A Novel Ink-Stained Paper for Solar Heavy Metal Treatment and Desalination

High-performance, flexible and non-toxic ink-stained paper is successfully prepared by a two-step ultrasonic process. Owing to the superior features of light absorption, wettability and heat management via our homemade mimetic tree system, the prepared ink-stained paper-black with an average pore size of 2 µm (ISP₂-Black) shows outstanding steam generation performance (85.8% for 1.25 kg m⁻² h⁻¹ and 85.5% for 3.70 kg m⁻² h⁻¹ at 1 and 3 suns, respectively), and good durability. Furthermore, an outdoor prototype system is realized by fresh water generation up to 1.24 kg m⁻² d⁻¹ for direct solar steam generation. Moreover, the ISP₂-Black also exhibits good performance in solar heavy metal treatment and desalination. This work provides a facile method to fabricate ink-stained paper and a practical route for more cost-efficient fresh water production and wastewater/polluted water treatment.