Fig. 1. Design of system.

(A) Working principle with separated radiation and condensation side. The radiation shield—optimized by accounting for the surrounding radiative environment—allows one to improve substantially the dew harvesting potential of the system and can be applied for any selective emitter. (B) Structure of selective emitter. It consists of PDMS and silver, coated on a transparent glass substrate (chromium is used for oxidation protection and adhesion). (C) Measured spectral absorptivity/emissivity of the selective emitter. The average emissivity in the atmospheric transparency window is very high (${\overline{\mathrm{\epsilon }}}_{8-13}\approx 0.93$), while the average absorptivity in the solar spectrum range is very low (${\overline{\mathrm{\alpha }}}_{0.25-2.5}\approx 0.04$).