Flexible and Salt Resistant Janus Absorbers by Electrospinning for Stable and Efficient Solar Desalination

TLDR

Recent progress in interfacial solar steam generation has positioned direct solar desalination as a promising, cost‑effective, environmentally friendly water solution, but salt deposition threatens high, stable production rates. The authors aim to demonstrate that a flexible Janus absorber fabricated by sequential electrospinning can enable stable and efficient solar desalination. The Janus absorber decouples solar absorption and water pumping into an upper hydrophobic carbon‑black‑nanoparticle‑coated PMMA layer for light absorption and a lower hydrophilic PAN layer for water pumping, allowing salt to deposit only in the PAN layer where it is rapidly dissolved by continuous water flow. The absorber achieves 72 % efficiency and a stable water output of 1.3 kg m⁻² h⁻¹ over 16 days under 1‑sun, outperforming most prior absorbers and demonstrating an efficient, stable, portable solar steam generator.

Abstract

Abstract With recent progress in interfacial solar steam generation, direct solar desalination is considered a promising technology for providing a clean water solution through a cost effective and environmental‐friendly pathway. As a high and stable water production rate is the key to enable widespread applications, salt deposition becomes a critical issue that needs to be addressed. Herein, the authors demonstrate that a flexible Janus absorber fabricated by sequential electrospinning can enable stable and efficient solar desalination. Taking advantage of the unique structure of Janus, two functions of steam generation, solar absorption and water pumping, are decoupled into different layers, with an upper hydrophobic carbon black nanoparticles (CB) coating polymethylmethacrylate (PMMA) layer for light absorption, and a lower hydrophilic polyacrylonitrile (PAN) layer for pumping water. Therefore, salt can only be deposited in the hydrophilic PAN layer and quickly be dissolved because of continuous water pumping. Janus absorber demonstrates high efficiency (72%) and stable water output (1.3 kg m –2 h –1 , over 16 days) under 1‐sun, not achieved in most previous absorbers. With a unique structure design achieved by scalable process, this flexible Janus absorber provides an efficient, stable and portable solar steam generator for direct solar desalination.