Solar steam generation from a porous evaporator is a promising approach for harvesting fresh water. Parasitic heat loss can be reduced by using a 3D evaporator that extends above the free surface; however, capillary rise constrains the height of such structures to a centimeter scale. Here, we demonstrate solar steam generation from a synthetic tree, which uses transpiration instead of capillary rise to pump water up insulating tubes of any desired height. A nanoporous ceramic disk coated with graphite was used for the synthetic leaf, which was attached to the upper end of a vertical array of plastic tubes. Using a solar still, it was observed that the synthetic tree harvested approximately three times more condensed water than an equivalent bulk reservoir.

On a subfreezing surface, nucleating embryos usually form as supercooled condensate that later freezes into ice, as opposed to desublimation. Ice nucleating proteins (INPs) have been widely used to quickly freeze existing supercooled water; however, nobody has studied how they might affect the initial mode of embryo formation. We show that INPs deposited on a substrate can switch the mode of embryo nucleation to desublimation, rather than supercooled condensation, beneath a critical temperature. By patterning a hydrophobic surface with an array of hydrophilic stripes, the INPs can be selectively deposited by evaporating water that exclusively spreads along the hydrophilic regions. The resulting array of desublimating ice stripes created dry zones free of condensation or frost in the intermediate areas, as the hygroscopic ice stripes served as overlapping humidity sinks.