Tree-inspired braiding fibrous frameworks enabling high-efficiency and salt-rejecting solar evaporation

Abstract

Solar steam generation (SSG) in a green way for desalination is a promising application, but achieving high-efficiency and salt-rejecting SSG is still a challenge, especially in hypersaline brines. In this study, a bioinspired composite fibrous framework (BCFF), inspired by the ecological structure of natural trees, was designed with photothermal carbon fibers and hydrophilic polypyrrole-decorated Tencel via a textile braiding technology. The morphology of trees with strong trunks and lush leaves was mimicked to regulate the micro/macrostructure distribution and illumination area of BCFFs. The BCFF exhibits a high evaporation rate of 4.58 kg m⁻² h⁻¹ under one sun illumination via distributed photothermal conversion. Importantly, considering the salt fouling resulting from the imbalance between water supply and steam evaporation, a rational design of BCFFs is proposed to perform stable desalination. The experimental results indicated that the BCFF can achieve stable solar desalination even in 15 wt% brine over several operation cycles. Furthermore, the desalination and purification performance is competitive in the practical environment with a daily water collection of over 20 L m⁻². This bioinspired evaporator balances excellent effectiveness and practicality, providing a viable path for solar desalination.