Structural Engineering in Sn-Doped WO₃ Multi-Phase Systems for Enhanced Transparent Heat Insulation

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Transparent thermal insulation is crucial for building energy conservation and global carbon neutrality.
• Tungsten oxide (WO3) shows potential for near-infrared (NIR) absorption but suffers from low efficiency and narrow spectral coverage.
• Limitations in pure WO3 hinder its application in energy-saving glass.

Purpose of the Study:

• To synthesize and evaluate Sn-doped WO3 materials for enhanced transparent thermal insulation.
• To optimize the Sn:W molar ratio for superior NIR shielding and thermal insulation performance.
• To elucidate the structural mechanisms behind the improved NIR absorption in Sn-doped WO3.

Main Methods:

• One-step hydrothermal synthesis of Sn-doped WO3 with varying Sn:W molar ratios (0.1:1 to 2.0:1).
• Characterization of material properties and evaluation of transparent thermal insulation performance.
• Analysis of structural transformations and phase changes induced by Sn doping.

Main Results:

• Sn-doped WO3 with a Sn:W ratio of 0.9:1 exhibited the highest performance.
• Achieved NIR shielding efficiency of 93.9% (1.84 times higher than pure WO3) and a thermal insulation index (THI) of 4.38 (184-317% increase).
• Sn doping induced a phase transformation from monoclinic to tetragonal WO3, forming a multiphase structure (Sn-doped WO3, SnO2, WSn0.33O3) that enhances NIR absorption via oxygen vacancies and polaron effects.

Conclusions:

• Sn doping significantly enhances the NIR absorption and transparent thermal insulation properties of WO3.
• The optimized Sn:W ratio of 0.9:1 provides a pathway to high-performance energy-saving glass.
• Structural modifications and multiphase formation are key to achieving superior NIR shielding, offering insights for developing advanced thermal insulation materials.