Water‐Light Induced Self‐Blacking System Constituted by Quinoa Cellulose and Graphene Oxide for High Performance of Salt‐Rejecting Solar Desalination

Abstract Salt deposits are a key challenge of solar driven desalination technology due to the fact that the evaporation rate of the system sharply deteriorates when salt accumulates. In this paper, a self‐blacking aerogel (SBA) is first demonstrated with excellent deposited salt self‐cleaning performance, and the self‐cleaning mechanism is illustrated by the theory of chemical potential. The color of the SBA can be changed from light brown to black under the inducement of water and light, and its light absorption ability clearly increases from 34.5% to 77.0% in the whole spectral range (200–2500 nm). SBA is fabricated by quinoa bran cellulose (QBC) and graphene oxide (GO) with an evaporation rate of 3.6 kg m⁻² h⁻¹ under one sun. Importantly, for natural solar irradiation, the average evaporation rate reaches up to 12.6 and 12 kg m⁻² day⁻¹ in the period of 15 days of outdoor experiments for pure water and stimulated seawater respectively, which can meet the drinking water demand for 5–6 people. This work provides a convenient strategy to improve the salt deposit problem with high evaporation rate, and low cost for practical desalination, with water purification applications.