Spectrum Selective Interfaces and Materials toward Nonphotothermal Saltwater Evaporation: Demonstration with a White Ceramic Wick

Most solar desalination efforts are photothermal: they evaporate water with “black” materials that absorb as much sunlight as possible. Such “brine-boiling” methods are limited by the high thermal mass of water, i.e., its capacity to store and release heat. Here, we study the light-enhanced evaporation by a hard, white, aluminum nitride wick, and propose a route to selectively target salt-water bonds instead of bulk heating via deep-UV interactions. Through experiments and analyses that isolate the effects of light absorption and heating in aluminum nitride, we provide experimental evidence of a light-driven, spectrum-selective path to nonphotothermal saltwater evaporation. Leverage of these light-matter interactions in white ceramic wicks may achieve low-cost, low-energy desalination, reduce the heat island effects of traditional solar technologies, and contribute to future cooling technologies where drought is also a concern.