Potential scalable fabrication of high-performance photothermal fabric via chemical dyeing for solar-powered brine distillation

Abstract

Here, a one-pot chemical dyeing method, based on the grafting modification of commercial cotton fabric with pyrrole-2-carbaldehyde via hydroxyl–aldehyde acetalization and pyrrole-aldehyde condensation, was designed to prepare a robust high-performance photothermal fabric. The prepared photothermal fabric not only maintained the hierarchical porous texture and excellent water wicking capacity of cotton fabric, but also exhibited high sunlight absorption and strong tolerance to harsh conditions, hand-laundering, and high-power ultrasonication. These outstanding properties endowed it with an ultrahigh water evaporation rate (1.74 kg∙m−2∙h−1) on a 2D platform under 1-sun irradiation, overcoming the planar evaporator upper limit (1.47 kg∙m−2∙h−1). Furthermore, a self-floating and self-rotating cylindrical 3D evaporator assembled using the above fabric achieved stable, high evaporation rates averaged at 2.08, 2.03, and 1.67 kg∙m−2∙h−1 from long-time evaporation tests under 1-sun irradiation with NaCl solutions of 3.5, 10, and 25 wt%, respectively. In addition, water yields at 7.51 and 5.42 kg∙m−2 were obtained from 6-h outdoor tests with 3.5 and 25-wt% NaCl solutions, respectively, demonstrating excellent applicability to brine desalination under natural sunlight (0.21–0.848 kW∙m−2). This study provided a scalable route to develop high-performance photothermal materials, which hopefully promotes the practical application of interfacial solar evaporation to seawater desalination and industrial brine minimization.