Near-infrared reflectance and thermal performance of Na2V6O16·xH2O nanoribbon as a novel cool brown pigment

• Na2V6O16·xH2O nanoribbon was utilized as an infrared reflective pigment for the first time.
• Nanoribbons possess high NIR solar reflectance of 59.1% compared with nanoparticles.
• The reduction in inner surface temperature of reflective panel in the device is 4.5 °C.
• The estimated energy saving is 27.2 W m−2 (10.8%).
• The Na2V6O16·xH2O nanoribbon can well serve as a cool brilliant brown pigment.

The ultra-thin and super-long Na2V6O16·xH2O nanoribbon was for the first time utilized as a cool color pigment with high near-infrared reflectance and thermal performance. The nanoribbon appears brilliant brown with red and yellow hues and the spectral absorption edge is below 575 nm. The nanoribbon has high spectral reflectance (62.4–76.2%) in 700–1000 nm wavelength region and near-infrared solar reflectance (59.1%) compared with its nanoparticle counterpart and conventional pigment of the similar color due to its unique morphology. In the experimental test, the coating colored with the nanoribbon reduced inner surface temperature of reflective panel by 4.5 °C and heat flux by 27.2 W m−2 (10.8%). Na2V6O16·xH2O nanoribbon pigment can effectively reduce solar heat gain and cooling energy demand.

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