Sunflower-Stalk-Based Solar-Driven Evaporator with a Confined 2D Water Channel and an Enclosed Thermal-Insulating Cellular Structure for Stable and Efficient Steam Generation

Abstract

Given the worsening freshwater scarcity around the world, the interfacial solar-driven steam generation for seawater desalination and wastewater treatment has attracted wide attention due to its rich energy resources, convenience, and environmental friendliness. However, challenges still remain for developing highefficiency interfacial solar-driven steam generation devices from low-cost, readily available, and green material resources. Herein, taking advantage of the delicate composite structure of the sunflower stalk, a sunflower-stalk-based solar-driven evaporator with a confined two-dimensional (2D) water supply pathway and an enclosed thermal-insulating structure is reported. The pith of sunflower stalks is composed of well-arranged honeycomb-like parenchyma cells that endow sunflower stalks with low thermal conductivity comparable to that of synthetic plastic foam. The low-tortuosity vascular bundles in the skin can serve as a natural 2D water pathway for rapid water transportation. The benefit of these functions is that an evaporator based on a carbon-nanotubecoated sunflower stalk (C-Ss) achieves a high evaporation rate of 1.76 kg m −2 h −1 under 1 sun irradiation (1 kW m −2 ). The C-Ss also shows a highly stable evaporation performance, high ion rejection efficiency, and a self-cleaning ability during the actual seawater desalination process. With advantages of abundant resources, easy fabrication, and sustainability, this C-Ss-based evaporator provides a promising choice for freshwater production in developing regions.

High-Porosity Lamellar Films Prepared by a Multistage Assembly Strategy for Efficient Photothermal Water Evaporation and Power Generation

“…When the salt concentration exceeds the solubility of the device interface, the salt crystals accumulate after the brine reaches supersaturation. The accumulated salt deposits reduce the light scattering and absorption of the lamellar films, induce the decrease of the evaporation surface, affect the evaporation efficiency of the system, and further deteriorate. , These salt deposits can be removed by manual or mechanical treatment, but these passive processes consume cost and time and are difficult to carry out . It is noteworthy that the 1-PSS@CNT/rGO lamellar film showed a certain self-cleaning ability.…”

Hierarchically Designed Three-Dimensional Composite Structure on a Cellulose-Based Solar Steam Generator

“…Currently, the materials of many interface photothermal evaporators will cause damage to the environment and marine ecosystem. The use of biodegradable and green material resources − like three-dimensional (3D) interconnected, natural, and biodegradable bacterial cellulose (BC), a cellulose-based nanofiber network with a porosity of nearly 98% and a large aspect ratio can solve this problem. − Moreover, high purity and crystallinity are also advantages of BC. It can be physically entangled between nanosized BC fibers and has high mechanical strength .…”

Rational Design of Biomass-Derived Composite Aerogels for Solar-Driven Seawater Desalination and Sewage Treatment

“…The pivotal element in a solar-driven interfacial evaporation unit is the solar–thermal material. To date, carbon materials, conjugated polymers, plasmonic metals, and semiconductors have acted as solar absorbers and made significant progress. − Water passage materials are also essential for continuous upward pumping by capillary action. For this purpose, aerogel networks assembled by chemical or physical cross-linking are the top choices due to their facilely modulated structures, lightweight, and scalable capability. , In addition, the monolithic solar–thermal performance relies on the coupling of solar absorbers and water passage materials in a proper configuration. − Although many solar evaporators have been constructed, their integration into practical applications still faces some challenges.…”