Bionic snail-shell-shaped evaporator featuring silver-nanoparticle-decorated carbon nanotubes for efficient solar desalination

A SDIE system characterized by a biomimetic snail-shell structure is fabricated • The highest water evaporation of 2.21 kg m −2  h −1 was obtained from CNT-Ag@PA12 • Antibacterial and salt-resistant design ensures 20-day stable operation without decay • Collected water showed potential for irrigation and household water use. Solar-driven interfacial evaporation can help reduce the problem of global freshwater shortages. However, it remains challenging to integrate devices that simultaneously achieve high-efficiency light absorption, rapid water transport capability, excellent evaporation effect, and strong salt tolerance. This work develops a bio-inspired snail-shell-shaped evaporation device by optimizing the design with the aid of simulations and experiments. A shell-shaped structure with capillary channels that can rapidly convey water to sustain an ultra-thin-water layer stability. In addition, we applied silver-nanoparticle-decorated carbon nanotubes (CNT Ag) composites that contain carbon nanotubes and silver nanoparticles on the top for photo-thermal functions. Multi-physics simulation determined the main geometric parameters required by this structure; experimentally validated the optimized design of this structure. The CNT-Ag film exhibited a broad-band solar absorption coefficient of up to 99.1% and efficiently localized heat at the evaporation boundary. As a result of combining the strengths of both structures and materials, the evaporator achieved an evaporation rate of 2.21 kg m −2  h −1 under one-sun irradiation. Furthermore, the directional salt-formation ability brought about by the structure and the antibacterial and anti-biocontamination capabilities caused by silver ions enable the evaporator to exhibit long-term stability and effective seawater desalination capabilities. In summary, this work presents a practical approach to building durable and effective solar desalination using a combination of biologically inspired structure design, composite photothermal materials, and regulation of heat and mass transfer. Download: Download high-res image (247KB) Download: Download full-size image