Floating photothermal fabric based on spike-like dendrite fiber for highly efficient solar-thermal clean water production

Abstract

Solar energy-driven interfacial water evaporation devices are expected to play a crucial role in obtaining fresh water from seawater. Using suitable micro-nano substrate materials can enhance the evaporation rate of flexible interfacial evaporators. However, current flexible micro-nano evaporator substrates are often made of porous gels, which are prone to undesirable heat loss during evaporation due to water filling the pores. In this study, we present a flexible photothermal fabric evaporator that integrates micro-nano structured nickel dendrite photothermal fibers as the photothermal layer with hydrophilic cotton wire serving as the water channel. These components are seamlessly combined through a traditional weaving process, creating an innovative design. The dendrite substrate is fabricated via an electrodeposition process, which can be tailored to produce an enhanced micro-nano surface. Following this, the dendrite is coated with a PANI photothermal conversion material using the electrophoresis method. The hydrophilic cotton wire effectively ensures a continuous water supply and efficiently channels water toward the dendrite's surface through a pronounced gradient capillary effect. As a result, the photothermal fabric achieves a remarkable surface temperature of 97.2 °C, an impressive evaporation rate of 2.13 kg·m⁻²·h⁻¹, and a high evaporation efficiency of 85.6 % under illumination intensities of 1 kW·m⁻². Additionally, it demonstrates robust long-term stability, enduring at least 15 consecutive cycles without significant degradation. This efficient construction and utilization of the micro-nano interface, combined with a sustained and adequate water supply, highlight the potential of dendrite photothermal fabric for seawater desalination applications.