Figure 3d displays the transmittances of the CF, CAF and DAF with a thickness of 100 µm from 300 to 2500 nm, which were measured by a UV-visible near-infrared spectrophotometer. The transmittance values for the CF, CAF, and DAF, respectively, are calculated as 92%, 29.4%, and 86.3% in the solar range (
Tsolar of 300-2500 nm); 95.1%, 7.5%, and 91.0% in the visible or luminous (
Tlum, 380-780 nm); and 92.7%, 36.6%, and 85.7% in the near-infrared range (
TNIR, 780-2500 nm). The DAF exhibits a lower
Tsolar and
TNIR than those of CF due to the scattering in the near-infrared range caused by the intra-layer nanopore structures reducing solar thermal gain. The distinctive mesoporous structure of DAF plays a crucial role in minimizing light scattering, resulting in an enhanced transmittance within the 380-780 nm range compared to CAF. Notably, the
Tlum of DAF decreases with increasing thickness, as illustrated in Fig. S13. The DAF exhibits exceptional thermal-insulating performance due to the formation of delaminated stacked structures and intra-layer nanopore structures that inhibit gas heat conduction. The thermal conductivity of the CF, CAF and DAF is measured as 474, 44, and 33 mW m
−1 k
−1 (
Fig. 3e), respectively. Thermographic images of the CF, CAF, and DAF samples with similar sizes on a hot stage (surface temperature of 50 °C) were in situ measured by an infrared thermal imaging camera, demonstrating the conduction of heat flow from the hot stage to the interior of the sample over the periods of 0, 60, 120, and 180 s (
Fig. 3f), respectively. The top-surface temperature of the DAF is 2.1-2.3 °C lower than those of the CF and CAF when these samples are placed on the hot stage and stabilized for 180 s, indicating that the DAF has superior thermal-insulating performance.