Fibrous MXene Aerogels with Tunable Pore Structures for High-Efficiency Desalination of Contaminated Seawater

Highlights

• The super-elastic and robust MXene aerogels are created herein by assembling the 1D fibrous MXenes with sufficiently large aspect ratios and superior flexibility.

• The underlying regulatory mechanism and a complete diagram for the pore structure evolution of MXene aerogels are revealed for the first time, which are particularly instructive for future structure-specific designs.

• Fibrous MXene aerogels exhibit 8.3% plastic deformation at the 1000th compressions and achieve high evaporation rate (1.48 kg m ⁻² h ⁻¹) and light to thermal conversion efficiency (92.08%) on oil-contaminated seawater.

Abstract

The seawater desalination based on solar-driven interfacial evaporation has emerged as a promising technique to alleviate the global crisis on freshwater shortage. However, achieving high desalination performance on actual, oil-contaminated seawater remains a critical challenge, because the transport channels and evaporation interfaces of the current solar evaporators are easily blocked by the oil slicks, resulting in undermined evaporation rate and conversion efficiency. Herein, we propose a facile strategy for fabricating a modularized solar evaporator based on flexible MXene aerogels with arbitrarily tunable, highly ordered cellular/lamellar pore structures for high-efficiency oil interception and desalination. The core design is the creation of 1D fibrous MXenes with sufficiently large aspect ratios, whose superior flexibility and plentiful link forms lay the basis for controllable 3D assembly into more complicated pore structures. The cellular pore structure is responsible for effective contaminants rejection due to the multi-sieving effect achieved by the omnipresent, isotropic wall apertures together with underwater superhydrophobicity, while the lamellar pore structure is favorable for rapid evaporation due to the presence of continuous, large-area evaporation channels. The modularized solar evaporator delivers the best evaporation rate (1.48 kg m ⁻² h ⁻¹) and conversion efficiency (92.08%) among all MXene-based desalination materials on oil-contaminated seawater.