Interfacial solar vapor generation (ISVG) is an emerging approach that directly uses sunlight to desalinate water while achieving zero liquid discharge. However, the vast majority of materials that have been studied for this process maintain a two-dimensional (2D) structure that floats at the air-water interface. In this process, water is wicked through a porous substrate that functions as both a water supplier using capillary action to wick water to the evaporative interface and an insulator that retains photothermally generated heat at that same evaporative interface. While optimization of material properties, heat localization, and water transport capabilities have led to extremely high solar-vapor conversion efficiencies, the evaporative flux rates of 2D evaporators remain low (typically between 1.5 and 3.0 kg m h) resulting in a relatively large spatial footprint. This work describes recent advancements in the development of three-dimensional interfacial solar vapor generation (3D-ISVG), graphene oxide (GO)-based material that operates near the capillary wicking limit to achieve a normalized flux rate as high as 34.7 kg m h under 1-sun condition (1 kW/m). Through this investigation, we have been adapting the unique properties of 3D-ISVG—which include omnidirectional light absorption, enhanced response to forced convection, and salt resiliency—into a sustainable desalination technology to increase the resiliency of water access for small-island communities. Specifically working with Bungin Island in Indonesia, we have conducted interviews with households to understand the unique intricacies that impede water access, and how these factors impact homes differently based on their location on the island. Based on this information, we are developing a sustainable desalination technology that incorporates context-specific factors into its design. Furthermore, we have continued to investigate how 3D-ISVG performance will be impacted by operational realities, such as fouling, operating in high humidity, and imperfect solar irradiating conditions. This work is culminating into a prototype that can passively produce drinking water using abundantly-available resources (such as sunlight, seawater, wind, and natural temperature gradients), and can serve as a starting place for future co-designing workshops to develop a sustainable desalination technology for small-island communities.

Developing interfacial solar vapor generation into a sustainable desalination technology for small-island communities

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