frequency microwave attenuation capacity could be effectively optimized. The minimum reflection loss (RL_min) of paraffin composite with 40% (in mass fraction) loading exhibits −54.7 dB at 4.1 GHz for a thickness of 4.0 mm. Surprisingly, the paraffin composite with 50% (in mass fraction) loading could almost cover 2–4 GHz (S-band) in the thickness range of 3.5–5.5 mm. The strong low-frequency microwave attenuation property of Fe₃O₄@C 3D foam is mainly attributed to excellent low-frequency impedance matching, natural resonance, interfacial/dipole polarization, multiple reflection and scattering. This method provides a new perspective for preparing lightweight and high performance low-frequency microwave absorbing materials.