A team of chemists and materials scientists at Sichuan University, in China, has developed a photoluminescent aerogel with a visible light reflectance of 104%. In their study, published in the journal Science, the group created their aerogel from readily available biomass.

Changyu Shen and Xianhu Liu, with Zhengzhou University, also in China, have published a Perspective piece in the same journal issue outlining work surrounding the development of polymeric passive radiative cooling materials and the work by the team on this new effort.

As the climate warms, scientists are looking for ways to help people stay cool. One avenue of research is the development of passive radiative cooling materials—these provide cooling abilities due to their nature rather than via a process.

Adding a layer of a passive cooling material to the roof of a house, for example, could reduce the amount of heat absorbed, making it easier and cheaper to cool. In this new study, the team in China reports that a passive radiative cooling material reflects more light than it receives due to its photoluminescence properties.

With photoluminescence, molecules absorb photons in the visible region and then excite their electrons to a higher state, resulting in light emission. Thus, if a material were to reflect 100% of the light that strikes it and additionally had photoluminescence, it could, in theory, reflect more light than it received.

To create such a material, the research team added freeze-dried salmon sperm DNA to a sample of gelatin. They allowed it to sublimate, leaving behind a layered aerogel that was highly compressed. The research team explains that it is held together via hydrogen bonds between phosphates in the DNA and amino acids in the gelatin.

To use the resulting material, water is added so that it sticks to a surface. The researchers note that in the event of damage, the material has a self-healing capacity induced by adding water. They claim it is also environmentally friendly.

Testing showed it capable of reflecting 104% of the light that strikes it—the team also found that using it to coat a structure resulted in cooling the structure’s surface to 16°C below ambient temperature.

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