Three‐Layered Hollow Nanospheres Based Coatings with Ultrahigh‐Performance of Energy‐Saving, Antireflection, and Self‐Cleaning for Smart Windows

Abstract In this study, a well‐controlled interfacial engineering method for the synthesis of SiO 2 /TiO 2 /VO 2 three‐layered hollow nanospheres (TLHNs) and TLHNs‐based multifunctional coatings is reported. The as‐prepared coatings allow for an outstanding integration of thermochromism from the outer VO 2 (M) layer, photocatalytic self‐cleaning capability from the middle TiO 2 (A) layer, and antireflective property from internal SiO 2 HNs. The TLHNs coatings exhibit excellent optical performance with ultrahigh luminous transmittance ( T lum‐l = 74%) and an improved solar modulation ability (Δ T sol = 12%). To the best knowledge, this integrated optical performance is the highest ever reported for TiO 2 /VO 2 ‐based thermochromic coatings. An ingenious computation model is proposed, which allows the n eff of nanostructured coatings to be rapidly obtained. The experimental and calculated results reveal that the unique three‐layered structure significantly reduces the refractive index (from 2.25 to 1.33 at 600 nm) and reflectance (Rave, from 22.3 to 5.3%) in the visible region as compared with dense coatings. Infrared thermal imaging characterization and self‐cleaning tests provide valid evidence of SiO 2 /TiO 2 /VO 2 TLHNs coatings' potential for energy‐saving and self‐cleaning smart windows. The exciting inexpensive and universal fabrication process for well‐defined structures may inspire various developments in processable and multifunctional devices.