Bioinspired Hydrophilic–Hydrophobic Janus Composites for Highly Efficient Solar Steam Generation
Zhen Qin, Hang Sun, Yanan Tang, Shengyan Yin, Lixue Yang, Mingwei Xu, Zhenning Liu
Abstract
Solar energy has received extensive attention as a renewable and sufficient energy source. Herein, inspired by the Janus wettability of lotus leaves, we have constructed a bioinspired hydrophilic–hydrophobic Janus hybrid system of carbonized carrot powder (CC powder)-modified cotton cloth with Nafion coating on one side (cotton cloth-NCC) for highly efficient solar steam generation. In cotton cloth-NCC, CC powder functions as a light absorber to achieve high light absorption, whereas the hydrophilic cotton cloth ensures efficient water transport. Meanwhile, the coating of Nafion establishes a hydrophobic–hydrophilic Janus structure, which can not only modulate water supply but also prevent salt deposition even with the high-concentration salt solution. The cotton cloth-NCC has been further shaped into a waved structure (w-cotton cloth-NCC) to increase the water evaporation area and achieve high light absorption (95%). Under 1 sun irradiation, w-cotton cloth-NCC yields a pure water steam generation rate of 1.88 kg m–2 h–1 and a seawater evaporation rate of 1.52 kg m–2 h–1. Furthermore, the w-cotton cloth-NCC also has a good purification effect on sewage: Escherichia coli can be completely removed, and the removal rate of Rhodamine B reaches 98.3%. The simple approach presented here for the construction of a high-efficient, low-cost, environmentally sustainable, long-term stable hydrophobic–hydrophilic Janus solar steam evaporator holds great promise for application in both environmental purification and photothermal conversion.