Graphene oxide-based efficient and scalable solar desalination under one sun with a confined 2D water path

TLDR

Solar steam generation and desalination is a promising low‑carbon technology for water scarcity, yet current designs achieve high efficiency only for limited water volumes with concentrators or insulation, and conventional bulk‑water contact causes intrinsic thermal loss. The authors aim to create a solar desalination device that uses a confined two‑dimensional water path to overcome these limitations. They fabricate a foldable graphene oxide film that acts as a >94 % solar absorber, vapor channel, and thermal insulator, enabling scalable production. The resulting device delivers 80 % solar‑to‑vapor efficiency, reduces salinity by four orders of magnitude, operates independently of water quantity without insulation, and offers a portable, scalable clean‑water solution.

Abstract

Because it is able to produce desalinated water directly using solar energy with minimum carbon footprint, solar steam generation and desalination is considered one of the most important technologies to address the increasingly pressing global water scarcity. Despite tremendous progress in the past few years, efficient solar steam generation and desalination can only be achieved for rather limited water quantity with the assistance of concentrators and thermal insulation, not feasible for large-scale applications. The fundamental paradox is that the conventional design of direct absorber-bulk water contact ensures efficient energy transfer and water supply but also has intrinsic thermal loss through bulk water. Here, enabled by a confined 2D water path, we report an efficient (80% under one-sun illumination) and effective (four orders salinity decrement) solar desalination device. More strikingly, because of minimized heat loss, high efficiency of solar desalination is independent of the water quantity and can be maintained without thermal insulation of the container. A foldable graphene oxide film, fabricated by a scalable process, serves as efficient solar absorbers (>94%), vapor channels, and thermal insulators. With unique structure designs fabricated by scalable processes and high and stable efficiency achieved under normal solar illumination independent of water quantity without any supporting systems, our device represents a concrete step for solar desalination to emerge as a complementary portable and personalized clean water solution.