Bioinspired and Biodegradable Hydrothermally Treated Cellulose Nanocrystal Aerogels for High Efficiency Solar Steam Generation and Sustainable Water Purification

Abstract

Access to clean water is crucial for human survival, yet a significant portion of the global population continues to face challenges from water scarcity and contamination. Traditional water purification methods such as desalination and distillation are energy-intensive, necessitating the adoption of green alternatives to reduce greenhouse gas emissions and mitigate global warming. High-efficiency solar steam generation has emerged as a promising solution. Although many solar evaporators have shown impressive evaporation rates, construction of these using only sustainable materials remains challenging. Inspired by the microstructure of natural wood, a series of hydrothermally-treated cellulose nanocrystal aerogels (HTCAs) is proposed as efficient and eco-friendly solar steam generators. The HTCAs are prepared through a one-pot hydrothermal treatment, avoiding the use of hazardous chemicals, and entirely based on sustainable cellulose nanocrystals. They present low tortuosity porous microstructures and exhibit high evaporation rate (1.70 kg m−2 h−1 under 1 sun irradiation) with low water evaporation enthalpy (841 ± 35 J g−1). Integration with advanced water purification techniques also demonstrates their effectiveness in removing contaminants. This strategy mimics the microstructure of wood through unidirectional freeze-drying and offers a sustainable pathway to biodegradable solar steam generators, potentially alleviating the global water scarcity within the carbon neutrality framework.