Doping Sodium Tungsten Bronze-Like (Na₅W₁₄O₄₄) Near-Infrared Shielding Functional Units in Bulk Borosilicate Glasses for Energy-Saving Window Applications

Abstract

Tungsten bronze is an effective near-infrared (NIR) shielding material for fabricating energy-saving smart windows. While high-performing NIR-shielding glasses can be fabricated by coating a tungsten bronze film on window glasses, these glasses suffer a short lifespan due to the adhesion and degeneration of film. In this work, we show that tungsten bronze-like material Na5W14O44 can be distributed in the bulk glass matrix during the facile melt-quenching glass fabrication process under an air atmosphere, overcoming the limitations of film-based glasses. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed the presence of tungsten bronze-like Na5W14O44 functional units in the SiO2–B2O3–NaF glass matrix. The addition of a small amount of H2WO4 and Sb2O3 is critical for the formation of Na5W14O44 functional units because H2WO4 provides W for Na5W14O44, and Sb2O3 acts as a reducing agent that helps the formation of W5+ in Na5W14O44 under an air atmosphere. Furthermore, the NIR-shielding ability can be tuned by adjusting the concentration of Sb2O3 in the range of 0–1.5 mol % and of H2WO4 in the range of 4–6 mol %. The optimized composition containing 1.25 mol % of Sb2O3 and 5 mol % of H2WO4 exhibits excellent NIR-shielding ability (ΔT = 62.8%), high visible light transmittance (T max = 67.7%), and excellent thermal insulation. This performance is comparable to cesium tungsten bronze film-based glasses and much better than soda lime glass and ITO glass under sun irradiation. This study sheds light on fabricating energy-saving windows in a simple and cost-effective way with flexibility for fine tuning of NIR-shielding performance.

Photothermal-Driven Polymer for a Smart Window with Adaptive Solar Modulation

“…CWO has a wide and deep absorption peak at the wavelength range of 1000−520 cm −1 , which is considered to be closely correlated with the local surface plasmon resonance. 25 Compared with CWO, the presence of the absorption peak at 1296 cm −1 of PDA@CWO corresponds to C−O stretching and primary amine vibration from polydopamine. The TEM image of PDA@CWO also shows the successful formation of PDA shell deposits on the surface of the CWO core (Figure 2c).…”

“…Figure b shows the FTIR spectra of CWO and PDA@CWO. CWO has a wide and deep absorption peak at the wavelength range of 1000–520 cm –1 , which is considered to be closely correlated with the local surface plasmon resonance . Compared with CWO, the presence of the absorption peak at 1296 cm –1 of PDA@CWO corresponds to C–O stretching and primary amine vibration from polydopamine.…”

Silica/Cesium Tungsten Bronze Composite Nanospheres with Synergistically Enhanced Thermal Insulation Properties for Transparent Coatings

“…It is well known that visible radiation (400–780 nm, 45%) and near-infrared radiation (780–2500 nm, 52%) are the main heat sources of sunlight and can penetrate ordinary transparent building glass, greatly increasing the energy consumption and carbon emissions in the building cooling process. , Near-infrared shielding materials are ideal fillers for transparent thermal insulation coatings because they can effectively absorb or reflect NIR light without affecting the visible light transmittance. In recent years, tungsten bronze (M x WO 3 , M = Li + , Na + , K + , Rb + , Cs + ) doped with alkali metal elements has become the focus in this field due to its excellent optical properties, − especially for the application of Cs-doped hexagonal tungsten bronze (Cs x WO 3 , abbreviated as CWO) in architectural glass and automotive films. − The near-infrared shielding effect of cesium tungsten bronze is achieved by absorbing near-infrared light under the action of local surface plasmon resonance and small polaritons, revealing excellent photothermal conversion capability . Studies have been conducted to apply CWO to solar water evaporation, wearable solar storage fabrics, and other fields , with the help of its good photothermal conversion.…”