Synergistic Engineering of Polypyrrole-Cellulose Aerogels with Vertical Channels for Salt-Resistant Solar Evaporation and Multipollutant Water Purification

Abstract

Interfacial solar steam generation (ISSG) offers a sustainable and low-carbon pathway to mitigate global freshwater scarcity. However, the widespread adoption of conventional evaporators is limited by issues such as high cost, low efficiency, salt crystallization, and heavy metal contamination. To overcome these challenges, we developed a composite aerogel, denoted as CNF/PVA/PEI@polypyrrole (CPP). This material was fabricated by first constructing an aerogel substrate from cellulose nanofiber (CNF), polyvinyl alcohol (PVA), and polyethylenimine (PEI), followed by in-situ polymerization of polypyrrole. The resulting CPP aerogel possesses abundant hydrophilic groups, vertically aligned channels, and a hierarchical porous structure, endowing it with excellent compressibility, a high light absorption of 93.0%, and efficient photothermal conversion. Under 1 sun irradiation, the evaporator achieved a rate of 1.85 kg·m⁻²·h⁻¹. It also demonstrated remarkable salt resistance, maintaining a rate of 1.50 kg·m⁻²·h⁻¹ in 20 wt% high-salinity brine. Furthermore, the CPP aerogel effectively removed ions from seawater and purified wastewater contaminated with heavy metals and organic pollutants. This work provides a new strategy for designing high-performance solar evaporators with promising applications in desalination and complex wastewater remediation.