An All-Passive and Macropatterned Architecture Design for Water Harvesting.

Abstract

Solar evaporation designs show great promise in water harvesting without electricity inputs. Unfortunately, they have been heavily limited by a low water yield. To overcome this challenge, we introduced a new architecture featuring both system-level and materials-level designs. At the system level, we implemented a macropatterned architecture with a decoupled design for water evaporation and condensation to enhance water yield efficiency. This design also ensures that condensed water droplets do not block the solar evaporation process. At the materials level, solar selective heating and radiative cooling were applied to improve passive water yield performance. As a proof of concept, our design showed an indoor water collection rate of 2.06 kg m^-2 h^-1 under one sun and an average outdoor water collection rate of 1.85 kg m^-2 h^-1 over five consecutive days. The decoupled, all-passive, and macropatterned architecture offers substantial potential for commercial water collection applications toward mitigating global water scarcity.