Dual-asymmetric ANF-based aerogels with vertically aligned channels for efficient, salt-tolerant, and recyclable water purification

Robust ANF/CNT/PPy bilayer aerogels feature vertical porous channels. • Amide groups lower vaporization enthalpy via H-bonds for fast evaporation. • Vertical pores induce self-desalting to prevent salt crystallization. • Unlike disposable devices, the robust aerogel is intrinsically recyclable. Solar-driven interfacial evaporation (SDIE) has emerged as a promising strategy to alleviate global freshwater scarcity by harnessing renewable solar energy. However, its large-scale implementation remains impeded by critical bottlenecks, primarily salt accumulation-induced performance decay, low energy utilization, and suboptimal evaporation rates. To bridge these gaps, we engineered a vertically aligned, hierarchical porous bilayer aerogel based on aramid nanofibers (ANF), designed to synergize robust salt resistance with localized thermal confinement. Strategically, the upper photothermal conversion layer integrates carbon nanotubes (CNTs) and polypyrrole (PPy) to maximize broad-spectrum light absorption and heat generation. Conversely, the underlying ANF layer serves a dual function: its vertically aligned channels ensure rapid water replenishment to prevent salt crystallization, while its intrinsically low thermal conductivity minimizes downward heat loss, thereby optimizing energy utilization. Consequently, this superhydrophilic architecture yields a remarkable evaporation rate of 3.35 kg m −2  h −1 and a superior energy conversion efficiency of 94.68% under 1 sun illumination. Beyond high efficiency, the evaporator exhibits exceptional operational stability, maintaining performance during continuous 10-h seawater desalination. Additionally, the bilayer aerogel exhibits outstanding salt tolerance and recyclability. Meanwhile, its superior corrosion resistance and wastewater purification capabilities enable SDIE technology to operate stably and continuously in real-world applications, showcasing remarkable application potential. Download: Download high-res image (483KB) Download: Download full-size image