Boosting interfacial solar steam generation by three-dimensional bilayer cellulose aerogels

Area of Science:

• Materials Science
• Renewable Energy
• Environmental Engineering

Background:

• Interfacial solar steam generation (ISSG) offers a sustainable method for producing clean water via desalination and purification.
• Current ISSG technologies require improvements in evaporation rate, freshwater quality, and cost-effectiveness.

Purpose of the Study:

• To develop a low-cost, highly efficient evaporator for ISSG.
• To investigate the performance of a novel 3D bilayer aerogel for solar water production.

Main Methods:

• Fabrication of a 3D bilayer aerogel using cellulose nanofiber (CNF) as a skeleton, polyvinyl alcohol phosphate ester (PVAP) as a filler, and carbon nanotubes (CNT) as a light absorber.
• Characterization of the aerogel's light absorption, water transfer rate, and thermal conductivity.
• Evaluation of the aerogel's performance in solar steam generation under varying conditions, including solar desalination and outdoor testing.

Main Results:

• The CNF/PVAP/CNT (CPC) aerogel exhibited broadband light absorption and an ultrafast water transfer rate.
• The aerogel demonstrated effective heat confinement, minimizing thermal losses.
• Under 1 sun irradiation, CPC-3 achieved an evaporation rate of 4.02 kg m^-2 h^-1 with 125.1% energy conversion efficiency.
• Ultrahigh evaporation rates of 11.37 kg m^-2 h^-1 were achieved by utilizing additional convective flow and environmental energy.
• Continuous solar desalination of seawater yielded an evaporation rate of 10.70 kg m^-2 h^-1.
• Outdoor testing under weak sunlight resulted in a cumulative evaporation of 73.2 kg m^-2 d^-1, sufficient for 20 people's daily drinking water needs.

Conclusions:

• The developed CPC aerogel is a promising material for efficient and cost-effective solar steam generation.
• Its high performance in desalination and water purification highlights its potential for practical applications.
• The material's cost-effectiveness (1.085 L h^-1 $^-1) supports its viability for large-scale implementation in solar desalination, wastewater treatment, and metal extraction.