Dual-hydrophilic Janus evaporator for Long-term and efficient Bimode solar evaporation

Abstract

Solar steam generation has emerged as a promising and sustainable technology to solve the global water scarcity. However, the fabrication of low-cost and high-efficiency evaporator with long-term stability remains a great challenge. Herein, a dual-hydrophilic Janus evaporator coupled with inclined isolating structure is fabricated to realize long-term efficient solar evaporation and flexible salt manipulating, where the upper electrospun Mo2C-C@PAN membrane serves as the evaporation layer and the bottom nonwoven fabric functions is used as mass transporting layer. The encapsulating feature of the Mo2C-C@PAN enables better energy confinement and reduces the usage of solar absorber by ∼50 % without deteriorating the evaporation performance. The hydraulic conductivity difference prevents the Marangoni effect inner the Janus evaporator, while the inclined isolating structure enables unidirectional ions transporting. With features of adequate water transport, enhancement of energy confinement, and salt manipulation, the constructed inclined Janus evaporators can not only work stably for 200 h in 10 wt% NaCl solution without salt accumulation, but also achieve efficient salt harvesting with rate of ∼260 g m−2 d−1 under one sun. This study provides new possibilities for a dual-hydrophilic Janus evaporator for a long-term, efficient, and synergistic extraction of fresh water and mineral salt resources.