Graphene oxide-based evaporator with one-dimensional water transport enabling high-efficiency solar desalination

Solar steam generation is a promising water treatment technique which can harvest solar energy for water purification. In our work, for the first time, we designed a jellyfish-like solar steam generator that consists of the porous carbon black/graphene oxide (CB/GO) composite layer (body), aligned GO pillars (tentacles) and expanded polystyrene (EPS) matrix. The jellyfish-like evaporator was fabricated using the vertical three-dimensional (3D) printing technique, which can fast, automatically and precisely manufacture sophisticated components. The vertical GO pillars were directly 3D printed on and thus attached to the porous CB/GO composite layer. The porous CB/GO composite layer possesses a high broadband light absorption (99.0%) within a wavelength range from 250 to 2500 nm. The linear water transport inside the GO pillars can greatly decrease the contact area between the evaporation layer and bulk water, effectively suppressing the heat dissipation. The assembled evaporator displays an impressive energy conversion efficiency of 87.5% under one-sun illumination (1 kW cm⁻²) and superior water desalination performance. The ion concentrations (Na⁺, K⁺, Mg²⁺ and Ca²⁺ ions) of the seawater (Dead Sea and Chesapeake Bay) after purification are far below the ion concentration limit set by the World Health Organization (WHO) for drinking water. The jellyfish-like evaporator provides an effective water purification solution to alleviate the problem of water scarcity.