Ultra-efficient, Anisotropic Cellulose Aerogel with Polydopamine Interfacial Bridged Structure and Photothermal Modification for Seawater Desalination.

Abstract

Solar-driven interfacial evaporators represent a promising technique to address the energy crisis and freshwater scarcity issues. However, simultaneously achieving both high evaporation efficiency and long-term stability in a single evaporator system under multifactorial environmental conditions remains challenging. Herein, inspired by the anisotropic channel structure of wood, a novel evaporator featuring a vertical channel structure and excellent photothermal conversion performance for evaporation is developed through the covalent-bond bridging of MXene-polydopamine-cellulose nanocrystals. Polydopamine-modified MXene acts as a photothermal material, exhibiting excellent photothermal conversion efficiency. The vertical channels endow the evaporator with efficient thermal management and rapid mass transfer capabilities to dynamically balance the feedwater supply and photothermic energy input. Thereby, the evaporator exhibits an enhanced evaporation rate of 2.29 kg m^-2 h^-1, accompanied by a remarkable 97.34% evaporation efficiency under 1-sun illumination. Additionally, the evaporator possesses a mechanical strength as high as 0.454 MPa, which ensures its long-term stability. Over 14 d of testing, stable evaporation rates of 2.27 kg m^-2 h^-1 were maintained over 8-h cycles with no salt crystallization. This work introduces a novel evaporator design with a strong evaporation capability, which has potential applications in addressing the energy crisis and water scarcity challenges.