Architecting scalable polyelectrolyte wicking fabric for efficient and continuous salt-tolerant solar evaporation

Abstract

Solar-driven evaporation enables environmentally sustainable production of freshwater. However, evaporators with a homogeneous structure often experience salt accumulation and high energy loss due to heat conduction to the underlying bulk water, resulting in a low evaporation rate. Herein, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and MXene are easily anchored on cotton fabric (PEDOT:PSS/MXene@CF) to prepare a novel polyelectrolyte solar evaporator. More importantly, the polyelectrolyte photothermal layer develops a stable, conductive, and hydrophilic architecture for effective light-to-heat transformation and salt-tolerant interface by utilizing a multilevel bonding network that includes hydrogen bonding (-SO3H…OH), electrostatic attraction (SO3−…Ti4+), and π-π stacking. The hydrophilic characteristics of the PEDOT:PSS polyelectrolyte and MXene significantly lower the water evaporation enthalpy, and this unique porous structure offers strong light absorption (∼90%) and an antigravitational wicking effect, facilitating rapid water transport and steam escape. An excellent water evaporation rate of 2.02 kg m−2 h−1 in 3.5 wt% NaCl with long-lasting anti-fouling capabilities is made possible by the synergistic interaction. Importantly, the system produced 11.6 kg m−2 of freshwater per day, where its performance was validated under natural light. As a result, our work offers a practical, multipurpose platform that tackles important issues in solar-powered desalination, providing a scalable and sustainable approach to reducing the world's water shortage.

Keywords: PEDOT:PSS/MXene, Polyelectrolyte, Salt-tolerance, Solar desalination, Solar evaporation, Wicking fabric