posted on 2024-03-05, 14:09authored byShiwang Bao, Xiaoyu Zhang, Lin Zhang, Xin Ning, Haitao Niu, Hua Zhou
Previous research on water harvesting driven by directional
water
transport from ubiquitous atmospheric moisture is mainly based on
one-dimensional (1D) filaments with asymmetric hydrophilic/hydrophobic
wettability along the filaments, two-dimensional (2D) surfaces with
hydrophilic and hydrophobic patterns, and three-dimensional (3D) porous
structures with “Janus” wettability from hydrophilic
to hydrophobic. However, it remains an ongoing challenge to design
and construct porous fibrous membranes with efficient directional
water transport capability in the thickness direction and excellent
water-collection performance. Herein, a sandwich-structured nanofibrous
membrane showing unusual dual-directional wicking capability has been
developed for water harvesting. In comparison to the Janus membrane
with a water-collection efficiency of 45.92 g/cm2/h, such
a dual-directional wicking fibrous membrane has a much higher water-collection
capacity (425.96 g/cm2/h) and excellent water-storage capacity.
The highly efficient water-harvesting capacity originates from the
strong force to draw water from the outer hydrophobic layer to the
middle superhydrophilic layer and the permeable channels formed by
the hydrophobic fibrous structures. The large pores in the outer hydrophobic
layer and the small pores in the middle superhydrophilic layer facilitate
water harvesting because of the dual-directional water-transport ability.
The successful preparation of dual-directional wicking nanofiber membranes
would be valuable for the development of advanced water harvesters
for diversified applications.