Assembling carbon dots on vertically aligned acetate fibers as ideal salt-rejecting evaporators for solar water purification

Abstract A low-cost and anti-salt-fouling system to perform solar interfacial water purification in long-term stability is considered to be a promising ways to solve freshwater scarcity crisis globally. However, the present self-regenerating solar evaporators are still confronted with challenges in terms of the relatively low evaporation rate, unsatisfactory solar-to-vapor efficiency, intricate or costly preparation steps. Herein, we present a novel and controllable system established by assembling carbon dots (CDs) on vertically aligned acetate fibers (VAAFs) with very low thermal conductivity and excellent water transport capacity. As-prepared VAAFs@CDs-T can spontaneously reject salt accumulation through rapid fluid convection within the evaporating interfaces and simultaneously sustain efficient heat localization. Thus, it not only possesses superior salt-rejection capability in long-term operation, but also enables considerably high water evaporation rate at 2.6 kg m−2 h−1 with 93.9% solar-to-steam efficiency under one sun even treating with 20 wt% salt solution and industrial wastewater. Total materials cost of this system is merely $15.01 m−2, outperforming most previous solar evaporators in the cost-effectiveness. Moreover, CDs can be replaced with other zero-dimensional materials and hereby achieving further enhanced evaporation efficiency is hopeful for this system.