High Near-Infrared Reflectance Orange Pigments of Fe-Doped La2W2O9: Preparation, Characterization, and Energy Consumption Simulation

A new series of orange highly near-infrared reflective pigments based on Fe-doped La2W2O9 were effectively fabricated via solution combustion synthesis. The acquired pigment powders were characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, ultraviolet–visible–near-infrared spectrophotometry, and CIE 1976 L*a*b* color scales. Then, the energy consumption of the air-conditioning system was simulated based on EnergyPlus software. The results showed that the doping of Fe3+ ions will change the color of the pigment from white to orange. Meanwhile, the band gaps of La2W1.85Fe0.15O9-δ and La2W1.8Fe0.2O9-δ shifted from 3.71 to 3.07 eV and 2.96 eV, respectively. The typical La2W1.85Fe0.15O9-δ pigment powders showed the highest near-infrared reflectance of 89.25% between 700 and 2500 nm and impressive color (L* = 74.20, a* = 22.69, and c* = 22.42). The simulation results illustrated that the homeowner could save $7.32 per month by coating the walls and roofs of the building with the energy-saving paint composed of La2W1.8Fe0.2O9-δ. Excellent chemical stability and high near-infrared reflectance made the synthesized pigments a potential candidate for energy-saving coatings.