Construction of Nanocellulose Aerogels with Environmental Drying Strategy without Organic Solvent Displacement for High-Efficiency Solar Steam Generation

Abstract

Solar desalination is one of the effective means to alleviate water scarcity, in which aerogel-like evaporators have attracted extensive attention in the field of efficient desalination. However, the current preparation methods for aerogels still mainly rely on high-cost solutions, such as freeze-drying or supercritical drying. Herein, a preparation scheme for aerogels that can be realized under atmospheric pressure conditions is reported. In this paper, a foam skeleton template (FST) strategy is proposed, in which flake graphite is entangled by cellulose nanofibers (CNFs) and codispersed between the foam cell walls, and subsequently connected with the nascent Ca²⁺ in the inner wall to form a tough and stable three-dimensional network structure, which can effectively avoid the structural collapse caused by atmospheric drying. The cellulose/graphite aerogel (CGA) prepared using the FST strategy possesses lightweight (36 mg cm^–3) and porous (porosity >97%) properties. The 3D porous structure and wetting characteristics of the CGA provided excellent energy management, rapid water transport capability, and a reduced enthalpy of evaporation, which enabled it to achieve a fast water evaporation rate of 3.8 kg m^–2 h^–1 with 98.4% energy efficiency. This FST strategy provides a solution for the low-cost development of aerogel and desalination.